MB39A114 Datasheet, PDF (17/54 Pages) Fuji Electric – DC/DC Converter IC for Charging Li-ion Battery

MB39A114
(7) Current detection amplifier block (Current Amp2)
The current detection amplifier (Current Amp2) detects a voltage drop which occurs between both ends of the
output sense resistor (RS) due to the flow of the charge current, using the +INC2 terminal (pin 24) and −INC2
terminal (pin 1) . Then it outputs the signal amplified by 20 times to the error amplifier (Error Amp2) at the next
stage.
(8) PWM comparator block (PWM Comp.)
The PWM comparator circuit is a voltage-pulse width converter that controls the output duty of the error amplifier
(Error Amp.1 to Error Amp.3) according to the output voltage.
It is compared between triangular wave voltage generated in triangular wave oscillator and error amplifier output
voltage and during intervals when the triangular wave voltage is lower than the error amplifier output voltage,
an external output transistor is switched on.
(9) Output block (OUT)
The output circuit uses a totem-pole configuration and is capable of driving an external P-ch MOS FET device.
For the output “L” level, set the output amplitude to 6 V (Typ) using the voltage generated by the bias voltage
block (VH) .
This results in higher conversion efficiency and suppressing the withstand voltage of the connected external
transistor even in a wide range of input voltages.
(10) Power control (CTL)
Setting the CTL terminal (14 pin) low places the IC in the standby mode.
(Power supply current 10 µA max at standby mode.)
CTL function table
CTL
L
H
Power
OFF (Standby)
ON (Active)
(11) Bias voltage block (VH)
The bias voltage circuit outputs VCC − 6 V (Typ) as the minimum potential of the output circuit. In the standby
mode, this circuit outputs the potential equal to VCC.
2. Protection Function
(1) Under voltage lockout protection circuit (UVLO)
The transient state, which occurs when the power supply (VCC) is turned on, a momentary decrease in supply
voltage or internal reference voltage (VREF), may cause the control IC to malfunction, resulting in breakdown
or degradation of the system. To prevent such malfunctions, under voltage lockout protection circuit detects a
internal reference voltage drop and fixes the OUT terminal (pin 20) at 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.
At UVLO operating (VREF voltage is lower than UVLO threshold voltage.)
OUT
CS
CVM
OVP
H
L
H
H
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