Sanyo VPC-S122EXBL Service Manual page 8

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 +14.5 V (A) power output (L5051, Q5051)
Analog -7.0 V (A) power output (L5041, Q5041)
Analog +3.4 V (A) power output (IC503)
VDD 3 power output (L5021)
VDD 1.1 power output (L5031)
VDD 1.8 power output (L5061)
VDD 1.8_LVDS (IC504)
LCD backlight system power output (L5071, Q5071)
Motor system power BOOST3.8 V output (L5301)
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 one channel (CH8). This model is used six chan-
nels for switching regulator and one channel for linear regula-
tor.
Only CH1 (BOOST 3.8 V), CH2 (VDD 3), CH3 (VDD 1.1),
CH4 (-7.0 V (A)), CH5 (+14.5 V (A)), CH6 (VDD 1.8), CH7
(LCD backlight) and CH8 (+3.4 V (A)) are used.
Feedback from CH1 (BOOST 3.8 V), CH2 (VDD 3), CH3 (VDD
1.1), CH4 (-7 V (A)), CH5 (+14.5 V (A)), CH6 (VDD 1.8) power
supply outputs 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 CH8 (+3.4 V (A)) is provided so that regula-
tor 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 (C4) of IC501, all
output is turned off. The control signal (P ON) are recontrolled
to restore output.
3. Analog +14.5 V (A) Power Output
+14.5 V (A) is output. Feedback for the +14.5 V (A) is pro-
vided to the switching controller (Pin (E4) of IC501) so that
PWM control can be carried out.
4. Analog -7 V Power Output
-7.0 V (A) is output. Feedback for the -7.0 V (A) is provided to
the switching controller (Pin (F4) of IC501) so that PWM con-
trol 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 built-in linear
regulator IC (IC503).
6. VDD 3 Power Output
VDD 3 (3.25 V) is output. Feedback for the VDD 3 is provided
to the switching controller (Pin (F1) of IC501) so that PWM
control can be carried out.
7. VDD 1.1 Power Output
VDD 1.1 (1.1 V) is output. Feedback for the VDD 1.1 is pro-
vided to the switching controller (Pin (F2) of IC501) so that
PWM control can be carried out.
8. VDD 1.8 Power Output
VDD 1.8 (1.8 V) is output. Feedback for the VDD 1.8 output
is provided to the switching controller (Pin (D4) of IC501) so
that voltage control can be carried out.
9. VDD 1.8_LVDS Power Output
VDD 1.8_LVDS (1.8 V) is output. VDD 1.8_LVDS output is so
that voltage control can be carried out at the internal circuit of
linear regulator IC (IC504).
10. LCD Backlight Power Output
Regular current (approximately 20 mA) is being transmitted
to LED for LCD backlight. Feedback for the both ends volt-
age of registance that is being positioned to in series LED
are provided to the switching controller (Pin (E3) of IC501) so
that PWM control to be carried out.
11. Motor System Power Output
BOOST 3.8 V (3.6 V) is output. Feedback for the BOOST 3.8
V output is provided to the switching controller (Pin (A6) of
IC501) so that PWM control can be carried out.
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