Sanyo VPC-CA102BK 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)
VAA 2.8 CMOS power output (L5041)
CMOS 1.8 CMOS power output (IC501 ch5)
VDD 3 power output (L5021)
VDD 1.8 power output (L5061)
VDD 1.1 power output (L5031)
LCD backlight system power output (L5071)
Motor system power BOOST 5.2 V output (L5301)
VDD 5 power output (IC502)
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 six channels, linear regulator one channel and load
switch one channel. This model is used six channels for switch-
ing regulator and one channel for load switch.
Only CH1 (BOOST 5.2 V), CH2 (VDD 3), CH3 (VDD 1.1),
CH4 (VAA 2.8), CH6 (VDD 1.8), CH7 (LCD backlight) and
CH5 (CMOS 1.8) are used.
Feedback from CH1 (BOOST 5.2 V), CH2 (VDD 3), CH3 (VDD
1.1), CH4 (VAA 2,8), 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.
CH5 (CMOS 1.8) is as source of CH6 (VDD 1.8) output so
that ON/OFF control can be carried out.
2-1. Short-circuit protection circuit
If output is short-circuited for the length of time determined
by IC501, all output is turned off. The control signal (P ON)
are recontrolled to restore output.
3. VAA 2.8 Power Output
VAA 2.8 (2.8 V) is output. Feedback for the VAA 2.8 is pro-
vided to the switching controller (Pin (G3) of IC501) so that
PWM control can be carried out.
4. CMOS 1.8 Power Output
CMOS 1.8 (1.8 V) is output. +1.8 V (D) is as source of VDD
1.8 power so that ON/OFF control can be carried out at IC501
ch5.
5. VDD 3 Power Output
VDD 3 (3.25 V) is output. Feedback for the VDD 3 output is
provided to the switching controller (IC501) so that PWM con-
trol can be carried out.
6. 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 (G2) 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 output is
provided to the switching controller (Pin (C6) of IC501) so
that PWM control can be carried out.
8. LCD Backlight Power Output
Regular current is being transmitted to LED for LCD back-
light. Feedback for the LED cathode is provided to the switch-
ing controller (Pin (B4) of IC501) so that PWM control to be
carried out.
9. Motor System Power Output
BOOST 5.3 V is output. Feedback for the BOOST 5.3 V out-
put is provided to the switching controller (IC501) so that PWM
control can be carried out.
10. HDMI VDD 5 Power Output
HDMI power VDD 5 (5 V) is output. Feedback for the VDD5
output is as source of BOOST 5.3 V power so that voltage
control can be carried out at the internal circuit IC505.
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