Sanyo VPC-SH1BK 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 VDD 3 output system (L5021)
Digital VDD 1.8 output system (L5031)
CMOS analog +2.7 V (A) output system (L5061)
LCD backlight output system (L5071, D5071)
Motor system BOOST 5.3 V output system (L5301, D5301)
Digital VDD 1.1 output system (IC502, L5101)
Charge circuit (IC521)
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 (digital system), CH6
(analog system) and CH7 (LCD backlight system) are used.
Feedback from motor system (CH1), digital system (CH2,
CH3), analog system (CH6) are received, and the PWM duty
is varied so that each one is maintained at the correct volt-
age setting level.
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 5.3 V Output
+5.3 V is output. BOOST 5.3 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. VDD 3 is so that PWM control can be car-
ried out at the internal circuit of the switching controller (IC501).
5. (CH3) 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).
6. (CH6) Analog 2.7 V Output
+2.7 V is output. Feedback for the +2.7 V (A) output is pro-
vided to the switching controller (Pin (G2) of IC501) so that
PWM control can be carried out.
7. (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.
8. Digital 1.1 V Output
+1.1 V is output. Feedback for the VDD 1.1 is provided to the
switching controller (Pin (1) of IC502) so that PWM control
can be carried out.
9. Camera Charging Circuit
If the camera's power is turned off, power save and sleep
while it is connected to the AC adaptor, the battery will be
recharged. In the above condition, a CTL signal is sent from
the microprocessor and recharging starts.
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