MAX16809ATU+T - Maxim Integrated

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 control-

ler 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,

constant-current-sinking LED driver outputs rated for

36V continuous operation. The LED current-control cir-

cuitry achieves ±3% current matching among strings

and enables paralleling of outputs for LED string cur-

rents 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 dimming

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 pad 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

Industrial and Medical Displays

●Ambient, Mood, and Accent Lighting

19-0656; Rev 3; 4/14

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

*EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

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

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

OUT

LEDs

STAND-ALONE OPERATION

MAX16809

OUT8

OUT9

OUT10

OUT11

OUT12

OUT13

OUT14

OUT15

MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

Typical Operating Circuits continued at end of data sheet.

Typical Operating Circuits

Pin Configuration appears at end of data sheet.

Ordering Information

EVALUATION KIT AVAILABLE

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).

(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

REFERENCE

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

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

Load Regulation ∆VLOAD 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

Discharge Current IDIS

VRTCT = 2V, TJ = +25°C 7.9 8.3 8.7 mA

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

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

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│

MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

Electrical Characteristics (PWM Controller)

Stresses beyond those listed under “bsolute 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.

Absolute Maximum Ratings

(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

OUT Low-Side On-Resistance VRDS_ONL ISINK = 200mA TJ = -40°C to +85°C (Note 2) 4.5 10 Ω

TJ = -40°C to +125°C 4.5 12

OUT High-Side On-Resistance VRDS_ONH ISOURCE =

100mA

TJ = -40°C to +85°C (Note 2) 3.5 7.5 Ω

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

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

Electrical Characteristics (PWM Controller) (continued)

(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

OUT_ _ Output Current IOUT_ _

0°C ≤ TA ≤ +125°C, VOUT = 1V to 2.5V,

RSET = 360Ω43.25 47.5 51.75

TA = -40°C, VOUT = 1V to 2.5V,

RSET = 360Ω40 55

OUT_ _ Leakage Current OE = V+ 1 µA

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│

MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

Electrical Characteristics (LED Driver)

(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 4 ns

DIN Hold Time tDH 8 ns

DOUT Propagation Delay tDO 10 50 ns

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

DOUT Fall Time tDFCDOUT = 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

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

5V Timing Characteristics

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 = ∆VCOMP/∆VCS, 0.05V ≤ VCS ≤ 0.25V.

Note 5: See Figures 3 and 4.

Note 6: A 65Ω pullup 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.

(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 4 ns

DIN Hold Time tDH 8 ns

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

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

3.3V Timing 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.)

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

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

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)

VREF (V)

IREF = 1mA

4.65

4.75

4.70

4.85

4.80

5.00

4.95

4.90

5.05

0 2010 30 40 50 60 70

REFERENCE VOLTAGE

vs. REFERENCE LOAD CURRENT

MAX16809 toc05

IREF (mA)

VREF (V)

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

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

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

STARTUP CURRENT

vs. TEMPERATURE

MAX16809 toc02

TEMPERATURE (°C)

ICC (µA)

VCC = 7.5V

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

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

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.)

SUPPLY CURRENT vs. SUPPLY VOLTAGE

(INTERFACE IDLE, ALL OUTPUTS OFF, R

SET = 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

6A = +125°C TA = +85°C

= +25

TA = -40°C

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)

(mA)

TA = +125°C

CT = 100pF

TA = -40°C

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

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)

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)

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

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

TIMING RESISTANCE

vs. OSCILLATOR FREQUENCY

MAX16809 toc10

FREQUENCY (Hz)

(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

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)

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

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.)

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

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 = 720, 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

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

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°C TA = +85°C

TA = -40°C

TA = +25°C

3.0 5.5

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°C TA = +85°C

TA = -40°C

TA = +25°C

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

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.)

OUT_ _ CURRENT vs. SET RESISTANCE

(V+ = 5.0V)

MAX16809 toc27

SET RESISTANCE (kΩ)

OUT_ _ CURRENT (mA)

4321

0 5

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. 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°C TA = +85°C

TA = +25°C

TA = -40°C

23.0

3.0 5.5

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

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

Typical Operating Characteristics

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 incorpo-

rates an integrated low-side driver, a programmable oscil-

lator (20kHz to 1MHz), an error amplifier, a low-voltage

(300mV) current sense for higher 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 gen-

erate 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 driveoutput is an open-drain, con -

stant-current sink that should be connected to the

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.

