MAX16809ATU+T - Hytronics

General Description

The MAX16809 is an integrated, high-efficiency white or

RGB LED driver. It is designed for LCD backlighting

and other LED lighting applications with multiple strings

of LEDs. The MAX16809’s current-mode PWM con-

troller regulates the necessary voltage to the LED array.

Depending on the input voltage and LED voltage

range, this device can be used with boost or buck-

boost (SEPIC) topologies.

The MAX16809 LED driver includes 16 open-drain, con-

stant-current-sinking LED driver outputs rated for 36V

continuous operation. The LED current-control circuitry

achieves ±3% current matching among strings and

enables paralleling of outputs for LED string currents

higher than 55mA. The output-enable pin is used for

simultaneous PWM dimming of all output channels.

Dimming frequency range is 50Hz to 30kHz and dim-

ming ratio is up to 5000:1. The constant-current outputs

are single resistor programmable and the LED current

can be adjusted up to 55mA per output channel.

The MAX16809 operates either in stand-alone mode or

with a microcontroller (μC) using an industry-standard, 4-

wire serial interface.

The MAX16809 includes overtemperature protection,

operates over the full -40°C to +125°C temperature

range, and is available in a 5mm x 7mm thermally

enhanced, 38-pin TQFN exposed paddle package.

Features

♦16 Constant-Current Output Channels (Up to

55mA Each)

♦±3% Current Matching Among Outputs

♦Paralleling Channels Allows Higher Current per

LED String

♦Outputs Rated for 36V Continuous Voltage

♦Output-Enable Pin for PWM Dimming (Up to 30kHz)

♦One Resistor Sets LED Current for All Channels

♦Wide Dimming Ratio Up to 5000:1

♦Low Current-Sense Reference (300mV) for High

Efficiency

♦8V to 26.5V Input Voltage or Higher with External

Biasing Devices

♦4-Wire Serial Interface to Control Individual

Output Channels

Applications

LCD White or RGB LED Backlighting:

LCD TVs, Desktop, and Notebook Panels

Automotive Navigation, Heads-Up,

and Infotainment Displays

Industrial and Medical Displays

Ambient, Mood, and Accent Lighting

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

________________________________________________________________

Maxim Integrated Products

19-0656; Rev 2; 8/09

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

PART TEMP RANGE PIN-PACKAGE

MAX16809ATU+ -40°C to +125°C 38 TQFN-EP*

Denotes a lead(Pb)-free/RoHS-compliant package.

EP = Exposed pad.

OUT0

OUT1

OUT2

OUT3

OUT4

OUT5

OUT6

OUT7

SET

DIN

PGND

VCC

V+

DOUT

CLK

REF RTCT

CREF

RSET

CIN

CBYP

RCS

CC2

CC1

OUT CS AGND COMP

RC1 R2

COUT

3V TO 5.5V

VIN VOUT

LEDs

STAND-ALONE OPERATION

MAX16809

OUT8

OUT9

OUT10

OUT11

OUT12

OUT13

OUT14

OUT15

Typical Operating Circuits

Typical Operating Circuits continued at end of data sheet.

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS (PWM CONTROLLER)

(VCC = +15V, V+ = +3V to +5.5V referenced to PGND, RT= 10kΩ, CT= 3.3nF, REF = open, COMP = open, CREF = 0.1μF, VFB = 2V,

CS = AGND, AGND = PGND = 0V; all voltages are measured with respect to AGND, unless otherwise noted. TJ= TA = -40°C to

+125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)

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 to AGND..........................................................-0.3V to +30V

Current into VCC (VCC > 24V) .............................................30mA

V+ to PGND..............................................................-0.3V to +6V

OUT to AGND.............................................-0.3V to (VCC + 0.3V)

OUT Current (10μs duration) .................................................±1A

FB, COMP, CS, RTCT, REF to AGND.......................-0.3V to +6V

COMP Sink Current.............................................................10mA

OUT0–OUT15 to PGND..........................................-0.3V to +40V

DIN, CLK, LE, OE, SET to PGND..................-0.3V to (V+ + 0.3V)

DOUT Current...................................................................±10mA

OUT0–OUT15 Sink Current.................................................60mA

Total PGND Current (1s pulse time) .................................960mA

Continuous Power Dissipation (TA= +70°C)

38-Pin TQFN (derate 35.7mW/°C* above +70°C)......2857mW

Operating Temperature Range .........................-40°C to +125°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

Per JEDEC51 Standard (Multilayer Board).

