BD9394FP Datasheet, PDF (13/31 Pages) Rohm – White LED Driver for large LCD Panels (DCDC Converter type)

BD9394FP, BD9394EFV
Datasheet
c About unused LED terminal automatic detecting function
This IC is detected automatically that it is an unused channel by asssuming the LED terminal to be OPEN at starting. It
explains the sequence.
Sequence;
① STB=ON
② All systems are ON at initial timing of PWM=H. SS starts charging.
③ When the output voltage is boosted enough, and enough current flows through the LED, LED_OK signal is switched
in the IC. PWM=L from the Rise timing of this signal for about 20us
④ During this PWM=L period, LED pins with LED connections' output voltage becomes 0.2V and above, where as
unused LED pins are below 0.2V.
⑤ During this time, determination on whether the LED pins are 0.2V above/below is done.
⑥ After the determination, unused LED pins are pulled up to 5V.
⑦The AUTO signal remains “L” level.
In addition, automatic determination of the OPEN decision will only be in SS range, therefore, please set the application so
that the step-up/boost be completed before SS> 3.7V.
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TSZ22111・15・001
13/28
TSZ02201-0F1F0C100180-1-2
09.Nov.2012 Rev.002