MB3878 Datasheet, PDF (15/24 Pages) Fujitsu Component Limited. – DC/DC Converter IC for Charging

MB3878
s AC ADAPTOR VOLTAGE DETECTION
With an external resistor connected to the +INE2 terminal(pin 3), the IC enters the dynamically-controlled
charging mode to reduce the charge current to keep AC adaptor power constant when the partial potential point
A of the AC adaptor voltage (Vcc) becomes lower than the voltage at the -INE2 terminal.
AC adaptor detected voltage setting: Vth
Vth (V) = (R1 + R2) / R2 × −INE2
−INE2 setting voltage range : 1.176 V to 4.2 V (equivalent to 7 V to 25 V for Vcc)
−INE2
4
A
VCC
3
R1 +INE2
R2
<Error Amp.2>
−
+
s OPERATION TIMING DIAGRAM
Error Amp.1 FB1
Error Amp.3 FB3
Error Amp.2 FB2
OUT
AC adaptor dynamically- _Constant
controlled charging
voltage control
Constant current control
2.5 V
1.5 V
AC adaptor dynamically-
controlled charging
15