Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
EVALUATION KIT AVAILABLE
General Description
The MAX16838 is a dual-channel LED driver that inte-
grates both the DC-DC switching boost regulator and
two 150mA current sinks. A current-mode switching
DC-DC controller provides the necessary voltage to
both strings of HB LEDs. The MAX16838 accepts a wide
4.75V to 40V input voltage range and directly withstands
automotive load-dump events. For a 5V Q10% input volt-
age, connect VIN to VCC. The wide input range allows
powering HB LEDs for small-to-medium-sized LCD dis-
plays in automotive and display backlight applications.
An internal current-mode switching DC-DC controller
supports the boost or SEPIC topologies and operates
in an adjustable frequency range between 200kHz and
2MHz. The current-mode control provides fast response
and simplifies loop compensation. The MAX16838 also
features an adaptive output-voltage adjustment scheme
that minimizes the power dissipation in the LED current
sink paths. The MAX16838 can be combined with the
MAX15054 to achieve a buck-boost LED driver with two
integrated current sinks.
The channel current is adjustable from 20mA to 150mA
using an external resistor. The external resistor sets both
channel currents to the same value. The device allows
connecting both strings in parallel to achieve a maximum
current of 300mA in a single channel. The MAX16838
also features pulsed dimming control with minimum
pulse widths as low as 1Fs, on both channels through a
logic input (DIM).
The MAX16838 includes an output overvoltage protec-
tion, open LED, shorted LED detection and overtempera-
ture protection. The device operates over the -40NC to
+125NC automotive temperature range. The MAX16838
is available in the 20-pin TSSOP and 4mm x 4mm, 20-pin
TQFN packages.
Applications
Automotive Display Backlights
LCD Display Backlights
Automotive Lighting Applications
Features
S Integrated, 2-Channel, 20mA to 150mA Linear LED
Current Sinks
S Boost or SEPIC Power Topologies for Maximum
Flexibility
S Adaptive Voltage Optimization to Minimize Power
Dissipation in Linear Current Sinks
S 4.75V to 40V or 5V ±10% Input Operating Voltage
Range
S 5000:1 PWM Dimming at 200Hz
S Open-Drain Fault Indicator Output
S LED Open/Short Detection and Protection
S Output Overvoltage and Overtemperature
Protection
S Programmable LED Current Foldback at Lower
Input Voltages
S 200kHz to 2MHz Resistor Programmable
Switching Frequency with External
Synchronization
S Current-Mode Control Switching Stage with
Internal Slope Compensation
S Enable Input
S Thermally Enhanced, 20-Pin TQFN (4mm x 4mm)
and 20-Pin TSSOP Packages
19-4972; Rev 4; 3/16
Typical Operating Circuit and Pin Configurations appear at
end of data sheet.
Ordering Information
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
/V denotes an automotive qualified part.
PART TEMP RANGE PIN-PACKAGE
MAX16838ATP+ -40NC to +125NC20 TQFN-EP*
MAX16838ATP/V+ -40NC to +125NC20 TQFN-EP*
MAX16838AUP+ -40NC to +125NC20 TSSOP-EP*
MAX16838AUP/V+ -40NC to +125NC20 TSSOP-EP*
Simplified Schematic
RISET
R2OV
R1OV
COUT
LED
STRINGS
RRT RCS
CIN
IN DRAIN OV
NDRV
GATE
OUT1
OUT2
ISET
CS
RT
LEDGNDPGNDSGND
COMP
DIM
DRV
CFB
EN
4.75V TO 40V LD
VCC
RCOMP
CCOMP
FLT
MAX16838
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
2 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
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.
IN, OUT_, DRAIN to SGND ...................................-0.3V to +45V
EN to SGND ...............................................-0.3V to (VIN + 0.3V)
PGND to SGND ....................................................-0.3V to +0.3V
LEDGND to SGND ...............................................-0.3V to +0.3V
DRV to PGND .......... -0.3V to the lower of (VIN + 0.3V) and +6V
GATE to PGND ........................................................ -0.3V to +6V
NDRV to PGND .......................................-0.3V to (VDRV + 0.3V)
VCC, FLT, DIM, CS, OV, CFB, to SGND .................-0.3V to +6V
RT, COMP, ISET to SGND .........................-0.3V to (VCC + 0.3V)
DRAIN and CS Continuous Current .................................. Q2.5A
OUT_ Continuous Current ................................................175mA
VDRV Short-Circuit Duration .....................................Continuous
Continuous Power Dissipation (TA = +70NC)
20-Pin TQFN (derate 25.6mW/NC above +70NC) ............2051mW
20-Pin TSSOP (derate 26.5mW/NC above +70NC) ......2122mW
Operating Temperature Range ........................ -40NC to +125NC
Junction Temperature .....................................................+150NC
Storage Temperature Range ............................ -65NC to +150NC
Soldering Temperature (reflow) ......................................+260NC
ELECTRICAL CHARACTERISTICS
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, DRAIN, COMP, OUT_, FLT = unconnected, VOV
= VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = TJ = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = 25NC.) (Note 2)
ABSOLUTE MAXIMUM RATINGS
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
20 TQFN
Juction-to-Ambient Thermal Resistance (BJA) .......... +39NC/W
Junction-to-Case Thermal Resistance (BJC) ............... +6NC/W
20 TSSOP
Junction-to-Ambient Thermal Resistance (BJA) ..... +37.7NC/W
Junction-to-Case Thermal Resistance (BJC) ............... +2NC/W
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage Range VIN Internal LDO on 4.75 40 V
Input Voltage Range VIN VIN = VCC 4.55 5.5 V
Quiescent Supply Current IQVDIM = 5V 3.1 5 mA
Standby Supply Current ISH VEN = SGND (Note 3) 15.5 40 FA
Undervoltage Lockout UVLOIN VIN rising, VDIM = 5V 4 4.3 4.55 V
Undervoltage Lockout Hysteresis 177 mV
DRV REGULATOR
Output Voltage VDRV 5.75V < VIN < 10V, 0.1mA < ILOAD < 30mA 4.75 5 5.25 V
6.5V < VIN < 40V, 0.1mA < ILOAD < 3mA
Dropout Voltage VDO
(VIN - VDRV)VIN = 4.75V, IOUT = 30mA 0.11 0.5 V
Short-Circuit Current Limit DRV shorted to GND 97 mA
VCC Undervoltage Lockout
Threshold UVLOVCC VCC rising 3.4 4.0 4.4 V
VCC (UVLO) Hysteresis 123 mV
3Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, DRAIN, COMP, OUT_, FLT = unconnected, VOV
= VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = TJ = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = 25NC.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RT OSCILLATOR
Switching Frequency Range fSW 200 2000 kHz
Duty Cycle DMAX fSW = 200kHz 87 90 95 %
fSW = 2000kHz 83 85 91 %
Oscillator Frequency Accuracy fSW = 200kHz to 2MHz -7.5 +7.5 %
Synchronization Logic-High VRT rising 1.8 3.6 V
Synchronization Logic-Low VRT falling 2.5 V
Logic-Level Before SYNC
Capacitor 3.1 3.8 V
Synchronization Pulse Width 50 ns
SYNC Frequency Range fSYNC 1.1 x
fSW
1.5 x
fSW Hz
PWM COMPARATOR
Leading-Edge Blanking 66 ns
Propagation Delay to NDRV Including leading-edge blanking time 100 ns
SLOPE COMPENSATION
Slope Compensation Peak
Voltage per Cycle Voltage ramp added to CS 0.12 V
CS LIMIT COMPARATOR
CS Threshold Voltage VCS_MAX VCOMP = 3V 285 300 315 mV
CS Limit Comparator Propagation
Delay to NDRV
10mV overdrive (including leading-edge
blanking time) 100 ns
CS Input Current ICS 0 P VCS P 0.35V -1.3 +0.5 FA
ERROR AMPLIFIER
OUT_ Regulation Voltage VDIM = 5V 0.9 1 1.1 V
Transconductance Gm 340 600 880 FS
No-Load Gain A (Note 4) 50 dB
COMP Sink Current ISINK VDIM = VOUT_ = 5V, VCOMP = 3V 400 800 FA
COMP Source Current ISOURCE VDIM = 5V, VOUT_ = VCOMP = 0V 400 800 FA
MOSFET DRIVER
NDRV On-Resistance ISINK = 100mA, VIN > 5.5V 1.5 4 I
ISOURCE = 100mA, VIN > 5.5V 1.5 4 I
Peak Sink Current VNDRV = 5V 0.8 A
Peak Source Current VNDRV = 0V 0.8 A
POWER MOSFET
Power Switch On-Resistance ISWITCH = 0.5A, VGS = 5V 0.15 0.35 I
Switch Leakage Current VDRAIN = 40V, VGATE = 0V 0.003 1.2 FA
Switch Gate Charge VDRAIN = 40V, VGS = 4.5V 3.1 nC
4 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, DRAIN, COMP, OUT_, FLT = unconnected, VOV
= VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = TJ = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = 25NC.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
LED CURRENT SINKS
OUT_ Current Range IOUT_ VDIM = 5V, VOUT_ = 1.0V 20 150 mA
LED Strings Current Matching IOUT_ = 100mA, RISET = 15kI Q2 %
Maximum Peak-to-Peak Boost
Ripple
1% IOUT variation, IOUT = 100mA,
RISET = 15kI0.3 0.5 V
Output Current Accuracy
IOUT_ = 100mA,
RISET = 15kI
TA = +25NC 97 100 103 mA
TA = -40NC to +125NC 95 100 105 mA
IOUT_ = 20mA, RISET
= 75kITA = -40NC to +125NC 18.7 20 21.3 mA
OUT_ Leakage Current VDIM = 0V, VOUT_ = 40V 1 300 nA
Current Foldback Threshold
Voltage 1.23 V
CFB Input Bias Current 0 P VCFB P 1.3V -0.3 +0.3 FA
ENABLE COMPARATOR (EN)
Enable Threshold VENHI VEN rising 1.1 1.24 1.34 V
Enable Threshold Hysteresis VEN_HYS 71 mV
Enable Input Current VEN = 40V -500 +50 +700 nA
DIM LOGIC
DIM Input Logic-High VIH 2.1 V
DIM Input Logic-Low VIL 0.8 V
Hysteresis VDIM_HYS 110 mV
DIM Input Current IDIM VDIM = 5V or 0 -600 +100 nA
DIM to LED Turn-On Time VDIM rising edge to 90% of set current 50 290 1000 ns
DIM to LED Turn-Off Time VDIM falling edge to 10% of set current 10 121 700 ns
IOUT_ Rise Time tRRise time measured from 10% to 90% 120 600 ns
IOUT_ Fall Time tFFall time measured from 90% to 10% 50 500 ns
LED FAULT DETECTION
LED Shorted Fault Indicator
Threshold
3.1 5.5 V
TA = +125NC 3.55 4.2 4.85
LED String Shorted Shutoff
Threshold
6 9.5 V
TA = +125NC 6.8 7.7 8.6
Shorted LED Detection FLAG
Delay 6Fs
5Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, DRAIN, COMP, OUT_, FLT = unconnected, VOV
= VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = TJ = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = 25NC.) (Note 2)
Note 2: All devices are 100% tested at TA = +125NC. Limits over temperature are guaranteed by design, not production tested.