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│

MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

Pin Description

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.

Figure 1a. Internal Block Diagram

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

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

Switch-Mode Controller

Current-Mode Control Loop

The advantages of current-mode control over volt-

age-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 cur-

rent-mode controller are reduced to that of a single-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 com-

parator, 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

comparator, 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 3.5Ω and 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 = (QG x 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 Amplier

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:

OUT FB

V 1 x V



= +





where VFB = 2.5V.

Oscillator

The oscillator frequency is programmable using an exter-

nal capacitor and a resistor at RTCT (see RT and CT

in the Typical Operating Circuits). RT is connected from

RTCT to the 5V reference (REF), and CT is connected

from RTCT to AGND. REF charges CT through RT until

its voltage reaches 2.8V. CT then discharges through an

8.3mA internal current sink until CT's voltage reaches

1.1V, at which time CT is allowed to charge through RT

again. 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 RT x CT

where tC is in seconds, RT in ohms (Ω), and CT in

Farads (F).

The discharge time is then:

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

where tD is in seconds, RT in ohms (Ω), and CT in

Farads (F).

Figure 1b. OUT_ _ Driver Internal Diagram

V+

W/L OUT_ _

68W/L

945R

REST

1.23

1.23V

PGNDSET

MAX16809

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│

MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

The oscillator frequency is then:

( )

OSC CD

t t

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:

I−

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.

Figure 2. Buck-Boost (SEPIC) Operation

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

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

LED Driver

4-Wire Interface

The MAX16809 also operates in a stand-alone mode (see

the Typical Operating Circuits). For use with a microcon-

troller, 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 regis-

ter 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.

L = Low Logic Level

H = High Logic Level

X = Don't Care

P = Present State (Shift Register)

R = Previous State (Latched)

Table 1. 4-Wire Serial-Interface Truth Table

SERIAL

DATA

INPUT

DIN

CLOCK

INPUT SHIFT REGISTER CONTENTS LOAD

INPUT LATCH CONTENTS BLANKING

INPUT

OUTPUT CONTENTS

CURRENT AT OUT_ _

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

X X X … X X H L L L … L L

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

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 minimum

allowed value of RSET is 311Ω, which sets the output

currents to 55mA. The maximum allowed value of RSET is

5kΩ (IOUT_ _ = 3.6mA) and the maximum allowed capac-

itance at SET is 100pF.

Use the following formula to set the output current:

SET

OUT_ _

17,100V

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 sen-

sor 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 overdissipating,

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.

Figure 4. LE and CLK to OUT_ _ Timing

Figure 3. 4-Wire Serial-Interface Timing Diagram

OUT_ _

CLK

OUT_ _

CLK

OUT_ _

tCRR

tCRF

tLRR

tLRF

D15 D14

tDS

tDH

tCL

tCP

tDO

tOEW

tOEF

tFtR

tOER

tLS

tLW

tCH

D1 D0

D15

CLK

DIN

DOUT

OUT_ _

80%

20%

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│

MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

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 output 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 proportion-

al 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 MAX19:

i 15

OUTi OUTi

i 0

CC CC

PD DUTY (V x I ) V x I

(V x I )



= × + ++ ∑





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 con-

figuration. Minimize ground noise by connecting AGND,

PGND, the input bypass-capacitor ground lead, and the

output-filter ground lead to a single point (star ground con-

figuration). Also, minimize trace lengths to reduce stray

capacitance, trace resistance, and radiated noise. The

trace between the output voltage-divider and the FB pin

must be kept short, as well as the trace between AGND

and PGND.

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

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

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MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

Typical Operating Circuits (continued)

PACKAGE

TYPE

PACKAGE

CODE

OUTLINE

NO.

LAND

PATTERN NO.

38 TQFN-EP T3857M+1 21-0172 90-0007

TOP VIEW

MAX16809

TQFN

DOUT

SET

V+

PGND

DIN

CLK

1 2 3 4 5 6 7 8 9 10 11 12

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.

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│

MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

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.

Chip Information

PROCESS: BiCMOS

Pin Conguration

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

3 4/14 No /V OPNs; removed Automotive reference from Applications section 1

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 specications 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 and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.

MAX16809 Integrated 16-Channel LED Driver with

Switch-Mode Boost and SEPIC Controller

│

Revision History

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.