BD9422EFV_15 Datasheet, PDF (22/30 Pages) Rohm – White LED Driver for large LCD panel

BD9422EFV
●3.8.3 Protective operation sequence at FAIL_MODE=H
・Basic sequence
Datasheet
・Actual sequence
Error detect
MASK synchronize
(4clk) (3clk) ^{CP charge time}
(CLK)
Figure 29.
CP reset time
(1024clk)
…
…
2V detect hold CP reset time
CP charge time
(3clk) _(1024clk)
…
…
…
(ERR)
2V
CP
FAIL
PWM*
LED*
SHORT detect state
SHORT detect state
After it pasts CP charge time and CP
reset time, FAIL Output 1shot pulse.
LSP detect voltage
If error signal input in this period, it is ignored.
Discharge CP by 2 times error signal
Charge is started at 1 times error detect, but it moved to reset period at 2 times error
detect immediately, therefore error signal can’t be detected.
Figure 30.
The above chart is sample of SHORT detection, but the chart of OPEN detection is also same structure.
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1.Sep.2015 Rev.006