General Description
The MAX16816 is a current-mode, high-brightness LED
(HB LED) driver designed to control two external
n-channel MOSFETs for single-string LED current regu-
lation. The MAX16816 integrates all the building blocks
necessary to implement fixed-frequency HB LED dri-
vers with wide-range dimming control and EEPROM-
programmable LED current binning with a factor of up
to 1.6. This device is configurable to operate as a step-
down (buck), step-up (boost), or step-up/step-down
(buck-boost) current regulator.
Current-mode control with adjustable leading-edge
blanking simplifies control-loop design. Adjustable slope
compensation stabilizes the current loop when operating
at duty cycles above 50%. The MAX16816 operates over
a wide input voltage range and is capable of withstand-
ing automotive load-dump events. Multiple MAX16816
devices can be synchronized to each other or to an
external clock. The MAX16816 includes a floating
dimming driver for brightness control with an external
n-channel MOSFET in series with the LED string.
HB LEDs using the MAX16816 can achieve efficiencies
of over 90% in automotive applications. The MAX16816
also includes a 1.4A source and 2A sink gate driver for
driving switching MOSFETs in high-power LED driver
applications, such as front light assemblies. Dimming
control allows for wide PWM dimming range at frequen-
cies up to 5kHz. Higher dimming ratios (up to 1000:1)
are achievable at lower dimming frequencies.
The MAX16816 provides user-programmable features
through on-chip nonvolatile EEPROM registers.
Adjustable features include a programmable soft-start,
LED current (binning), external MOSFET gate driver sup-
ply voltage, slope compensation, leading-edge blanking
time, and disabling/enabling of the RT oscillator.
The MAX16816 is available in a 32-pin TQFN package
with exposed pad and operates over the -40°C to
+125°C automotive temperature range.
Applications
Automotive Exterior: Rear Combination Lights
(RCL), Daytime Running Lights (DRL), Fog and
Front Lighting, High-Beam/Low-Beam/Turn Lights
General Illumination
Navigation and Marine Indicators
Neon Replacement, Emergency Lighting
Signage and Beacons
Features
oEEPROM-Programmable LED Current Binning
oWide Input Range: 5.9V to 76V with Cold Start
Operation to 5.4V
oIntegrated Floating Differential LED Current-
Sense Amplifier
oFloating Dimming Driver Capable of Driving an
n-Channel MOSFET
o5% or Better LED Current Accuracy
oMultiple Topologies: Buck, Boost, Buck-Boost,
SEPIC
oResistor-Programmable Switching Frequency
(125kHz to 500kHz) and Synchronization
Capability
o200Hz On-Board Ramp Allows Analog-Controlled
PWM Dimming and External PWM Dimming
oOutput Overvoltage, Overcurrent, and LED Short
Protection
oEnable/Shutdown Input with Shutdown Current
Below 45µA
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
________________________________________________________________
Maxim Integrated Products
1
VIN
DIM
RCS
CF
RT
CREG1
RUV2
DRV
DRI
REG1
DIM
FAULT
CS
VCC
SNS+
FB
QGND
RTSYNC
CS- CS+
LO
COMP REG2
DGT
HI
OV
UVEN
SNS-
AGND
RSENSE
R2
C2
ROV1
ROV2
CLMP
SGND
CCLMP
CREG2
R1
C1
RD
LEDs
BUCK-BOOST CONFIGURATION
RUV1
CUVEN
QS
MAX16816
Typical Operating Circuits
19-1054; Rev 0; 1/08
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
Pin Configuration appears at end of data sheet.
Ordering Information
+
Denotes a lead-free package.
*
EP = Exposed pad.
PART TEMP RANGE PIN-
PACKAGE
PKG
CODE
MAX16816ATJ+ -40°C to +125°C 32 TQFN-EP* T3255M-4
Typical Operating Circuits continued at end of data sheet.
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 1µF, CCLMP = 0.1µF, RT= 25kΩ, TA= TJ= -40°C to +125°C, unless otherwise noted.
Typical specifications are at TA= +25°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VCC, HI, LO, CLMP to QGND.................................-0.3V to +80V
CS+, CS-, DGT, UVEN, FAULT to QGND...............-0.3V to +80V
UVEN to QGND ..........................................-0.3V to (VCC + 0.3V)
DRV to SGND .........................................................-0.3V to +18V
DRI, REG2, DIM to AGND ......................................-0.3V to +18V
QGND, SGND to AGND ........................................-0.3V to +0.3V
SNS+ to SNS- ...........................................................-0.3V to +6V
CS, FB, COMP, SNS+, SNS-, OV, REF,
RTSYNC to AGND ................................................-0.3V to +6V
REG1, CLKOUT to AGND ........................................-0.3V to +6V
CS+ to CS- .............................................................-0.3V to +12V
HI to LO ..................................................................-0.3V to +36V
CS+, CS-, DGT, CLMP to LO .................................-0.3V to +12V
CS+, CS-, DGT, CLMP to LO ........................-0.3V to (HI + 0.3V)
HI to CLMP .............................................................-0.3V to +28V
Continuous Power Dissipation* (TA= +70°C)
32-Pin TQFN (derate 34.5mW/°C above +70°C) .......2758mW
Thermal Resistance
θJA................................................................................29°C/W
θJC...............................................................................1.7°C/W
Operating Temperature Range .........................-40°C to +125°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage Range VCC 5.5 76 V
Supply Current to VCC IQ_VCC Exclude current to the gate driver, IREG2 2.7 4.5 mA
Supply Current to HI IQ_HI VHI = 14V 0.5 1.0 mA
Shutdown Current to VCC ISHDN_VCC VUVEN ≤ 300mV 25 45 µA
Shutdown Current to HI ISHDN_HI VUVEN ≤ 300mV 1 10 µA
UVEN
VCC_R VCC rising 5.5 6.0
VCC UVLO Threshold VCC_F VCC falling 5.0 5.5 V
VCC Threshold Hysteresis VCC_HYS 0.4 V
VUVR VUVEN rising 1.10 1.244 1.36
UVEN Threshold VUVF VUVEN falling 1.00 1.145 1.26 V
UVEN Input Current IUVEN (VUVEN = 0V and VCC = 14V) (VUVEN = 76V
and VCC = 77V) -0.2 +0.2 µA
REGULATORS
0 < IREG1 < 2mA, 7.5V < VCC < 76V 4.75 5.00 5.25
REG1 Regulator Output VREG1 IREG1 = 2mA, VCC = 5.7V 4.00 4.50 5.25 V
REG1 Dropout Voltage IREG1 = 2mA (Note 1) 0.5 1.0 V
REG1 Load Regulation ΔV/ΔIV
CC = 7.5V, IREG1 = 0 to 2mA 25 Ω
REG2 Dropout Voltage VCC ≥ 9.5V, REG2 control register is ‘0011’,
IREG2 = 20mA (Note 1) 0.5 1.0 V
REG2 Load Regulation ΔV/ΔIVCC ≥ 9.5V, REG2 control register is ‘0011’,
IREG2 = 0 to 20mA 25 Ω
*
As per JEDEC 51 standard, Multilayer Board (PCB).
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
_______________________________________________________________________________________ 3
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
REG2 control register is ‘0000’,
VCC ≥ 7.5V, IREG2 = 1mA 4.75 5 5.25
REG2 control register is ‘0011’,
VCC ≥ 9.5V, IREG2 = 1mA 6.65 7.0 7.35
REG2 control register is ‘1111’,
VCC ≥ 17.5V, IREG2 = 1mA 13.5 15 16.5
REG2 control register is ‘0000’,
VCC = 5.7V, 0 ≤ IREG2 ≤ 20mA 4 4.5 5.25
REG2 control register is ‘0000’,
VCC = 7.5V, 0 ≤ IREG2 ≤ 20mA 4.75 5 5.25
REG2 Regulation Voltage
REG2 control register is ‘1111’,
VCC = 17.5V, 0 ≤ IREG2 ≤ 20mA 13.5 15 16.5
V
HIGH-SIDE REGULATOR (CLMP) (All voltages referred to VLO) (Note 2)
CLMP UVLO Threshold VCLMP_TH VCLMP rising 2.0 2.5 3.0 V
CLMP UVLO Threshold
Hysteresis VCLMP_HYS 0.22 V
8.7V ≤ (VHI - VLO) ≤ 36V, ICLMP = 1mA 5.5 8.0 10.0
CLMP Regulator Output
Voltage VCLMP 5.0V ≤ (VHI - VLO) ≤ 8.7V, ICLMP = 250µA (VHI - VLO)
- 0.7
V
CURRENT-SENSE AMPLIFIER (CSA)
Differential Input Voltage
Range VCS+ - VCS- 0 0.3 V
Common-Mode Range VCC ≤ 68V 0 VCC V
CS+ Input Bias Current ICS+ VCS+ = 0.3V, VCS- = 0V -250 +250 nA
CS- Input Bias Current ICS- VCS+ = 0.3V, VCS- = 0V 400 µA
Unity-Gain Bandwidth From (CS+ to CS-) to CS 1.0 MHz
REF OUTPUT BUFFER
REF Output Voltage VREF -100µA ≤ IL ≤ +100µA 2.85 3.0 3.15 V
DIM DRIVER
Minimal Pulse Width fDIM = 200Hz (Note 3) 20 40 µs
VCLMP - VLO = 4V 5 20
Source Current VCLMP - VLO = 8V 30 67 mA
VCLMP - VLO = 4V 10 22
Sink Current VCLMP - VLO = 8V 40 76 mA
GATE DRIVER
DRI Voltage Range VDRI VCC ≥ 2.5V above VDRI 515V
DRI UVLO Threshold VUVLO_TH 4.0 4.2 4.4 V
DRI UVLO Threshold
Hysteresis VUVLO_HYST 0.3 V
ELECTRICAL CHARACTERISTICS (continued)
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 1µF, CCLMP = 0.1µF, RT= 25kΩ, TA= TJ= -40°C to +125°C, unless otherwise noted.
