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MAX16824/MAX16825

High-Voltage, Three-Channel Linear

High-Brightness LED Drivers

EVALUATION KIT AVAILABLE

19-1107; Rev 3; 1/13

For pricing, delivery, and ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

General Description

The MAX16824/MAX16825 three-channel LED drivers

operate over a 6.5V to 28V input voltage range. These

devices provide three open-drain constant-current-sink-

ing outputs that are rated to 36V and deliver up to

150mA of current to each string of high-brightness LEDs

(HB LEDs). The current at each output is programmable

by means of an external current-sense resistor. The

MAX16824 features three PWM inputs that control the

duty cycle of the output current, allowing a wide LED

dimming range to be implemented. The PWM inputs

also function as on/off control for each corresponding

output. The MAX16825 offers a 4-wire serial interface, a

3-bit shift register, and a 3-bit transparent latch. The ser-

ial interface allows a microcontroller to configure the out-

put channels using four inputs (DIN, CLK, LE, OE) and a

data output (DOUT). DOUT allows multiple drivers to be

cascaded and operated together.

The MAX16824/MAX16825’s on-board pass elements

minimize the need for external components, while at the

same time, providing ±5% LED current accuracy.

Additional features include a +5V (±5%) regulated output

with 4mA output current capability and thermal protection.

The MAX16824/MAX16825 are available in a thermally

enhanced 16-pin TSSOP-EP package and specified over

the -40°C to +125°C temperature range.

Applications

Industrial Lighting

Architectural and Decorative Lighting

Mood Lighting

Indoor and Outdoor LED Video Displays

Automotive Lighting

LCD Display Backlighting

Features

o 6.5V to 28V Operating Range

o Outputs Connected to 36V Supply for Long LED

Strings

o Three 36V-Rated Output Channels with

Independently Adjustable LED Current

o 150mA Output Current Per Channel

o ±5% LED Current Accuracy

o PWM Dimming

Three Independent Dimming Control Inputs

(MAX16824)

4-Wire Serial Interface LED Current Chopping

(MAX16825)

o +5V (±5%) Regulated Output with 4mA Source

Capability

o Fast Transient Dimming Response

o 200mV Current-Sense Reference Reduces Power

Loss

o Thermal Shutdown

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

o Thermally Enhanced, 16-Pin TSSOP Exposed Pad

Package

OUT1

OUT3

OUT2

CS1

CS2

CS3

PWM1

PWM2

PWM3

REG

GND

REG

UP TO 36V

CS2

CS1

CS3

MAX16824

Typical Operating Circuits

Ordering Information

PART TEMP RANGE PIN PACKAGE

MAX16824AUE+ -40°C to +125°C 16 TSSOP-EP*

MAX16824AUE/V+ -40°C to +125°C 16 TSSOP-EP*

MAX16825AUE+ -40°C to +125°C 16 TSSOP-EP*

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

EP = Exposed pad.

/V denotes an automotive qualified part.

Pin Configurations appear at end of data sheet.