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

REFERENCE

Output Voltage VREF IREF = 1mA, TJ = +25°C 4.95 5 5.05 V

Line Regulation ΔVLINE 12V< VCC < 25V, IREF = 1mA 0.4 4 mV

Load Regulation ΔVLOAD 1mA < IREF < 20mA 6 50 mV

Total Output-Voltage Variation VREFT (Note 2) 4.875 5.125 V

Output Noise Voltage VNOISE 10Hz < f < 10kHz 50 μV

Output Short-Circuit Current ISHORT VREF = 0V 30 180 mA

OSCILLATOR

Initial Accuracy TJ = +25°C 51 54 57 kHz

Voltage Stability 12V < VCC < 25V 0.2 0.5 %

Temperature Stability 1%

RTCT Ramp Peak-to-Peak 1.7 V

RTCT Ramp Valley 1.1 V

VRTCT = 2V, TJ = +25°C 7.9 8.3 8.7

Discharge Current IDIS VRTCT = 2V, -40oC ≤ TJ ≤ +125°C 7.5 8.3 9.0 mA

Frequency Range fOSC 20 1000 kHz

ERROR AMPLIFIER

FB Input Voltage VFB FB shorted to COMP 2.45 2.5 2.55 V

Input Bias Current IB(FB) -0.01 -0.1 μA

Open-Loop Gain AVOL 2V ≤ VCOMP ≤ 4V 100 dB

Unity-Gain Bandwidth fGBW 1 MHz

Power-Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25V 60 80 dB

COMP Sink Current ISINK VFB = 2.7V, VCOMP = 1.1V 2 6 mA

COMP Source Current ISOURCE VFB = 2.3V, VCOMP = 5V 0.5 1.2 1.8 mA

COMP Output-Voltage High VOH VFB = 2.3V, RCOMP = 15kΩ to AGND 5 5.8 V

COMP Output-Voltage Low VOL VFB = 2.7V, RCOMP = 15kΩ to VREF 0.1 1.1 V

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (PWM CONTROLLER) (continued)

(VCC = +15V, V+ = +3V to +5.5V referenced to PGND, RT= 10kΩ, CT= 3.3nF, REF = open, COMP = open, CREF = 0.1μF, VFB = 2V,

CS = AGND, AGND = PGND = 0V; all voltages are measured with respect to AGND, unless otherwise noted. TJ= TA = -40°C to

+125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CURRENT-SENSE AMPLIFIER

Current-Sense Gain ACS (Notes 3, 4) 2.85 3 3.40 V/V

Maximum Current-Sense Signal VCS_MAX (Note 3) 0.275 0.300 0.325 V

Power-Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25V 70 dB

Current-Sense Input Bias Current ICS VCOMP = 0V -1 -2.5 μA

Current Sense to OUT Delay tPWM 50mV overdrive 60 ns

MOSFET DRIVER

TJ = -40°C to +85°C (Note 2) 4.5 10

OUT Low-Side On-Resistance VRDS_ONL ISINK = 200mA TJ = -40°C to +125°C 4.5 12

TJ = -40°C to +85°C (Note 2) 3.5 7.5

OUT High-Side On-Resistance VRDS_ONH ISOURCE =

100mA TJ = -40°C to +125°C 3.5 10

Source Current (Peak) ISOURCE CLOAD = 10nF 2 A

Sink Current (Peak) ISINK CLOAD = 10nF 1 A

Rise Time tRCLOAD = 1nF 15 ns

Fall Time tFCLOAD = 1nF 22 ns

UNDERVOLTAGE LOCKOUT/STARTUP

Startup Voltage Threshold VCC_START 7.98 8.4 8.82 V

Minimum Operating Voltage After

Turn-On VCC_MIN 7.1 7.6 8.0 V

Undervoltage-Lockout Hysteresis UVLOHYST 0.8 V

PULSE-WIDTH MODULATION (PWM)

Maximum Duty Cycle DMAX 94.5 96 97.5 %

Minimum Duty Cycle DMIN 0%

SUPPLY CURRENT

Startup Supply Current ISTART VCC = 7.5V 32 65 μA

Operating Supply Current ICC VFB = VCS = 0V 3 5 mA

VCC Zener Voltage VZICC = 25mA 24 26.5 V

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (LED DRIVER)

(V+ = +3V to +5.5V, AGND = PGND = 0V; all voltages are measured with respect to PGND, unless otherwise noted. TA= TJ= -40°C

to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Operating Supply Voltage V+ 3.0 5.5 V

Output Voltage VOUT_ _ 36 V

Standby Current (Interface Idle, All

Output Ports High Impedance)

RSET = 360Ω, DIN, LE, CLK = PGND or V+,

OE = V+, DOUT unconnected 3.6 4.5 mA

Standby Current

(Interface Active, All Output Ports

High Impedance)

RSET = 360Ω, fCLK = 5MHz, OE = V+,

DIN, LE = PGND or V+, DOUT unconnected 3.8 4.8 mA

Supply Current

(Interface Idle, All Output Ports

Active Low)

I+ RSET = 360Ω, OE = PGND, DIN,

LE = V+, DOUT unconnected 30 52.5 mA

INTERFACE (DIN, CLK, DOUT, LE, OE)

Input-Voltage High

(DIN, CLK, LE, OE)VIH 0.7

x V+ V

Input-Voltage Low

(DIN, CLK, LE, OE)VIL 0.3

x V+ V

Hysteresis Voltage

(DIN, CLK, LE, OE)VHYST 0.8 V

Input Leakage Current

(DIN, CLK) ILEAK -1 +1 μA

OE Pullup Current to V+ IOE V+ = 5.5V, OE = PGND 0.25 1.5 25 μA

LE Pulldown Current to PGND ILE V+ = 5.5V, LE = V+ 0.25 1.5 25 μA

Output-Voltage High (DOUT) VOH ISOURCE = 4mA V+

- 0.5V V

Output-Voltage Low (DOUT) VOL ISINK = 4mA 0.5 V

0°C ≤ TA ≤ +125°C, VOUT = 1V to 2.5V,

RSET = 360Ω43.25 47.5 51.75

OUT_ _ Output Current IOUT_ _ TA = -40°C, VOUT = 1V to 2.5V,

RSET = 360Ω40 55

OUT_ _ Leakage Current OE = V+ 1 μA

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

_______________________________________________________________________________________ 5

5V TIMING CHARACTERISTICS

(V+ = +4.5V to +5.5V, AGND = PGND = 0V; all voltages are measured with respect to PGND, unless otherwise noted. TA= TJ=

