A S 11 0 9
C o n s ta n t - C u r r e n t , 8 - B i t L E D D r i v e r w i t h D i a g n o s t i c s
D a ta S he e t
1 General Description
The AS1109 is designed to drive up to 8 LEDs through a
fast serial interface and features 8 output constant cur-
rent drivers and an on-chip diagnostic read-back func-
tion.
The high clock-frequency (up to 50MHz), 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)
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 applica-
tions.
The AS1109 is available in a 16-pin SOIC-150, a 16-pin
QFN (4x4mm) and the 16-pin SSOP-150 package.
2 Key Features
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8 Constant-Current Output Channels
Excellent Output Current Accuracy
- Between Channels: ±2%
- Between AS1109 Devices: ±2%
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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
SSOP-150 Package
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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.
Figure 1. Main Diagram and Pin Assignments
+V
LED
GND 1
OUTN0 OUTN1 OUTN2 OUTN3 OUTN4 OUTN5 OUTN6 OUTN7
SDI 2
CLK 3
SDI
16
V
DD
15 REXT
14 SDO
AS1109
LD 4
SDO
OUTN0 5
OUTN1 6
AS1109
13 OEN
12 OUTN7
11 OUTN6
10 OUTN5
9 OUTN4
CLK
LD
OEN
REXT
GND
V
DD
OUTN2 7
OUTN3 8
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