Note 3: The shutdown current does not include currents in the OV and CFB resistive dividers.
Note 4: Gain = DVCOMP/DVCS, 0.05V < VCS < 0.15V.
Typical Operating Characteristics
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, VDRAIN = VCOMP = VOUT_, FLT = unconnected,
VOV = VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = +25NC, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
FLT LOGIC
Output-Voltage Low VOL VIN = 4.75V and ISINK = 5mA 0.4 V
Output Leakage Current VFILT = 5.5V -300 +300 nA
OVERVOLTAGE PROTECTION
OV Trip Threshold VOV rising 1.19 1.23 1.265 V
OV Hysteresis 70 mV
OV Input Bias Current 0 P VOV P 1.3V -100 +100 nA
THERMAL SHUTDOWN
Thermal Shutdown 165 oC
Thermal Shutdown Hysteresis 15 oC
IIN vs. SUPPLY VOLTAGE
MAX16838 toc02
SUPPLY VOLTAGE (V)
IIIN (mA)
363228242016128
2.5
3.0
3.5
4.0
4.5
5.0
2.0
44
0
TA = +125°C
TA = +25°C
TA = -40°C
VIN = 12V
SWITCHING WAVEFORM AT 200Hz
(50% DUTY CYCLE)
MAX16838 toc01
10V/divVLX
ILED
VOUT
100mA/div
20V/div
0V
0V
0A
1ms/div
6 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Typical Operating Characteristics (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, VDRAIN = VCOMP = VOUT_, FLT = unconnected,
VOV = VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = +25NC, unless otherwise noted.)
IIN vs. FREQUENCY
FREQUENCY (MHz)
2.01.81.4 1.60.6 0.8 1.0 1.20.4
1
2
3
4
5
6
7
8
9
10
0
0.2 2.2
MAX16838 toc03
IIN (mA)
VIN = 12V
SWITCHING FREQUENCY
vs. TEMPERATURE
TEMPERATURE (°C)
SWITCHING FREQUENCY (kHz)
1109565 80-10 5 20 35 50-25
351
352
353
354
355
356
357
358
359
360
350
-40 125
MAX16838 toc04
VIN = 12V
VISET vs. TEMPERATURE
TEMPERATURE (°C)
VISET (V)
1109580655035205-10-25
1.216
1.217
1.218
1.219
1.220
1.221
1.222
1.223
1.215
-40 125
MAX16838 toc05
VIN = 12V
VDIM = 0V
VISET vs. ILED
ILED (mA)
VISET (V)
140120100806040
1.229
1.229
1.230
1.230
1.230
1.229
20 160
MAX16838 toc06
VIN = 12V
VEN_TH vs. TEMPERATURE
TEMPERATURE (°C)
VEN_TH (V)
1109580655035205-10-25
1.15
1.20
1.25
1.30
1.10
-40 125
MAX16838 toc07
VEN RISING
VEN FALLING
EN LEAKAGE CURRENT
vs. TEMPERATURE
TEMPERATURE (°C)
EN LEAKAGE CURRENT (nA)
1109580655035205-10-25
50
100
150
200
250
300
0
-40 125
MAX16838 toc08
VEN = 40V
VEN = 12V
7Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Typical Operating Characteristics (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, VDRAIN = VCOMP = VOUT_, FLT = unconnected,
VOV = VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = +25NC, unless otherwise noted.)
INPUT VOLTAGE (V)
DRV VOLTAGE (V)
40302010
4.980
4.985
4.990
4.995
5.000
5.005
5.010
4.975
05
0
DRV LINE REGULATION
MAX16838 toc09
TA = +125°C
TA = -40°C
TA = +25°C
DRV LOAD REGULATION
MAX16838 toc10
LOAD (mA)
VDRV (V)
252015105
4.970
4.975
4.980
4.985
4.990
4.995
5.000
5.005
5.010
4.965
03
0
TA = -40°C
TA = +25°C
TA = +125°C
VIN = 12V
FREQUENCY vs. RRT
RRT (kI)
FREQUENCY(MHz)
3632282420161284
0.5
1.0
1.5
2.0
2.5
0
04
0
MAX16838 toc11
VIN = 12V
LODIM MODE RESPONSE
MAX16838 toc12
10V/div
VIN
VDIM
VLED_
IOUT_
5V/div
100mA/div
0V
20V/div
0V
0V
0A
20ms/div
DIM ON-TIME < 5 x fSW
LED SWITCHING WITH DIM AT 200Hz
(50% DUTY CYCLE)
MAX16838 toc13
10mA/div
IOUT1
IOUT2
VDIM
100mA/div
0V
5V/div
0A
0A
2ms/div
ILED vs. RISET
RISET (kI)
ILED (mA)
25 30 35 40 45 50 55 60 65 70 7515 20
110
100
90
80
70
50
40
30
20
10
60
120
130
140
150
0
10
MAX16838 toc14
VIN = 12V
8 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Typical Operating Characteristics (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, VDRAIN = VCOMP = VOUT_, FLT = unconnected,
VOV = VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = +25NC, unless otherwise noted.)
