AS1109

Constant-Current, 8-Bit LED Driver with Diagnostics

www.ams.com/LED-Driver-ICs/AS1109

Revision 1.21

1 - 24

1 General Description

The AS1109 is designed to drive up to 8 LEDs through a fast serial

interface and features 8 output constant current drivers and an on-

chip diagnostic read-back function.

The high clock-frequency (up to 50MHz), adjustable output current,

and flexible serial interface makes the device perfectly suited for

high-volume transmission applications.

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

The serial interface with Schmitt trigger inputs includes an integrated

shift register. 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

registers store global fault status information 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.

With an operating temperature range from -40 to +125°C the

AS1109 is also ideal for industrial applications.

The AS1109 is available in a 16-pin SOIC-150, a 16-pin QFN

(4x4mm) and the 16-pin QSOP-150 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: 3µA



Fast Serial Interface: up to 50MHz



Cascaded Configuration



Fast Output Drivers Suitable for PWM



16-pin SOIC-150, 16-pin QFN (4x4mm) and 16-pin QSOP-150

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 panels, 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