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MB3878
15
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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)
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OPERATION TIMING DIAGRAM
−
+
VCC
R1
R2
+INE2
−INE2
A
<Error Amp.2>
4
3
2.5 V
1.5 V
Error Amp.1
Error Amp.3
Error Amp.2
FB1
FB3
FB2
OUT
Constant
voltage control
AC adaptor dynamically-
controlled charging
Constant current control
AC adaptor dynamically-
controlled charging