AS1109 데이터 시트보기 (PDF) - austriamicrosystems AG
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AS1109 Datasheet PDF : 25 Pages
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AS1109
Datasheet - Detailed Description
Figure 14. Switching Global Error Mode Timing Diagram
OEN
LD
tTESTING
tGSW(ERROR)
tSU(ERROR)
CLK
tP(I/O)
tGSW(ERROR)
tP(I/O)
tGSW(ERROR)
tP(I/O)
SDI
TFLAG(IN)
OFLAG(IN)
SFLAG(IN)
SDO
Don’t
Care
TFLAG
Don’t
Care
OFLAG
Don’t
Care
SFLAG
Acquisition of Error
tP4
Status
tSW(ERROR)
tSW(ERROR)
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 AS1109.
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
(TFLAG, OFLAG, SFLAG) is delivered to pin SDO if any errors are encountered.
Table 5. Global Error Mode Selections
Clock
Pulses
0
1
2
3
4
Output Port
Don't Care
Enabled
Enabled
Don't Care
Don't Care
Error-Detection Mode
Global Error Flag/Shutdown Condition
Over-Temperature Detection
Open-LED Detection
Shorted-LED Detection
Low-Current Diagnostic Mode
Shutdown Mode
TFLAG = SDO = 1: No over-temperature warning.
TFLAG = SDO = 0: Over-temperature warning.
OFLAG = SDO = 1: No open-LED error.
OFLAG = SDO = 0: Open-LED error.
SFLAG = SDO = 1: No shorted-LED error.
SFLAG = SDO = 0: Shorted-LED error.
SDI = 1: Wakeup
SDI = 0: Shutdown
Note: For a valid result SDI must be 1 for the first device.
If there are multiple AS1109s 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*tP(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 AS1109, or LED produced the error.
Note: When no error has occurred, the detailed error report can be skipped, setting LD and subsequently OEN low.
www.ams.com/LED-Driver-ICs/AS1109
Revision 1.21
10 - 24
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