BD9394FP Datasheet, PDF (17/31 Pages) Rohm – White LED Driver for large LCD Panels (DCDC Converter type)

BD9394FP, BD9394EFV
Datasheet
●・Timer Latch Time Setting
This IC has a built-in timer latch counter. Timer latch time is set by counting the clock frequency which is
set at the RT pin.
●Timer Latch Time
When various abnormal conditions happen, counting starts from the timing, latch occurs after below time has passed.
Furthermore, even if PWM=L, if abnormal condition continues, timer count will not reset.
LATCH_TIME
= 2¹²
× ^RRT
1.5 ×10¹⁰
= 4096× ^{RRT [kΩ][}s]
1.5 ×10⁷
Here, LATCH_TIME = time until latch condition occurs
R_RT = Resistor value connected to RT pin
【Setting Example】
Example of LED Short protection timing chart
Timer latch time when RT=75kohm
LATCH_TIME
=
4096×
R_RT [kΩ]
1.5×10⁷
=
4096×
75[kΩ]
1.5×10⁷
= 0.02[s]　
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TSZ22111・15・001
17/28
TSZ02201-0F1F0C100180-1-2
09.Nov.2012 Rev.002