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AS1123

Datasheet - D e t a i l e d D e s c r i p t i o n

Detailed Open-LED Error Report

The detailed open-LED error report can be read out immediately after global error mode has been run. SDI must be 1 for the first device.

Figure 15. Detailed Open-LED Error Report Timing Diagram

Detailed Open-LED Error Report Example:

Consider a case where three AS1123s 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:[1111111111111111] IC2:[111XX11111111X11] IC3:[1111111111111111]

IC2 has three open LEDs switched on due to input. 3*16 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 one open LED at position

14. For such a test it is recommended to enter low-current diagnostic mode first (see Low-Current Diagnostic Mode on page 14) to reduce screen

flickering.

This test can be used also on-the-fly without using an all 1s test pattern (see Figure 19 on page 16).

Note:

In an actual report there are no spaces in the output. LEDs turned off during test time cannot be tested and will show a logic 1 in the

detailed error report.

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 1 1 1 1 1 1 1 1

LED Status:

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

1 1 1 X X 1 1 1 1 1 1 1 1 X 1 1

1 1 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 1 1 1 1 1

1 1 1 0 0 1 1 1 1 1 1 1 1 0 1 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Global Flag Readout

Detailed Error Report Readout

SDI

OEN

LD

CLK

SDO

Open Error Report Output

New Data Input

DBit0

DBit1

DBit2

DBitn

DBit12

DBit13

DBit14

OBit0

OBit1

OBit2

OBitn

OBit12

OBit13

OBit14

Don’t

Care

Don’t

Care

OBit15

DBit15

For detailed timing information see Timing Diagrams on page 8.