BD9285F Datasheet, PDF (27/39 Pages) Rohm – Boost 1channel white LED driver For large LCDs

BD9285F
3.7.2 starting up 2 (PWM signal inputs and STB succeeds)
Datasheet
(*1)…TC54 starts up if STB turns from L to H.
(*2)…At the moment the release of V5UVLO (the UVLO of the pin TC54), or the time of the positive edge of PWM=L to H, the
soft start starts. The GATE pulse outputs only during PWM1=H. And as the SS is less than 1.1V, the pulse does not output.
The pin SS continues charging in spite of the assertion of PWM and OVP.
(*3)…The soft start interval will end if the voltage of the pin SS, Vss reaches to 3.0V. By this time, BD9285 boost Vout where the
set LED current flows. It is started to monitor the abnormal detection of SCP and OPEN.
(*4)…As STB=L, instantaneously the boost operation is stopped. (GATE=L, SS=L) On the other hand, the discharge circuit
works in the interval “STB=L and V5UVLO=H”. Please refer to the time chart in the section 3.7.3 for details.
(*5)…As STB=H again, it is the same operation as the timing of (*1).
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TSZ02201-0F1F0C100030-1-2
11.Jul.2012 Rev.001