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2.2.3.3 Switching Element and Isolation Transformer
In a flyback converter operated in the discontinuous mode, the energy stored in the flyback
transformer (actually an inductor) must be zero at the beginning and end of each switching period.
During the "ON" time, energy taken from the input is stored in the transformer when the switching
transistor turn-off, this stored energy is all delivered to the output.
2.2.3.4 Output Rectifier and Filter
The structure of each output is illustrated as below
Since the transformer T601 acts as a storing energy inductance, diode D1 and capacitor C1 are to
produce a dc output and additional L1, C2 to suppress high-frequency switching spikes.
2.2.3.5 Control Circuit
Circuit Operation Theory
T601
D1
1N4004
R613
R614
D611
36K
100K
1N4148
C615
D612
2200P
1N4148
50V
(PE)
C617
R612
+
4.7U
47
50V
(EL)
C616
0.01U
100V
M603
(PE)
ZD603
5.1V
M604
No Copy/Reproduction Allowed
FR701
T601
C53
B61
6
11
(SHORT)
R604
C613
82K
0.01U
2W
1KV
ZD601
(D)
C50
(OPEN)
12
C614
D610
D613
UF4007
(OPEN)
(OPEN)
FR702
10
C51
L606
1
(SHORT)
(BEAD)
L608
D608
C608
47U
RGP10D
(BEAD)
8
25V
C624
(EL)
220P
Q602
1KV
FS14SM-12
(D)
L607
15
(BEAD)
R619
D614
R608
470
UF4007
20K
2W
18
R607
*
0.15
2W
16
FR704
(SHORT)
9
13
EGP30B
R611
1K
L1
+
+
C1
C625
(OPEN)
7
6
8
VREF
VCC
OUT
IC601
ISSEN
UC3842
4
R/C
COMP
FB
1
2
C619
IC603
MCR100-3
0.022U
A
50V
C618
(D)
0.01U
50V
R615
K
G
(D)
51K
R620
10K
R616
10K
API Confidential
C2
R607
0.15
2W
R611
1K
3
*
GND
5
ZD602
*
24V
C620
R622
820P
510
50V
(D)
C627
+
10U
50V
(EL)
+6.5VA
R738
82
1/2W
4
1
2-9
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