OUT1

OUT3

OUT2

CS1

CS2

CS3

CLK

DIN

REG

GND

REG

CS2

CS1

CS3

MICROCONTROLLER

MAX16825

UP TO 36V

Summary of content (13 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers General Description Features The MAX16824/MAX16825 three-channel LED drivers operate over a 6.5V to 28V input voltage range. These devices provide three open-drain constant-current-sinking outputs that are rated to 36V and deliver up to 150mA of current to each string of high-brightness LEDs (HB LEDs). The current at each output is programmable by means of an external current-sense resistor.
PAGE 2
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers ABSOLUTE MAXIMUM RATINGS IN to GND ...............................................................-0.3V to +30V OUT1, OUT2, OUT3 to GND ..................................-0.3V to +40V CS1, CS2, CS3, REG to GND...................................-0.3V to +6V PWM1, PWM2, PWM3 to GND .................................-0.3V to +6V DIN, CLK, LE, OE, DOUT to GND ............................-0.
PAGE 3
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers ELECTRICAL CHARACTERISTICS (continued) (VIN = 12V, CREG = 1µF to GND, IREG = 0, RCS_ = 2Ω from CS_ to GND, TJ = TA = -40°C to +125°C, unless otherwise noted. Typical values are at TJ = TA = +25°C.
PAGE 4
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers ELECTRICAL CHARACTERISTICS (continued) (VIN = 12V, CREG = 1µF to GND, IREG = 0, RCS_ = 2Ω from CS_ to GND, TJ = TA = -40°C to +125°C, unless otherwise noted. Typical values are at TJ = TA = +25°C.
PAGE 5
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers Typical Operating Characteristics (continued) (VIN = 12V, CREG = 1µF to GND, IREG = 0, RCS_ = 2Ω from CS_ to GND, TA = +25°C, unless otherwise noted. Typical values are at TA = +25°C.) SUPPLY CURRENT vs. TEMPERATURE 120 IOUT_ = 95mA 100 80 60 40 5.04 2.85 ILOAD = 0 5.02 5.00 4.98 2.65 4.96 ILOAD = 4mA ILOAD = 1mA 4.94 4.92 VPWM1 = VPWM2 = VPWM3 = 0 2.25 4.
PAGE 6
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers Pin Description PIN FUNCTION MAX16825 1 1 OUT1 Channel 1 LED Driver Output. OUT1 is an open-drain, constant-current-sinking output rated to 36V. 2 2 CS1 Channel 1 Sense Amplifier Negative Input. Connect a current-sense resistor between CS1 and GND to program the output current level for channel 1. 3 3 IN Positive Input Supply. Bypass with a 0.1µF (min) capacitor to GND. 4 4 REG +5V-Regulated Output.
PAGE 7
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers OUT1 200mV IN BANDGAP AND 5V REGULATOR REG CS1 OUT2 THERMAL SHUTDOWN CS2 OUT3 PWM1 PWM2 PWM CONTROL AND LOGIC CS3 PWM3 MAX16824 GND Figure 1. Internal Block Diagram (MAX16824) Detailed Description The MAX16824/MAX16825 are three-channel LED drivers that operate from a 6.5V to 28V input voltage range.
PAGE 8
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers OUT1 IN 200mV BANDGAP AND 5V REGULATOR REG CS1 OUT2 THERMAL SHUTDOWN CS2 OUT3 DIN CS3 CLK DOUT LE OE SHIFT REGISTER SHIFT REGISTER SHIFT REGISTER LATCH LATCH LATCH LOGIC MAX16825 GND Figure 2.
PAGE 9
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers On-board pass elements minimize the need for external components while providing ±5% LED current accuracy. Additional features include a +5V (±5%) regulated output with 4mA output current capability and thermal protection. The MAX16824/MAX16825 use a feedback loop to linearly control the current at each output. The voltage across each sense resistor is regulated to 200mV by the internal feedback loop.
PAGE 10
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers 50% tLW 50% LE tCH tCL 50% 50% 50% 50% tLS tCP CLK tDH tDS DIN 50% DO D1 50% D2 tDO 50% DOUT DO tOEW OE 50% 50% tOEH tOEL 80% OUT_ 20% tF tR Figure 3. 4-Wire Serial-Interface Timing Diagram data. Holding OE low allows the output channels to follow the state of the output latches. The duty cycle depends on LE’s frequency. All output channels are affected at the same time.
PAGE 11
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers 50% LE tLRF OUT_ 50% 50% LE tLRR 50% OUT_ 50% CLK tCRF OUT_ 50% 50% CLK tCRR 50% OUT_ Figure 4.
PAGE 12
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers A third method is to hold both LE and OE in the enabled state. This allows the data bits to directly control the output channels, and hence, pulse dim the output current. Make sure that the clock frequency does not exceed the maximum rate at which the device can change the state of the output channels.
PAGE 13
MAX16824/MAX16825 High-Voltage, Three-Channel Linear High-Brightness LED Drivers Revision History REVISION NUMBER REVISION DATE 0 11/07 Initial release 1 1/08 Updated data sheet with automotive temperature specification 1, 2, 3, 4, 7 2 4/09 Updated the Ordering Information and LED Supply Voltage Considerations sections.