Sanyo VPC-AZ1EX Service Manual page 5

1-3. CA3 CIRCUIT DESCRIPTION
1. Outline
This is the main CA3 power block, and is comprised of the
following blocks.
Switching controller (IC511)
Lens system 3.4 V power output (L5106, Q5104, D5105,
C5117)
Backlight power output (L5102, Q5101, C5113)
LCD system power output (Q5107, T5101)
2. Switching Controller (IC511)
This is the basic circuit which is necessary for controlling the
power supply for a PWM-type switching regulator, and is pro-
vided with six built-in channels. They are CH5 (lens system
3.4 V), CH4 (backlight) and CH3 (LCD system). CH1, CH2
and CH6 are not used. Feedback from 3.4 V (D) C (CH5) and
+12.4 V (L) power supply output are received, and the PWM
duty is varied so that each one is maintained at the correct
voltage setting level. CH4 is feedback from 10 mA power sup-
ply output are received, and the PWM duty is varied so that
each one is maintained at the correct voltage setting level.
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 (18) of IC511, all
output is turned off. The control signal (P(A) ON, LCD ON
and BL ON) are recontrolled to restore output.
3. Lens system 3.4 V Power Output
3.4 V (D) C is output for lens. Feedback for the 3.4 V (D) is
provided to the swiching controller (Pin (8) of IC511) so that
PWM control can be carried out.
4. Backlight Power Output
10 mA (L) is output. The backlighting turns on when current
flows in the direction from pin (1) to pin (2) of CN531. At this
time, a feedback signal is sent from pin (2) of CN531 to pin
(12) of IC511 through R5122 so that PWM control is carried
out to keep the current at a constant level (10 mA).
5. LCD System Power Output
12.4 V (L), 15 V (L) and 4 V (L) are output. Feedback for the
12.4 V (L) is provided to the switching controller (Pin (28) of
IC511) so that PWM control can be carried out.
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