MB3886 Fujitsu Microelectronics, Inc., MB3886 Datasheet - Page 20

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MB3886

Manufacturer Part Number
MB3886
Description
2-channel Dc/dc Converter Ic With Overcurrent Protection Symmetrical-phase Type
Manufacturer
Fujitsu Microelectronics, Inc.
Datasheet
20
MB3886
SETTING THE OVERVOLTAGE DETECTION VOLTAGE
An overvoltage output from the DC/DC converter can be detected by connecting external resistors from the DC/
DC converter output voltage to the INC1 terminal (pin 10) and INC2 terminal (pin 21) of the overvoltage
comparators (OVP Comp. 1 and 2) .
When the DC/DC converter output voltage rises and the detection voltage exceeds the setting voltage, the output
of the overvoltage comparator (OVP Comp. 1, 2) becomes the “H” level and the latch is set to fix only the main
output of the relevant channel at the “L” level and the synchronous-rectification output at the “H” level. At the
same time, the overvoltage protection circuit fixes the PSIG1 terminal (pin 1) at the “L” level when the overvoltage
is detected on CH1 or the PSIG2 terminal (pin 30) at the “L” level when it is detected on CH2. Note that the
overvoltage protection circuit works for each channel separately.
To reset the actuated protection circuit, either set the CTL1 terminal (pin 2) or CTL2 terminal (pin 29) to the “L”
level, or decrease the V
Overvoltage detection voltage : V
V
OVP
(V) : = 1.47
(R3 ( )
V
R3
R4
CC
O
voltage to the reset voltage (1.7 V Min) or less.
( INC2)
R4 ( ) )
INC1
OVP
21
10
R4 ( )
1.47 V
OVP
Comp.
CTL1 (CTL2)
R
S
Q

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