Nikon COOLPIX 4500 Maintenance Manual
VAA11901-R.3579.A
- E5 ･ E4500 -
1-4. PW1 POWER CIRCUIT DESCRIPTION
1. PW1 Circuit Outline
The switching regulator consists of a DC-DC converter,
and it uses a digital power supply, CCD power supply,
LCD panel power supply and LED backlight power
supply. The controller is used QFA7708R.
The switching regulator consists of a DC-DC converter,
and it uses a digital power supply, CCD power supply,
LCD panel power supply and LED backlight power
supply. The controller is used QFA7708R.
1-1. Switching Controller QFA7708R (IC501)
This is the basic circuit which is necessary for control-
ling the power supply for a PWM-type switching regu-
lator, and is provided with five built-in channels.
CH1: CCD power supply circuit
CH2: digital 1.8 V power supply circuit
CH3: digital 3.4 V power supply circuit
CH4: LCD panel power supply circuit
CH5: LED backlight circuit
This is the basic circuit which is necessary for control-
ling the power supply for a PWM-type switching regu-
lator, and is provided with five built-in channels.
CH1: CCD power supply circuit
CH2: digital 1.8 V power supply circuit
CH3: digital 3.4 V power supply circuit
CH4: LCD panel power supply circuit
CH5: LED backlight circuit
1-2. Short-circuit protection circuit
If output is short-circuited for the length of time deter-
mined by the condenser which is connected to Pin (37)
of IC501, all output is turned off. The power is restored
by ON and OFF.
If output is short-circuited for the length of time deter-
mined by the condenser which is connected to Pin (37)
of IC501, all output is turned off. The power is restored
by ON and OFF.
1-3. Digital 3.4 V Power Supply Output
Consists of a step-down type switching regulator, and
outputs 3.35 V ± 2 %.
Consists of a step-down type switching regulator, and
outputs 3.35 V ± 2 %.
1-4. Digital 1.8 V Power Supply Output
Consists of a step-down type switching regulator, and
outputs 1.85 V ± 2 %.
Consists of a step-down type switching regulator, and
outputs 1.85 V ± 2 %.
1-5. CCD Power Circuit and Digital 5 V Power
Supply Circuit
15.2 V ± 0.5 V, ±7.7 V ± 0.5 V and 5.1 V ± 0.1 V are
output by flyback transformer. The voltage is adjusted
to 5.1 V. Digital 5 V and CCD 5.1 V are shared.
output by flyback transformer. The voltage is adjusted
to 5.1 V. Digital 5 V and CCD 5.1 V are shared.
1-6. LCD Panel Power Supply Circuit
Consists of a step-up type switching regulator, and out-
puts 12.1 V ± 2 %.
Consists of a step-up type switching regulator, and out-
puts 12.1 V ± 2 %.
1-7. LED Backlight Power Supply Circuit
Consists of a step-up switching regulator, and carries
out constant-current control for the LEDs.
Consists of a step-up switching regulator, and carries
out constant-current control for the LEDs.
2. AC Adaptor and Battery Distinction
Differentiated by the voltage at pin 47 of the 8-bit
microprocessor. When an AC adaptor is being used, pin
47 becomes low. When a battery is being used, the volt-
age at pin 47 becomes high.
Differentiated by the voltage at pin 47 of the 8-bit
microprocessor. When an AC adaptor is being used, pin
47 becomes low. When a battery is being used, the volt-
age at pin 47 becomes high.
3. Battery Charging Protection Circuit
A FET (UPA1915TE) switch is inserted into the (+) end
of the battery harness so that charging current does not
flow to the battery by mistake when a battery and an
AC adaptor are being used together. When a voltage is
being generated by the AC adapter, Q5101 is turned off,
so that the battery circuit is isolated. If there is no volt-
age coming from the AC adaptor, Q5101 turns on and
power is supplied from the battery.
A FET (UPA1915TE) switch is inserted into the (+) end
of the battery harness so that charging current does not
flow to the battery by mistake when a battery and an
AC adaptor are being used together. When a voltage is
being generated by the AC adapter, Q5101 is turned off,
so that the battery circuit is isolated. If there is no volt-
age coming from the AC adaptor, Q5101 turns on and
power is supplied from the battery.