Sanyo VPC-S4U, Service Manual

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ASIC,
memory
CCD
8bit
CPU
LCD
MONITOR
Power supply voltage
Power OFF
Playback mode
Shooting mode (OVF)
Shooting
USB connection
1.70 V, 3.25 V
12 V, -8 V
3.45 V
3.2 V
15 V, 5.0 V
OFF OFF
32KHz
OFF
ON OFF 4MHz ON
ON OFF 4MHz
ON
OFF OFF 4MHz OFF
ON ON
4MHz
ON
ON OFF 4MHz OFF
Table 4-3. Power supply control
Shooting mode (LCD)
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, IC955 is operating and
creating 3.6 V, a regulated 3.2 V voltage is normally input to the 8-bit microprocessor (IC301) by IC302, 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 power switch is off, the 8-bit microprocessor halts 4 MHz of the main clock, and operates 32.768 kHz of subclock.
When the battery is removed, the 8-bit microprocessor power switches the lithum secondary battery for memory backup by
IC302, and operates at low consumption. At this condition, the 8-bit microprocessor halts the main clock, and operates clock
counting by sub clock.
Also, the battery for backup is charged 10 hours from it to be attached.
When the power switch is on, the 8-bit microprocessor starts processing. The 8-bit microprocessor first sets both the PON signal
at pin (32) and the PAON signal at pin (33) to High, and then turn on the power circuit. After PON signal is to High, sets external
port of ASIC after approximately 100 ms. According to setting of this external port, carry out setting of the operating frequency
and oscillation control in the ASIC. Also, it starts communication with ASIC, and confirms the system is operative.
When the through image is operating, set the PAON signal to High and then turn on the CCD. When the through image is playing,
set the PAON signal to Low and then turn off the CCD. When LCD panel turns on, set LCD ON signal at pin (34), LCD ON2 signal
at pin (31) and LCD ON3 signal at pin (36) to High, and then turn on the power. Set LCD BL signal at pin (35) to High, and turn
on the backlight power.
When the power switch is off, the lens will be stowed, and PON, PAON, LCDON and BLON signals to Low and the power supply
to the whole system is halted. The 8-bit microprocessor halts oscillation of the main clock, and set operation mode of clock
ocillation.