UC3844, UC3845, UC2844, UC2845
L1
MBR1635
2200
+
4.7W
3300pF
MDA
202
4.7k
250
5.0V/4.0A
T1
+
+
+
+
1000
56k
115VA
C
5.0V RTN
12V/0.3A
MUR110
1000
1N4935
68
1N4935
L2
10
7(12)
+
+
±12V RTN
47
100
1000
10
L3
8(14)
+
−
+
+
5.0V
ref
−12V/0.3A
+
0.01
MUR110
680pF
1N4937
Bias
+
+
−
33k
7(11)
1N4937
2.7k
4(7)
2(3)
22W
OSC
T
S
6(10)
+
MTP
4N50
1.0nF
1N5819
18k
+
−
Q
−
+
5(8)
3(5)
R
EA
Comp/Latch
4.7k
1.0k
470pF
1(1)
0.5W
5(9)
T1 − Primary: 45 Turns # 26 AWG
T1 − Secondary ± 12 V: 9 Turns # 30 AWG
ꢁT1 − (2 strands) Bifiliar Wound
Figure 30. 27 Watt Off−Line Flyback Regulator
T1 − Secondary 5.0 V: 4 Turns (six strands)
ꢁT1 − #26 Hexfiliar Wound
T1 − Secondary Feedback: 10 Turns #30 AWG
ꢁT1 − (2 strands) Bifiliar Wound
T1 − Core: Ferroxcube EC35−3C8
Test
Conditions
Results
T1 − Bobbin: Ferroxcube EC35PCB1
T1 − Gap ≈ 0.01" for a primary inductance of 1.0 mH
Line Regulation:
5.0 V
± 12 V
V
in
= 95 VAC to 130 VAC
D = 50 mV or ± 0.5%
D = 24 mV or ± 0.1%
L1 − 15 mH at 5.0 A, Coilcraft Z7156.
L2, L3 − 25 mH at 1.0 A, Coilcraft Z7157.
Load Regulation: 5.0 V
V
V
= 115 VAC, I = 1.0 A to 4.0 A
D = 300 mV or ± 3.0%
D = 60 mV or ± 0.25%
in
out
± 12 V
= 115 VAC, I = 100 mA to 300
in
mA
out
Output Ripple:
Efficiency
5.0 V
± 12 V
V
= 115 VAC
40 mV
80 mV
in
pp
pp
V
in
= 115 VAC
70%
All outputs are at nominal load currents, unless otherwise noted.
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