Rainbow Electronics MAX6981 User Manual

General Description

The MAX6981 serial-interfaced LED driver provides
eight open-drain, constant-current-sinking LED driver
outputs rated at 36V. The device operates from a 3V to

5.5V supply. The MAX6981 supply and the LEDs’ sup­ply can power up in any order. The constant-current
outputs are programmed together up to 55mA using a
single external resistor. The MAX6981 operates with a
25Mbps, industry-standard, 4-wire serial interface.

The MAX6981 includes circuitry that automatically
detects open-circuit LEDs. Fault status is loaded into
the serial-interface shift register when LE goes high and
is automatically shifted out on DOUT when the next
data transmission is shifted in.

The MAX6981 uses the industry-standard shift-register­plus-latch-type serial interface. The driver accepts data
shifted into an 8-bit shift register using data input DIN
and clock input CLK. Input data appears at output
DOUT eight clock cycles later to allow cascading of
multiple MAX6981s. 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 output­enable input, OE, gates all eight outputs on and off,
and is fast enough to be used as a PWM input for LED
intensity control.

The MAX6981 is one of a family of 10 shift-register-plus­latch-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.
All versions operate from a 3V to 5.5V supply, and are
specified over the -40°C to +125°C temperature range.

Applications

Variable Message Signs

Marquee Displays

Point-of-Order Signs

Traffic Signs

Gaming Features

Architectural Lighting

Features

♦ 25Mbps Industry-Standard 4-Wire Serial Interface

at 5V

♦ 3V to 5.5V Logic Supply

♦ 8 Constant-Current LED Outputs Rated at 36V

♦ Up to 55mA Continuous Current per Output

♦ Output Current Programmed by Single Resistor

♦ 3% Current Matching Between Outputs

♦ 6% Current Matching Between ICs

♦ Reports Open-Circuit LED Faults

♦ -40°C to +125°C Temperature Range

MAX6981

8-Port, 36V Constant-Current LED Driver

with LED Fault Detection

________________________________________________________________ Maxim Integrated Products 1

Pin Configuration

Ordering Information

XX-XXXX; Rev 0; 10/05

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.

Typical Application Circuit and Selector Guide appear at
end of data sheet.

*EP = Exposed pad.

PART TEMP RANGE

MAX6981AUE -40°C to +125°C 16 TSSOP-EP* U16E-3

MAX6981APE -40°C to +125°C 16 PDIP A16-2

MAX69812AA

-40°C to +125°C 16 SSOP P16-1

PIN­PACKAGE

PKG
CODE

TOP VIEW

GND

1

DIN

2

CLK

3

4

LE

OUT0

OUT1

OUT2

OUT3

MAX6981

5

6

7

8

TSSOP/PDIP/SSOP

16

V+

15

SET

14

DOUT

13

OE

12

OUT7

OUT6

11

10

OUT5

9

OUT4