BD9483F Datasheet, PDF (25/32 Pages) Rohm – White LED Driver for large LCD Panels (DCDC Converter type)

BD9483F,FV
Datasheet
●3.7.6 LED OCP detection
STB
PWM1or
PWM2
INSENSE
3.0V
3.0V
3.0V
3.0V
Abnormal
COUNTOR
SS
Smaller than
4count
4count
GATE
DIMOUT
FAILB
3.0V
3.0V
0.4V
4count
STATE
NORMAL LEDOCP NORMAL _LEDOCP Latch off Reset _{NORMAL LEDOCP}
abnormal
(*1)
(*2)
abnormal
(*3)
(*4) (*5)
(OFF)
(*6)
(*7)
abnormal
(*8)
Figure 38.
Latch off
(*1)…If ISENSE>3.0V, LEDOCP is detected, it becomes GATE=L. To detect LEDOCP continuously, The DIMOUT is
compulsorily high, regardless of the PWM dimming signal.
(*2)…When the LEDOCP releases within 4 counts of the GATE frequency, the boost operation restarts.
(*3) …As the LEDOCP is detected again, the boost operation is stopped, too.
(*4)…If the LEDOCP detection continues up to 4 counts of GATE frequency. IC will be latched off.
(*5)…Once IC is latched off, the boost operation doesn't restart even if the LEDOCP releases. And both CH1 and CH2 will be
stopped.
(*6)…The latch off state can be reset by the STB=L.
(*7)…It normally starts by STB=L to H.
(*8)…The operation of the LEDOCP detection is not related to the logic of the PWM.
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28.Nov.2013 Rev.003