BD9420F Datasheet, PDF (13/31 Pages) Rohm – White LED Driver for large LCD Panels (DCDC Converter Type)

BD9420F
●OVP/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.
○OVP detect setting equation
Assuming that voltage of VOUT rising abnormally and detecting
OVP is “VOVP_DET”, R1 and R2 setting will be made by the
following equation.
+
- ^3.0V/2.8V
OVP
-
+ ^0.1V
Datasheet
VOUT
R1
R2
○OVP release setting equation
When R1 and R2 setting is determined by the equation shown above, OVP release voltage VOVP_CAN will be give by the
following equation :
○SCP detect setting
The SCP setting「VSCP_DET」 voltage is calculated as below when R1,R2 is decided above:
VSCP_DET

0.1V

(R1[k]  R2[k])
R2[k]
[V ]
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31.Jan.2014 Rev.002