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BD9421F_15 Datasheet, PDF (13/31 Pages) Rohm – White LED Driver for large LCD Panels (DCDC Converter Type) | |||
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BD9421F
âOVP/SCP setting procedure (OVP Pin)
The OVP pin is an input pin for overvoltage protection and short
circuit protection of DC/DC output voltage. The OVP pin is a high
impedance type and no pull-down resistor inside, resulting in
unstable potential in the open circuit state. To avoid this problem, be
sure to make input voltage setting with the use of a resistive divider.
âOVP detect setting equation
Assuming that voltage of VOUT rising abnormally and detecting
OVP is âVOVPDETâ, R1 and R2 setting will be made by the
following equation.
+
- 3.0V/2.8V
OVP
-
+ 0.1V
Datasheet
VOUT
R1
R2
âOVP release setting equation
When R1 and R2 setting is determined by the equation shown above, OVP release voltage VOVPCAN will be given by the
following equation :
âSCP detect setting
The SCP settingãVSCPDETã voltage is calculated as below when R1,R2 is decided above:
VSCPDET
ï½
0.1V
ï´
(R1[kï] ï« R2[kï])
R2[kï]
[V ]
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TSZ22111 ⢠15 ⢠001
13/27
TSZ02201-0F1F0C100310-1-2
25.Sep.2015 Rev.003
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