-40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 5)

PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS

INTERFACE TIMING CHARACTERISTICS

CLK Clock Period tCP 40 ns

CLK Pulse-Width High tCH 19 ns

CLK Pulse-Width Low tCL 19 ns

DIN Setup Time tDS 4ns

DIN Hold Time tDH 8ns

DOUT Propagation Delay tDO 10 50 ns

DOUT Rise Time tDR CDOUT = 10pF, 20% to 80% 10 ns

DOUT Fall Time tDF CDOUT = 10pF, 80% to 20% 10 ns

LE Pulse-Width High tLW 20 ns

LE Setup Time tLS 15 ns

LE Rising to OUT_ _ Rising Delay tLRR (Note 6) 110 ns

LE Rising to OUT_ _ Falling Delay tLRF (Note 6) 340 ns

CLK Rising to OUT_ _ Rising Delay tCRR (Note 6) 110 ns

CLK Rising to OUT_ _ Falling Delay tCRF (Note 6) 340 ns

OE Rising to OUT_ _ Rising Delay tOER(Note 6) 110 ns

OE Falling to OUT_ _ Falling Delay tOEF(Note 6) 340 ns

OUT_ _ Turn-On Fall Time tF80% to 20% (Note 6) 210 ns

OUT_ _ Turn-Off Rise Time tR20% to 80% (Note 6) 130 ns

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

6 _______________________________________________________________________________________

3.3V TIMING CHARACTERISTICS

(V+ = +3V to < +4.5V, AGND = PGND = 0V; all voltages are measured with respect to PGND, unless otherwise noted. TA= TJ=

-40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 5)

PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS

INTERFACE TIMING CHARACTERISTICS

CLK Clock Period tCP 52 ns

CLK Pulse-Width High tCH 24 ns

CLK Pulse-Width Low tCL 24 ns

DIN Setup Time tDS 4ns

DIN Hold Time tDH 8ns

DOUT Propagation Delay tDO 12 70 ns

DOUT Rise Time tDR CDOUT = 10pF, 20% to 80% 12 ns

DOUT Fall Time tDF CDOUT = 10pF, 80% to 20% 12 ns

LE Pulse-Width High tLW 20 ns

LE Setup Time tLS 15 ns

LE Rising to OUT_ _ Rising Delay tLRR (Note 6) 140 ns

LE Rising to OUT_ _ Falling Delay tLRF (Note 6) 400 ns

CLK Rising to OUT_ _ Rising Delay tCRR (Note 6) 140 ns

CLK Rising to OUT_ _ Falling Delay tCRF (Note 6) 400 ns

OE Rising to OUT_ _ Rising Delay tOER(Note 6) 140 ns

OE Falling to OUT_ _ Falling Delay tOEF(Note 6) 400 ns

OUT_ _ Turn-On Fall Time tF80% to 20% (Note 6) 275 ns

OUT_ _ Turn-Off Rise Time tR20% to 80% (Note 6) 150 ns

Note 1: This device is 100% production tested at TJ= +25°C and +125°C. Limits to -40°C are guaranteed by design.

Note 2: Guaranteed by design, not production tested.

Note 3: Parameter is measured at trip point of latch with VFB = 0V.

Note 4: Gain is defined as A = ΔVCOMP/ΔVCS, 0.05V ≤VCS ≤0.25V.

Note 5: See Figures 3 and 4.

Note 6: A 65Ωpullup resistor is connected from OUT_ _ to 5.5V. Rising refers to VOUT_ _ when current through OUT_ _ is turned off

and falling refers to VOUT_ _ when current through OUT_ _ is turned on.

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

_______________________________________________________________________________________

BOOTSTRAP UVLO vs. TEMPERATURE

MAX16809 toc01

TEMPERATURE (°C)

VCC (V)

1109565 80-10 5 20 35 50-25

-40 125

VCC RISING

VCC FALLING

HYSTERESIS

-40 -10 5 20-25 35 50 9580 11065 125

STARTUP CURRENT

vs. TEMPERATURE

MAX16809 toc02

TEMPERATURE

(

°C

)

ICC (μA)

VCC = 7.5V

3.5

3.7

4.9

4.1

3.9

4.3

4.5

4.7

5.1

OPERATING SUPPLY CURRENT

vs. TEMPERATURE AFTER STARTUP

(fOSC = fSW = 300kHz)

MAX16809 toc03

ICC (mA)

-40 -10 5 20-25 35 50 9580 11065 125

TEMPERATURE

(

°C

)

CT = 560pF

4.90

4.94

4.92

5.00

4.98

4.96

5.02

5.04

5.06

5.08

REFERENCE VOLTAGE

vs. TEMPERATURE

MAX16809 toc04

VREF (V)

-40 -10 5 20-25 35 50 9580 11065 125

TEMPERATURE (°C)

IREF = 1mA

IREF = 20mA

4.65

4.75

4.70

4.85

4.80

5.00

4.95

4.90

5.05

02010 30 40 50 60 70

REFERENCE VOLTAGE

vs. REFERENCE LOAD CURRENT

MAX16809 toc05

IREF (mA)

VREF (V)

4.980

4.984

4.982

4.988

4.986

4.992

4.990

4.994

4.998

4.996

5.000

10 14 1612 18 20 22 24 26

REFERENCE VOLTAGE

vs. SUPPLY VOLTAGE

MAX16809 toc06

VCC (V)