Typical specifications are at TA= +25°C.)
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 1µF, CCLMP = 0.1µF, RT= 25kΩ, TA= TJ= -40°C to +125°C, unless otherwise noted.
Typical specifications are at TA= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
ZOUT_L VDRI = 7.0V, DRV sinking 250mA 2.8 4
Driver Output Impedance ZOUT_H VDRI = 7.0V, DRV sourcing 250mA 5.0 8
Ω
Peak Sink Current ISK VDRI = 7.0V 2.5 A
Peak Source Current ISR VDRI = 7.0V 1.4 A
PWM, ILIM, AND HICCUP COMPARATOR
PWM Comparator Offset
Voltage VCOMP - (VSNS+ -VSNS-) 0.8 V
Peak Current-Limit
Comparator Trip Threshold 160 200 245 mV
Peak Current-Limit
Comparator Propagation
Delay (Excluding Blanking
Time)
50mV overdrive 40 ns
HICCUP Comparator Trip
Threshold 235 300 385 mV
SNS+ Input Bias Current VSNS+ = 0V, VSNS- = 0V -100 -65 µA
SNS- Input Bias Current VSNS+ = 0V, VSNS- = 0V -100 -65 µA
BLANKING TIME
Blanking Time Control Register is ‘00’ 150
Blanking Time Control Register is ‘01’ 125
Blanking Time Control Register is ‘10’ 100
Blanking Time
Blanking Time Control Register is ‘11’ 75
ns
ERROR AMPLIFIER
FB Input Bias Current VFB = 1V -100 +100 nA
EAMP Output Sink Current VFB = 1.735V, VCOMP = 1V 3 7 mA
EAMP Output Source Current VFB = 0.735V, VCOMP = 1V 2 7 mA
EAMP Input Common-Mode
Voltage VCOM (Note 5) 0 1.6 V
EAMP Output Clamp Voltage 1.3 2.0 2.7 V
Voltage Gain AVRCOMP = 100kΩ to AGND 80 dB
Unity-Gain Bandwidth GBW RCOMP = 100kΩ to AGND, CCOMP = 100pF
to AGND 0.5 MHz
OSCILLATOR, OSC SYNC, CLK, AND CLKOUT
fSW_MIN 125
SYNC Frequency Range fSW_MAX 500 kHz
RTOF bit set to ‘0’, RT = 100kΩ106 125 143
RTSYNC Oscillator Frequency RTOF bit set to ‘0’, RT = 25kΩ475 500 525 kHz
SYNC High-Level Voltage VSIHL 2.8 V
SYNC Low-Level Voltage VSILL 0.4 V
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 1µF, CCLMP = 0.1µF, RT= 25kΩ, TA= TJ= -40°C to +125°C, unless otherwise noted.
Typical specifications are at TA= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
CLKOUT High Level ISINK = 0.8mA 2.8 V
CLKOUT Low Level ISOURCE = 1.6mA 0.4 V
CLKOUT Maximum Load
Capacitance CCLK_CAP fSW = 500kHz 500 pF
DIM SYNC, DIM RAMP, AND DIM PWM GEN
Internal RAMP Frequency fRAMP 160 200 240 Hz
External Sync Frequency
Range fDIM 80 2000 Hz
External Sync Low-Level
Voltage VLTH 0.4 V
External Sync High-Level
Voltage VHTH 3.2 V
DIM Comparator Offset VDIMOS 170 200 300 mV
DIGITAL SOFT-START AND BINNING
Digital Soft-Start Duration register is ‘000’ 4096
Digital Soft-Start Duration register is ‘001’ 2048
Digital Soft-Start Duration register is ‘010’ 1536
Digital Soft-Start Duration register is ‘011’ 1024
Digital Soft-Start Duration register is ‘100’ 768
Digital Soft-Start Duration register is ‘101’ 512
Digital Soft-Start Duration register is ‘110’ 256
Soft-Start Duration tSS
Digital Soft-Start Duration register is ‘111’ 0
µs
Binning Adjustment register is ‘0000’ 100.00
Binning Adjustment register is ‘0001’ 106.67
Binning Adjustment register is ‘0010’ 113.33
Binning Adjustment register is ‘0011’ 120.00
Binning Adjustment register is ‘0100’ 126.67
Binning Adjustment register is ‘0101’ 133.33
Binning Adjustment register is ‘0110’ 140.00
Binning Adjustment register is ‘0111’ 146.67
Binning Adjustment register is ‘1000’ 153.33
Binning Adjustment register is ‘1001’ 160.00
Binning Range
Binning Adjustment register is ‘1010’ 166.67
mV
OVERVOLTAGE COMPARATOR, LOAD OVERCURRENT COMPARATOR
OVP Overvoltage Comparator
Threshold VOV VOV rising 1.20 1.235 1.27 V
OVP Overvoltage Comparator
Hysteresis VOV_HYST 63.5 mV
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
6 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 1µF, CCLMP = 0.1µF, RT= 25kΩ, TA= TJ= -40°C to +125°C, unless otherwise noted.
Typical specifications are at TA= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SLOPE COMPENSATION
Slope Compensation register is ‘0000’,
clock generated by RT0
Slope Compensation register is ‘0001’,
clock generated by RT20
Slope Compensation register is ‘0010’,
clock generated by RT40
Slope Compensation register is ‘0011’,
clock generated by RT60
Slope Compensation register is ‘0100’,
clock generated by RT80
Slope Compensation register is ‘0101’,
clock generated by RT100
Slope Compensation register is ‘0110’,
clock generated by RT120
Slope Compensation register is ‘0111’,
clock generated by RT140
Slope Compensation register is ‘1000’,
clock generated by RT160
Slope Compensation register is ‘1001’,
clock generated by RT180
Slope Compensation register is ‘1010’,
clock generated by RT200
Slope Compensation register is ‘1011’,
clock generated by RT220
Slope Compensation register is ‘1100’,
clock generated by RT240
Slope Compensation register is ‘1101’,
clock generated by RT260
Slope Compensation register is ‘1110’,
clock generated by RT280
Slope Compensation Peak-to-
Peak Voltage Per Cycle
Slope Compensation register is ‘1111’,
clock generated by RT300
mV/
cycle
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
_______________________________________________________________________________________ 7
ELECTRICAL CHARACTERISTICS (continued)
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 1µF, CCLMP = 0.1µF, RT= 25kΩ, TA= TJ= -40°C to +125°C, unless otherwise noted.
Typical specifications are at TA= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Slope Compensation register is ‘0000’,
external clock applied to RTSYNC 0
Slope Compensation register is ‘0001’,
external clock applied to RTSYNC 2
Slope Compensation register is ‘0010’,
external clock applied to RTSYNC 4
Slope Compensation register is ‘0011’,
external clock applied to RTSYNC 6
Slope Compensation register is ‘0100’,
external clock applied to RTSYNC 8
Slope Compensation register is ‘0101’,
external clock applied to RTSYNC 10
Slope Compensation register is ‘0110’,
external clock applied to RTSYNC 12
Slope Compensation register is ‘0111’,
external clock applied to RTSYNC 14
Slope Compensation register is ‘1000’,
external clock applied to RTSYNC 16
Slope Compensation register is ‘1001’,
external clock applied to RTSYNC 18
Slope Compensation register is ‘1010’,
external clock applied to RTSYNC 20
Slope Compensation register is ‘1011’,
external clock applied to RTSYNC 22
Slope Compensation register is ‘1100’,
external clock applied to RTSYNC 24
Slope Compensation register is ‘1101’,
external clock applied to RTSYNC 26
Slope Compensation register is ‘1110’,
external clock applied to RTSYNC 28
Slope Compensation
Slope Compensation register is ‘1111’,
external clock applied to RTSYNC 30
mV/µs
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
8 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 1µF, CCLMP = 0.1µF, RT= 25kΩ, TA= TJ= -40°C to +125°C, unless otherwise noted.
Typical specifications are at TA= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
FAULT I/O
FAULT Leakage Current 5.5V < VFAULT < 76V -1 +1 µA
FAULT Input Low Current VFAULT = 0V 500 µA
FAULT Pulldown Current VFAULT = 2V 0.7 1.2 1.8 mA
FAULT Pulldown Input
Logic-Low VIL 0.4 V
FAULT Output Logic-High Sourcing 10µA 2.8 V
FAULT Output Logic-Low Sinking 10µA 0.4 V
P r og r am m i ng S l ot at P ow er - U p VUVEN > 1.244V and VCC > 5.9V (Note 4) 6.4 8.0 ms
THERMAL SHUTDOWN
Thermal Shutdown
Temperature TJ_SHDN +165 oC
Thermal Shutdown Hysteresis ΔTJ_SHDN 20 oC
EEPROM
Data Retention tDR TA = +125°C (Note 5) 10 years
EEPROM Write Time tWRA (Note 5) 14 ms
Endurance TA = +85°C, read and write (Note 5) 50k cycles
ELECTRICAL CHARACTERISTICS – 1-Wire®System
(CREG1 = 1µF, CREG2 = 1µF, TA= TJ= -40°C to +125°C, unless otherwise noted. Typical specifications are at TA= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
I/O GENERAL DATA
1-Wire Time Slot Duration tSLOT 65 µs
Recovery Time tREC (Note 6) 5 µs
I/O, 1-Wire RESET, PRESENCE DETECT CYCLE
Reset Low Time tRSTL 480 640 µs
Presence Detect Sample Time tMSP 65 75 µs
I/O, 1-Wire WRITE
Write-0 Low Time tW0L 60 µs
Write-1 Low Time tW1L 515µs
I/O, 1-Wire READ
Read Low Time tRL 510µs
Read Sample Time tMSR 12 15 µs
1-Wire is a registered trademark of Dallas Semiconductor Corp., a wholly owned subsidiary of Maxim Integrated Products, Inc.
