UC3844B, UC3845B, UC2844B, UC2845B
L1
MBR1635
2200
5.0V/4.0A
4.7W
+
T1
4.7k
+
+
+
+
250
MDA
202
3300
pF
1000
56k
115 Vac
5.0V RTN
12V/0.3A
MUR110
1000
1N4935 1N4935
L2
10
68
7(12)
+
+
47
100
12V RTN
5.0V Ref
1000
10
L3
1N4937
+
+
0.01
8(14)
33k
+
-
R
R
-12V/0.3A
MUR110
Bias
7(11)
6(10)
+
-
680pF
1N4937
2.7k
22
Osc
4(7)
2(3)
MTP
4N50
T
1.0nF
+
1N5819
S
R
18k
Q
5(8)
3(5)
100
pF
EA
150k
1(1)
1.0k
Comp/Latch
4.7k
0.5
470pF
5(9)
T1 - Primary: 45 Turns #26 AWG
L1
- 15 mH at 5.0 A, Coilcraft Z7156
L2, L3
- 25 mH at 5.0 A, Coilcraft Z7157
Secondary 12 V: 9 Turns #30 AWG (2 Strands) Bifiliar Wound
Secondary 5.0 V: 4 Turns (six strands) #26 Hexfiliar Wound
Secondary Feedback: 10 Turns #30 AWG (2 strands) Bifiliar Wound
Core: Ferroxcube EC35-3C8
Bobbin: Ferroxcube EC35PCB1
Gap: ≈ 0.10" for a primary inductance of 1.0 mH
Figure 30. 7 W Off−Line Flyback Regulator
Test
Conditions
Results
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%
Load Regulation: 5.0 V
12 V
V
in
V
in
= 115 Vac, I = 1.0 A to 4.0 A
D = 300 mV or 3.0%
D = 60 mV or 0.25%
out
= 115 Vac, I = 100 mA to 300 mA
out
Output Ripple:
5.0 V
12 V
V
in
= 115 Vac
40 mV
80 mV
pp
pp
Efficiency
V
in
= 115 Vac
70%
All outputs are at nominal load currents unless otherwise noted.
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