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| BD9415FS Datasheet, PDF (21/34 Pages) Rohm – White LED Driver for 4Ch Large LCD Panels (DC/DC converter type) | |||
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BD9415FS
3.5. Timing Chart
3.5.1 PWM Start Up
VCC
7.5V
STB
REG90
2.0V
5.8V
UVLO
FAILB
(External PullUp)
2.5V
SSFB
LED_OK
(internal)
VOUT
PWMx
ILEDx
0.8V
LED Open Detection
LED Short Detection
OFF
(*1) (*2) (*3)
NORMAL
(*4)
Figure 24. Start Up
OFF
(*5)
(*1)â¦REG90 starts up when STB is changed from Low to High. In the state where the PWM signal is not inputted, SS terminal
is not charged and DCDC doesn't start to boost, either.
(*2)â¦When REG90 is more than 5.8V(Typ), the reset signal is released.
(*3)â¦The charge of the pin SS starts at the positive edge of PWM=L to H, and the soft start starts. The pin SS continues
charging in spite of the assertion of PWM or OVP level.
(*4)â¦The soft start interval will end if the LED_OK = H (internal signal), By this time, it boosts VOUT to the voltage where the
set LED current flows. The abnormal detection of FBMAX starts to be monitored.
(*5)â¦As STB=L, the boost operation is stopped instantaneously.( N=L, SSFB=L)
www.rohm.com
© 2015 ROHM Co., Ltd. All rights reserved.
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TSZ02201-0F2F0C100140-1-2
23.May.2016 Rev.001
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