FUJITSU MB3887 - Manual (Page 20)

MB3887
20
■ 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 adapter power constant when the partial potential
point A of the AC adapter voltage (VCC) becomes lower than the voltage at the
−
INE2 terminal.
AC adapter detection voltage setting : Vth
Vth (V)
=
(R1
+
R2)
/
R2
× −
INE2
■ OPERATION TIMING DIAGRAM
−
+
VCC
R1
R2
+
INE2
−
INE2
A
<Error Amp2>
4
3
2.5 V
1.5 V
Error Amp2 FB2
Error Amp1 FB1
Error Amp2 FB3
OUT
Constant voltage control Constant current control
AC adapter dynamically-
controlled charging