www.ams.com/LED-Driver-ICs/AS1110 Revision 1.6 15 - 24
AS1110
Datasheet - Detailed Description
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 I
LC. 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:
1111111111111111 1111111111111111 0100011111111111
LED Status:
11111XX111111111 1111111111111111 X111111111111111
Failure Code:
1111100111111111 1111111111111111 1111111111111111
Global Flag Readout Detailed Error Report Readout
SDI
OEN
LD
CLK
SDO
tH(L)
tSU(ERROR)
tP1
tSW(ERROR)
tP4
TFLAG
SFLAG
Acquisition of Error
Status
DBit14 DBit13 DBit12 DBitn DBit2 DBit1 DBit0
Don’t
Care
Don’t
Care
SBit14 SBit13 SBit12 SBitn SBit2 SBit1 SBit0SBit15
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)
