Canon PowrShot G5, Service Manual

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2-2
CHAPTER 2. TECHNICAL DESCRIPTION
2. Outline of Circuits
2.1 Power Supply Control
The power supply is controlled by the CPU and DSP mounted on the MAIN PCB ASS’Y.
2.1.1 Power Supply Block Diagram
Fig. 2 Power System Block Diagram
2.1.2 Power Supply Control Sequence
1) In the case of either "Battery is Installed" or External Power is Supplied to "DC-IN" connector;
2) In case that Dial Switch is in "LOCK" position when "Battery is Installed";
CPU activates the other main functions. (E0, E1)
Operating the Dial Switch
Rec. Mode
Play Mode
1. Controls CCD (E2)
2. Controls LCD (E3)
3. Controls LCD backlight (E3) 1. Controls LCD (E3)
2. Controls LCD backlight (E3)
Battery charging operation starts when external power is supplied to "DC-IN" connector.
DC/DC CONVERTER
PCB ASS’Y MAIN PCB ASS’Y
DC/DC
CONVERTER
D14
Q54
Q22
E0, E1 CONTROL
E2, E3
CONTROL
E4
E21
DC-IN
VDD0_3.3
VDD12-1.5
VDD2_5.5
VDD2_15
VDD2_N7.5
VDD3_12.3
VDD3_20
VBATF
VBAT
VDD4_5.0
REG
REG
REG
DSP
CPU
for System with CPU
for DSP
for CCD
for CCD
for LCD Backlight
for VIDEO Amp
for Motor Drive
BATTERY
CHARGE
CONTROL
E0 OUTPUT
E1 OUTPUT
E2 OUTPUT
E3 OUTPUT