Nikon coolpix L100 Repair Manual page 72

3. Key Operaiton
For details of the key operation, refer to the instruction manual.
SCAN
IN
SCAN
OUT
0
DETELE
1
2
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, IC302 is operating, and
a regulated 3.2 V voltage is normally input to the 8-bit microprocessor (IC301), 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 power switch is off, the 8-bit microprocessor halts 4 MHz of the built-in main clock, and operates 32.768 kHz of
subclock.
When the battery is removed, the 8-bit microprocessor halts 4 MHz of the built-in main clock, and operates clock counting by
32.768 kHz of sub clock.
Also, the battery for backup is charged 10 hours from it to be attached.
When the power switch is on, the 8-bit microprocessor starts processing. The 8-bit microprocessor first sets the PON signal to
High, and then turn on the power circuit. After PON signal is to High, sets external port of ASIC after approximately 40 ms.
According to setting of this external port, carry out setting of the operating frequency and oscillation control in the ASIC.
Also, it starts communication with ASIC, and confirms the system is operative.
When the through image is operating, set the PAON signal and PAON4 signal to High and then turn on the CCD.
When the through image is playing, set the PAON signal and PAON4 signal to Low and then turn off the CCD.
When LCD panel turns on, set BL ON signal (ASIC) to High, and turn on the backlight power.
When the power switch is off, PON, PAON, PAON4 and BLON signals to all Low and the power supply to the whole system is
halted. The 8-bit microprocessor halts oscillation of the built-in main clock, and set operation mode of clock ocillation.
Power supply voltage
Through image
Playback mode
1
0
RIGHT
DOWN OK
-
-
Table 4-2. Key Operation
Power OFF
Table 4-3. Power supply control
2
MODE
UP PW_TEST
LEFT
ASIC,
memory
1.2 V, 1.8 V
3.25 V
OFF
ON
ON
– 9 –
- E ･ L100 -
INC
VMA43007-R.3780.A
3
TEST
-
8bit
CCD
CPU
12.0 V, 3.4 V
3.2 V
-6 V
OFF 32.768 KHz
ON
4MHz
OFF
4MHz
LCD
MONITOR
3.25 V
OFF
ON
ON