REF

(V)

IREF = 1mA

450

470

460

500

490

480

510

520

540

530

550

-40 -10 5-25 20 35 50 65 80 95 110 125

OSCILLATOR FREQUENCY (fOSC)

vs. TEMPERATURE

MAX16809 toc07

TEMPERATURE (°C)

OSCILLATOR FREQUENCY (kHz)

RT = 3.65kΩ

CT = 560pF

7.88

7.90

8.02

7.94

7.92

7.96

7.98

8.00

8.04

-40 -10 5 20-25 35 50 9580 11065 125

OSCILLATOR RT/CT DISCHARGE CURRENT

vs. TEMPERATURE

MAX16809 toc08

TEMPERATURE (°C)

RT/CT DISCHARGE CURRENT (mA)

VRT/CT = 2V

Typical Operating Characteristics

(VCC = +15V, V+ = 3V to 5.5V, RT= 10kΩ, CT= 3.3nF, VREF = COMP = open, CREF = 0.1μF, VFB = 2V, CS = AGND = PGND = 0V.

Typical values are at TA= +25°C, unless otherwise noted.)

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

8 _______________________________________________________________________________________

0.20

0.24

0.22

0.30

0.28

0.26

0.32

0.34

0.38

0.36

0.40

CURRENT-SENSE TRIP THRESHOLD

vs. TEMPERATURE

MAX16809 toc09

CS THRESHOLD (V)

-40 -10 5 20-25 35 50 9580 11065 125

TEMPERATURE (°C)

TIMING RESISTANCE

vs. OSCILLATOR FREQUENCY

MAX16809 toc10

FREQUENCY (Hz)

RT (kΩ)

1M100k

100

1000

0.1

10k 10M

CT = 1nF

CT = 560pF

CT = 220pF

CT = 100pF

CT = 10nF

CT = 4.7nF

CT = 3.3nF

CT = 2.2nF

OUT IMPEDANCE vs. TEMPERATURE

(RDS_ON PMOS DRIVER)

MAX16809 toc11

TEMPERATURE (°C)

RDS_ON (Ω)

1109565 80-10 5 20 35 50-25

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

2.0

-40 125

ISOURCE = 100mA

OUT IMPEDANCE vs. TEMPERATURE

(RDS_ON NMOS DRIVER)

MAX16809 toc12

RDS_ON (Ω)

-40 -10 5 20-25 35 50 9580 11065 125

TEMPERATURE (°C)

ISINK = 200mA

100

PROPAGATION DELAY FROM CURRENT-LIMIT

COMPARATOR TO OUT vs. TEMPERATURE

MAX16809 toc13

PROPAGATION DELAY (ns)

-40 -10 5 20-25 35 50 9580 11065 125

TEMPERATURE (°C)

ERROR-AMPLIFIER OPEN-LOOP GAIN

AND PHASE vs. FREQUENCY

MAX16809 toc14

FREQUENCY (Hz)

GAIN (dB)

1M100k1k 10k10 1001

100

120

140

-20

0.01 100M

10M

-165

-140

-115

-90

-65

-40

-15

-190

PHASE

GAIN

PHASE (DEGREES)

1.5

1.6

2.2

1.8

1.7

1.9

2.0

2.1

2.3

-40 -10 5 20-25 35 50 9580 11065 125

COMP VOLTAGE LEVEL TO TURN

OFF DEVICE vs. TEMPERATURE

MAX16809 toc15

TEMPERATURE (°C)

VCOMP (V)

VCC = 15V

2.0

3.0

2.5

4.0

3.5

5.0

4.5

5.5

6.5

6.0

7.0

20 220 320 420120 520 620 720 920820 1020

SUPPLY CURRENT

vs. OSCILLATOR FREQUENCY

MAX16809 toc16

FREQUENCY (kHz)

ICC (mA)

TA = +125°C

CT = 100pF

TA = -40°C

SUPPLY CURRENT vs. SUPPLY VOLTAGE

(INTERFACE IDLE, ALL OUTPUTS OFF, RSET = 720Ω)

MAX16809 toc17

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

5.04.54.03.5

1.85

1.90

1.95

2.00

1.80

3.0 5.5

TA = +125°CTA = +85°C

TA = -40°C

TA = +25°C

Typical Operating Characteristics (continued)

(VCC = +15V, V+ = 3V to 5.5V, RT= 10kΩ, CT= 3.3nF, VREF = COMP = open, CREF = 0.1μF, VFB = 2V, CS = AGND = PGND = 0V.

Typical values are at TA= +25°C, unless otherwise noted.)

