AS1121

16-Channel LED Driver with Dot Correction and Greyscale PWM

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Revision 1.01

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Data sheet

1 General Description

The AS1121 is a 16-channel, constant current-sink LED driver. Each

of the 16 channels can be individually adjusted by 4096-step grey-

scale PWM brightness control and 64-step constant-current sink (dot

correction).

The dot correction circuitry adjusts the brightness variations between

the AS1121 channels and other LED drivers. Greyscale control and

dot correction circuitry are accessible via the SPI-compatible serial

interface. A single external resistor sets the maximum current value

of all 16 channels.

The open LED detection function indicates a broken or disconnected

LED at one or more of the outputs. The overtemperature protection-

flag indicates that the device is in an overtemperature condition.

An additional power-down pin puts the AS1121 into a 40nA standby-

mode.

The AS1121 is available in a 32-pin TQFN 5x5 mm package.

Figure 1. AS1121 - Block Diagram

2 Key Features

Greyscale PWM Control: 12-Bit (4096 Steps)

Dot Correction: 6-Bit (64 Steps)

Drive Capability (Constant-Current Sink): 0 to 40mA

LED Power Supply Voltage: up to 30V

Supply Voltage Range: 3.1V to 3.6V

SPI-Compatible Serial Interface

Output Delay for controlled Inrush Current (factory set, can be

turned off)

Factory set rise- and fall-time for EMI improvement

PWM Clock Rate: up to 10 MHz

Data Transfer Clock Rate: up to 30 MHz

CMOS Level I/O

Diagnostic Features

32-pin TQFN 5x5 mm Package

3 Applications

The device is ideal for mono-, multi-, and full-color LED displays,

LED signboards, and display backlights.

AS1121

Max OUTn

Current

27

VCC

Status

Open LED Detect,

Overtemperature,

Dot Correction

Data

Over-

temp

22

XERR

Open

LED

Detect

26

IREF

24

GSCLK

31

OEN

30

GND

23

SDO

.

.

.

Control

12-Bit Greyscale

PWM Control

Constant Current

Driver

21

OUT15

6-Bit Dot

Correction

Dot Correction

90

Register 95

Greyscale

180 Register191

Control

12-Bit Greyscale

PWM Control

Constant Current

Driver

Open&Short LED Detection

4

OUT0

6-Bit Dot

Correction

Dot Correction

0

Register

5

Greyscale

0

Register 11

Control

12-Bit Greyscale

PWM Control

Constant Current

Driver

5

OUT1

6-Bit Dot

Correction

Dot Correction

6

Register

11

Greyscale

12 Register 23

.

.

.

32 LD

Input

Shift

Register

Input

Shift

Register

2 SDI

1 CLK

Greyscale

Counter

Control

1.24V

3

MODE

Open&Short LED Detection

Open&Short LED Detection

29 PD

Delay

Delay

Delay