UC3842B 查看數據表（PDF） - Motorola => Freescale
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UC3842B Datasheet PDF : 16 Pages
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UC3842B, 43B UC2842B, 43B
Figure 28. Bipolar Transistor Drive
IB
Vin
+
0
Base Charge
–
Removal
C1
Q1
6(10)
5(8)
3(5)
RS
The totem pole output can furnish negative base current for enhanced transistor
turn–off, with the addition of capacitor C1.
Figure 29. Isolated MOSFET Drive
5.0V Ref
+
–
S
Q
R
Comp/Latch
VCC
Vin
7(12)
Isolation
Boundary
+
–
7(11)
6(10)
5(8)
3(5)
C
VGS Waveforms
Q1
+
+
0
0
–
–
50% DC
25% DC
ǒ Ǔ + * Ipk
V(Pin1) 1.4 NS
3 RS
Np
R
RS NS
NP
Figure 30. Latched Shutdown
8(14)
R
Bias
R
Osc
4(7)
+
1.0 mA 2R
2(3)
EA
R
1(1)
MCR
2N
101
3905
5(9)
2N
3903
The MCR101 SCR must be selected for a holding of < 0.5 mA @ TA(min). The simple two transistor circuit can
be used in place of the SCR as shown. All resistors are 10 k.
Figure 31. Error Amplifier Compensation
From VO
Ri
Rd
Cf
2.5V
2(3)
+
1.0mA 2R
EA
R
Rf
1(1)
Rf ≥ 8.8 k
5(9)
Error Amp compensation circuit for stabilizing any current mode topology except for boost and flyback
converters operating with continuous inductor current.
From VO
Rp
Ri
2.5V
2(3)
+
1.0mA 2R
Cp
Rd
Cf
Rf
EA
R
1(1)
5(9)
Error Amp compensation circuit for stabilizing current mode boost and flyback
topologies operating with continuous inductor current.
MOTOROLA ANALOG IC DEVICE DATA
13
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