MB39A125 Datasheet, PDF (26/64 Pages) Fujitsu Component Limited. – DC/DC Converter IC for Charging Li-ion Battery

MB39A125/126
2. Protection Functions
(1) Under voltage lockout protection circuit block (UVLO)
The transient state or a momentary decrease in power supply voltage or internal reference voltage (VREF) ,
which occurs when the power supply (VCC) is turned on, may cause malfunctions in the control IC, resulting in
breakdown or deterioration of the system.
To prevent such malfunction, the under voltage lockout protection circuit detects internal reference voltage drop
and fixes the OUT terminal (pin 20) to the “H” level. The system restores voltage supply when the internal
reference voltage reaches the threshold voltage of the under voltage lockout protection circuit.
Protection circuit (UVLO) operation function table : MB39A125
When UVLO is operating (VREF voltage is lower than UVLO threshold voltage, the logic of the following terminal
is fixed.)
OUTD
OUT
CS
ACOK
XACOK
Hi-Z
H
L
H
L
Protection circuit (UVLO) operation function table : MB39A126
When UVLO is operating (VREF voltage is lower than UVLO threshold voltage, the logic of the following terminal
is fixed.)
OUT
CS
ACOK
XACOK
H
L
H
L
(2) Low input voltage detection block (UV Comp.)
UV Comp. detects that power supply voltage (VCC) is lower than the battery voltage +0.2 V (Typ) and fixes the
OUT terminal (pin 20) to the “H” level.
The system restores voltage supply when the power supply voltage reaches the threshold voltage of the AC
adapter detection block.
Protection circuit (UV Comp.) operation function table : MB39A125
When UV Comp. is operating (VCC voltage is lower than UV Comp. threshold voltage, the logic of the following
terminal is fixed.)
OUTD
OUT
CS
L
H
L
Protection circuit (UV Comp.) operation function table : MB39A126
When UV Comp. is operating (VCC voltage is lower than UV Comp. threshold voltage, the logic of the following
terminal is fixed.)
OUT
CS
H
L
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