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

_______________________________________________________________________________________

SUPPLY CURRENT vs. SUPPLY VOLTAGE

(INTERFACE IDLE, ALL OUTPUTS OFF, RSET = 360Ω)

MAX16809 toc18

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

5.04.54.03.5

3.55

3.60

3.65

3.70

3.50

3.0 5.5

TA = +125°CTA = +85°C

TA = -40°C

TA = +25°C

SUPPLY CURRENT vs. SUPPLY VOLTAGE

(INTERFACE IDLE, ALL OUTPUTS ON, RSET = 720Ω)

MAX16809 toc19

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

5.04.54.03.5

TA = +125°CTA = +85°C

TA = -40°C

TA = +25°C

3.0 5.5

SUPPLY CURRENT vs. SUPPLY VOLTAGE

(INTERFACE IDLE, ALL OUTPUTS ON, RSET = 360Ω)

MAX16809 toc20

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (mA)

5.04.54.03.5

40 TA = +125°C

3.0 5.5

TA = +85°C

TA = -40°C

TA = +25°C

OUT_ _ CURRENT vs. OUT_ _ VOLTAGE

(RSET = 720Ω, V+ = 3.3V)

MAX16809 toc21

OUT_ _ VOLTAGE (V)

OUT_ _ CURRENT (mA)

2.52.01.51.00.5

TA = -40°C

TA = +25°C

TA = +85°C

TA = +125°C

0 3.0

OUT_ _ CURRENT vs. OUT_ _ VOLTAGE

(RSET = 360Ω, V+ = 3.3V)

MAX16809 toc22

OUT_ _ VOLTAGE (V)

OUT_ _ CURRENT (mA)

2.52.01.51.00.5

TA = -40°C

TA = +25°C

TA = +85°C

TA = +125°C

0 3.0

OUT_ _ CURRENT vs. OUT_ _ VOLTAGE

(RSET = 720Ω, V+ = 5.0V)

MAX16809 toc23

OUT_ _ VOLTAGE (V)

OUT_ _ CURRENT (mA)

2.52.01.51.00.5

TA = -40°C

TA = +25°C

TA = +85°C

TA = +125°C

0 3.0

_______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC = +15V, V+ = 3V to 5.5V, RT= 10kΩ, CT= 3.3nF, VREF = COMP = open, CREF = 0.1μF, VFB = 2V, CS = AGND = PGND = 0V.

Typical values are at TA= +25°C, unless otherwise noted.)

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

10 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC = +15V, V+ = 3V to 5.5V, RT= 10kΩ, CT= 3.3nF, VREF = COMP = open, CREF = 0.1μF, VFB = 2V, CS = AGND = PGND = 0V.

Typical values are at TA= +25°C, unless otherwise noted.)

OUT_ _ CURRENT vs. V+

(RSET = 360Ω, VOUT = 2V)

MAX16809 toc26

SUPPLY VOLTAGE (V)

OUT_ _ CURRENT (mA)

5.04.54.03.5

TA = -40°C

TA = +25°C

TA = +85°C

TA = +125°C

3.0 5.5

OUT_ _ CURRENT vs. SET RESISTANCE

(V+ = 5.0V)

MAX16809 toc27

SET RESISTANCE (kΩ)

OUT_ _ CURRENT (mA)

4321

OUT_ _ CURRENT vs. OUT_ _ VOLTAGE

(RSET = 360Ω, V+ = 5.0V)

MAX16809 toc24

OUT_ _ VOLTAGE (V)

OUT_ _ CURRENT (mA)

2.52.01.51.00.5

TA = -40°C

TA = +25°C

TA = +85°C

TA = +125°C

0 3.0

OUT_ _ CURRENT vs. V+

(RSET = 720Ω, VOUT = 2V)

MAX16809 toc25

SUPPLY VOLTAGE (V)

OUT_ _ CURRENT (mA)

5.04.54.03.5

23.5

24.0

24.5

25.0

TA = +125°CTA = +85°C

TA = +25°C

TA = -40°C

23.0

3.0 5.5

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

______________________________________________________________________________________ 11

Detailed Description

The MAX16809 LED driver includes an internal switch-

mode controller that can be used as a boost or buck-

boost (SEPIC) converter to generate the voltage

necessary to drive the multiple strings of LEDs. This

device incorporates an integrated low-side driver, a

programmable oscillator (20kHz to 1MHz), an error

amplifier, a low-voltage (300mV) current sense for high-

er efficiency, and a 5V reference to power up external

circuitry (see Figures 1a and 1b).

The MAX16809 LED driver includes a 4-wire serial

interface and a current-mode PWM controller to gener-

ate the necessary voltage for driving 16 open-drain,

constant-current-sinking output ports. The driver uses

current-sensing feedback circuitry (not simple current

mirrors) to ensure very small current variations over the

full allowed range of output voltage (see the

Typical

Operating Characteristics

). The 4-wire serial interface

comprises a 16-bit shift register and a 16-bit transpar-

ent latch. The shift register is written through a clock

input, CLK, and a data input, DIN, and the data propa-

gates to a data output, DOUT. The data output allows

multiple drivers to be cascaded and operated together.

The contents of the 16-bit shift register are loaded into

the transparent latch through a latch-enable input, LE.

The latch is transparent to the shift register outputs

when high and latches the current state on the falling

edge of LE. Each driver output is an open-drain, con-

stant-current sink that should be connected to the

Pin Description

PIN NAME FUNCTION

1, 31, 32,

36, 38 N.C. No Connection. Not internally connected. Leave unconnected.

2 FB Error-Amplifier Inverting Input

3 COMP Error-Amplifier Output

4–11 OUT8–OUT15 LED Driver Outputs. OUT8–OUT15 are open-drain, constant-current-sinking outputs rated for 36V.

12 OE Active-Low, Output Enable Input. Drive OE low to PGND to enable the OUT0–OUT15. Drive OE

high to disable OUT0–OUT15.

13 DOUT Serial-Data Output. Data is clocked out of the 16-bit internal shift register to DOUT on CLK’s

rising edge.

