MAXIM INTEGRATED PRODUCTS MAX6968 8-Port, 5.5V Constant-Current LED Driver User Manual

19-3555; Rev 2; 7/05

8-Port, 5.5V Constant-Current LED Driver

General Description Features

The MAX6968 serial-interfaced LED driver provides 25Mb Industry-Standard 4-Wire Serial Interface at 5V eight open-drain, constant-current sinking LED driver

3V to 5.5V Logic Supply

outputs rated at 5.5V. The MAX6968 operates from a 3V to 5.5V supply. The MAX6968 supply and the LEDs’

8 Constant-Current LED Outputs Rated at 5.5V

supply or supplies may power up in any order. The

Up to 55m A Continuous Current per Output

constant-current outputs are programmed together to up to 55m A using a single external resistor. The

Output Current Programmed by Single Resistor

MAX6968 operates with a 25Mb, industry-standard, 4-

wire serial interface. 3% Current Matching Between Outputs

The MAX6968 uses the industry-standard shift-register- 6% Current Matching Between ICs plus-latch-type serial interface. The driver accepts data

-40°C to +125°C Temperature Range

shifted into an 8-bit shift register using data input DIN and clock input CLK. Input data appears at the output DOUT eight clock cycles later to allow cascading of multiple MAX6968s. The latch-enable input LE loads the 8 bits of shift register data into an 8-bit output latch to set which LEDs are on and which are off. The output- enable input OE gates all eight outputs on and off, and Ordering Information is fast enough to be used as a PWM input for LED

PART TEMP RANGE PIN-PACKAGE

intensity control.

MAX6968AUE -40°C to +125°C 16 TSSOP-EP*

For applications requiring LED fault detection, refer to

the MAX6977 data sheet that automatically detects MAX6968APE -40°C to +125°C 16 PDIP

open-circuit LEDs. MAX6968AAE -40°C to +125°C 16 SSOP For safety-related applications requiring a watchdog *EP = Exposed pad. timer, refer to the MAX6978 data sheet that includes a fail-safe feature that blanks the display if the serial inter- face becomes inactive for more than 1s.

Typical Application Circuit and Selector Guide appear at

The MAX6968 is one of a family of 12 shift-register-plus-

end of data sheet.

latch-type LED drivers. The family includes 8-port and 16-port types, with 5.5V- or 36V-rated LED outputs, with and without open-circuit LED detection and watchdog.

Pin Configuration

All versions operate from a 3V to 5.5V supply, and are specified over the -40°C to +125°C temperature range.

TOP VIEW

Applications

GND V+

Variable Message Signs

DIN SET

Marquee Displays

CLK DOUT

Point-of-Order Signs

LE MAX6968AUE OE MAX6968APE

Traffic Signs OUT0 OUT7

MAX6968AAE

Gaming Features OUT1 OUT6 OUT2 OUT5

Architectural Lighting

OUT3 OUT4

TSSOP/PDIP/SSOP

Maxim Integrated Products

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.