COMP LEAKAGE CURRENT
vs. TEMPERATURE
TEMPERATURE (°C)
COMP LEAKAGE CURRENT (nA)
2.2
2.0
1.8
1.6
1.4
1.0
0.8
0.6
0.4
0.2
1.2
2.4
2.6
2.8
3.0
0
-40 -25 -10 5203550658095 110 125
MAX16838 toc15
VIN = 12V
VEN = HIGH
VCOMP = 2V
VDIM = LOW
OUT_ LEAKAGE CURRENT
vs. TEMPERATURE
TEMPERATURE (°C)
OUT_ LEAKAGE CURRENT (nA)
1109565 80-10 5 20 35 50-25
5
10
15
20
25
30
35
40
45
50
55
60
0
-40 125
MAX16838 toc16
VIN = 12V
VEN = HIGH VOUT = 40V
VOUT = 12V
POWER MOSFET RDSON
vs. TEMPERATURE
POWER MOSFET RDSON (I)
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0
MAX16838 toc18
1109565 80-10 5203550-25-40 125
TEMPERATURE (°C)
VIN = 12V
OV LEAKAGE CURRENT
vs. TEMPERATURE
OV LEAKAGE CURRENT (nA)
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
-2.0
VIN = 12V
VEN = HIGH
MAX16838 toc17
1109565 80-10 5203550-25-40 125
TEMPERATURE (°C)
9Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Pin Description
PIN NAME FUNCTION
TQFN TSSOP
1 4 NDRV Gate Drive for Switching MOSFET. Connect NDRV to GATE directly or through a resistor
to control the rise and fall times of the gate drive.
2 5 DRV
5V Regulator Output. MOSFET gate-driver supply input. Bypass DRV to PGND with a
minimum of 1FF ceramic capacitor. Place the capacitor as close as possible to DRV
and PGND.
3 6 VCC Internal Circuitry Supply Voltage. Bypass VCC to SGND with a minimum of 0.1FF
ceramic capacitor. Place the capacitor as close as possible to VCC and SGND.
4 7 IN Supply Input. Connect a 4.75V to 40V supply to IN. Bypass IN to PGND with a minimum
of 1FF ceramic capacitor. For a 5V Q10% supply voltage, connect VIN to VCC.
5 8 EN Enable/Undervoltage Lockout (UVLO) Threshold Input. EN is a dual-function input.
Connect EN to VIN through a resistor-divider to program the UVLO threshold.
6 9 SGND Signal Ground. SGND is the current return path connection for the low-noise analog
signals. Connect SGND, LEDGND, and PGND at a single point.
7 10 CFB
Current Foldback Reference Input. Connect a resistor-divider between IN, CFB, and
ground to set the current foldback threshold. When the voltage at CFB goes below
1.23V, the LED current starts reducing linearly. Connect to VCC to disable the current
foldback feature.
8 11 OV Overvoltage Threshold Adjust Input. Connect a resistor-divider from the switching
converter output to OV and SGND. The OV comparator reference is internally set to 1.23V.
9 12 ISET LED Current Adjust Input. Connect a resistor RISET from ISET to SGND to set the
current through each LED string (ILED) according to the formula ILED = 1512V/RISET.
10 13 FLT Open-Drain, Active-Low Flag Output. FLT asserts when there is an open/short-LED
condition at the output or when there is a thermal shutdown event.
11 14 OUT2
LED String Cathode Connection 2. OUT2 is the open-drain output of the linear current
sink that controls the current through the LED string connected to OUT2. OUT2 sinks
up to 150mA.
12 15 LEDGND LED Ground. LEDGND is the return path connection for the linear current sinks.
Connect SGND, LEDGND, and PGND at a single point.
13 16 OUT1
LED String Cathode Connection 1. OUT1 is the open-drain output of the linear current
sink that controls the current through the LED string connected to OUT1. OUT1 sinks
up to 150mA.
14 17 RT
Oscillator Timing Resistor Connection. Connect a timing resistor (RRT) from RT to SGND
to program the switching frequency. Apply an AC-coupled external clock at RT to
synchronize the switching frequency with an external clock source.
15 18 COMP Switching Converter Compensation Input. Connect an RC network from COMP to SGND
(see the Feedback Compensation section).
10 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Pin Description (continued)
PIN NAME FUNCTION
TQFN TSSOP
16 19 DIM Digital PWM Dimming Input
17 20 CS
Current-Sense Input. CS is the current-sense input for the switching regulator and is
also connected to the source of the internal power MOSFET. Connect a sense resistor
from CS to PGND to set the switching current limit.
18 1 DRAIN Internal Switching MOSFET Drain Output
19 2 GATE Internal Switching MOSFET Gate Input. Connect GATE to NDRV directly or through a
resistor to control the rise and fall times of the gate drive.
20 3 PGND Power Ground. PGND is the high-switching current return path connection. Connect
SGND, LEDGND, and PGND at a single point.
— — EP
Exposed Pad. EP is internally connected to SGND. Connect EP to a large-area
contiguous ground plane for effective power dissipation. Connect EP to SGND.
Do not use as the only ground connection.
11Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Simplified Functional Diagram
PWM
LOGIC
DRIVER
DRV
DRAIN
GATE
CS
NDRV
OUT
_
DIM
PGND
COMP
RT
CS
IN
DRV
VCC
EN
SGND LEDGND OV CFB ISET
POK SHDN
DIM
FLAG LOGIC
LOGIC
ARRAY = 2
PWM
COMP
GM
1.8V
1.0V
0.3V
1.17V
VBG
OV
DIM DUTY
TOO LOW
SOFT-
START
DAC
ILIM
SHORT-LED
DETECTOR
OPEN-LED
DETECTOR
MINIMUM
STRING
VOLTAGE
FLT
RT OSCILLATOR
CS BLANKING
SLOPE
COMPENSATION
THERMAL
SHUTDOWN
BANDGAP5V LDO
UVLO
UVLO
IN
SHDN
POK
VBG
VCC
VBG
0
1
10
OV
COMPARATOR
1
0
120mV
MAX16838
12 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Detailed Description
The MAX16838 high-efficiency, HB LED driver inte-
grates all the necessary features to implement a high-
performance backlight driver to power LEDs in small-to-
medium-sized displays for automotive as well as general
applications. The device provides load-dump voltage
protection up to 40V in automotive applications. The
MAX16838 incorporates a DC-DC controller with peak
current-mode control to implement a boost, coupled
inductor boost-buck, or SEPIC-type switched-mode
power supply and a 2-channel LED driver with 20mA
to 150mA constant-current-sink capability per channel.
