Switching Power Supply Section - Panasonic KX-F900 Service Manual

KX-F900
12. SWITCHING POWER SUPPLY SECTION
AC Input _ A
0--_ Input
HRectifier--l";-, 1
A-B Voltage Wave Form
ol
C-D Voltage Wave Form
__ SUB Printed
Circuit Board
IC101
0
E-F, r
G_HVO tage Wave Form
01-3F-3 r--
VV
Block Diagram
Converter
Control
Circuit
(MC101)
Over
Current
Circuit
D
E
F
utput Circuit
DC-DC
Converter
Circuit
I Error Detecting I--
Circuit /
_o 24V Output
OGND
+5V Output
[Input Circuit]
Input current goes into input rectifier circuit through filter circuit. Fitter circuit decreases noise terminal voltage and
noise electric field strength.
[Rectifier Circuit]
Input current is rectified by D101 and charge C106 to make DC voltage, then supply power to converter
circuit. Voltage is supplied to control IC's kick-on voltage through R102 and R103. Inrush current is limited by
thermistor TH 101.
[Converter circuit]
The converter circuit of this power supply circuit is called fly back converter.
We explain the operation of this circuit with the simple circuit.
O
Ei
O
T101
.<
.<
p-<
.<
.<
.<
J
_CONTROL CIRCUIT
D201
O
Eo
+
O
- 164-
P...PRIMARY WINDING
S...SECONDARY WINDING
B...CONTROL WINDING