AS1109

Constant-Current, 8-Bit LED Driver with Diagnostics

Preliminary

Pro duct Brief

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Revision 1.05

1 - 2

1 General Description

The AS1109 was designed to drive up to 8 LEDs

through a fast serial interface and features 8 output con-

stant current drivers and an on-chip diagnostic read-

back function.

The high clock-frequency (up to 30MHz), adjustable out-

put current, and flexible serial interface makes the

device perfectly suited for high-volume transmission

applications.

Output current is adjustable (up to 100mA/channel)

The serial interface includes an integrated shift register

with Schmitt trigger inputs allows display data to be

shifted-in. Additionally, an internal data register stores

the currently displayed data.

The device features integrated diagnostics for over-

temperature, open-LED, and shorted-LED conditions.

Integrated shift registers store global fault status infor-

mation during load as well as the detailed temperature/

open-LED/shorted-LED diagnostics results.

The AS1109 also features a low-current diagnostic

mode to minimize display flicker during fault testing.

The AS1109 is available in a 16-pin SOIC-150 package

and the 16-pin SSOP Package.

Figure 1. Main Diagram and Pin Assignments

2 Key Features

!

8 Constant-Current Output Channels

!

Excellent Output Current Accuracy

- Between Channels: <±2%

- Between AS1109 Devices: <±2%

!

Output Current Per Channel: 0.5 to 100mA

!

Controlled In-Rush Current

!

Over-Temperature, Open-LED, Shorted-LED

Diagnostics Functions

!

Low-Current Test Mode

!

Global Fault Monitoring

!

Low Shutdown Mode Current: 10µA

!

Fast Serial Interface: 30MHz

!

Cascaded Configuration

!

Extremely Fast Output Drivers Suitable for PWM

!

16-pin SOIC-150 and 16-pin SSOP Package

3 Applications

The device is ideal for fixed- or slow-rolling displays

using static or multiplexed LED matrix and dimming

functions, large LED matrix displays, mixed LED display

and switch monitoring, displays in elevators, public

transports (underground, trains, buses, taxis, airplanes,

etc.), large displays in stadiums and public areas, price

indicators in retail stores, promotional panels, bar-graph

displays, industrial controller displays, white good pan-

els, emergency light indicators, and traffic signs.

AS1109

SDI

SDO

CLK

LD

OEN

REXT

1

GND

AS1109

16

2

SDI

3

CLK

4

LD

5

OUTN0

15 REXT

14 SDO

13 OEN

9 OUTN4

8

OUTN3

7

OUTN2

6

OUTN1

12 OUTN7

11 OUTN6

10 OUTN5

OUTN0 OUTN1 OUTN2 OUTN3 OUTN4 OUTN5 OUTN6 OUTN7

GND