BD9285F ROHM [Rohm], BD9285F Datasheet - Page 32

• Manufacturer Part Number: BD9285F
• Description: Boost 1channel white LED driver For large LCDs
• Manufacturer: ROHM [Rohm]

3.7.7 LED OPEN detection
(*1)…During starting up, even if the normality, ISENSE<0.1V because of the low Vout. Therefore the OPEN detection will be
(*2)…In the same way, as PWM=L, ISENSE<0.1V because of DIMOUT=L. OPEN will be masked, too.
(*3)…Though the OPEN is detected if ISENSE<0.1V as the PWM=H, it is not judged immediately to abnormal state. The
(*4)…The CP counter will start if the OPEN detection continues 4 clock of the GATE frequency. To detect the OPEN state
(*5)…When the OPEN detection continues up to 4649 count with the CP counter, IC will be latched off. At this time, it asserts
(*6)…The latch off state can be reset by the STB=L.
(*7)…It normally starts by STB=L to H, in this figure.
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TSZ22111・15・001
BD9285F
masked for the soft start period.
behavior of GATE, FAILB keeps the normal operation.
continuously, it compulsorily becomes DIMOUT=H regardless of the PWM logic.
GATE=L, DIMOUT=L, FAILB=L for the first time.
CPcountor
DIMOUT
ISENSE
PWM1and
STATE
FAILB
GATE
PWM2
STB
SS
STANDBY
OFF
(*1)
1.1V
0.1V
(*2)
SS
・・・・・
3.0V
NORMAL
(*3)
0.1V
① ② ③ ④
32/36
(*4)
4096count
CP COUNTOR
・・・・・
(*5)
latch
off
(*6)
RESET
(off)
TSZ02201-0F1F0C100030-1-2
STANDBY
(*7)
0.1V
1.1V
SS
11.Jul.2012 Rev.001
Datasheet