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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 VDD1.8 output system (L5031)
CMOS analog +2.8 V (A) output system (L5061)
LCD backlight output system (L5071, D5071)
Motor system BOOST 5.3 V output system (L5301, D5301)
Digital VDD1.1 output system (IC502, L5101)
2. Switching Power 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 controller IC to reset the
power.
3. (CH1) Motor System 5.0 V Output
+5.0 V is output. BOOST 5.0 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 1.8 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 +2.8 V Output
+2.8 V is output. Feedback for the +2.8 V (A) output is pro-
vided to 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 VDD1.1 is provided to
switching controller (Pin (1) of IC502) so that PWM control
can be carried out.
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