14 SET LED Current Setting. Connect RSET from SET to PGND to set the LED current.

15 V+ LED Driver Positive Supply Voltage. Bypass V+ to PGND with a 0.1μF ceramic capacitor.

16, 17 PGND Power Ground

18 DIN Serial-Data Input. Data is loaded into the internal 16-bit shift register on CLK’s rising edge.

19 CLK Serial-Clock Input

20 LE

Latch-Enable Input. Data is loaded transparently from the internal shift register(s) to the output

latch(es) while LE is high. Data is latched into the output latch(es) on LE’s falling edge, and

retained while LE is low.

21–28 OUT0–OUT7 LED Driver Outputs. OUT0–OUT7 are open-drain, constant-current-sinking outputs rated for 36V.

29 RTCT PWM Controller Timing Resistor/Capacitor Connection. A resistor RT from RTCT to REF and a

capacitor CT from RTCT to AGND set the oscillator frequency.

30 CS PWM Controller Current-Sense Input

33 AGND Analog Ground

34 OUT MOSFET Driver Output OUT. Connects to the gate of the external n-channel MOSFET.

35 VCC Power-Supply Input. Bypass VCC to AGND with a 0.1μF ceramic capacitor or a parallel

combination of a 0.1μF and a higher value ceramic capacitor.

37 REF 5V Reference Output. Bypass REF to AGND with a 0.1μF ceramic capacitor.

—EP

Exposed Paddle. Connect to the ground plane for improved power dissipation. Do not use as the

only ground connection.

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

12 ______________________________________________________________________________________

cathode of a string of LEDs connected in series. The

constant-current capability is up to 55mA per output,

set for all 16 outputs by an external resistor, RSET. The

device can operate in a stand-alone mode (see the

Typical Operating Circuits

The number of channels can be expanded by using the

MAX6970 and MAX6971 family in conjunction with the

MAX16809.

26.5V

EN_REF

SNS

300mV

UVLO

ILIM

VEA

CPWM

VOLTAGE-

DIVIDER

VDD

THERMAL

SHUTDOWN

VOLTAGE

DIVIDER

OSC

CLK

PREREG

REG_OK

5V REG

REFERENCE

2.5V

DELAY

VCC

V+

CURRENT

REFERENCE

POWER-ON

RESET

THERMAL

SHUTDOWN

AGND

VCC

REF

OUT

RTCT

DOUT

V+

SET

COMP

CLK

DIN

D0 D1 D2 D3 D4 D5 D6 D7

OUT0

OUT1

OUT2

OUT3

OUT4

OUT5

OUT6

OUT7

D8 D9 D10 D11 D12 D13 D14 D15

OUT8

OUT9

OUT10

OUT11

OUT12

OUT13

OUT14

OUT15

PGND

MAX16809

SERIAL-TO-PARALLEL SHIFT REGISTER

OUTPUT LATCHES

CONSTANT-CURRENT SINK

Figure 1a. Internal Block Diagram

MAX16809

Switch-Mode Controller

Current-Mode Control Loop

The advantages of current-mode control over voltage-

mode control are twofold. First, there is the feed-for-

ward characteristic brought on by the controller’s ability

to adjust for variations in the input voltage on a cycle-

by-cycle basis. Second, the stability requirements of

the current-mode controller are reduced to that of a sin-

gle-pole system unlike the double pole in the voltage-

mode control scheme. The MAX16809 uses a

current-mode control loop where the output of the error

amplifier is compared to the current-sense voltage

(VCS). When the current-sense signal is lower than the

inverting input of the CPWM comparator, the output of

the comparator is low and the switch is turned on at

each clock pulse. When the current-sense signal is

higher than the inverting input of the CPWM compara-

tor, the output is high and the switch is turned off.

Undervoltage Lockout (UVLO)

The turn-on supply voltage for the MAX16809 is 8.4V

(typ). Once VCC reaches 8.4V, the reference powers up.

There is a 0.8V of hysteresis from the turn-on voltage to

the UVLO threshold. Once VCC reaches 8.4V, the

MAX16809 operates with VCC down to 7.6V. Once VCC

goes below 7.6V (typ), the device is in UVLO. When in

UVLO, the quiescent supply current into VCC falls back

to 32μA (typ), and OUT and REF are pulled low.

MOSFET Driver

OUT drives an external n-channel MOSFET and swings

from AGND to VCC. Ensure that VCC remains below the

absolute maximum VGS rating of the external MOSFET.

OUT is a push-pull output with the on-resistance of the

pMOS typically 3.5Ωand the on-resistance of the nMOS

typically 4.5Ω. The driver can source 2A and sink 1A typi-

cally. This allows for the MAX16809 to quickly turn on and

off high gate-charge MOSFETs. Bypass VCC with one or

more 0.1μF ceramic capacitors to AGND, placed close to

VCC. The average current sourced to drive the external

MOSFET depends on the total gate charge (QG) and

operating frequency of the converter. The power dissipa-

tion in the MAX16809 is a function of the average output

drive current (IDRIVE). Use the following equation to cal-

culate the power dissipation in the device due to IDRIVE:

IDRIVE = (QGx fSW)

PD = (IDRIVE + ICC) x VCC

where ICC is the operating supply current. See the

Typical Operating Characteristics

for the operating

supply current at a given frequency.

Error Amplifier

The MAX16809 includes an internal error amplifier. The

inverting input is at FB and the noninverting input is

internally connected to a 2.5V reference. Set the output

voltage using a resistive divider between output of the

converter VOUT, FB, and AGND. Use the following for-

mula to set the output voltage:

where VFB = 2.5V.

