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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 Timng 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 mnimzing 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: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
LED Status: 1 1 1 1 1 X X 1 1 1 1 1 1 1 1 1
Failure Code: 1 1 1 1 1 0 0 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
0 1 0 0 0 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
X 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
Global Flag Readout
Detailed Error Report Readout
SDI
OEN
LD
CLK
SDO
t
H(L)
t
SU(ERROR)
t
P1
t
SW(ERROR)
t
P4
T
T
FLAG
S
FLAG
A
S
DBit14 DBit13 DBit12
DBitn
DBit2
DBit1
DBit0
Dont
Care
Dont
Care
SBit14 SBit13 SBit12
SBitn
SBit2
SBit1
SBit0
SBit15
New Data Input
Shorted-LED Error Report Output
O
FLAG
t
P4
t
TESTING
DBit15
For detailed timng information see
Timng Diagrams on page 9
.
t
GSW(ERROR)
t
GSW(ERROR)
t
GSW(ERROR)