4. Power Supply ControlThe 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 microprocessor 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 (70) and the P ON signal at pin (71) to high, and then turns on the DC/DC converter. After this, low signals are output from pins (96), (97) and (98) so that the ASIC is set to the active condition. If the LCD monitor is on, the LCD ON signal at pin (95) 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.
| | | ASIC, | CCD | 8 bit | MODE | LCD |
| | | memory | CPU | LCD | MONITOR |
| | | |
| | Supply voltage | 3.3 V | 5 V (A) | 3.2 V | 3.2 V | 5V (L) |
| | +12 V etc. | (ALWAYS) | (ALWAYS) | +12V etc. |
| | | |
| | Power OFF | OFF | OFF | 32KHz | OFF | OFF |
| | Power switch ON- | OFF | OFF | 4 MHz | ON | OFF |
| |
| | Auto power down |
| | | | | | |
| | Shutter switch ON | ON | ON →OFF | 4 MHz | ON | OFF |
| CAM | Resolution, Flash, | OFF | OFF | 4 MHz | ON | OFF |
| Self timer switch ON |
| | | | | | |
| | LCD finder | ON | ON | 4 MHz | ON | ON |
| | Play back | ON | OFF | 4 MHz | ON | ON |
| | | | | | | |
Table 4-3. Camera Mode (Battery Operation)Note) P. SAVE = 4 MHz = Main clock operation, 32 kHz = Sub clock operation