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1-2. CP1 POWER CIRCUIT DESCRIPTION
1. Outline
This is the main power circuit, and is comprised of the follow-
ing blocks.
Switching controller (IC501)
Analog system power output (T5001, Q5001, IC502)
Digital 3.25 V power output (L5004)
Digital 1.45 V power output (L5005)
5 V system power output (L5003, Q5003)
LCD 15 V system power output (L5001, Q5002)
Backlight power output (L5002)
Motor system power output (IC955, L9551, Q9551)
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, only CH1 (5 V system),
CH2 (digital 3.25 V), CH3 (digital 1.45 V),CH4 (analog sys-
tem), CH6 (LCD system) and CH7 (backlight sysetm) are used.
Feedback from 5 V system (CH1), 3.25 V (D) (CH2), 1.45 V
(D) (CH3), analog system (CH4), LCD system (CH6) and back-
light system (CH7) 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 backlight power (CH7) is provided to the
both ends voltage of registance so that regular current can
be controlled to be current that was setting.
2-1. Short-circuit Protection Circuit
If output is short-circuited for the length of time setting inside
(Pin (32) of IC501), all output is turned off. The control signal
(P ON) are recontrolled to restore output.
3. Analog System Power Output
+12 V (A), +3.45 V (A) and -6.0 V (A) are output. Feedback for
the +12 V (A) is provided to the switching controller (Pin (48)
of IC501) so that PWM control can be carried out. +3.45 V (A)
is output which dropped 3.4 V by 5V system power output at
regulator IC502.
4. Digital 3.25 V Power Output
+3.25 V (D) is output. Feedback for the +3.25 V (D) is pro-
vided to the switching controller (Pins (23) of IC501) so that
PWM control can be carried out.
5. Digital 1.45 V Power Output
+1.45 V (D) is output. Feedback for the +1.45 V (D) is pro-
vided to the swiching controller (Pin (22) of IC501) so that
PWM control can be carried out.
6. 5 V System Power Output
+5 V is output. Feedback for the +5 V is provided to the
swiching controller (Pin (27) of IC501) so that PWM control
can be carried out.
7. LCD System Power Output
+15 V (L) and 5 V (L) are output. Feedback for the +15 V (L) is
provided to the swiching controller (Pin (40) of IC501) so that
PWM control can be carried out.
8. Backlight Power Output
Regular current is being transmitted to LED for LCD back-
light. Feedback for the both ends voltage of registance that is
being positioned to in series LED are provided to the switch-
ing controller (Pin (37) of IC501) so that PWM control to be
carried out.
9. Motor System Power Output
3.7 V is output. Feedback for the 3.7 V is provided to (Pin (1)
of IC955) so that PWM control can be carried out.
– 5 –
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