Sanyo VPC-X1200GXR Service Manual page 7

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 (L5004)
Digital VDD1.2 output system (L5003)
Digital VDD1.8 ASIC output system (IC501-LD0)
Digital VDD1.8 DDR output system (IC503)
Analog +14.0 V (A) output system (L5007)
Analog +12.0 V (A) output system (IC504)
Analog -6.0 V (A) output system (L5008, Q5008)
Analog +3.4 V (A) output system (IC502)
LCD backlight output system (L5006, Q5006)
Motor system BOOST 4.2 V output system
(L5301, D5301, Q5301)
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 one built-in channel
(LD0).
Only CH1 (motor system), CH2, CH3 and CH4 (digital sys-
tem), CH7 and CH8 (analog system) and CH6 (LCD back-
light system) are used.
Feedback from motor system (CH1), digital system (CH2,
CH3 and CH4), analog system (CH7 and CH8) are received,
and the PWM duty is varied so that each one is maintained
at the correct voltage setting level. (CH2 is output by LD0.)
Feedback for the LCD backlight power output (CH6) is so
that regular current can be controlled to be current that was
setting.
2-1. Short-circuit protection circuit
If CH3-CH8 output are short-circuited, CH2-CH8 are turned
off. To reset output, it is necessary to reset the contrller IC to
reset the power.
3. (CH1) Motor System 4.2 V Output
4.2 V is output. Feedback for the BOOST 4.2 V output is
provided to (Pin (C5) of IC501) so that PWM control can be
carried out.
4. (CH2) Digital 1.8 V Output (for ASIC)
+1.8 V is output. Feedback for the VDD1.8 output is provided
to (Pin (B3) of IC501) so that output voltage is controlled.
5. (CH3) Digital 1.2 V Output
+1.26 V is output. Feedback for the VDD1.2 output is pro-
vided to (Pin (E2) of IC501) so that PWM control can be car-
ried out.
6. (CH4) Digital 3.25 V Output
+3.25 V is output. Feedback for the VDD3 output is provided
to (Pin (F2) of IC501) so that PWM control can be carried
out.
7. (CH6) LCD Backlight Output
Regular current is being transmitted to LED for LCD back-
light. Feedback for the voltage to step-down LED is provided
to (Pin (B5) of IC501) so that PWM control to be carried out.
8. (CH7) Analog 14.0 V Output
+14.0 V is output. Feedback for the +14.0 V (A) output is
provided to (Pin (E7) of IC501) so that PWM control can be
carried out.
9. (CH8) Analog -6.0 V Output
-6.0 V is output. Feedback for the -6.0 V (A) output is pro-
vided to (Pin (C7) of IC501) so that PWM control can be car-
ried out.
10. Analog +3.4 V Output (IC502)
+3.4 V is output. IC502 series regulater drops motor system
4.2 V to 3.4 V.
11. Digital 1.8 V Output (for DDR) (IC503)
+1.8 V is output. IC503 series regulater drops motor system
4.2 V to 1.8 V.
12. Analog 12.0 V Output (IC504)
+12.0 V is output. IC504 series regulater drops analog 14.0
V to 12.0 V.
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