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
_______________________________________________________________________________________ 9
Note 1: Dropout voltage is defined as the input to output differential voltage at which the output voltage drops 100mV below its nom-
inal value measured at output.
Note 2: VCLMP_TH determines the voltage necessary to operate the current-sense amplifier. The DIM driver requires 2.5V for (VCLMP
- VLO) to drive a FET. VHI is typically one diode drop above VCLMP. A large capacitor connected to VCLMP slows the
response of the LED current-sense circuitry, resulting in current overshoot. To ensure proper operation, connect a 0.1µF
capacitor from CLMP to LO.
Note 3: Minimum pulse width required to guarantee proper dimming operation.
Note 4: FAULT multiplexes a programming interface and fault indication functionality. At power-up initialization, an internal timer
enables FAULT and two programming passcodes must be entered within the programming slot to enter programming
mode. If the programming passcodes are not received correctly within the programming slot, FAULT goes back towards
fault indication. Cycling power to the device is required to re-attempt entry into programming mode.
Note 5: Not production tested. Guaranteed by design.
Note 6: Recovery time is the time required for FAULT to be pulled high by the internal 10kΩresistor.
Typical Operating Characteristics
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 10µF, CCLMP = 0.1µF, RCS = 0.1Ω, Binning adjustment register is ‘0000’, TA= +25°C,
unless otherwise noted.)
SHUTDOWN CURRENT
vs. TEMPERATURE
MAX16816 toc01
TEMPERATURE (°C)
ISHDN_VCC (μA)
120100-40 -20 040 6020 80
19
20
21
22
23
24
25
26
18
-60 140
OPERATING CURRENT
vs. TEMPERATURE
MAX16816 toc02
TEMPERATURE (°C)
ICC (mA)
120100806040200-20-40
2.8
3.0
3.2
3.4
3.6
3.8
4.0
2.6
-60 140
DGT AND DRV
NOT SWITCHING
OUTPUT CURRENT
vs. TEMPERATURE
MAX16816 toc03
TEMPERATURE (°C)
LED CURRENT (mA)
120100-40 -20 040 6020 80
250
300
350
400
450
500
550
600
200
-60 140
RCS = 0.2Ω
RCS = 0.3Ω
ELECTRICAL CHARACTERISTICS
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
10 ______________________________________________________________________________________
OUTPUT CURRENT
vs. SUPPLY VOLTAGE
MAX16816 toc04
VCC (V)
LED CURRENT (mA)
72645648403224168
50
100
150
200
250
300
350
0
080
OUTPUT CURRENT
vs. BINNING CODES
MAX16816 toc05
BIN (DIGITAL CODE)
LED CURRENT (A)
875 62 3 41
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0
09
OUTPUT CURRENT
vs. BINNING CODES
MAX16816 toc06
BIN (DIGITAL CODE)
OUTPUT CURRENT (mA)
875 62 3 41
100
200
300
400
500
600
700
800
900
0
09
RCS = 0.2Ω
Typical Operating Characteristics (continued)
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 10µF, CCLMP = 0.1µF, RCS = 0.1Ω, Binning adjustment register is ‘0000’, TA= +25°C,
unless otherwise noted.)
REG2 OUTPUT VOLTAGE
vs. TEMPERATURE
MAX16816 toc07
TEMPERATURE (°C)
REG2 OUTPUT VOLTAGE (V)
12010060 80-20 0 20 40-40
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
-60 140
IREG2 = 20mA
REG2 CONTROL REGISTER = '1111', VCC = 20V
REG2 CONTROL REGISTER = '0000'
REG2 OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
MAX16816 toc08
VCC (V)
REG2 OUTPUT VOLTAGE (V)
726448 5616 24 32 408
2
4
6
8
10
12
14
16
18
0
080
IREG2 = 20mA
REG2 CONTROL REGISTER = '1111', VCC = 20V
REG2 CONTROL REGISTER = '0000'
REG2 OUTPUT VOLTAGE
vs. REG2 CONTROL REGISTER
MAX16816 toc09
DRPS (DIGITAL CODE)
REG2 OUTPUT VOLTAGE (V)
13
12
10 11345678912
5
6
7
8
9
10
11
12
13
14
15
16
4
014 15
IREG2 = 20mA
REG1 OUTPUT VOLTAGE
vs. TEMPERATURE
MAX16816 toc10
TEMPERATURE (°C)
REG1 OUTPUT VOLTAGE (V)
120100-40 -20 040 6020 80
4.7
4.8
4.9
5.0
5.1
5.2
5.3
5.4
4.6
-60 140
IREG1 = 2mA
REG1 OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
MAX16816 toc11
VCC (V)
REG1 OUTPUT VOLTAGE (V)
70605040302010
1
2
3
4
5
6
0
080
IREG1 = 2mA
CLMP OUTPUT VOLTAGE
vs. TEMPERATURE
MAX16816 toc12
TEMPERATURE (°C)
CLMP OUTPUT VOLTAGE (V)
120100-40 -20 0 40 6020 80
7.6
7.7
7.8
7.9
8.0
8.1
8.2
8.3
7.5
-60 140
VHI - VLO = 9V
CLMP VOLTAGE = VCLMP - VLO
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________
11
REF VOLTAGE
vs. TEMPERATURE
MAX16816 toc13
TEMPERATURE (°C)
REF VOLTAGE (V)
11590-35 -10 15 40 65
2.98
3.00
3.02
3.04
3.06
3.08
3.10
3.12
2.96
-60 140
IREF = 100μA
REF VOLTAGE
vs. SINK CURRENT
MAX16816 toc14
IREF (μA)
REF VOLTAGE (V)
1751257525-25-75-125-175
3.005
3.010
3.015
3.020
3.025
3.000
-225 225
PWM OSCILLATION FREQUENCY
vs. TEMPERATURE
MAX16816 toc15
TEMPERATURE (°C)
PWM FREQUENCY (kHz)
11590-35 -10 15 40 65
122
126
132
131
130
129
128
127
124
123
121
125
133
134
135
120
-60 140
RT = 100kΩ
RT RESISTANCE
vs. PWM FREQUENCY
MAX16816 toc16
1/RT RESISTANCE (kΩ-1)
PWM FREQUENCY (kHz)
0.0350.0250.015
150
200
250
300
350
400
450
500
550
100
0.005 0.045
200Hz DIMMING OPERATION
MAX16816 toc17
2ms/div
10%
DIMMING
1A/div
50%
DIMMING
1A/div
90%
DIMMING
1A/div
0A
0A
0A
LED CURRENT DUTY CYCLE
vs. DIM VOLTAGE
MAX16816 toc18
DIM VOLTAGE (V)
LED CURRENT DUTY CYCLE (%)
21
10
20
30
40
50
60
70
80
90
100
0
03
DRIVER DRV RISE TIME
vs. DRI VOLTAGE
MAX16816 toc19
DRI VOLTAGE (V)
DRV RISE TIME (ns)
131197
10
20
30
40
50
60
70
0
515
5nF CAPACITOR CONNECTED
FROM DRV TO AGND
Typical Operating Characteristics (continued)
(VCC = VUVEN = 14V, CREG1 = 1µF, CREG2 = 10µF, CCLMP = 0.1µF, RCS = 0.1Ω, Binning adjustment register is ‘0000’, TA= +25°C,
unless otherwise noted.)
DRIVER DRI FALL TIME
vs. DRI VOLTAGE
MAX16816 toc20
DRI VOLTAGE (V)
DRV FALL TIME (ns)
131197
5
10
15
20
25
30
35
40
45
0
515
5nF CAPACITOR CONNECTED
FROM DRV TO AGND
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
12 ______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
1, 24 N.C. No Connection. Not internally connected.
2 UVEN
Undervoltage Lockout (UVLO) Threshold/Enable Input. UVEN is a dual-function adjustable UVLO threshold
input with an enable feature. Connect UVEN to VCC through a resistive voltage-divider to program the UVLO
threshold. Connect UVEN directly to VCC to use the 5.9V (max) default UVLO threshold. Apply a voltage
greater than 1.244V to UVEN to enable the device.
3 REG1
5V Regulator Output. REG1 is an internal low-dropout voltage regulator that generates a 5V (VCC > 6V)
output voltage and supplies power to internal circuitry. Bypass REG1 to AGND through a 1µF ceramic
capacitor.
4 AGND Analog Ground. Use proper single-point ground design and decoupling to avoid ground impedance loop
errors.
5 REF Accurate 3V Buffered Reference Output. Connect REF to DIM through a resistive voltage-divider to apply a
DC voltage for analog-controlled dimming functionality. Leave REF unconnected if unused.
6 DIM
Dimming Control Input. Connect DIM to an external PWM signal for PWM dimming. For analog-controlled
dimming, connect DIM to REF through a resistive voltage-divider. The dimming frequency is 200Hz under
these conditions. Connect DIM to AGND to turn off the LEDs.
7 RTSYNC
Sync Input/Output. The internal PWM clock is selectable through the RTOF EEPROM bit. Connect an
external resistor to RTSYNC and set the RTOF register to ‘0’ to select a clock frequency between 125kHz
and 500kHz. Set RTOF register to ‘0’ and connect RTSYNC to an external clock to synchronize the device
with external clock. Set RTOF register to ‘1’ to use the fixed 125kHz oscillator. Under these conditions,
RTSYNC is powered off and may be left in any state. See the Oscillator, Clock, and Synchronization section.
8 CLKOUT Clock Output. CLKOUT buffers the oscillator/clock. Connect CLKOUT to the SYNC input of another device
to operate the MAX16816 in a multichannel configuration. CLKOUT is a logic output.
9, 10, 11 I.C. Internally Connected. Must be connected to AGND.
12 COMP Error-Amplifier Output. Connect the compensation network from COMP to FB for stable closed-loop control.
Use low-leakage ceramic capacitors in the feedback network.
