UC3842AN ON Semiconductor, UC3842AN Datasheet - Page 14

• Manufacturer Part Number: UC3842AN
• Description: IC CTRLR CURRENT MODE HP 8DIP
• Manufacturer: ON Semiconductor
• Type: High Performance Current Mode Controllersr

Specifications of UC3842AN

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 500kHz
• Duty Cycle: 96%
• Voltage - Supply: 11.5 V ~ 25 V
• Buck: No
• Boost: No
• Flyback: Yes
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: Yes
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 8-DIP (0.300", 7.62mm)
• Frequency-max: 500kHz
• Output Voltage Range: 4.9 V to 5.1 V
• Input Voltage Range: 30 V
• Operating Temperature Range: 0 C to + 70 C
• Mounting Style: Through Hole
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: UC3842ANOS

4.7k
18k
Line Regulation: 5.0 V
Load Regulation: 5.0 V
Output Ripple:
Efficiency
All outputs are at nominal load currents, unless otherwise noted.
0.01
4700pF
10k
From V
8(14)
4(7)
2(3)
1(1)
115Va
MPS3904
R
R
c
O
R
i
d
The buffered oscillator ramp can be resistively summed with either the voltage feedback or current sense inputs to provide slope compensation.
± 12 V
± 12 V
± 12 V
Slope
Test
5.0 V
4.7W
+
−
C
f
EA
+
Osc
8(14)
R
C
4(7)
2(3)
T
R
1(1)
Bias
T
f
UC3842A, UC3843A, UC2842A, UC2843A
MDA
202
Figure 34. 27 Watt Off−Line Flyback Regulator
+
5(9)
−
EA
R
R
V
V
V
V
V
in
in
in
in
in
+
+
5.0V
= 95 Vac to 130 Vac
= 115 Vac, I
= 115 Vac, I
= 115 Vac
= 115 Vac
Osc
Figure 33. Slope Compensation
+
1.0mA
+
−
−3.0 m
−
ref
Bias
+
Comp/Latch
250
S
R
2R
Q
http://onsemi.com
R
out
out
5(9)
+
−
Conditions
= 1.0 A to 4.0 A
= 100 mA to 300 mA
1.0V
−m
+
+
−
56k
7(12)
14
5.0V
+
−
+
−
m
ref
Comp/Latch
7(11)
6(10)
5(8)
3(5)
S
R
100
Q
+
1N4935
1N4937
4.7k
22W
470pF
68
+
−
1.0k
+
−
7(12)
1N4935
+
3300pF
4N50
MTP
0.5W
47
V
7(11)
6(10)
5(8)
3(5)
T1
CC
680pF
T1 − Primary: 45 Turns # 26 AWG
T1 −
T1 −
T1 −
T1 −
T1 −
T1 −
2.7k
T1 −
T1 −
T1 −
MBR1635
MUR110
MUR110
Secondary ± 12 V: 9 Turns # 30 AWG
Secondary 5.0 V: 4 Turns (six strands)
Secondary Feedback: 10 Turns #30 AWG
Core: Ferroxcube EC35−3C8
Bobbin: Ferroxcube EC35PCB1
Gap ≈ 0.01" for a primary inductance of 1.0 mH
L2, L3 − 25 mH at 1.0 A, Coilcraft Z7157.
1000
2200
1000
D = 300 mV or ± 3.0%
D = 60 mV or ± 0.25%
(2 strands) Bifiliar Wound
#26 Hexfiliar Wound
(2 strands) Bifiliar Wound
D = 50 mV or ± 0.5%
D = 24 mV or ± 0.1%
L1 − 15 mH at 5.0 A, Coilcraft Z7156.
1N4937
+
+
+
40 mV
80 mV
Results
1000
L1
L2
L3
70%
V
R
10
10
in
S
pp
pp
+
+
+
5.0V/4.0A
5.0V RTN
12V/0.3A
±12V RTN
−12V/0.3A