The MAX16838 can be combined with the MAX15054 to
achieve boost-buck topology without a coupled inductor
(see Figure 5).
The MAX16838 features a constant-frequency peak
current-mode control with internal slope compensation
to control the duty cycle of the PWM controller. The
DC-DC converter generates the required supply volt-
age for the LED strings from a wide input supply range.
Connect LED strings from the DC-DC converter output
to the 2-channel constant current sinks that control the
current through the LED strings. A single resistor
connected from ISET to ground sets the forward current
through both LED strings.
The MAX16838 features adaptive LED voltage control
that adjusts the converter output voltage depending
on the forward voltage of the LED strings. This feature
minimizes the voltage drops across the constant-current
sinks and reduces power dissipation in the device. The
MAX16838 provides a very wide PWM dimming range
where a dimming pulse as narrow as 1Fs is possible at
a 200Hz dimming frequency.
A logic input (EN) shuts down the device when pulled low.
The device includes an internal 5V LDO to power up the
internal circuitry and drive the internal switching MOSFET.
The MAX16838 includes output overvoltage protec-
tion that limits the converter output voltage to the pro-
grammed OV threshold in the event of an open-LED
condition. The device also features an overtemperature
protection that shuts down the controller if the die tem-
perature exceeds +165°C. In addition, the MAX16838
has a shorted LED string detection and an open-drain
FLT signal to indicate open LED, shorted LED, and over-
temperature conditions.
Current-Mode DC-DC Controller
The MAX16838 uses current-mode control to provide
the required supply voltage for the LED strings. The
internal MOSFET is turned on at the beginning of every
switching cycle. The inductor current ramps up linearly
until it is turned off at the peak current level set by the
feedback loop. The peak inductor current is sensedfrom
the voltage across the current-sense resistor (RCS)
connected from the source of the internal MOSFET to
PGND. A PWM comparator compares the current-sense
voltage plus the internal slope compensation signal with
the output of the transconductance error amplifier. The
controller turns off the internal MOSFET when the voltage
at CS exceeds the error amplifier’s output voltage. This
process repeats every switching cycle to achieve peak
current-mode control.
Error Amplifier
The internal error amplifier compares an internal feed-
back (FB) signal with an internal reference voltage
(VREF) and regulates its output to adjust the inductor
current. An internal minimum string detector measures
the minimum LED string cathode voltage with respect
to SGND. During normal operation, this minimum VOUT_
voltage is regulated to 1V through feedback. The result-
ing DC-DC converter output voltage is 1V above the
maximum required total LED voltage.
The converter stops switching when LED strings are
turned off during PWM dimming. The error amplifier is
disconnected from the COMP output to retain the com-
pensation capacitor charge. This allows the converter to
settle to a steady-state level immediately when the LED
strings are turned on again. This unique feature provides
fast dimming response without having to use large out-
put capacitors. If the PWM dimming on-pulse is less than
five switching cycles, the feedback controls the voltage
on OV such that the converter output voltage is regu-
lated at 95% of the OV threshold. This mode ensures
that narrow PWM dimming pulses are not affected by
the response time of the converter. During this mode,
the error amplifier remains continuously connected to
the COMP output.
Adaptive LED Voltage Control
The MAX16838 reduces power dissipation using an
adaptive LED voltage control scheme. The adaptive LED
voltage control regulates the DC-DC converter output
based on the operating voltage of the LED strings.
13Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
The voltage at each of the current-sink outputs (OUT_)
is the difference between the DC-DC regulator output
voltage (VLED) and the total forward voltage of the LED
string connected to the output (OUT_). The DC-DC con-
verter then adjusts VLED until the output channel with
the lowest voltage at OUT_ is 1V relative to LEDGND. As
a result, the device minimizes power dissipation in the
current sinks and still maintains LED current regulation.
For efficient adaptive control functionality, use an equal
number of HB LEDs of the same forward voltage rating
in each string.
Current Limit
The MAX16838 includes a fast current-limit comparator
to terminate the on-cycle during an overload or a fault
condition. The current-sense resistor (RCS) connected
between the source of the internal MOSFET and ground
sets the current limit. The CS input has a 0.3V voltage
trip level (VCS). Use the following equation to calculate
RCS:
RCS = (VCS)/IPEAK
where IPEAK is the peak current that flows through the
MOSFET.
Undervoltage Lockout
The MAX16838 features two undervoltage lockouts:
UVLOIN and UVLOVCC. The undervoltage lockout
threshold for VIN is 4.3V (typ) and the undervoltage
lockout threshold for VCC is 4V (typ).
Soft-Start
The MAX16838 features a soft-start that activates during
power-up. The soft-start ramps up the output of the con-
verter in 64 steps in a period of 100ms (typ), unless both
strings reach regulation point, in which case the soft-start
would terminate to resume normal operation immediately.
Once the soft-start is over, the internal soft-start circuitry
is disabled and the normal operation begins.
Oscillator Frequency/External Synchronization
The MAX16838 oscillator frequency is programmable
between 200kHz and 2MHz using one external resis-
tor (RRT) connected between RT and SGND. The PWM
MOSFET driver output switching frequency is the same
as the oscillator frequency. The oscillator frequency is
determined using the following formula:
fSW = (7.342X109/RRT)(Hz)
where RRT is in ω.
