Circuit - Casio A-10 Operation, Service Manual & Parts List

3 V Circuit
DC-DC converter MAX608ESA (U22) generates +3.77 V and it makes up 3 V system.
V3MAIN : The reference voltage for the detector.
V3SYS : +3.3 V source for U1, U3, U4, U6, D601, D602, Q3~Q7.
V3RAM : +3.3 V source for DRAM (U7 and U8).
V3ROM : +3.3 V source for ROM (U301).
ONSTATUSB : Controls ON/OFF of V3ROM. From pin 90 of SYSTEM LSI.
V3IRDA : +3.3 V source for IrDA Transceiver TFDS3000 (U18).
PIRB : Controls ON/OFF of V3IRDA. From pin 156 of SYSTEM LSI.
VSUB : +3 V source for detecting memory backup battery.
V3AUD : +3 V source for audio amplifier MC34119 (U5).
VDET3B : Controls ON/OFF of V3AUD. From detector circuit.
PDUMMYM : Controls ON/OFF of the load at detecting voltage.
FS1
Primary Circuit
SHDN EXT
V+
MAX608 (U22)
CS
DC-DC converter
D3
Q20
VDD EXT
VOUT
U26
Q14
3.4 V Regulator
PDUMMYM
(Normally L)
Q15
D5
Q16
Q48
CR2032
Q41
— 36 —
V3SYS
V3ROM (To ROM)
ONSTATUSB
OFF: H
ON: L
V3IRDA
(To IrDA)
PIRB
(Normally H)
VSUB
(To Detector)
Q44
V3AUD
(To Audio Amp.)
VDET3B