Sanyo VPC-J2 Service Manual page 8

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 lithium secondary 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.
The 8-bit microprocessor first sets both the P (A) ON signal at pin (6) and the P ON signal at pin (5) to high, and then turns on the
DC/DC converter. After this, high signals are output from pins (60), (61), (62), (63) and (64) so that the ASIC is set to the active
condition. If the LCD monitor is on, the LCD ON signal at pin (21) and the LCD ON 2 signal at pin (53) 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-
Shutter switch ON
CAMERA
Play back
Note) 4 MHz = Main clock operation, 32 kHz = Sub clock operation
5. 16-bit D/A circuit (Audio)
This circuit converts the audio signals (analog signals) from the microphone to 16-bit digital signals.
6. 16-bit A/D circuit (Audio)
The audio signals which were converted to digial form by the 16-bit A/D circuit are temporarily to a sound buffer and then
recorded in the SSFDC card. During playback, the 16-bit D/A circuit converts these signals into analog audio signals.
Auto power OFF
Monitor OFF
LCD finder
Table 4-3. Camera Mode (Battery Operation)
ASIC,
CCD
memory
5 V (A)
3.3 V
+15 V (A) etc.
OFF OFF
OFF OFF
ON ON→OFF
OFF
OFF
ON ON
ON
OFF
– 8 –
8 bit LCD
CPU MONITOR
3.2 V
+15 V (L)
(ALWAYS)
32KHz OFF
4 MHz OFF
4 MHz OFF
4 MHz OFF
4 MHz ON
4 MHz ON