Constant-Current, 16-Channel LED Driver with Diagnostics
1 General Description
The AS1123 is designed to drive up to 16 LEDs through a fast serial
interface and features 16 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 40mA/channel) using an external
The serial interface with Schmitt trigger inputs includes an integrated
shift register. Additionally, an internal data register stores the cur-
rently 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 AS1123 also features a low-current diagnostic mode to minimize
display flicker during fault testing.
The AS1123 is available in a 24-pin QSOP and a 24-pin TQFN
Figure 1. AS1123 - Typical Application Diagram
2 Key Features
16 Constant-Current Output Channels
Excellent Output Current Accuracy
- Between Channels: <±3%
- Between Devices: <±3%
Output Current Per Channel: 0.5mA to 40mA
Over-Temperature, Open-LED, Shorted-LED
Low-Current Test Mode
Global Fault Monitoring
Fast Serial Interface: 50MHz
Extremely Fast Output Drivers Suitable for PWM
Output Delay for controlling Inrush Current (on request)
24-pin QSOP and 24-pin TQFN (4x4mm) Package
The device is ideal for fixed- or slow-rolling displays using static or
multiplexed LED matrix and dimming functions, large LED matrix dis-
plays, mixed LED display and switch monitoring, displays in eleva-
tors, 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 con-
troller displays, white good panels, emergency light indicators, and
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