Synchronize the oscillator with an external clock by
AC-coupling the external clock to the RRT input. The
capacitor used for the AC-coupling should satisfy the
following relation:
3
SYNC
T
9.862
C 0.144 10 ( F)
R
−
≤ −× µ
where RRT is in I.
The pulse width for the synchronization signal should
satisfy the following relations:
PW S
CLK
PW SS
CLK
tV 0.8
t
t
0.8 V V 3.4
t
<
− +>
where tPW is the synchronization source pulse width,
tCLK is the synchronization clock time period, and VS
is the synchronization pulse voltage level. See Figure 1.
5V LDO Regulator (DRV)
The internal LDO regulator converts the input voltage
at IN to a 5V output voltage at DRV. The LDO regulator
output supports up to 30mA current, enough to provide
power to the internal control circuitry and the gate driver.
Figure 1. Synchronizing External Clock Signal
VS
tPW
tCLK
14 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Connect a 4.7I resistor from VCC to DRV to power the
rest of the chip from the VCC pin with the 5V internal
regulator. Bypass DRV to PGND with a minimum of 1FF
ceramic capacitor as close as possible to the device. For
input voltage range of 4.5V to 5.5V, connect IN to VCC.
LED Current Control (ISET)
The MAX16838 features two identical constant-current
sources used to drive multiple HB LED strings. The
current through each of the channels is adjustable
between 20mA and 150mA using an external resistor
(RISET) connected between ISET and SGND. Select
RISET using the following formula:
= Ω
ISET OUT _
1512
R ()
I
where IOUT_ is the desired output current for both
channels in amps.
For single-channel operation, connect channel 1 and
channel 2 together. See Figure 2.
LED Dimming Control
The MAX16838 features LED brightness control using an
external PWM signal applied at DIM. The device accepts
a minimum pulse width of 1Fs. Therefore, a 5000:1 dim-
ming ratio is achieved when using a PWM frequency of
200Hz. Drive DIM high to enable both LED current sinks
and drive DIM low to disable both LED current sinks.
The duty cycle of the PWM signal applied to DIM also
controls the DC-DC converter’s output voltage. If the
turn-on duration of the PWM signal is less than five
oscillator clock cycles, then the boost converter regu-
lates its output based on feedback from the OV input.
During this mode, the converter output voltage is regu-
lated to 95% of the OV threshold voltage. If the turn-on
duration of the PWM signal is greater than or equal to
six oscillator clock cycles, then the converter regulates
its output such that the minimum voltage at OUT_ is 1V.
When the DIM signal crosses the 5 or 6 oscillator clock
cycle boundary, the control loop of the MAX16838 expe-
riences a discontinuity due to an internal mode transi-
tion that can cause flickering (the boost output voltage
changes as described in the previous paragraph). To
avoid flicker, the following is recommended:
S Avoid crossing the 5 or 6 oscillator clock cycle
boundary. Furthermore, DIM duty cycles that close to
the 5 or 6 cycle boundary should not be used.
S Do not set the OVP level higher than 3V above the
maximum LED operating voltage.
S Optimize the compensation components so that
recovery is as fast as possible, If the loop phase
margin is less than 45°, the output voltage can ring
during the 5 or 6 oscillator clock cycle boundary
crossing, which can contribute to flicker.
Fault Protections
The MAX16838 fault protections include cycle-by-cycle
current limiting, DC-DC converter output overvoltage
protection, open-LED detection, short-LED detection,
and overtemperature detection. An open-drain LED fault
flag output (FLT) goes low when an open-LED/short-LED
or overtemperature condition is detected.
Open-LED Management and Overvoltage Protection
The MAX16838 monitors the drains of the current sinks
(OUT_) to detect any open string. If the voltage at
any output falls below 300mV and the OV threshold is
triggered (i.e., even with OUT_ at the OV voltage the
string is not able to regulate above 300mV), then the
MAX16838 interprets that string to be open, asserts FLT,
and disconnects that string from the operation loop. The
MAX16838 features an adjustable overvoltage threshold
input (OV). Connect a resistor-divider from the switching
converter output to OV and SGND to set the overvoltage
threshold level.
Figure 2. Configuration for Higher LED String Current
OUT1
OUT2
MAX16838
40mA TO 300mA
BOOST
CONVERTER
OUTPUT
15Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Use the following formula to program the overvoltage
threshold:
OV
OV OV
R2
V 1.23V 1 R1
= ×+
Open-LED detection is disabled when PWM pulse width
is less than five switching clock cycles.
Short-LED Detection
The MAX16838 features a two-level short-LED detection
circuitry. If a level 1 short is detected on any one of the
strings, FLT is asserted. A level 1 short is detected if
the difference between the total forward LED voltages
of the two strings exceeds 4.2V (typ). If a level 2 short
is detected on any one of the strings, the particular LED
string with the short is turned off after 6Fs and FLT is
asserted. A level 2 short is detected if the difference
between the total forward LED voltages of the two strings
exceeds 7.8V (typ). The strings are reevaluated on each
DIM rising edge and FLT is deasserted if the short is
removed. Short-LED detection is disabled when PWM
pulse width is less than five switching clock cycles.
