www.ams.com/LED-Driver-ICs/AS1110 Revision 1.6 11 - 24
AS1110
Datasheet - Detailed Description
Figure 13. Switching Global Error Mode Timing Diagram
8.3 Error-Detection Mode
Acquisition of the error status occurs at the rising edge of OEN. Error-detection mode is started on the rising edge of LD when OEN is high. The
CLK signal must be low when entering error detection mode. Error detection for open- and shorted-LEDs can only be performed for LEDs that
are switched on during test time. To switch between error-detection modes clock pulses are needed (see Table 5).
Note: To test all LEDs, a test pattern that turns on all LEDs must be input to the AS1110.
8.4 Global Error Mode
Global error mode is entered when error-detection mode is started. Clock pulses during this period are used to select between temperature,
open-LED, and shorted-LED tests, as well as low-current diagnostic mode and shutdown mode (see Table 5). In global error mode, an error flag
(T
FLAG, OFLAG, SFLAG) is delivered to pin SDO if any errors are encountered.
Note: For a valid result SDI must be 1 for the first device.
If there are multiple AS1110s in a chain, the error flag will be gated through all devices. To get a valid result at the end of the chain, a logic 1 must
be applied to the SDI input of the first device of the chain. If one device produces an error this error will show up after n*t
P(I/O) + tSW(ERROR) at
pin SDO of the last device in the chain. This means it is not possible to identify which device in the chain produced the error. Therefore, if a global
error occurs, the detailed error report can be run to identify which AS1110, or LED produced the error.
Note: When no error has occurred, the detailed error report can be skipped, setting LD and subsequently OEN low.
Table 5. Global Error Mode Selections
Clock
Pulses
Output Port Error-Detection Mode Global Error Flag/Shutdown Condition
0 Don't Care Over-Temperature Detection
T
FLAG = SDO = 1: No over-temperature warning.
T
FLAG = SDO = 0: Over-temperature warning.
1 Enabled Open-LED Detection
O
FLAG = SDO = 1: No open-LED error.
O
FLAG = SDO = 0: Open-LED error.
2 Enabled Shorted-LED Detection
S
FLAG = SDO = 1: No shorted-LED error.
S
FLAG = SDO = 0: Shorted-LED error.
3 Don't Care Low-Current Diagnostic Mode
4 Don't Care Shutdown Mode
SDI = 1: Wakeup
SDI = 0: Shutdown
tTESTING
tSU(ERROR)
OFLAG(IN) SFLAG(IN)TFLAG(IN)
TFLAG OFLAG SFLAG
tSW(ERROR)
SDI
OEN
LD
CLK
SDO
Don’t
Care
Don’t
Care
tGSW(ERROR)
tP(I/O)
tP4
tP(I/O) tP(I/O)
tSW(ERROR)
tGSW(ERROR)
tGSW(ERROR)
Don’t
Care
Acquisition of Error
Status
