AS1109
Data Sheet - Application Information
9 Application Information
Error Detection
The AS1109 features two types of error detection. The error detection can be used on-the-fly, for active LEDs, without
any delay, or by entering into low-current diagnosis mode.
Error Detection On-The-Fly
Error detection on-the-fly will output the status of active LEDs during operation. Without choosing an error mode this
will output the temperature flag at every input/output cycle. Triggering one clock pulse for open or two clock pulses for
short detection during error detection mode outputs the detailed open- or short-error report with the next input/output
cycle (see Figure 20). LEDs that are turned off cannot be tested and their digits at the error output must be ignored.
Figure 20. Normal Operation with Error Detection During Operation – 128 Cascaded AS1109s
Data1
Data2
Data3
Data3
Display
SDI
Data2
Data4
T/O or S Error Code
Data0
T/O or S Error Code
Data2
T/O or S Error Code
Data1
SDO
CLK
GEF
GEF
Clock for Error
Mode 0x/1x/2x
Clock for Error
Mode 0x/1x/2x
1024x
1024x
1024x
Rising Edge of OEN
Acquisition of Error Status
Rising Edge of OEN
Acquisition of Error Status
OEN
Falling Edge of LD; Error Register is
copied into Shift Register
Falling Edge of LD; Error Register is
copied into Shift Register
LD
Current
≤ 100mA
GEF = Global Error Flag
Error Detection with Low-Current Diagnosis Mode
This unique feature of the AS1109 uses an internal all 1s test pattern for a flicker free diagnosis of all LEDs. This error
detection mode can be started anytime, and does not require any SDI input (see Figure 21).
Figure 21. Low-Current Diagnosis Mode with Internal All 1s Test Pattern – 128 Cascaded AS1109s
2µs Low-Current Diagnosis Mode
Data0
Data1
Display
SDI
Data1
Data2
O or S Error Code of
All 1s Test Patern
Temperature Error Code
1024x
SDO
GEF
GEF
3x Clocks Low-
Current Mode
Clock for Error
Mode 1x/2x
1024x
CLK
Rising Edge of OEN
Acquisition of Error Status
OEN
Falling Edge of LD; Error Register
is copied into Shift Register
LD
Load Internal All 1s Test Pattern
Current
≤ 100mA
≤ 100mA
≤ 0.8mA
GEF = Global Error Flag
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