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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 capacitor. 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, low signals are output from pins (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 (7) 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-
Auto power OFF
Shutter switch ON
CAMERA
Play back
Note) 4 MHz = Main clock operation, 32 kHz = Sub clock operation
Monitor OFF
LCD finder
Table 4-3. Camera Mode (Battery Operation)
ASIC,
CCD
memory
5 V (A)
3.3 V
+12 V etc.
OFF
OFF
OFF
OFF
ON→ → → → → OFF
ON
OFF
OFF
ON
ON
ON
OFF
– 11 –
8 bit
LCD
CPU
MONITOR
3.2 V
5V (L)
(ALWAYS)
+12V etc.
32KHz
OFF
4 MHz
OFF
4 MHz
OFF
4 MHz
OFF
4 MHz
ON
4 MHz
ON
I
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