BD9420F Datasheet, PDF (24/31 Pages) Rohm – White LED Driver for large LCD Panels (DCDC Converter Type)

BD9420F
Datasheet
○Timing of Error detection
This IC is individual Latch OFF. Therefore, Error detection is every channel.
The detection timing of LED OPEN, SHORT and GND SHORT Protection is different with PWM Duty or Timing of Error state as
follows:
(A).Other channels will be in Error states within 4counts of internal CLK. [When PWM=100%]
※Error detection is same timing.
(B).Other channels will be in Error states after 4counts of internal CLK. [When PWM=100%]
PWM _H
0.3V
CL1_Voltage
0V
0.3V
CL2_Voltage
0V
Oscllator
(Internal IC)
CH1_Error_Detect
(Internal IC)
CH2_Error_Detect
(Internal IC) ^L
4CLK
Error detect
Error no detect
※Error detection is only first Error state channel.
(C).Other channels will be in Error states after 4counts of internal CLK. [When except PWM=100%]
※First Error state channel is Latch OFF. Then, the detection of the following channel can detect whenever the new edge
of PWM comes. Finally, all Error state channels are Latch off.
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TSZ02201-0F1F0C100300-1-2
31.Jan.2014 Rev.002