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AS1109

Datasheet - Detailed Descr i p ti on

8.6.2 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

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:

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 14) 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.

Input Data: 1 111 1111

11 1111 11

1 111 1111

111 111 11

1 1111 111

LED Status: 1 111 1111

11 1X X 1 11

1 111 1111

1X 1 111 11

1 1111 111

Failure Code: 1 111 1111

11 1001 11

1 111 1111

101 111 11

1 1111 111

Global Flag Readout

Detailed Error Report Readout

SDI

OEN

LD

CLK

SDO

tH(L)

Open Error Report Output

New Data Input

tP4

tP1

tP4

tSW(ERROR)

tSU(ERROR)

tTESTING

DBit0

DBit1

DBit2

DBit3

DBit4

DBit5

DBit6

OBit0

OBit1

OBit2

OBit3

OBit4

OBit5

OBit6

Don’t

Care

Don’t

Care

OBit7

TFlag

OFlag

DBit7

For detailed timing information see Timing Diagrams on page 8.

tGSW(ERROR)

tGSW(ERROR)

tGSW(ERROR)