Nikon coolpix L100 Repair Manual page 69

1-3. PWA POWER CIRCUIT DESCRIPTION
1. Outline
This is the main power circuit, and is comprised of the follow-
ing blocks.
Switching controller (IC501)
Analog +12 V (A) power output (L5061)
Analog -6 V (A) power output (L5051, Q5051)
Analog +3.4 V (A) power output (IC503)
VDD 3 power output (L5021)
VDD 1.2 power output (L5031)
VDD 1.8_ASIC power output (IC501 REG ch)
VDD 1.8_DDR power output (IC502)
LCD backlight system power output (L5071)
Motor system power BOOST 5.2 V output (L5301, Q5301)
VR microprocessor power V5.0P output (supply from BOOST
5.2 V)
2. Switching Controller (IC501)
This is the basic circuit which is necessary for controlling the
power supply for a PWM-type switching regulator, and is pro-
vided with seven built-in channels and linear regulator is pro-
vided with two channels (REG ch and LED ch). This model is
used six channels for switching regulator and 1 channel (REG
ch) for linear regulator.
Only CH1 (BOOST 5.2 V), CH2 (VDD 3), CH3 (VDD 1.2),
CH5 (-6 V (A)), CH6 (+12 V (A)), CH7 (LCD backlight) and
REG ch (VDD1.8_ASIC) are used.
Feedback from CH1 (BOOST 5.2 V), CH2 (VDD 3), CH3 (VDD
1.2), CH5 (-6 V (A)) and CH6 (+12 V (A)) power supply out-
puts are received, and the PWM duty is varied so that each
one is maintained at the correct voltage setting level.
Feedback for the CH7 (LCD backlight power) is provided to
the both ends voltage of registance so that regular current
can be controlled to be current that was setting.
Feedback for the REG ch (VDD1.8_ASIC) so that regulator
output can be adjusted.
2-1. Short-circuit protection circuit
If output is short-circuited for the length of time determined
by the condenser which is connected to Pin (1) of IC501, all
output is turned off. The control signal (P ON) are recontrolled
to restore output.
3. Analog +12 V (A) Power Output
+12 V (A) is output. Feedback for the +12 V (A) is provided to
the switching controller (Pin (40) of IC501) so that PWM con-
trol can be carried out.
4. Analog -6 V Power Output
-6 V (A) is output. Feedback for the -6 V (A) is provided to the
switching controller (Pin (42) of IC501) so that PWM control
can be carried out.
5 Analog +3.4 V Power Output
+3.4 V (A) is output. +3.4 V (A) output is so that voltage con-
trol can be carried out at the internal circuit of linear regulator
IC (IC503).
6. VDD 3 Power Output
VDD 3 (3.25 V) is output. Feedback for the VDD 3 output is
provided to the swiching controller (Pin (30) of IC501) so that
PWM control can be carried out.
7. VDD 1.2 Power Output
VDD 1.2 (1.26 V) is output. Feedback for the VDD 1.2 output
is provided to the swiching controller (Pin (31) of IC501) so
that PWM control can be carried out.
8. VDD 1.8_ASIC Power Output
VDD1.8_ASIC (1.8 V) is output. Feedback for the VDD
1.8_ASIC (1.8 V) output is provided to the switching control-
ler (Pin (2) of IC501) so that voltage control can be carried
out.
9. VDD 1.8_DDR Power Output
VDD 1.8_DDR (1.8 V) is output. VDD 1.8_DDR (1.8 V) output
is so that voltage control can be carried out at the internal
circuit of linear regulator IC (IC502).
10. LCD Backlight Power Output
Regular current (approximately 21 mA) is being transmitted
to LED for LCD backlight. Feedback for the both ends voltage
of registance that is being positioned to in series LED are
provided to the switching controller (Pin (39) of IC501) so that
PWM control to be carried out.
11. Motor System Power Output
BOOST 5.2 V is output. Feedback for the BOOST 5.2 V out-
put is provided to the switching controller (Pin (29) of IC501)
so that PWM control can be carried out.
12. VR Microprocessor Power V5.0P Output
V5.0P (5.2 V) is output. V5.0P (5.2 V) output is supplied from
BOOST 5.2 V to control output (ON/OFF) by using Q5081.
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- E5 ･ L100 -
INC
VMA43007-R.3780.A