MB39A132QN-G-ERE1 Datasheet, PDF (16/56 Pages) Fujitsu Component Limited. – ASSP For Power Management Applications (Rechargeable Battery) Synchronous Rectification DC/DC Converter IC for Charging Li-ion Battery

MB39A132
■ FUNCTIONAL DESCRIPTION
MB39A132 is an N-ch MOS driver-supported DC/DC converter which uses pulse width modulation (PWM)
for charging Li-ion battery and controls the charge voltage and current when charging the battery. To stabilize
the power supplied from a battery or an adapter to a system, this DC/DC converter has a battery charging
control function and an AC adapter voltage detection function.
When MB39A132 controls charge voltage (constant voltage mode), it can freely set the charge voltage with
the voltage input to the ADJ3 pin (pin 18) and the CELLS pin (pin 25). It compares the BATT pin (pin 17)
voltage and the internal reference voltage with the error amplifier (Error Amp3), outputs PWM control signals
and then outputs the charge voltage freely set by the IC.
When MB39A132 controls charge current (constant current mode), it amplifies the voltage drop occurring
on both ends of the charge current sense resistor (Rs) by 25 times with the current detection amplifier
(Current Amp2), and then outputs the amplified voltage to the OUTC2 pin (pin 11). It compares the output
voltage of the current detection amplifier (Current Amp2) and the voltage set in the ADJ2 pin (pin 14) with
the error amplifier (Error Amp2), and then outputs PWM control signals for executing constant-current charge.
When MB95A132 controls AC adapter power, in the case of an output voltage drop in the AC adapter, the
converter amplifies the voltage difference between the voltage applied to the -INC1 pin (pin 2) that has
dropped and the +INC1 pin (pin 3) voltage (VVREF) by 25 times with the current detection amplifier (Error
Amp1), and then outputs the amplified voltage value to the OUTC1 pin (pin 10). It compares the output
voltage of the current detection amplifier (Current Amp1) to the ADJ1 pin (pin 7) voltage using the error
amplifier (Error Amp1) to output PWM control signals for controlling the charge current so that the AC adapter
power can be kept constant.
The triangular wave voltage generated by the triangular wave oscillator is compared with the output voltage
of one of the three error amplifiers (Error Amp1, Error Amp2 and Error Amp3) that has the lowest potential.
The main FET is turned on during the period when the triangular wave voltage is lower than the error amplifier
output voltage.
In addition, the AC Comp. detects installation/removal of the AC adapter and its information is output through
the ACOK pin (pin 5).
16
DS04–27265–3E