Oscillator

The oscillator frequency is programmable using an

external capacitor and a resistor at RTCT (see RT and

CTin the

Typical Operating Circuits

). RTis connected

from RTCT to the 5V reference (REF), and CTis con-

nected from RTCT to AGND. REF charges CTthrough

RTuntil its voltage reaches 2.8V. CTthen discharges

through an 8.3mA internal current sink until CT’s voltage

reaches 1.1V, at which time CTis allowed to charge

through RTagain. The oscillator’s period is the sum of

the charge and discharge times of CT. Calculate the

charge time as follows:

tC= 0.57 x RTx CT

where tCis in seconds, RT in ohms (Ω), and CTin

Farads (F).

The discharge time is then:

tD= (RTx CTx 1000) / [(4.88 x RT) - (1.8 x 1000)]

where tDis in seconds, RT in ohms (Ω), and CTin

Farads (F).

RxV

OUT FB

⎛

⎝

⎜⎞

⎠

⎟

V+

W/L OUT_ _

68W/L

945R

REST

1.23

1.23V

PGNDSET

MAX16809

Figure 1b. OUT_ _ Driver Internal Diagram

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

______________________________________________________________________________________ 13

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

14 ______________________________________________________________________________________

The oscillator frequency is then:

Reference Output

REF is a 5V reference output that can source 20mA.

Bypass REF to AGND with a 0.1μF capacitor.

Current Limit

The MAX16809 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 external MOSFET and

AGND, sets the current limit. The CS input has a volt-

age trip level (VCS) of 0.3V. Use the following equation

to calculate RCS:

IP-P is the peak current that flows through the MOSFET.

When the voltage produced by this current (through the

current-sense resistor) exceeds the current-limit com-

parator threshold, the MOSFET driver (OUT) turns the

switch off within 60ns. In most cases, a small RC filter is

required to filter out the leading-edge spike on the

sense waveform. Set the time constant of the RC filter at

50ns.

Buck-Boost (SEPIC) Operation

Figure 2 shows a buck-boost application circuit using

the MAX16809 in a stand-alone mode of operation.

SEPIC topology is necessary when the total forward

voltage of the LEDs in a string is such that VOUT can be

below or above VIN.

CS CS

−

ftt

OSC CD

()

MAX16809

OUT0

OUT1

OUT2

OUT3

OUT4

OUT5

OUT6

OUT7

OUT8

OUT9

OUT10

OUT11

OUT12

OUT13

OUT14

OUT15

EXTERNAL

DIM INPUT

EXTERNAL

CLOCK INPUT

SET

DIN

PGND

VCC

V+

DOUT

CLK

REF RTCT

CREF

CIN

RSET

RCS

CC2

CC1

OUT CS AGND COMP

RC1

COUT

CBYP

3V TO 5.5V

VIN VOUT

Figure 2. Buck-Boost (SEPIC) Operation

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

______________________________________________________________________________________ 15

LED Driver

4-Wire Interface

The MAX16809 also operates in a stand-alone mode

(see the

Typical Operating Circuits

). For use with a

microcontroller, the MAX16809 features a 4-wire serial

interface using DIN, CLK, LE, OE inputs and DOUT as

a data output. This interface is used to write the LED

channels’ data to the MAX16809. The serial-interface

data word length is 16 bits, D0–D15. See Figure 3.

The functions of the five interface pins are as follows:

DIN is the serial-data input, and must be stable when it

is sampled on the rising edge of CLK. Data is shifted in

MSB first. This means that data bit D15 is clocked in

first, followed by 15 more data bits, finishing with the

LSB, D0.

CLK is the serial-clock input that shifts data at DIN into

the MAX16809’s 16-bit shift register on its rising edge.

LE is the latch-enable input of the MAX16809 that trans-

fers data from the 16-bit shift register to its 16-bit output

latches (transparent latch). The data latches on the

falling edge of LE (Figure 4). The fourth input (OE) pro-

vides output-enable control of the output drivers. When

OE is driven high, the outputs (OUT0–OUT15) are forced

to high impedance without altering the contents of the

output latches. Driving OE low enables the outputs to fol-

low the state of the output latches. OE is independent of

the serial interface operation. Data can be shifted into

the serial-interface shift register and latched, regardless

of the state of OE. DOUT is the serial-data output that

shifts data out from the MAX16809’s 16-bit shift register

on the rising edge of CLK. Data at DIN propagates

through the shift register and appears at DOUT 16 clock

cycles later. Table 1 shows the 4-wire serial-interface

truth table.

Table 1. 4-Wire Serial-Interface Truth Table

CLOCK

INPUT SHIFT REGISTER CONTENTS LOAD

INPUT LATCH CONTENTS BLANKING

INPUT

OUTPUT CONTENTS

CURRENT AT OUT_ _

SERIAL

DATA

INPUT

DIN CLK D0 D1 D2 … Dn-1 Dn LE D0 D1 D2 … Dn-1 Dn OE D0 D1 D2 … Dn-1 Dn

H H R0 R1 … Rn-2 Rn-1

L L R0 R1 … Rn-2 Rn-1

X R0 R1 R2 … Rn-1 Rn

X X X … X X L R0 R1 R2 … Rn-1 Rn

P0 P1 P2 … Pn-1 Pn H P0 P1 P2 … Pn-1 Pn L P0 P1 P2 … Pn-1 Pn

XXX…X X H LLL… L L

L = Low Logic Level

H = High Logic Level

X = Don’t Care

P = Present State (Shift Register)

R = Previous State (Latched)

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

16 ______________________________________________________________________________________

Selecting External Component

RSET to Set LED Output Current

The MAX16809 uses an external resistor, RSET, to set

the LED current for outputs OUT0–OUT15. The mini-

mum allowed value of RSET is 311Ω, which sets the out-

put currents to 55mA. The maximum allowed value of

RSET is 5kΩ(IOUT_ _ = 3.6mA) and the maximum

allowed capacitance at SET is 100pF.

