Sanyo VPC-AZ1EX Service Manual page 6

1-4. PW1 POWER CIRCUIT DESCRIPTION
1. Outline
This is the main power circuit, and is comprised of the follow-
ing blocks.
Switching controller (IC501)
5.6 V system power output (L5001, Q5001)
5 V system power output (IC502)
Analog system power output (T5001, Q5002)
Digital 3.4 V system power output (L5005, Q5010)
Digital 1.8 V system power output (L5007, Q5014)
2. Switching Controller
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, only CH3 (analog system),
CH2 (digital 1.8 V), CH5 (digital 3.4 V) and CH6 (5.6 V sys-
tem) are used. CH1 and CH4 are not used. Feedback from
15.2 V (A) (CH1), 1.8 V (D) (CH2), 3.4 V (D) (CH5) and 5.6 V
(CH6) power supply outputs 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
If output is short-circuited for the length of time determined
by the condenser which is connected to Pin (18) of IC501, all
output is turned off. The control signal (P ON) are recontrolled
to restore output.
3. Analog System Power Output
15.2 V (A) and -7.7 V (A) are output. Feedback for the 15.2 V
(A) is provided to the switching controller (Pin (28) of IC501)
so that PWM control can be carried out.
4. Digital 1.8 V Power Output
1.8 V (D) is output. Feedback for the 1.8 V (D) is provided to
the switching controller (Pins (31) of IC501) so that PWM
control can be carried out.
5. Digital 3.4 V Power Output
3.4 V (D) is output. Feedback for the 3.4 V (D) is provided to
the swiching controller (Pin (8) of IC501) so that PWM control
can be carried out.
6. 5.6 V System Power Output
5.6 V is output. Feedback is provided to the swiching control-
ler (Pin (4) of IC501) so that PWM control can be carried out.
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