Pw1 Power Circuit Description - Sanyo VPC-J1 Service Manual

1-3. PW1 POWER CIRCUIT DESCRIPTION

1. Outline
This is the main power circuit, and is comprised of the follow-
ing blocks.
Switching power controller (IC501)
Analog system power output (Q5001, T5001)
Digital 1.8 V power output (Q5011, L5007)
Digital 3.3 V power output (Q5010, L5005)
LED backlight power output (Q5015, L5010)
5 V system power output (Q5018, L5017)
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 five built-in channels, only CH1 (analog system
power output), CH2 (digital 3.3 V system power output), CH3
(digital 1.8 V system power output), CH4 (LED back light power
output) and CH5 (5 V system power output) are used. Feed-
back from 15.0 V (A) (CH1), 3.3 V (D) (CH2), 1.8 V (D) (CH3),
LED backlight output (CH4) and 5 V (CH5) power supply out-
puts 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 (27) of IC501, all
output is turned off. The control signal (P ON) are recontrolled
to restore output.
3. Analog System Power Output
15.0 V (A) and -7.6 V (A) are output. Feedback for the 15.0 V
(A) is provided to the switching controller (Pin (23) 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 (15) of IC501) so that PWM con-
trol can be carried out.
5. Digital 3.3 V Power Output
3.3 V (D) is output. Feedback for the 3.3 V (D) is provided to
the swiching controller (Pin (42) of IC501) so that PWM con-
trol can be carried out.
6. LED Backlight Power Output
A constant current flows to the backlight LEDs. Feedback for
the voltage of R5057 is provided to the power controller (Pin
(18) of IC501) so that PWM control can be carried out.
7. 5 V System Power Output
5 V is output. Feedback for the 5 V is provided to the swiching
controller (Pin (39) of IC501) so that PWM control can be
carried out.
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