AS1109
Data Sheet - Detailed Description
Detailed Open-LED Error Report
The detailed open-LED error report can be read out immediately after global error mode has been run.
Figure 16. Detailed Open-LED Error Report Timing Diagram
Global Flag Readout
Detailed Error Report Readout
OEN
LD
tTESTING
tH(L)
tP4
tSU(ERROR)
tGSW(ERROR)
tGSW(ERROR)
CLK
SDI
tGSW(ERROR)
Don’t
Care
DBit6 DBit5 DBit4 DBit3 DBit2 DBit1 DBit0
New Data Input
DBit7
tSW(ERROR)
Don’t
Care
OBit7 OBit6 OBit5 OBit4 OBit3 OBit2 OBit1 OBit0
TFlag
tP4
OFlag
SDO
Open Error Report Output
tP1
For detailed timing information see Timing Diagrams on page 9.
Detailed Open-LED Error Report Example
Consider a case where five AS1109s are cascaded in one chain. A 1 indicates a LED is on, a 0 indicates a LED is off,
and an X indicates an open LED. The open-LED test is only applied to LEDs that are turned on. This test is used with
a test pattern where all LEDs are on at test time.
IC1:[11111111] IC2:[111XX111] IC3:[11111111] IC4:[1X111111] IC5:[11111111]
IC2 has two open LEDs and IC4 has one open LED switched on due to input. 5*8 clock cycles are needed to write the
entire error code out. The detailed error report would look like this:
Input Data: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
LED Status: 1 1 1 1 1 1 1 1 1 1 1 X X 1 1 1 1 1 1 1 1 1 1 1 1 X 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Failure Code: 1 1 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Comparing this report with the input data indicates that IC2 is the device with two open LEDs at position 4 and 5 and
IC4 with an open LED at second position. For such a test it is recommended to enter low-current diagnostic mode first
(see Low-Current Diagnostic Mode on page 15) to reduce onscreen flickering.
Note: In an actual report there are no spaces in the output.
LEDs turned off during test time cannot be tested.
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