13 CS
Current-Sense Voltage Output. CS outputs a voltage proportional to the current sensed through the current-
sense amplifier. Connect CS through a passive network to FB as dictated by the chosen compensation
scheme.
14 FB Error-Amplifier Inverting Input
15 OV
Overvoltage Protection Input. Connect OV to HI through a resistive voltage-divider to set the overvoltage
limit for the load. When the voltage at OV exceeds the 1.235V (typ) threshold, an overvoltage fault is
generated and the switching MOSFET turns off. The MOSFET is turned on again when the voltage at OV
drops below 1.17V (typ).
16, 17 SGND Switching Ground. SGND is the ground for non-analog and high-current gate-driver circuitry.
18 DRV Gate-Driver Output. Connect DRV through a series resistor to the gate of an external n-channel MOSFET to
reduce EMI. DRV can sink 1A or source 0.5A.
19 DRI Gate-Driver Supply Input. Connect DRI to REG2 to power the primary switching MOSFET driver.
20 SNS+ Positive Peak Current-Sense Input. Connect SNS+ to the positive side of the switch current-sense resistor,
RSENSE.
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 13
Pin Description (continued)
PIN NAME FUNCTION
21 SNS- Negative Peak Current-Sense Input. Connect SNS- to the negative side of the switch current-sense resistor,
RSENSE.
22 QGND Analog Ground. Ensure a low-impedance connection between QGND and AGND.
23 DGT Dimming Gate-Driver Output. Connect DGT to the gate of an external n-channel MOSFET for dimming. DGT
is powered by the internal regulator, CLAMP, and is referenced to LO.
25 LO
Low-Voltage Input. LO is the return point for the LED current. When using the MAX16816 in a buck-boost
configuration, connect LO to VCC. When using the device in a boost configuration only, connect LO to
AGND. Connect LO to the junction of the inductor and LED current-sense resistor, RCS, when using a buck
configuration.
26 CS+ Noninverting Current-Sense Amplifier Input. Connect CS+ to the positive side of an external sense resistor,
RCS, connected in series with the load (LEDs).
27 CS- Inverting Current-Sense Amplifier Input. Connect CS- to the negative side of an external sense resistor, RCS,
connected in series with the load (LEDs).
28 CLMP
Internal CLAMP Regulator Bypass. CLAMP supplies an 8V (typ) output when VHI ≥ 9V. If VHI is lower than
9V, VCLMP is one diode drop below VHI. The CLAMP regulator powers the current-sense amplifier and
provides the high reference for the dimming driver. VCLMP must be at least 2.5V higher than VLO to enable
the current-sense amplifier and dimming MOSFET driver. Bypass CLMP to LO with a 0.1µF ceramic
capacitor.
29 HI High-Voltage Input. HI is referred to LO. HI supplies power to the current-sense amplifier and dimming
MOSFET gate driver through the CLMP regulator.
30 REG2
Internal Regulator Output. REG2 is an internal voltage regulator that generates EEPROM-programmable
(5V to 15V) output and supplies power to internal circuitry. Connect REG2 to DRI to power the switching
MOSFET driver during normal operation. Bypass REG2 to AGND with a 10µF ceramic capacitor.
31 VCC Supply Voltage Input
32 FAULT
FAULT Input/Output. FAULT is a bidirectional high-voltage logic input/output. FAULT multiplexes a 1-Wire
programming interface with a fault indicator. FAULT is internally pulled up to 5V through a 10kΩ resistor and
a 1.8mA (max) current pulldown to ground.
EP EP Exposed Pad. Connect EP to AGND. EP also functions as a heatsink to maximize thermal dissipation. Do not
use as the main ground connection.
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
14 ______________________________________________________________________________________
BLANKING
TIME
200Hz
SGND
15V
REG2
HI
COMP
UVLO
AND
EN
DGT
FB
DRIVER
UVEN
DIM
DRV
SNS-
PWM
EAMP
+
-
COMP
+
-
OVP
LO
VCC
5V
REG1
POR
EN
REF
VOV
+
-
VBUF
DDR
QGND
REG1
DRI
FAULT
CLAMP
SS
D-I
SOFT-START
D-I
ILIM
+
-
-200mV
HIC
+
-
+
-
-300mV
AGND 200mV
SLOPE
OV
X1
CS- CS+
+
CSA
REG2
SNS+
CLMP
3.0V
RLS
CS
UGB
CMP
+
-1.3 x VSS
OSC
RTSYNC
CLKOUT
OSC
OV
OC
CONTROL
BLOCK
SLOPE
COMP
1-Wire
INTERFACE
SLOPE
VCLMP
VCLMP
VLO
VLO
THERMAL
SHUTDOWN
VSS
-+
800mV +
-
MAX16816
-
REG2 DRIVER
D-I
D-I
D-I BLANKING
D-I
OS
0.926V
BINNING
INDICATES A USER-PROGRAMMABLE EEPROM FEATURE
BINNING
REG2 DRIVER
TRIM REGISTERS
BLANKING
SLOPE COMP
SOFT-START
RTOSCSEL
D-I
Functional Diagram
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 15
Detailed Description
The MAX16816 is a current-mode PWM LED driver for
use in driving HB LEDs. An output current accuracy of
5% is achievable using two current regulation loops:
one current regulation loop controls the external switch-
ing MOSFET peak current through a sense resistor,
RSENSE, from SNS+ to SNS- while the other current reg-
ulation loop controls the average LED string current
through the sense resistor, RCS, in series with the
LEDs. The wide operating supply range of 5.9V/5.4V
(ON/OFF) to 76V makes the MAX16816 ideal in auto-
motive applications.
The MAX16816 provides LED binning through one pro-
grammable on-chip nonvolatile EEPROM. The LED cur-
rent can be scaled up to a factor of 1.6. This feature is
used to offset factory LED luminance variations and
allows the system to achieve overall luminance accuracy.
A programmable undervoltage lockout (UVEN) ensures
predictable operation during brownout conditions. The
UVEN input circuitry monitors the supply voltage, VCC,
and turns the driver off when VCC drops below the
UVLO threshold. Connect UVEN to VCC to use the 5.7V
(typ) default UVLO threshold. The MAX16816 includes
a cycle-by-cycle current limit that turns off the gate
drive to the external switching MOSFET (QS) during an
overcurrent condition and a programmable oscillator
that simplifies and optimizes the design of external
magnetics.
The MAX16816 is capable of synchronizing to an
external clock or operating in a stand-alone mode. A
single resistor, RT, can be used to adjust the switching
frequency from 125kHz to 500kHz for stand-alone
operation. To synchronize the device with an external
clock, apply a clock signal directly to the RTSYNC
input. A buffered clock output, CLKOUT, is available to
configure the MAX16816 for multichannel applications.
The external RT oscillator can be disabled by setting
EEPROM register RTOF to ‘1’.
The MAX16816 provides wide contrast pulsed dimming
(up to 1000:1) utilizing a separate dimming input. Apply
either a DC level voltage or low-frequency PWM signal
to the dimming input. DC level input results in a 200Hz
fixed dimming frequency.
The MAX16816 provides configurable on-chip non-
volatile EEPROM features including a programmable
soft-start, load current, external MOSFET gate-driver
supply voltage, blanking time, and slope compensation.
Protection features include peak current limiting, HICCUP
mode current limiting, output overvoltage protection,
short-circuit protection, and thermal shutdown. The
HICCUP current-limit circuitry reduces the power deliv-
ered to the load during severe fault conditions. A non-
latching overvoltage protection limits the voltage on the
external switching MOSFET (QS) under open-circuit
conditions in the LED string. During continuous opera-
tion at high input voltages, the power dissipation of the
MAX16816 could exceed the maximum rating and the
internal thermal shutdown circuitry safely turns off the
MAX16816 when the device junction temperature
exceeds +165°C. When the junction temperature drops
below the hysteresis temperature, the MAX16816 auto-
matically reinitiates startup.
Undervoltage Lockout/Enable (UVEN)
The MAX16816 features a dual-purpose adjustable
undervoltage lockout input and enable function
(UVEN). Connect UVEN to VCC through a resistive volt-
age-divider to set the undervoltage lockout (UVLO)
threshold. The device is enabled when the voltage at
UVEN exceeds the 1.244V (typ) threshold. Drive UVEN
to ground to disable the output.
Setting the UVLO Threshold
Connect UVEN directly to VCC to select the default 5.7V
(typ) UVLO threshold. Connect UVEN to VCC through a
resistive voltage-divider to select a UVLO threshold
(Figure 1). Select the desired UVLO threshold voltage,
VUVLO, and calculate resistor values using the following
equation:
where RUV1 + RUV2 ≤270kΩ. VUVEN is the 1.244V (typ)
UVEN threshold voltage.
R R x V
V - V
UV1 UV2 UVEN
UVLO UVEN
=⎛
⎝
⎜
⎞
⎠
⎟
MAX16816
VCC
UVEN
QGND
RUV2
RUV1
CUVEN
VIN
Figure 1. Setting the UVLO Threshold
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
16 ______________________________________________________________________________________
The capacitor CUVEN is required to prevent chattering
at the UVLO threshold due to line impedance drops
during power-up and dimming. If the undervoltage set-
ting is very close to the required minimum operating
voltage, there can be large jumps in the voltage at VCC
during dimming, which may cause the MAX16816 to
turn on and off when the dimming signal transitions
from low to high. The capacitor CUVEN should be large
enough to limit the ripple on UVEN to less than the
100mV (min) UVEN hysteresis so that the device does
not turn off under these circumstances.
Soft-Start
The MAX16816 features a digitally programmable soft-
start delay that allows the load current to ramp up in a
controlled manner, minimizing output overshoot. Soft-
start begins once the device is enabled and VCC
exceeds the UVLO threshold. Soft-start circuitry slowly
increases the internal soft-start voltage, VSS, resulting
in a controlled rise of the load current. Signals applied
to DIM are ignored until the soft-start duration is com-
plete and a successive delay of 200µs has elapsed.
