Power Supply Circuit; Primary Circuit - Casio PA-2400U Service Manual And Parts List

POWER SUPPLY CIRCUIT

The power supply circuit consists of 5 blocks which are Primary circuit, 5 V circuit, 3 V circuit , PCMCIA
power circuit and LCD power circuit as follows;
Alkaline
Li-ion

Primary Circuit

The voltages from both batteries, alkaline and Li-ion, apply to V5 and V3 circuits through the fuse when the
batteries is loaded.
CHGDTCTB is for Li-ion detect. When Li-ion is full charged CHGDTCTB becomes L.
ACDTCTB is for AC adapter detector. It detects whether AC adapter is used or not. When AC adapter is
used ACDTCTB becomes L.
IODTCT is for I/O BOX detector. It detects whether I/O BOX is used or not. When I/O BOX is used IODTCT
becomes L.
Alkaline Li-ion
(1.6 ~ 3.4 V) (3.0 ~ 3.6 V)
AC Adapter
I/O BOX
F102
Fuse
Primary
circuit
AC Adapter
IVR2430
F100
D100
L100
C105
L105
5V circuit
3V circuit
CR2032 X 2
CHGDTCTB (to MB87A915)
D101
Q102
D102
D110
C142
— 37 —
PCMCIA
PCMCIA
power circuit
5 V system
LCD
LCD
power circuit
3 V system
To Detector (VSUB)
F101
To 3V and V5 circuits.
ACDTCTB (to MB87A915)
IODTCT (to MB87A915)