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
resistor (R
EXT).
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
+V
LED
1
GND
AS1109
16
VDD
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
VDD
