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AS1110

Datasheet - Detailed Descr i p ti on

8.6.3 Detailed Shorted-LED Error Report

The detailed shorted-LED error report can be read out immediately after global error mode has been run (see Global Error Mode on page 11).

SDI must be 1 for the first device.

Figure 16. Detailed Shorted-LED Error Report Timing Diagram

Detailed Shorted-LED Error Report Example

Consider a case where three AS1110s are cascaded in one chain. A 1 indicates a LED is on, a 0 indicates a LED is off, and an X indicates a

shorted LED. This test is used on-the-fly.

IC1:[11111XX111111111] IC2:[1111111111111111] IC3:[X100011111111111]

IC1 has two shorted LEDs which are switched on, IC3 has one shorted LED switched off due to input. 3*16 clock cycles are needed to write the

entire error code out. The detailed error report would look like this:

Showing IC1 as the device with two shorted LEDs at position 6 and 7, and IC3 with one shorted LED at position 1. The shorted LED at position 1

of IC3 cannot be detected, since LEDs turned off at test time are not tested and will show a logic "1" at the detailed error report. To test all LEDs

this test should be run with an all 1s test pattern. For a test with an all on test pattern, low-current diagnostic mode should be entered first to

reduce on-screen flickering.

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.

8.6.4 Low-Current Diagnostic Mode

To run the open- or shorted-LED test, a test pattern must be used that will turn on each LED to be tested. This test pattern will cause a short

flicker on the screen while the test is being performed. The low-current diagnostic mode can be initiated prior to running a detailed error report to

reduce this on-screen flickering.

Note:

Normally, displays using such a diagnostic mode require additional cables, resistors, and other components to reduce the current. The

AS1110 has this current-reduction capability built-in, thereby minimizing the number of external components required.

Low-current diagnostic mode can be initiated via 3 clock pulses during error-detection mode. After the falling edge of LD, a test pattern displaying

all 1s can be written to the shift register which will be used for the next error-detection test.

On the next falling edge of OEN, current is reduced to ILC. With the next rising edge of OEN the current will immediately increase to normal

levels and the detailed error report can be read out entering error-detection mode.

Input Data: 1 1 1 1111 1111 111 11

1 1111 111 1111 1111

01 0001 1111 111 111

LED Status: 1 1 1 11X X 1111 111 11

1 1111 111 1111 1111

X 1 1111 1111 111 111

Failure Code: 1 1 1 1100 1111 111 11

1 1111 111 1111 1111

11 1111 1111 111 111

Global Flag Readout

Detailed Error Report Readout

SDI

OEN

LD

CLK

SDO

tH(L)

tSU(ERROR)

tP1

tSW(ERROR)

tP4

TFLAG

SFLAG

DBit14 DBit13 DBit12

DBitn

DBit2

DBit1

DBit0

Don’t

Care

Don’t

Care

SBit14 SBit13 SBit12

SBitn

SBit2

SBit1

SBit0

SBit15

New Data Input

Shorted-LED Error Report Output

OFLAG

TFLAG

tP4

tTESTING

Global Flag Readout

DBit15

For detailed timing information see Timing Diagrams on page 9.

tGSW(ERROR)

tGSW(ERROR)

tGSW(ERROR)