Sanyo VPC-C5 Service Manual page 6

1-3. PWA and VF1 POWER CIRCUIT
DESCRIPTION
1. Outline (PWA)
This is the main power circuit, and is comprised of the follow-
ing blocks.
Switching power controller (IC501)
Analog 15 V power output (Q5005, L5012)
Analog -7.6 V power output (Q5012, L5013)
Analog 3.4 V power output (IC503)
Digital 1.65 V power output (L5006)
Digital 3.3 V power output (L5005)
5 V system power output (L5004)
Digital 2.5 V power output (IC502)
1-1. 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 15 V power
output), CH2 (analog -7.6 V power output), CH_M (digital 3.3
V system power output), CH_SD (digital 1.65 V system power
output) and CH_SU (5 V system power output) are used. Feed-
back from 15.0 V (A) (CH1), -7.6 V (A) (CH2), 3.3 V (D)
(CH_M), 1.65 V (D) (CH_SD) and 5 V (CH_SU) power supply
outputs are received, and the PWM duty is varied so that each
one is maintained at the correct voltage setting level.
1. Short-circuit Protection
If output is short-circuited for the length of time setting inside
IC501, all output is turned off. The control signal (P ON) are
recontrolled to restore output.
1-2. Analog 15 V Power Output
15.0 V (A) is output. Feedback for the 15.0 V (A) is provided
to the switching controller (Pin (3) of IC501) so that PWM
control can be carried out.
1-3. Analog -7.6 V Power Output
-7.6 V (A) is output. Feedback for the -7.6 V (A) is provided to
the switching controller (Pin (31) of IC501) so that PWM con-
trol can be carried out.
1-4. Analog 3.4 V Power output
+3.4 V (A) is output. +3.4 V (A) is output which dropped 3.4 V
by 5V system power output at regulator IC503.
1-5. Digital 1.65 V Power Output
1.65 V (D) is output. Feedback for the 1.65 V (D) is provided
to the switching controller (Pins (9) of IC501) so that PWM
control can be carried out.
1-6. 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 (13) of IC501) so that PWM con-
trol can be carried out.
1-7. 5 V System Power Output
5 V is output. Feedback for the 5 V is provided to the swiching
controller (Pin (17) of IC501) so that PWM control can be
carried out.
1-8. Digital 2.5 V Power Output
+2.5 V (D) is output. +2.5 V (D) is output which dropped 2.5 V
by 3.3 V (D) system power output at regulator IC502.
2. Outline (VF1)
This is the power circuit in the VF1 board, and is comprised
of the following blocks.
LCD 8.5 V power output (IC513)
Backlight power output (IC514, Q5102, L5102)
2-1. LCD 8.5 V Power Output
LCD 8.5 V is output. LCD 8.5 V is output which dropped 8.5 V
by analog 15 V and backlight power output at regulator IC513.
2-2. Backlight Power Output
Regular current is being transmitted to LED for LCD back-
light. Feedback for the voltage of R5126 is provided to the
controller (Pin (1) of IC514) so that PWM control can be car-
ried out.
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