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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)
Analog system power output (Q5001, T5001)
Digital 1.8 V power output (L5006)
Digital 3.3 V power output (L5005)
LCD and LED backlight power output (Q5005, L5009)
5 V system power output (L5004)
5.3 V lens system power output (IC955, Q9562, L9551)
2. Switching Controller
This is the basic circuit which is necessary for controlling the
power supply for a PWM-type switching regulator, and is pro-
vided with five built-in channels, only CH1 (analog system
power output), CH_M (digital 3.3 V system power output),
CH_SD (digital 1.8 V system power output), CH3 (LCD and
LED back light power output) and CH_SU (5 V system power
output) are used. Feedback from 15.0 V (A) (CH1), 3.3 V (D)
(CH_M), 1.8 V (D) (CH_SD), LED backlight output (CH3) and
5 V (CH_SU) power supply outputs are received, and the PWM
duty is varied so that each one is maintained at the correct
voltage setting level.
2-1. Short-circuit Protection
If output is short-circuited for the length of time setting inside
IC501, all output is turned off. The control signal (P ON) are
recontrolled to restore output.
3. Analog System Power Output
15.0 V (A) and -7.6 V (A) are output. Feedback for the 15.0 V
(A) is provided to the switching controller (Pin (3) of IC501)
so that PWM control can be carried out.
4. Digital 1.8 V Power Output
1.8 V (D) is output. Feedback for the 1.8 V (D) is provided to
the switching controller (Pins (9) of IC501) so that PWM con-
trol can be carried out.
5. Digital 3.3 V Power Output
3.3 V (D) is output. Feedback for the 3.3 V (D) is provided to
the swiching controller (Pin (13) of IC501) so that PWM con-
trol can be carried out.
6. LCD and LED Backlight Power Output
A constant current flows to LCD 8.5 V (L) power and the back-
light LEDs. Feedback for the voltage of R5046 and R5065
are provided to the power controller (Pin (39) of IC501) so
that PWM control can be carried out.
7. 5 V System Power Output
5 V is output. Feedback for the 5 V is provided to the swiching
controller (Pin (17) of IC501) so that PWM control can be
carried out.
8. 5.3 V Lens System Power Output
Lens power (5.3 V) is output. Feedback for the boost 5.3 V is
provided to the swiching controller (Pin (1) of IC955) so that
PWM control can be carried out.