Enable (EN)
EN is a logic input that completely shuts down the
device when connected to logic-low, reducing the
current consumption of the device to less than 15FA
(typ). The logic threshold at EN is 1.24V (typ). The volt-
age at EN must exceed 1.24V before any operation can
commence. There is a 71mV hysteresis on EN. The EN
input also allows programming the supply input UVLO
threshold using an external voltage-divider to sense the
input voltage, as shown in Figure 3. Use the following
equation to calculate the value of R1EN and R2EN in
Figure 3:
= −×
ON
EN EN
UVLOIN
V
R1 1 R2
V
where VUVLOIN is the EN rising threshold (1.24V) and
VON is the desired input startup voltage. Choose an
R2EN between 10kI and 50kI. Connect EN to IN if not
used.
Current Foldback
The MAX16838 includes a current-foldback feature to
limit the input current at low VIN. Connect a resistor-
divider between IN, CFB, and SGND to set the current-
foldback threshold. When the voltage at CFB goes below
1.23V, then the LED current starts reducing proportion-
ally to VCFB.
This feature can also be used for analog dimming of the
LEDs. Connect CFB to VCC to disable this feature.
Applications Information
Boost-Circuit Design
First, determine the required input supply voltage range,
the maximum voltage needed to drive the LED strings
including the minimum 1V across the constant LED
current sink (VLED), and the total output current needed
to drive the LED strings (ILED).
Calculate the maximum duty cycle (DMAX) using the
following equation:
DMAX = (VLED + VD – VIN_MIN)/(VLED + VD)
where VD is the forward drop of the rectifier diode,
VIN_MIN is the minimum input supply voltage, and
VLED is the output voltage. Select the switching
frequency (fSW) depending on the space, noise, dynam-
ic response, and efficiency constraints.
Figure 3. Setting the MAX16838 Undervoltage Lockout
Threshold
MAX16838
1.24V
EN
R1EN
R2EN
VIN
16 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Inductor Selection in Boost Configuration
Select the maximum peak-to-peak ripple on the inductor
current (ILP-P). Use the following equations to calculate
the maximum average inductor current (ILAVG) and
peak inductor current (ILPEAK):
ILAVG = ILED/(1 - DMAX)
Assuming ILP-P is 40% of the average inductor current:
ILP-P = ILAVG x 0.4
ILPEAK = ILAVG + ILP-P/2
Calculate the minimum inductance value LMIN with the
inductor current ripple set to the maximum value:
LMIN = VIN_MIN x DMAX/(fSW x ILP-P)
Choose an inductor that has a minimum inductance
greater than the calculated LMIN and current rating
greater than ILPEAK. The recommended saturation
current limit of the selected inductor is 10% higher than
the inductor peak current. The ILP-P can be chosen
to have a higher ripple than 40%. Adjust the minimum
value of the inductance according to the chosen ripple.
One fact that must be noted is that the slope compensa-
tion is fixed and has a 120mV peak per switching cycle.
The dv/dt of the slope compensation ramp is 120fSWV/
Fs, where fSW is in kHz. After selecting the inductance
it is necessary to verify that the slope compensation is
adequate to prevent subharmonic oscillations. In the
case of the boost, the following criteria must be satisfied:
120fSW > RCS (VLED - 2VIN_MIN)/2L
where L is the inductance value in FH, RCS is the
current-sense resistor value in ω, VIN_MIN is the mini-
mum input voltage in V, VLED is the output voltage, and
fSW is the switching frequency in kHz.
If the inductance value is chosen to keep the inductor
in discontinuous conduction mode, the equation above
does not need to be satisfied.
Output Capacitor Selection in
Boost Configuration
For the boost converter, the output capacitor
supplies the load current when the main switch is on.
The required output capacitance is high, especially at
higher duty cycles.
Calculate the output capacitor (COUT) using the follow-
ing equation:
COUT > (DMAX x ILED)/(VLED_P-P x fSW)
where VLED_P-P is the peak-to-peak ripple in the LED
supply voltage. Use a combination of low-ESR and high-
capacitance ceramic capacitors for lower output ripple
and noise.
Input Capacitor Selection in Boost Configuration
The input current for the boost converter is continuous
and the RMS ripple current at the input capacitor is low.
Calculate the minimum input capacitor CIN using the fol-
lowing equation:
CIN = ILP-P/(8 x fSW x VIN_P-P)
where VIN_P-P is the peak-to-peak input ripple voltage.
This equation assumes that input capacitors supply
most of the input ripple current.
Rectifier Diode Selection
Using a Schottky rectifier diode produces less forward drop
and puts the least burden on the MOSFET during reverse
recovery. A diode with considerable reverse-recovery time
increases the MOSFET switching loss. Select a Schottky
diode with a voltage rating 20% higher than the maximum
boost-converter output voltage and current rating greater
than that calculated in the following equation:
( ) ( )
-=
D AVG MAX
I IL 1 D A
Feedback Compensation
The voltage feedback loop needs proper compensa-
tion for stable operation. This is done by connecting
a resistor (RCOMP) and capacitor (CCOMP) in series
from COMP to SGND. RCOMP is chosen to set the high-
frequency integrator gain for fast transient response,
while CCOMP is chosen to set the integrator zero to main-
tain loop stability. For optimum performance, choose the
components using the following equations:
××
=× × × ×−
ZRHP CS LED
COMP COMP LED MAX
f RI
R5 FP1 GM V (1 D )
where:
−
=××
2
LED MAX
ZRHP LED
V (1 D )
f 2 LI
π
is the right-half plane zero for the boost regulator.
RCS is the current-sense resistor in series with the
source of the internal switching MOSFET. ILED is the total
LED current that is the sum of the LED currents in both
the channels. VLED is the output voltage of the boost
regulator. DMAX is the maximum duty cycle that occurs
17Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
at minimum input voltage. GMCOMP is the transconduc-
tance of the error amplifier.
=×× ×
LED
LED OUT
I
FP1 2V C
π
is the output pole formed by the boost regulator.