Use the Digital Soft-Start Duration register in the EEPROM
to select a soft-start duration from 0 (no delay) to
4.096ms. See the
EEPROM and Programming
section for
more information on using the Digital Soft-Start Duration
register.
Regulators (REG1, REG2, CLAMP)
The MAX16816 includes a fixed 5V voltage regulator,
REG1; an EEPROM-adjustable regulator, REG2; and an
internal 8V regulator, CLAMP. REG1 and REG2 power
up when VCC exceeds the UVLO threshold. REG1 sup-
plies power to internal circuitry and remains on during
PWM dimming. REG1 is capable of driving external
loads up to 2mA.
Use the REG2 Control Register in the EEPROM to
select an output voltage from 5V to 15V for REG2.
Connect REG2 to DRI to generate the supply voltage
for the primary switching MOSFET driver, DRV. REG2 is
capable of delivering up to 20mA of current. See the
EEPROM and Programming
section for more information
on configuring the REG2 output voltage.
CLAMP is powered by HI and supplies power to the
current-sense amplifier (CSA). CSA is enabled when
VCLMP goes 2.5V above VLO and is disabled when
(VCLMP - VLO) falls below 2.28V. The CLAMP regulator
also provides power to the dimming MOSFET control
circuitry. CLMP is the output of the CLAMP regulator.
Do not use CLMP to power external circuitry. Bypass
CLMP to LO with a 0.1µF ceramic capacitor. A larger
capacitor will result in overshoot of the load current.
Reference Voltage Output (REF)
The MAX16816 includes a 5% accurate, 3V (typ)
buffered reference output, REF. REF is a push-pull out-
put capable of sourcing/sinking up to 200µA of current
and can drive a maximum load capacitance of 100pF.
Connect REF to DIM through a resistive voltage-divider
to supply an analog signal for dimming. See the
Dimming Input (DIM)
section for more information.
Dimming MOSFET Driver (DDR)
The MAX16816 requires an external n-channel MOSFET
for PWM dimming. Connect the MOSFET to the output of
the DDR dimming driver, DGT, for normal operation.
VDGT swings between VLO and VCLMP. The DDR dim-
ming driver is capable of sinking or sourcing up to
20mA of current. The average current required to drive
the dimming MOSFET (IDRIVE_DIM) depends on the
MOSFET’s total gate charge (QG_DIM) and the dimming
frequency of the converter, fDIM. Use the following equa-
tion to calculate the supply current for the n-channel dim-
ming FET driver.
IDRIVE_DIM = QG_DIM x fDIM
n-Channel MOSFET Switch Driver (DRV)
The MAX16816 drives an external n-channel MOSFET
for switching. Use an external supply or connect REG2
to DRI to power the MOSFET driver. The driver output,
VDRV, swings between ground and VDRI. Ensure that
VDRI remains below the absolute maximum VGS rating
of the external MOSFET. DRV is capable of sinking 2A
or sourcing 1.4A of peak current, allowing the
MAX16816 to switch MOSFETs in high-power applica-
tions. The average current sourced to drive the external
MOSFET depends on the total gate charge (QG) and
operating frequency of the converter, fSW. The power
dissipation in the MAX16816 is a function of the aver-
age output drive current (IDRIVE). Use the following
equations to calculate the power dissipation in the
gate-driver section of the MAX16816 due to IDRIVE:
IDRIVE = QGx fSW
PD= IDRIVE x VDRI
where VDRI is the supply voltage to the gate driver.
Dimming Input (DIM)
The dimming input, DIM, functions with either analog or
PWM control signals. Once the internal pulse detector
detects three successive edges of a PWM signal with a
frequency between 80Hz and 2kHz, the MAX16816
synchronizes to the external signal and pulse-width
modulates the LED current at the external DIM input
frequency with the same duty cycle as the DIM input. If
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 17
an analog control signal is applied to DIM, the
MAX16816 compares the DC input to an internally gen-
erated 200Hz ramp to pulse-width modulate the LED
current (fDIM = 200Hz). The output current duty cycle is
linearly adjustable from 0 to 100% (0.2V < VDIM < 2.8V).
Use the following formula to calculate voltage, VDIM,
necessary for a given output current duty cycle, D:
VDIM = (D x 2.6) + 0.2V
where VDIM is the voltage applied to DIM in volts.
Connect DIM to REF through a resistive voltage-divider
to apply a DC DIM control signal (Figure 2). Use the
required dimming input voltage, VDIM, calculated
above and select appropriate resistor values using the
following equation:
R4= R3x VDIM / (VREF - VDIM)
where VREF is the 3V reference output voltage and
15kΩ≤R3 + R4≤150kΩ.
A minimum 20µs pulse width is necessary for proper
operation during dimming.
Oscillator, Clock, and Synchronization
The MAX16816 is capable of stand-alone operation, of
synchronizing to an external clock, and of driving exter-
nal devices in SYNC mode. For stand-alone operation,
set the EEPROM Oscillator Enable/Disable (RTOF) bit
to ‘1’ to use the fixed internal 125kHz oscillator or set
RTOF to ‘0’ and program the switching frequency by
connecting a single external resistor, RT, between
RTSYNC and ground. Select a switching frequency,
fSW, between 125kHz and 500kHz and calculate RT
using the following formula:
where the switching frequency is in kHz and RTis in kΩ.
To synchronize the MAX16816 with an external clock
signal ranging from 125kHz to 500kHz, set the RTOF bit
to ‘0’ and connect the clock signal to the RTSYNC
input. The MAX16816 synchronizes to the clock signal
after the detection of 5 successive clock edges at
RTSYNC.
A buffered clock output, CLKOUT, can drive the
RTSYNC input of an external PWM controller for multi-
channel applications. CLKOUT can drive capacitive
loads up to 500pF.
If the PWM switching frequency is set to 125kHz, the
RTSYNC oscillator can be temporarily disabled by setting
the EEPROM RTOF bit to ‘1’. In this case, the internal
125kHz frequency-fixed oscillator drives the PWM. See the
EEPROM and Programming
section for more information
on setting the Oscillator Enable/Disable bit in the EEPROM.
Multichannel Configuration
The MAX16816 is capable of multichannel operation
and is configurable as a master or slave in a Master-
Slave configuration, or in a Peer-to-Peer configuration.
Connect CLKOUT to the SYNC input of an external
device to use the MAX16816 as a master clock signal.
Connect an external clock signal to RTSYNC to config-
ure the MAX16816 as a slave. To setup two MAX16816
devices in a daisy-chain configuration, drive the
RTSYNC input of one MAX16816 with the CLKOUT
buffer of another (Figure 3).
ILIM and HICCUP Comparator
RSENSE sets the peak current through the inductor for
switching. The differential voltage across RSENSE is
compared to the 200mV voltage-trip limit of the current-
limit comparator, ILIM. Set the current limit 20% higher
than the peak switch current at the rated output power
and minimum voltage. Use the following equation to
calculate RSENSE:
RSENSE = VSENSE / (1.2 x IPEAK)
R
500kHz
f2 k
TSW
=× 5Ω
MAX16816
REF
AGND
R3
R4
DIM
Figure 2. Creating DIM Input Signal from REF
MAX16816 MAX16816
RTSYNC CLKOUT RTSYNC CLKOUT
MASTER/PEER SLAVE/PEER
RT
Figure 3. Master-Slave/Peer-Peer Clock Configuration
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
18 ______________________________________________________________________________________
where VSENSE is the 200mV maximum differential volt-
age between SNS+ and SNS- and IPEAK is the peak
inductor current at full load and minimum input voltage.
When the voltage drop across RSENSE exceeds the
ILIM threshold, the MOSFET driver (DRV) terminates
the on-cycle and turns the switch off, reducing the cur-
rent through the inductor. The FET is turned back on at
the beginning of the next switching cycle.
When the voltage across RSENSE exceeds the 300mV
(typ) HICCUP threshold, the HIC comparator terminates
the on-cycle of the device, turning the switching MOS-
FET off. Following a startup delay of 8ms (typ), the
MAX16816 reinitiates soft-start. The device will continue
to operate in HICCUP mode until the overcurrent condi-
tion is removed.
A programmable built-in leading-edge blanking circuit
of the current-sense signal prevents these comparators
from prematurely terminating the on-cycle of the exter-
nal switching MOSFET (QS). Select a blanking time
from 75ns to 150ns by configuring the Blanking Time
register in the EEPROM. In some cases, the maximum
blanking time may not be adequate and an additional
RC filter may be required to prevent spurious turn-off.
Load Current Sense
The load sense resistor, RCS, monitors the current
through the LEDs. The internal floating current-sense
amplifier, CSA, measures the differential voltage across
RCS, and generates a voltage proportional to the load
current through RCS at CS. This voltage on CS is
referred to AGND. The closed-loop regulates the load
current to a value, ILED, given by the following equation:
ILED = VSS / RCS
where VSS is the binning adjustment voltage. Set the value
of VSS in the Binning Adjustment register in the EEPROM
between 100mV and 166mV. See the
EEPROM and
Programming
section for more information on adjusting
the binning voltage.
Slope Compensation
The amount of slope compensation required is largely
dependent on the down-slope of the inductor current
when the switching MOSFET, QS, is off. The inductor
down-slope depends on the input-to-output voltage dif-
ferential of the converter, the inductor value, and the
switching frequency. For stability, the compensation
slope should be equal to or greater than half of the
inductor current down-slope multiplied by the current-
sense resistance (RSENSE).
See the
EEPROM and Programming
section for more infor-
mation on the ESLP register.
Internal Voltage-Error Amplifier (EAMP)
The MAX16816 includes a built-in voltage amplifier,
with three-state output, which can be used to close the
feedback loop. The buffered output current-sense sig-
nal appears at CS, which is connected to the inverting
input, FB, of the error amplifier through resistor R1. The
noninverting input is connected to an internally trimmed
current reference.
