Nikon COOLPIX 4500 Maintenance Manual

Page of 65
VAA11901-R.3579.A
- E8 ・ E4500 -
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 microprocessor opererates in sleep mode using the backup lithum ion 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 (64) and (63) so that the ASIC and 
the SPARC lite are 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 SPARC lite processing is completed, the ASIC 
and the SPARC lite return to the reset condition, all DC/DC converters are turned off and the power supply to the 
whole system is halted.
SPARC
Lite
ASIC,
memory
CCD
8bit
CPU
LCD
MONITOR
LCD
MONITOR
Power voltage
3.3V
3.3V
5V(A)
+15V -7.7V
3.3V
(ALWAYS)
3.3V
(ALWAYS)
5V (L)
+12V etc.
SLD
OFF
OFF
OFF
OFF
32KHz
OFF
OFF
PLAY
ON
ON
OFF
3KHz
ON
ON
M-REC
A-REC
Power switch ON-Auto power 
OFF
OFF
OFF
OFF
3KHz
ON
OFF
Shutter switch ON
ON
ON
ON→  OFF
3KHz
ON
OFF
MOS, QSW, SBM etc. ON
OFF
OFF
OFF
3KHz
ON
OFF
LCD finder
ON
ON
ON
3KHz
ON
ON
Table 5-3. Camera Mode
SPARC
Lite
ASIC,
memory
CCD
8bit
CPU
MODE
LCD
LCD
MONITOR
Power voltage
3.3V
3.3V
5V (A)
+15V -7.7V
3.3V
(ALWAYS)
3.3V
(ALWAYS)
5V (L)
+12V etc.
SLD
OFF
OFF
OFF
OFF
32KHz
OFF
OFF
M-REC
A-REC
Power switch ON-Auto power 
OFF
OFF
OFF
OFF
3KHz
ON
OFF
Take a picture
ON
ON
ON→  OFF
3KHz
ON
OFF
Erase image
ON
ON
OFF
3KHz
ON
OFF
Download image
ON
ON
OFF
3KHz
ON
OFF
Continuous image
ON
ON
ON
3KHz
ON
OFF
Message from host
ON
ON
ON
3KHz
ON
OFF
Note) 3MHz = Main clock operation, 32kHz = Sub clock operation
Table 5-4. Host Mode