MB3887 Fujitsu, MB3887 Datasheet - Page 20

• Manufacturer Part Number: MB3887
• Description: DC/DC Converter IC
• Manufacturer: Fujitsu

20
MB3887
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
OPERATION TIMING DIAGRAM
Vth (V) = (R1 + R2) / R2 × −INE2
Error Amp2 FB2
Error Amp1 FB1
Error Amp2 FB3
OUT
Constant voltage control
VCC
R1
R2
A
+INE2
−INE2
4
3
Constant current control
<Error Amp2>
−
+
AC adapter dynamically-
controlled charging
2.5 V
1.5 V