The output of the error amplifier is controlled by the signal
applied to DIM. When DIM is high, the output of the ampli-
fier is connected to COMP. The amplifier output is open
when DIM is low. This enables the integrating capacitor to
hold the charge when the DIM signal has turned off the
gate drive. When DIM is high again, the voltage on the
compensation capacitors, C1and C2, forces the converter
into steady state almost instantaneously.
PWM Dimming
PWM dimming is achieved by driving DIM with either a
PWM signal or a DC signal. The PWM signal is con-
nected internally to the error amplifier, the dimming
MOSFET gate driver, and the switching MOSFET gate
driver. When the DIM signal is high, the dimming MOSFET
and the switching MOSFET drivers are enabled and the
output of the voltage-error amplifier is connected to
the external compensation network. Also, the buffered
current-sense signal is connected to CS. Preventing
discharge of the compensation capacitor when the
DIM signal is low allows the control loop to return the
LED current to its original value almost instantaneously.
When the DIM signal goes low, the output of the error
amplifier is disconnected from the compensation net-
work and the compensation capacitors, C1and C2,
voltage is preserved. Choose low-leakage capacitors
for C1and C2. The drivers for the external dimming and
switching MOSFETs are disabled, and the converter
stops switching. The inductor energy is now transferred
to the output capacitors.
When the DIM signal goes high and the gate drivers
are enabled, the additional voltage on the output
capacitor may cause a current spike on the LED string.
A larger output capacitor will result in a smaller current
spike. If the overcurrent spike exceeds 30% of the pro-
grammed LED current, the dimming is turned off and
the MAX16816 reinitiates soft-start.
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 19
FAULT
1-Wire Interface
The MAX16816 features a FAULT output multiplexed
with a 1-Wire programming interface. Once the voltage
at UVEN exceeds the UVLO threshold, the device is
enabled and FAULT will pulse low once, indicating the
beginning of the programming window. Two program-
ming mode entry codes must be entered within 8ms
after the pulse to enter programming mode (see Table
1). The MAX16816 will register the second entry code
only after the first code has been received. Once the
MAX16816 successfully enters programming mode, the
data and clock for the 1-Wire interface are supplied
through FAULT.
Once the programming window has passed, the EEPROM
is no longer accessible without cycling power to the
device. Under these conditions, FAULT will go low only
when a fault (overvoltage, overcurrent, or HICCUP mode)
occurs or when the supply voltage drops below the UVLO
threshold.
EEPROM and Programming
Nonvolatile EEPROM is available to configure the
MAX16816 through a 1-Wire serial interface. Registers
are located in a linear address space as shown in
Table 2. All other EEPROM locations are reserved.
Configure the six control registers to adjust parameters
including the REG2 voltage, soft-start durations, blank-
ing time, LED load current (binning), slope compensa-
tion, and to enable/disable the RTOF oscillator. See the
1-Wire Interface
section for more information about
1-Wire programming.
Table 1. Programming Mode Entry Codes
PROGRAMMING MODE
ENTRY CODE D7 D6 D5 D4 D3 D2 D1 D0 HEX
CODE
PASS_CODE_1 0 0 1 0 1 0 0 1 29h
PASS_CODE_2 0 0 0 0 1 0 0 1 09h
Table 2. EEPROM Memory Map
REGISTER
EEPROM
ADDRESS
RANGE
NO. OF
BITS TYPE DESCRIPTION
Binning Adjustment (BIN) 24h–27h 4 R/W Adjusts the LED current.
REG2 Control (DRPS) 28h–2Bh 4 R/W Sets the output voltage for REG2. Connect REG2 to DRI
to supply the high-side voltage for the gate driver, DRV.
Bl anki ng Ti m e Ad j ustm ent ( BLN K) 32h–33h 2 R/W Ad j usts the b l anki ng ti m e for d eb ounci ng .
Digital Soft-Start Duration (SS) 34h–36h 2 R/W
Adjusts the soft-start duration to allow the load current to
ramp up in a controlled manner, minimizing output
overshoot.
Internal Oscillator
Enable/Disable (RTOF) 37h 1 R/W Enables/disables the internal oscillator for stand-alone
operation or to synchronize with an external clock.
Slope Compensation (ESLP) 38h–3Bh 4 R/W Adjusts the slope compensation for stability.
MAX16816
Binning Adjustment Register (BIN)
The MAX16816 uses a feedback loop to control the
load current. The differential voltage across the current-
sense resistor, RCS, is compared with an internal
adjustable reference to regulate the LED current. The
voltage across the sense resistor is measured differen-
tially to achieve high immunity to common-mode noise.
The MAX16816 includes a factory-set regulation volt-
age of 133mV ±3% across RCS. Adjust the differential
regulation voltage by programming the binning adjust-
ment register (see Table 3). The reference voltage level
may not necessarily be equal to the regulation voltage.
There are offsets involved that are trimmed at the facto-
ry. Read the default register code and step up the code
by one to increase the regulation voltage by 6.66mV.
Step down the code by one to reduce the regulation
voltage by 6.66mV.
REG2 Control Register (DRPS)
REG2 is EEPROM configurable to supply a voltage rang-
ing from 5V to 15V and is capable of sourcing up to
20mA. Connect REG2 to the primary switching MOSFET
gate-driver supply input, DRI, for normal operation.
Adjust REG2 by programming the REG2 Control
Register. See Table 4.
Blanking Time Adjustment Register (BLNK)
The MAX16816 features a programmable blanking time
to mask out the current-sense signal for a short dura-
tion to avoid the ILIM and HICCUP comparators from
prematurely terminating the on-cycle of the switching
MOSFET. This blanking time allows for higher input cur-
rent during startup without triggering a fault condition.
The blanking time is adjustable in the range of 150ns to
75ns by configuring the EEPROM. See Table 5.
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
20 ______________________________________________________________________________________
Table 3. Binning Adjustment Register
EEPROM ADDRESS
REFERENCE
VOLTAGE LEVEL
(mV) 27h 26h 25h 24h
100.00 0 0 0 0
106.67 0 0 0 1
113.33 0 0 1 0
120.00 0 0 1 1
126.67 0 1 0 0
133.33 0 1 0 1
140.00 0 1 1 0
146.67 0 1 1 1
153.33 1 0 0 0
160.00 1 0 0 1
166.67 1 0 1 0
173.33* 1 0 1 1
180.00* 1 1 0 0
186.67* 1 1 0 1
193.33* 1 1 1 0
200.00* 1 1 1 1
*
Not recommended
Table 4. REG2 Control Register
EEPROM ADDRESS
REG2 OUTPUT
VOLTAGE
(V) 2Bh 2Ah 29h 28h
5.000 0 0 0 0
5.667 0 0 0 1
6.333 0 0 1 0
7.000* 0 0 1 1
7.667 0 1 0 0
8.333 0 1 0 1
9.000 0 1 1 0
9.667 0 1 1 1
10.333 1 0 0 0
11.000 1 0 0 1
11.667 1 0 1 0
12.333 1 0 1 1
13.000 1 1 0 0
13.667 1 1 0 1
14.333 1 1 1 0
15.000 1 1 1 1
*
Factory default
Table 5. Blanking Time
EEPROM ADDRESS
BLANKING TIME
(ns) 33h 32h
150* 0 0
125 0 1
100 1 0
75 1 1
*
Factory default
Digital Soft-Start Duration Register (SS)
The MAX16816 programmable soft-start feature allows
the load current to ramp up in a controlled manner, elimi-
nating output overshoot during startup. Soft-start begins
once the device is enabled and VCC has exceeded the
5.5V (min) rising threshold voltage. Adjust the soft-start
duration by configuring the EEPROM. Enter ‘111’ to dis-
able the soft-start feature. See Table 6.
Oscillator Enable/Disable Register (RTOF)
The MAX16816 features a programmable accurate
RTSYNC oscillator and resistor synchronized to an
external clock. Set the EEPROM bit RTOF to ‘1’ to dis-
able the external sync mode, and the RTSYNC oscilla-
tor, and to use the fixed internal frequency of 125kHz
as the switching frequency. Set RTOF to ‘0’ to synchro-
nize with an external oscillator or to program the exter-
nal oscillator frequency with an external resistor, RT.
See Table 7.
Slope Compensation Register (ESLP)
The MAX16816 uses an internally generated ramp to
stabilize the current loop when operating at duty cycles
above 50%. Set the compensating slope by adjusting
the peak ramp voltage through the on-chip EEPROM.
See Tables 8 and 9.
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 21
Table 6. Digital Soft-Start Duration
EEPROM ADDRESS
DURATION
(µs) 36h 35h 34h
4096* 0 0 0
2048 0 0 1
1860 0 1 0
1024 0 1 1
768 1 0 0
512 1 0 1
256 1 1 0
No SS 1 1 1
*
Factory default
Table 7. Oscillator Enable/Disable
EEPROM ADDRESS
RT OSCILLATOR 37h
RT Oscillator Off 1
RT Oscillator On* 0
Table 8. Slope Compensation with Clock
Generated by RT Oscillator
EEPROM ADDRESS
SLOPE
COMPENSATION
(mV/clock cycle) 3Bh 3Ah 39h 38h
00000
20 0001
40 0010
60 0011
80 0100
100 0101
120* 0 1 1 0
140 0111
160 1000
180 1001
200 1010
220 1011
240 1100
260 1101
280 1110
300 1111
Table 9. Slope Compensation with
External Clock Applied to RTSYNC or RT
Oscillator Off
EEPROM ADDRESS
SLOPE
COMPENSATION
(mV/µs) 3Bh 3Ah 39h 38h
00000
20001
40010
60011
80100
10 0101
12* 0110
14 0111
16 1000
18 1001
20 1010
22 1011
24 1100
26 1101
28 1110
30 1111
*
Factory default
*
Factory default
*
Factory default
MAX16816
Fault Protection
The MAX16816 features built-in overvoltage protection,
overcurrent protection, HICCUP mode current-limit pro-
tection, and thermal shutdown. Overvoltage protection
is achieved by connecting OV to HI through a resistive
voltage-divider. HICCUP mode limits the power dissi-
pation in the external MOSFETs during severe fault
conditions. Internal thermal shutdown protection safely
turns off the converter when the IC junction temperature
exceeds +165°C.
