Pw1 Power Circuit Description - Olympus Camedia C-7070 Repair Manual

[3] PW1 POWER CIRCUIT DESCRIPTION

1. Outline
This is the main power circuit, and is comprised of the
following blocks.
Switching controller (IC501)
Analog system power output (T5001, Q5041)
Digital 1.25 V power supply output (Q5071, L5071)
Digital 3.25 V power supply output (Q5091, L5091)
LCD system power supply output (L5111, Q5111)
LED backlight power supply output (L5131, Q5131)
Motor system power supply output (IC961, L9601, Q9601)
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 provided with six built-in channels, only CH1 (analog
system), CH2 (digital 1.25 V), CH3 (digital 3.25 V), CH4
(LCD system) and CH5 (LED backlight) are used. Feed-
back from analog system (CH1), 1.25 V (D) (CH2), 3.25 V
(D) (CH3), LCD system (CH4) and LED backlight (CH5)
power supply outputs are received, and the PWM duty is
varied so that each one is maintained at the correct volt-
age setting level.
Feedback for the backlight power (CH5) 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 determined
by the condenser which is connected to Pin (37) of IC501,
all output is turned off. The control signal (P ON) are re-
controlled to restore output.
H. DESCRIPTION OF MECHANISM
3. Analog System Power Output
+15.0 V (A), -7.6 V (A) and 3.45 V (A) are output. Feedback
for the +15.0 V (A) is provided to the switching controller
(Pin (40) of IC501) so that PWM control can be carried out.
4. Digital 1.25 V System Power Output
+1.25 V (D) is output. Feedback for the +1.25 V (D) is
provided to the swiching controller (Pin (43) of IC501) so
that PWM control can be carried out.
5. Digital 3.25 V System Power Output
+3.25 V (D) is output. Feedback for the +3.25 V (D) is
provided to the swiching controller (Pin (45) of IC501) so
that PWM control can be carried out.
6. LCD System Power Output
+8.5 V (L) and AF LED (8.5 V) are output. Feedback for the
+8.5 V (L) is provided to the switching power controller
(Pin (47) of IC501) so that PWM control can be carried out.
7. LED Backlight Power Output
Regular current (17.9 mA) is being transmitted to LED for
LCD backlight. Feedback for the both ends voltage of
registance that is being positioned to in series LED are
provided to the switching controller (Pin (2) of IC501) so
that PWM control to be carried out.
8. Motor System Power Output
5.6 V are output. Feedback for the 5.6 V is provided to the
switching power controller (Pin (3) of IC961) so that PWM
control can be carried out.
H-6
C-7070 Wide Zoom
Ver. 1