Sanyo VPC-WH1W Service Manual page 10

4. Power Supply Control
The 8-bit microprocessor controls the power supply for the overall system.
The following is a description of how the power supply is turned on and off. When the battery is attached or DC IN input, a
regulated 3.2 V (power off: 2.4 V) voltage is normally input to the 8-bit microprocessor (IC301) by IC302, so that clock counting
and key scanning is carried out even when the power switch is turned off, so that the camera can start up again. When the battery
is removed and DC IN does not input, the 8-bit microprocessor operates in sleep mode using the backup battery. At this time, the
8-bit microprocessor only carries out clock counting, and waits in standby for the battery to be attached again or DC IN input.
When a switch is operated, the 8-bit microprocessor supplies power to the system as required.
The 8-bit microprocessor first set the P ON signal at pin (31) and the P ON2 signal at pin (29) to high, and then turns on the DC/
DC converter. After this, low signal is output from pin (27) so that the ASIC is set to the reset condition. After this these pins set
to high, and set to active condition. Once it is completed, the ASIC returns to the reset condition, all DC/DC converters are turned
off and the power supply to the whole system is halted.
Power voltage
Power switch ON - Auto power OFF
CAMERA
Note) 4 MHz = Main clock operation, 32 kHz = Sub clock operation
Power OFF
LCD finder
Play back
Table 5-3. Camera Mode
ASIC,
memory
3.3 V 1.0 V 1.8 V
OFF
OFF
ON
ON
– 10 –
CMOS
8 bit CPU
2.8 V (A)
3.2 V
2.8 V (D), 1.8 V (D)
OFF 32KHz
OFF 32KHz
ON 4 MHz
OFF 4 MHz