Overvoltage Protection
The overvoltage protection (OVP) comparator com-
pares the voltage at OV with a 1.235V (typ) internal ref-
erence. When the voltage at OV exceeds the internal
reference, the OVP comparator terminates PWM
switching and no further energy is transferred to the
load. The MAX16816 reinitiates soft-start once the over-
voltage condition is removed. Connect OV to HI
through a resistive voltage-divider to set the overvolt-
age threshold at the output.
Setting the Overvoltage Threshold
Connect OV to HI or to the high-side of the LEDs
through a resistive voltage-divider to set the overvolt-
age threshold at the output (Figure 4). The overvoltage
protection (OVP) comparator compares the voltage at
OV with a 1.235V (typ) internal reference. Use the fol-
lowing equation to calculate resistor values:
where VOV is the 1.235V OV threshold. Choose ROV1
and ROV2 to be reasonably high value resistors to pre-
vent discharge of filter capacitors. This will prevent
unnecessary undervoltage and overvoltage conditions
during dimming.
Load-Dump Protection
The MAX16816 features load-dump protection up to 76V.
LED drivers using the MAX16816 can sustain single fault
load dump events. Repeated load dump events within
very short time intervals can cause damage to the dim-
ming MOSFET due to excess power dissipation.
Thermal Shutdown
The MAX16816 contains an internal temperature sensor
that turns off all outputs when the die temperature
exceeds +165°C. Outputs are enabled again when the
die temperature drops below +145°C.
Applications Information
Inductor Selection
The minimum required inductance is a function of oper-
ating frequency, input-to-output voltage differential, and
the peak-to-peak inductor current (ΔIL). Higher ΔIL
allows for a lower inductor value while a lower ΔIL
requires a higher inductor value. A lower inductor value
minimizes size and cost, improves large-signal tran-
sient response, but reduces efficiency due to higher
peak currents and higher peak-to-peak output ripple
voltage for the same output capacitor. On the other
hand, higher inductance increases efficiency by reduc-
ing the ripple current, ΔIL. However, resistive losses
due to extra turns can exceed the benefit gained from
lower ripple current levels, especially when the induc-
tance is increased without also allowing for larger
inductor dimensions. A good compromise is to choose
ΔILequal to 30% of the full load current. The inductor
saturating current is also important to avoid runaway
current during the output overload and continuous
short circuit. Select the ISAT to be higher than the maxi-
mum peak current limit.
Buck configuration: In a buck configuration the average
inductor current does not vary with the input. The worst-
case peak current occurs at high input voltage. In this
case the inductance, L, for continuous conduction
mode is given by:
where VINMAX is the maximum input voltage, fSW is the
switching frequency, and VOUT is the output voltage.
L
V x V V
V x f x I
OUT INMAX OUT
INMAX SW L
=−
()
Δ
R R x VV
V
OV1 OV2 OV_LIM OV
OV
=−
⎛
⎝
⎜
⎞
⎠
⎟
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
22 ______________________________________________________________________________________
AGND
ROV1
ROV2
OV
VLED+
MAX16816
Figure 4. Setting the Overvoltage Threshold
Boost configuration: In the boost converter, the average
inductor current varies with line and the maximum aver-
age current occurs at low line. For the boost converter,
the average inductor current is equal to the input cur-
rent. In this case the inductance, L, is calculated as:
where VINMIN is the minimum input voltage, VOUT is the
output voltage, and fSW is the switching frequency.
Buck-boost configuration: In a buck-boost converter
the average inductor current is equal to the sum of the
input current and the load current. In this case the
inductance, L, is:
where VINMIN is the minimum input voltage, VOUT is the
output voltage, and fSW is the switching frequency.
Output Capacitor
The function of the output capacitor is to reduce the
output ripple to acceptable levels. The ESR, ESL, and
the bulk capacitance of the output capacitor contribute
to the output ripple. In most of the applications, the out-
put ESR and ESL effects can be dramatically reduced
by using low-ESR ceramic capacitors. To reduce the
ESL effects, connect multiple ceramic capacitors in
parallel to achieve the required bulk capacitance.
In a buck configuration, the output capacitance, CF, is
calculated using the following equation:
where ΔVRis the maximum allowable output ripple.
In a boost configuration, the output capacitance, CF, is
calculated as:
where IOUT is the output current.
In a buck-boost configuration, the output capacitance,
CF, is calculated as:
where VOUT is the voltage across the load and IOUT is
the output current.
Input Capacitor
An input capacitor connected between VCC and
ground must be used when configuring the MAX16816
as a buck converter. Use a low-ESR input capacitor
that can handle the maximum input RMS ripple current.
Calculate the maximum allowable RMS ripple using the
following equation:
In most of the cases, an additional electrolytic capaci-
tor should be added to prevent input oscillations due to
line impedances.
When using the MAX16816 in a boost or buck-boost
configuration, the input RMS current is low and the
input capacitance can be small (see the
Typical
Operating Circuits
).
Operating the MAX16816 Without the
Dimming Switch
The MAX16816 can also be used in the absence of the
dimming MOSFET. In this case, the PWM dimming per-
formance is compromised but in applications that do
not require dimming the MAX16816 can still be used. A
short circuit across the load will cause the MAX16816
to disable the gate drivers and they will remain off until
the input power is recycled.
Switching Power MOSFET Losses
When selecting MOSFETs for switching, consider the
total gate charge, power dissipation, the maximum
drain-to-source voltage, and package thermal imped-
ance. The product of the MOSFET gate charge and
RDS(ON) is a figure of merit, with a lower number signi-
fying better performance. Select MOSFETs optimized
for high-frequency switching applications.
Layout Recommendations
Typically, there are two sources of noise emission in a
switching power supply: high di/dt loops and high dv/dt
surfaces. For example, traces that carry the drain cur-
rent often form high di/dt loops. Similarly, the heatsink
of the MOSFET connected to the device drain presents a
high dv/dt source; therefore, minimize the surface area of
the heatsink as much as possible. Keep all PCB traces
carrying switching currents as short as possible to mini-
mize current loops. Use ground planes for best results.
I
IVV - V
V
IN(RMS)
OUT OUT INMIN OUT
INMIN
=×× ( )
C 2 V I
VV V f
F
OUT OUT
R OUT INMIN SW
≥××
×+ ×
( ) Δ
C
VV I
VV f
F
OUT INMIN OUT
R OUT SW
≥−××
××
( )
2
Δ
C VVV
VL Vf
F
INMAX OUT OUT
R INMAX SW
≥−×
××× ×
( )
Δ22
L V x V
V V x f x I
OUT INMIN
OUT INMIN SW L
=
+
()
Δ
L V x V V
V x f x I
INMIN OUT INMIN
OSWL
=−
()
UT Δ
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 23
MAX16816
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. Use a multilayer
board whenever possible for better noise performance
and power dissipation. Follow these guidelines for
good PCB layout:
•Use a large copper plane under the MAX16816
package. Ensure that all heat-dissipating compo-
nents have adequate cooling. Connect the
exposed pad of the device to the ground plane.
•Isolate the power components and high current
paths from sensitive analog circuitry.
•Keep the high-current paths short, especially at the
ground terminals. This practice is essential for sta-
ble, jitter-free operation. Keep switching loops short.
•Connect AGND, SGND, and QGND to a ground
plane. Ensure a low-impedance connection
between all ground points.
•Keep the power traces and load connections
short. This practice is essential for high efficiency.
Use thick copper PCBs (2oz vs. 1oz) to enhance
full-load efficiency.
•Ensure that the feedback connection to FB is short
and direct.
•Route high-speed switching nodes away from the
sensitive analog areas.
•To prevent discharge of the compensation capaci-
tors, C1and C2, during the off-time of the dimming
cycle, ensure that the PCB area close to these
components has extremely low leakage.
Discharge of these capacitors due to leakage may
result in degraded dimming performance.
1-Wire Interface
EEPROM implementation uses a 1-Wire communica-
tion method. A 1-Wire net-based system consists of
three main elements: a bus master with controlling
software, the wiring and associated connectors, and
1-Wire devices. Data on the 1-Wire net is transferred
with respect to time slots. For example, the master pulls
the bus low and holds it for 15µs or less to write a logic
‘1’, and holds the bus low for at least 60µs to write a
logic ‘0’. During EEPROM programming the MAX16816
is a 1-Wire slave device only. Data and clock signals
are supplied through FAULT.
MAX16816 1-Wire Function Commands
Table 10 shows the list of 1-Wire function commands
for the MAX16816. Use these commands to start the
programming mode, write to the on-chip EEPROM, and
read EEPROM through the 1-Wire interface.
PASS_CODE_ONE: The PASS_CODE_ONE sequence
is the first code that the MAX16816 must receive from
the master. PASS_CODE_ONE must be received within
the initial 8ms programming window after startup.
PASS_CODE_TWO: The PASS_CODE_TWO sequence
is the second code that the MAX16816 must receive
during the 8ms programming window. The MAX16816
will start searching for PASS_CODE_TWO only after
PASS_CODE_ONE has been received.
EXT_EEM_MODE: The EXT_EEM_MODE command
clears the PASS_CODE_ONE and PASS_CODE_TWO
verification register. Use this command to exit program-
ming mode.
