2-8
API Confidential
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7277e Monitor Service Guide
2.2
Switching Power Supply Operation Theory
2.2.1 General Specification
Input Voltage : 90~264VAC (FULL RANGE)
Input Frequency : 47~63Hz
Output Requirement :
Output
MAX. Load Current
+6.3V
0.7A
+15V
1.0A
+80V
0.15A
+45V
1.0A
2.2.2 Block Diagram
DEGAUSS
CIRCUIT
RFI
FILTER
RECTIFIER
&
FILTER
SWITCHING
ELEMENT
FEEDBACK
CONTROL
CIRCUIT
ISOLATION
TRANSFOR
-MER
POWER
SAVING
CONTROL
OUTPUT
RECTIFIER
AND
FILTER
OUTPUT
AC
INPUT
2.2.3 Circuit Operation Theorem
2.2.3.1 RFI Filter
250V
2200P
(Y)
C602
3
4
1
2
L602
250V
2200P
(Y)
C603
L604
L603
250V
0.47U
(X)
C601
N
FG
L
R601
This circuit designed to inhibit electric and magnetic interference for meet FCC, VDE, VCCI
standard
requirements.
2.2.3.2 Rectifier and Filter
2
4
3
1
~
~
-
+
D602~D605
20D6 * 4
+
400V
220U
(EL)
C612
L
N
DC OUTPUT
AC INPUT
When power switch is turn on, the AC voltage is Rectifier and filter by D602~D605, C612. The DC
output voltage will be 1.4*(ac input)