Sanyo VPC-HD1A Service Manual page 11

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, a regulated 3.2 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, the 8-bit micro-
processor operates in sleep mode using the backup lithum battery. At this time, the 8-bit microprocessor only carries out clock
counting, and waits in standby for the battery to be attached again. When a switch is operated, the 8-bit microprocessor supplies
power to the system as required.
Both the PA ON signal from the ASIC and the P ON signal from the 8-bit microprocessor at pin (16) set to high, and then turns on
the DC/DC converter. After this, low signal is output from pin (18) so that the ASIC is set to the reset condition. After, this pin set
to high, and set to active condition. If the LCD monitor is on, the LCD ON 1 signal at pin (12) set to high, and the DC/DC converter
for the LCD monitor is turned on. 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 OFF
Power switch ON-
CAMERA
Play back
Note) 4 MHz = Main clock operation, 32 kHz = Sub clock operation
Auto power OFF
LCD monitor
Table 5-3. Camera Mode
ASIC,
CCD
memory
5 V (A)
3.3 V 1.2 V
+12 V etc.
OFF OFF
OFF OFF
ON ON
ON
OFF
– 11 –
8 bit LCD
CPU MONITOR
3.2 V
3.3 V
(ALWAYS)
12 V etc.
32KHz OFF
32KHz OFF
4 MHz ON
4 MHz ON