MB39A132QN-G-ERE1 Datasheet, PDF (19/56 Pages) Fujitsu Component Limited. – ASSP For Power Management Applications (Rechargeable Battery) Synchronous Rectification DC/DC Converter IC for Charging Li-ion Battery

MB39A132
2. Protection Functions
(1) Under voltage lockout protection circuit (VREF-UVLO)
A momentary decrease in internal reference voltage (VREF) may cause malfunctions in the control IC,
resulting in breakdown or degradation of the system. To prevent such malfunction, the under voltage lockout
protection circuit detects internal reference voltage drop and fixes the OUT1 pin (pin 30) and the OUT2 pin
(pin 27) at the “L” level. UVLO will be released when the internal reference voltage reaches the threshold
voltage of the under voltage lockout protection circuit.
Protection circuit (VREF-UVLO) operation function table
When UVLO is operating (VREF voltage is lower than UVLO threshold voltage.), the logic value of the
following pin is fixed.
OUT1
OUT2
CS
VB
L
L
L
L
(2) Under voltage lockout protection circuit (VCC-UVLO, VB-UVLO)
The transient state or the momentary decrease in power supply voltage, which occurs when the bias voltage
(VB) for output circuit is turned on, may cause malfunctions in the control IC, resulting in breakdown or
degradation of the system. To prevent such malfunction, the under voltage lockout protection circuit detects
a bias voltage drop and fixes the OUT1 pin (pin 30) and the OUT2 pin (pin 27) at the “L” level. UVLO will be
released when the power supply voltage or internal reference voltage reaches the threshold voltage of the
under voltage lockout protection circuit.
Protection circuit (VCC-UVLO, VB-UVLO) operation function table
When UVLO is operating (VCC voltage or VB voltage is lower than UVLO threshold voltage.), the logical
value of the following pin is fixed.
OUT1
OUT2
CS
L
L
L
(3) Under input voltage detection block (UV Comp.)
It compares the VCC pin (pin 1) voltage with the BATT pin (pin 17) voltage. If the VCC voltage is lower than
the BATT pin voltage plus 0.1 V (Typ), the comparator fixes the OUT1 pin (pin 30) and the OUT2 pin (pin
27) at "L" level.
The system resumes operation when the input voltage is higher than the threshold voltage of the under input
voltage detection comparator.
Protection circuit (UV Comp.) operation function table
When under input voltage is detected (Input voltage is lower than UV Comp. threshold voltage), the logical
value of the following pin is fixed.
OUT1
OUT2
CS
L
L
L
DS04–27265–3E
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