UC3842A Просмотр технического описания (PDF) - Motorola => Freescale
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UC3842A Datasheet PDF : 14 Pages
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UC3842A, 43A UC2842A, 43A
Figure 32. Slope Compensation
VCC
Vin
7(12)
8(14)
RT
MPS3904
RSlope
4(7)
From VO
CT
R
Bias
R
Osc
+
5.0Vref
+
+–
–
–m
+
–
+
–
7(11)
6(10)
Ri
1.0mA
2(3)
+
–
EA
2R
S
–
+
Q
R
5(8)
Rd
Cf
Rf
R
1.0V
Comp/Latch
m
1(1)
–3.0 m
5(9)
3(5)
RS
The buffered oscillator ramp can be resistively summed with either the voltage feedback or current sense inputs to provide slope compensation.
Figure 33. 27 Watt Off–Line Flyback Regulator
4.7Ω
115Vac
MDA
+
250
202
56k
8(14)
0.01
10k
4(7)
4700pF
18k
2(3)
4.7k
Bias
Osc
+
+
–
EA
5.0Vref
+
+–
7(12)
+
–+
S
–
Q
+
R
Comp/Latch
4.7k
1N4935
+
68
100
1N4937
3300pF
MBR1635 L1
T1
+
2200
1000
1N4935
+
47
MUR110
+ L2
1000
10
1000
10
+
MUR110
680pF
L3
5.0V/4.0A
+
5.0V RTN
12V/0.3A
+
±12V RTN
+
–12V/0.3A
7(11)
22Ω
6(10)
5(8)
3(5)
1.0k
2.7k
1N4937
MTP
4N50
L1 – 15 µH at 5.0 A, Coilcraft Z7156.
L2, L3 – 25 µH at 1.0 A, Coilcraft Z7157.
1(1)
5(9)
Test
Line Regulation: 5.0 V
± 12 V
Conditions
Vin = 95 Vac to 130 Vac
470pF
0.5Ω
Results
∆ = 50 mV or ± 0.5%
∆ = 24 mV or ± 0.1%
T1 – Primary: 45 Turns # 26 AWG
T1 – Secondary ± 12 V: 9 Turns # 30 AWG
T1 – (2 strands) Bifiliar Wound
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
T1 – Bobbin: Ferroxcube EC35PCB1
T1 – Gap ≈ 0.01” for a primary inductance of 1.0 mH
Load Regulation: 5.0 V
± 12 V
Output Ripple: 5.0 V
± 12 V
Vin = 115 Vac, Iout = 1.0 A to 4.0 A
∆ = 300 mV or ± 3.0%
Vin = 115 Vac, Iout = 100 mA to 300 mA ∆ = 60 mV or ± 0.25%
Vin = 115 Vac
40 mVpp
80 mVpp
Efficiency
Vin = 115 Vac
All outputs are at nominal load currents, unless otherwise noted.
70%
MOTOROLA ANALOG IC DEVICE DATA
13
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