SET_WRITE_EE: The SET_WRITE_EE command is the
write all command for the MAX16816. When the device
detects the SET_WRITE_EE command the write
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
24 ______________________________________________________________________________________
Table 10. MAX16816 1-Wire Function Commands
DATA BIT CODE
COMMAND D7 D6 D5 D4 D3 D2 D1 D0
HEX
CODE
PASS_CODE_ONE 0 010100129h
PASS_CODE_TWO 0 000100109h
EXT_EEM_MODE 0 000000101h
SET_WRITE_EE 0 000010004h
SET_WRITE_SCH ADD ADD ADD ADD DATA DATA DATA DATA —
SET_READ_SCH 0 000011006h
sequence begins. All EEPROM bits are copied to the
EEPROM from the scratchpad with a single
SET_WRITE_EE command. This command also sets an
internal BUSY flag to mask all other incoming signals.
SET_WRITE_SCH: The SET_WRITE_SCH command
transfers data to the scratchpad. The 4 MSBs contain the
register address and the 4 LSBs contain the data to be
written. The internal BUSY flag is not set by this com-
mand. Table 11 shows the MAX16816 EEPROM memory
organization. Use the SET_WRITE_EE command to trans-
fer data from the scratchpad to the EEPROM.
SET_READ_SCH: The SET_READ_SCH command is
the command to read data in the scratch pad buffer.
Once the MAX16816 receives the SET_READ_SCH
command, data on the scratchpad register is shifted
out. After 60 clock cycles, the MAX16816 completes
the SET_READ_SCH sequence. The BUSY signal is not
set by this command.
Programming
To program the MAX16816 on-chip EEPROM with a
pulldown device, directly connect FAULT to the DATA
IN input of a microcontroller (µC). Also, connect FAULT
to the DATA OUT output of a µC using an external
switch (Figure 5). Connect the EN of the µC directly to
UVEN to control the internal timer of the MAX16816 for
programming purposes. Ensure that VCC is greater
than the UVLO threshold because both UVEN and
FAULT are pulled up to 5V. See the
Electrical
Characteristic
tables for details.
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 25
Table 11. MAX16816 Memory Map (Scratchpad)
SCRATCHPAD
ADDRESS EEPROM ADDRESS REGISTER
1h Reserved Reserved
2h Reserved Reserved
3h Reserved Reserved
4h Reserved Reserved
5h Reserved Reserved
6h–9h 14h–23h Reserved
Ah 24h–27h Binning Adjustment Register
Bh 28h–2Bh REG2 Control Register
Ch 2Ch–2Fh Reserved
Dh 30h–33h Blanking Time Adjustment Register
Eh 34h–37h Digital Soft-Start Duration Register, Internal Oscillator Enable Bit
Fh 38h–3Bh Slope Compensation Register
MAX16816
VCC
FAULT
μC
READ
WRITE
DATA IN
DATA OUT
UVEN
EN
Figure 5. Programming Through a FAULT Pin
MAX16816
Programming Sequences
The µC (master) starts the communication with the
MAX16816 by pulling UVEN high. The MAX16816 then
does the handshaking with the µC by pulling FAULT low.
Once the µC receives the handshaking signal, it begins
the initialization sequences to reset the 1-Wire interface.
The sequence consists of a reset pulse from the µC fol-
lowed by a presence pulse from the MAX16816. At this
point the µC must send PASS_CODE_ONE and
PASS_CODE_TWO. These pass codes must be received
by the MAX16816 within the 8ms programming slot to
allow the MAX16816 to enter the EE programming mode.
1-Wire Signaling
The MAX16816 requires strict protocols to ensure data
integrity. The protocol consists of four types of signal-
ing on one line: reset sequence with Reset Pulse and
Presence Pulse, Write-Zero, Write-One, and Read-Data.
Except for the Presence Pulse, the bus master initiates
all falling edges.
Externally pull FAULT below VIL to indicate a logic-input
low. Release the pulldown device to indicate a logic-
input high. The MAX16816 will pull FAULT low below
VOL to indicate a logic-output low. FAULT is pulled high
with an internal 10kΩresistor above VOH to indicate a
logic-output high.
Initialization Procedure
(Reset and Presence Pulses)
All 1-Wire communication with the MAX16816 begins
with an initialization sequence that consists of a Reset
Pulse from the master followed by a Presence Pulse
from the MAX16816 (Figure 6). When the MAX16816
sends the Presence Pulse in response to the Reset
Pulse, it is indicating to the master that it is ready to
receive and transmit data.
During the initialization sequence, the bus master trans-
mits the reset pulse by pulling the 1-Wire bus low for a
minimum of 480µs. The bus master then releases the
bus and goes into receive mode. When the bus is
released, the pullup resistor pulls the 1-Wire bus high.
When the MAX16816 detects this rising edge, it waits
15µs to 60µs and then transmits a Presence Pulse by
pulling the 1-Wire bus low for 60µs to 240µs.
Read and Write Time Slots
The bus master writes data to the MAX16816 during
write time slots and reads data from the MAX16816
during read time slots. One bit of data is transmitted
over the 1-Wire bus per time slot.
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
26 ______________________________________________________________________________________
tRSTL
MASTER Tx "RESET PULSE" MASTER Rx "PRESENCE PULSE"
VOH
VOL OR VIL
0V
tMSP
RESISTOR MASTER MAX16816
Figure 6. 1-Wire Initialization Timing
Write Time Slots
There are two types of write time slots: Write-1 time
slots and Write-0 time slots. The bus master uses a
Write-1 time slot to write a logic ‘1’ to the MAX16816
and a Write-0 time slot to write a logic ‘0’. All write time
slots must be a minimum of 60µs in duration with a min-
imum of a 1µs recovery time between individual Write
slots. Both types of write time slots are initiated by the
master pulling the 1-Wire bus low (Figures 7 and 8).
To generate a Write-1 time slot, the bus master must
release the 1-Wire bus within 15µs after pulling the bus
low. When the bus is released, the pullup resistor will
pull the bus high. To generate a Write-0 time slot, the
bus master must continue to hold the bus low for the
duration of the time slot (at least 60µs) after pulling the
1-Wire bus low. The MAX16816 samples the 1-Wire bus
during a window that lasts from 15µs to 60µs after the
master initiates the Write time slot. If the bus is high
during the samples window, a ‘1’ is written to the
MAX16816. If the line is low, a ‘0’ is written to the
MAX16816.
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 27
RESISTOR MASTER
tW1L
tREC
tSLOT
VOH
VOL
0V
MAX16816
SAMPLING
WINDOW
Figure 7. 1-Wire Write-1 Time Slot
RESISTOR MASTER
VOH
VIL
tW0L
tREC
tSLOT
0V
MAX16816
SAMPLING
WINDOW
Figure 8. 1-Wire Write-0 Time Slot
MAX16816
Read Time Slots
The MAX16816 can only transmit data to the master
when the master issues read time slots.
All read time slots must be a minimum of 60µs in dura-
tion with a minimum of a 1µs recovery time between
slots. A read time slot is initiated by the master device
pulling the 1-Wire bus low for a minimum of 1µs and
then releasing it (Figure 9). After the master initiates the
read time slot, the MAX16816 will transmit a ‘1’ or a ‘0’
on the bus. The MAX16816 transmits a ‘1’ by leaving
the bus high and transmits a ‘0’ by pulling the bus low.
When transmitting a ‘0’, the MAX16816 will release the
bus before the end of the time slot, and the bus will be
pulled back to its high idle state by the pullup resistor.
Output data from the MAX16816 is valid for 15µs after the
falling edge that initiated the read time slot. Therefore, the
master must release the bus and then sample the bus
state within 15µs from the start of the slot.
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
28 ______________________________________________________________________________________
RESISTOR MASTER MAX16816
tREC
tSLOT
tRL
tMSR
MASTER
SAMPLING
WINDOW
VOH
VIL / VOL
0V
Figure 9. 1-Wire Read Time Slot
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 29
32 31 30 29 28 27 26
9 101112131415
18
19
20
21
22
23
24
7
6
5
4
3
2
1
MAX16816
TQFN
(5mm x 5mm)
+
TOP VIEW
UVEN
N.C.
REG1
AGND
REF
DIM
RTSYNC
8
CLKOUT
FAULT
VCC
REG2
HI
CLMP
CS-
CS+
25
LO
N.C.
DGT
QGND
SNS-
SNS+
DRI
DRV
17 SGND
OV
FB
16
SGND
CS
COMP
I.C.
I.C.
I.C.
*EP
*EP = EXPOSED PAD
Pin Configuration
Chip Information
PROCESS: BiCMOS
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
30 ______________________________________________________________________________________
VIN
RCS
CF
RT
RUV2
DRV
DRI
CS
VCC
SNS+
FB
QGND
RTSYNC
CS-
CS+ LO
COMP
REG2
DGT
OV
UVEN
SNS-
AGNDREG1
RSENSE
R2
C2
ROV1
ROV2
CLMP
SGND
CCLMP
CREG2
CREG1
R1
C1
RD
LEDs
RUV1
CUVEN
QS
FAULT
R3
R4
HI
REF
DIM
MAX16816
BOOST CONFIGURATION
Typical Operating Circuits (continued)
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
______________________________________________________________________________________ 31
VIN
RCS
CF
CREG1
RUV2
DRV
REG2
CS
VCC
SNS+
FB
QGND
RTSYNC
CS-
HI LO
COMP DRI
OV
UVEN
FAULT
SNS-
AGND
RSENSE
R2
C2
CLMP
SGND
CCLMP
CREG2
R1
C1
RD
LEDs
BUCK CONFIGURATION
RUV1
CUVEN
QS
MAX16816
REG1
DIM
CS+ DGT
RT
DIM
Typical Operating Circuits (continued)
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
32 ______________________________________________________________________________________
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
QFN THIN.EPS
MAX16816
Programmable Switch-Mode LED Driver
with Analog-Controlled PWM Dimming
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________
33
© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Heaney
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