Set the zero formed by RCOMP and CCOMP a decade
below the crossover frequency. Using the value of
RCOMP from above, the crossover frequency is at
fZRHP/5.
=
××
COMP COMP ZRHP
50
C 2R f
π
SEPIC Operation
Figure 4 shows a SEPIC application circuit using the
MAX16838. The SEPIC topology is necessary to keep
the output voltage of the DC-DC converter regulated
when the input voltage can rise above and drop below
the output voltage.
Boost-Buck Configuration
Figure 5 shows a boost-buck configuration with the
MAX16838 and MAX15054.
PCB Layout Considerations
LED driver circuits based on the MAX16838 device use
a high-frequency switching converter to generate the
voltage for LED strings. Take proper care while laying
out the circuit to ensure proper operation. The switching-
converter part of the circuit has nodes with very fast volt-
age changes that could lead to undesirable effects on
the sensitive parts of the circuit. Follow these guidelines
to reduce noise as much as possible:
1) Connect the bypass capacitor on VCC and DRV as
close as possible to the device, and connect the
capacitor ground to the analog ground plane using
vias close to the capacitor terminal. Connect SGND
Figure 4. SEPIC Configuration
RISET
R2OV
R1OV
COUT
LED
STRINGS
RRT RCS
R2EN
R1EN
CVCC
CDRV
RDRV
IN DRAIN OV
NDRV
GATE
OUT1
OUT2
ISET
CS
RT
LEDGNDPGNDSGND
COMP
DIM
DRV
CFB
EN
CIN
Cs
4.75V TO 40V L1
L2
D
VCC
RCOMP
CCOMP
FLT
MAX16838
18 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
of the device to the analog ground plane using a via
close to SGND. Lay the analog ground plane on the
inner layer, preferably next to the top layer. Use the
analog ground plane to cover the entire area under
critical signal components for the power converter.
2) Have a power ground plane for the switching-
converter power circuit under the power compo-
nents (input filter capacitor, output filter capacitor,
inductor, MOSFET, rectifier diode, and current-
sense resistor). Connect PGND to the power ground
plane as close to PGND as possible. Connect all
other ground connections to the power ground
plane using vias close to the terminals.
3) There are two loops in the power circuit that carry
high-frequency switching currents. One loop is
when the MOSFET is on—from the input filter
capacitor positive terminal, through the inductor, the
internal MOSFET, and the current-sense resistor, to
the input capacitor negative terminal. The other loop
is when the MOSFET is off—from the input capacitor
positive terminal, through the inductor, the rectifier
diode, output filter capacitor, to the input capaci-
tor negative terminal. Analyze these two loops and
make the loop areas as small as possible. Wherever
possible, have a return path on the power ground
plane for the switching currents on the top layer
copper traces, or through power components. This
reduces the loop area considerably and provides
a low-inductance path for the switching currents.
Reducing the loop area also reduces radiation dur-
ing switching.
4) Connect the power ground plane for the constant-
current LED driver part of the circuit to LEDGND as
close as possible to the device. Connect SGND to
PGND at the same point.
Figure 5. Boost-Buck Configuration
Q1
C1
VDD BST
D1
CBST
LX
HI
HDRV
GND
MAX15054
RISET
R1OV
R2OV
COUT
LED
STRINGS
RRT RCS
R1EN
VIN
R2EN
CVCC
D2
CDRV
RDRV
IN GATE NDRV
DRAIN
OV
OUT1
OUT2
ISET
CS
RT
LEDGNDPGNDSGND
COMP
DIM
DRV
CFB
EN
LD3
VCC
CIN
RCOMP
CCOMP
FLT
MAX16838
19Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Typical Operating Circuit
Pin Configurations
MAX16838
TOP VIEW
4
5
+
3
2
12
11
13
CFB
ISET
14
SGND
GATE
CS
DIM
PGND
67
VCC
910
*EP
*EXPOSED PAD
20 19 17 16
IN
EN
RT
OUT1
LEDGND
OUT2
OV DRAIN
8
18
DRV
115 COMP
NDRV
20
19
18
17
16
15
14
1
2
3
4
5
6
7
CS
DIM
COMP
RTNDRV
PGND
GATE
DRAIN
MAX16838
OUT1
LEDGND
OUT2IN
VCC
138 FLTEN
129 ISETSGND
1110 OVCFB
DRV
TSSOP
TQFN
FLT
+
*EP
RISET
R2OV
R1OV
COUT
LED
STRINGS
RRT RCS
R2EN
R1EN
CVCC
CIN
CDRV
RDRV
IN DRAIN OV
NDRV
GATE
OUT1
OUT2
ISET
CS
RT
LEDGNDPGNDSGND
COMP
DIM
DRV
CFB
EN
4.75V TO 40V LD
VCC
RCOMP
CCOMP
FLT
MAX16838
20 Maxim Integrated
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Chip Information
PROCESS: BiCMOS DMOS
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages.
Note that a “+”, “#”, or “-” in the package code indicates
RoHS status only. Package drawings may show a different
suffix character, but the drawing pertains to the package
regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
20 TQFN-EP T2044+3 21-0139 90-0037
20 TSSOP-EP U20E+1 21-0108 90-0114
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 21
© 2016 Maxim Integrated Products, Inc. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
MAX16838
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 9/02 Initial release —
1 12/09 Added /V part number, updated soldering temperature 1, 2
2 4/11 Corrected formulas for CSYNC and OVP 2, 13, 14
3 6/13 Updated Open-LED Management and Overvoltage Protection and Short-LED
Detection sections and corrected equation in Rectifier Diode Selection section 14, 16
4 3/16 Updated LED Dimming Control section 14
