Sanyo VPC-X1220EX 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 power controller (IC501)
Digital VDD3 output system (L5021)
Digital VDD1.1 output system (L5031)
Digital VDD1.8 output system (L5061)
Analog +14.5 V (A) output system (L5041, D5041)
Analog -7.0 V (A) output system (L5051, D5051)
Analog +3.4 V (A) output system (IC501 built-in LDO)
LCD backlight output system (L5071, D5071)
Motor system BOOST 3.8 V output system (L5301, D5301)
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 channels and two channels (LDO).
Only CH1 (motor system), CH2, CH3 and CH6 (digital sys-
tem), CH4, CH5 and CH8 (analog system) and CH7 (LCD
back-light system) are used.
Feedback from motor system (CH1), digital system (CH2, CH3
and CH6), analog system (CH4, CH5 and CH8) are received,
and the PWM duty is varied so that each one is maintained at
the correct voltage setting level. (CH8 is output by LDO.)
Feedback for the LCD backlight power output (CH7) is so that
regular current can be controlled to be current that was set-
ting.
2-1. Short-circuit protection circuit
If output is short-circuited for the length of time determined
by the IC501 register setting, all output is turned off. To reset
output, it is necessary to reset the contrller IC to reset the
power.
3. (CH1) Motor System 3.8 V Output
+3.8 V is output. BOOST 3.8 V output is so that PWM control
can be carried out at the internal circuit of the switching con-
troller (IC501).
4. (CH2) Digital 3.25 V Output
+3.25 V is output. VDD3 is so that PWM control can be car-
ried out at the internal circuit of the switching controller (IC501).
5. (CH3) Digital 1.1 V Output
+1.1 V is output. VDD 1.1 output is so that PWM control can
be carried out at the internal circuit of the switching controller
(IC501).
6. (CH4) Analog +14.5 V Output
+14.5 V is output. Feedback for the +14.5 V (A) output is pro-
vided to (Pin (B7) of IC501) so that PWM control can be car-
ried out.
7. (CH5) Analog -7.0 V Output
-7.0 V is output. Feedback for the -7.0 V (A) output is provided
to (Pin (B4) of IC501) so that PWM control can be carried
out.
8. (CH6) Digital 1.8 V Output
+1.8 V is output. VDD 1.8 output is so that PWM control can
be carried out at the internal circuit of the switching controller
(IC501).
9. (CH7) LCD Backlight Output
Regular current is being transmitted to LED for LCD back-
light. Detecting for the switching controller (Pin (C3) of IC501)
current flowing along connecting registance so that PWM can
be controlled.
10. (CH8) Analog 3.4 V Output
+3.4 V is output. +3.4 V (A) output is output at the built-in
linear regulator (IC501).
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