Use the following formula to set the output current:

where IOUT_ _ is the desired output current in milliamps

and the value for RSET is in ohms.

Overtemperature Cutoff

The MAX16809 contains an internal temperature sensor

that turns off all outputs when the die temperature

exceeds +165°C. The outputs are enabled again when

the die temperature drops below +140°C. Register con-

tents are not affected, so when a driver is overdissipat-

ing, the external symptom is the load LEDs cycling on

and off as the driver repeatedly overheats and cools,

alternately turning itself off and then back on again.

SET

OUT

=17 100

D15 D14

tDS

tDH

tCL

tCP

tDO

tOEW

tOEF

tFtR

tOER

tLS

tLW

tCH

D1 D0

D15

CLK

DIN

DOUT

OUT_ _

80%

20%

Figure 3. 4-Wire Serial-Interface Timing Diagram

OUT_ _

CLK

OUT_ _

CLK

OUT_ _

tCRR

tCRF

tLRR

tLRF

Figure 4. LE and CLK to OUT_ _ Timing

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

______________________________________________________________________________________ 17

Stand-Alone Operation

In stand-alone operation, the MAX16809 does not use

the 4-wire interface (see the

Typical Operating

Circuits

). Connect DIN and LE to V+ and provide at

least 16 external clock pulses to CLK to enable 16 out-

put ports. This startup pulse sequence can be provided

either using an external clock or the PWM signal. The

external clock can also be generated using the signal

at RTCT and an external comparator.

LED Dimming

PWM Dimming

All the output channels can be dimmed simultaneously

by applying a PWM signal (50Hz to 30kHz) to OE. This

allows for a wide range of dimming up to a 5000:1 ratio.

Each channel can be independently turned on and off

using a 4-wire serial interface. The dimming is propor-

tional to the PWM duty cycle.

LED Current Amplitude Adjustment

Using an analog or digital potentiometer as RSET allows

for LED current amplitude adjustment and linear dimming.

Computing Power Dissipation

Use the following equation to estimate the upper limit

power dissipation (PD) for the MAX16809:

where:

V+ = supply voltage

I+ = V+ operating supply current

DUTY = PWM duty cycle applied to OE

VOUTi = MAX16809 port output voltage when driving

load LED(s)

IOUTi = LED drive current programmed by RSET

PD = power dissipation

PCB Layout Guidelines

Careful PCB layout is critical to achieve low switching

losses and clean, stable operation. Use a multilayer

board whenever possible for better noise immunity.

Protect sensitive analog grounds by using a star

ground configuration. Minimize ground noise by con-

necting AGND, PGND, the input bypass-capacitor

ground lead, and the output-filter ground lead to a sin-

gle point (star ground configuration). Also, minimize

trace lengths to reduce stray capacitance, trace resis-

tance, and radiated noise. The trace between the out-

put voltage-divider and the FB pin must be kept short,

as well as the trace between AGND and PGND.

PD DUTY V x I V x

OUTi

()=×+++

∑

()

VxI

OUTi

CC CC

⎡

⎣

⎢

⎤

⎦

⎥

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

18 ______________________________________________________________________________________

MAX16809

PGND

VCC

V+

DOUT

DIN

CLK

SCLK

MOSI

MISO

μC

LOAD

ENABLE

RCS

CC2

CC1

OUT CS AGND COMP

LEDs

OPERATION WITH MICROCONTROLLER

RC1

COUT

3V TO 5.5V

VIN VOUT

OUT0

OUT1

OUT2

OUT3

OUT4

OUT5

OUT6

OUT7

OUT8

OUT9

OUT10

OUT11

OUT12

OUT13

OUT14

OUT15

SET REF RTCT

CREF

RSET

CIN

CBYP

Typical Operating Circuits (continued)

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

______________________________________________________________________________________ 19

TOP VIEW

MAX16809

TQFN

DOUT

SET

V+

PGND

DIN

CLK

123456789101112

N.C.

REF

N.C.

VCC

OUT

AGND

N.C.

OUT15

OUT14

OUT13

OUT12

OUT11

OUT10

OUT9

OUT8

COMP

N.C.

31 30 29 28 27 26 25 24 23 22 21 20

OUT0

OUT1

OUT2

OUT3

OUT4

OUT5

OUT6

OUT7

RTCT

N.C.

Pin Configuration Chip Information

PROCESS: BiCMOS

Package Information

For the latest package outline information and land patterns, go

to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in

the package code indicates RoHS status only. Package draw-

ings may show a different suffix character, but the drawing per-

tains to the package regardless of RoHS status.

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

38 TQFN-EP T3857-1 21-0172

MAX16809

Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

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

Revision History

REVISION

NUMBER

REVISION

DATE DESCRIPTION PAGES

CHANGED

0 10/06 Initial release —

1 3/07 Released the MAX16810 on the data sheet. 1, 14, 16, 22, 23

2 8/09 Removed the MAX16810 from the data sheet. 1–20