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UC3844 参数 Datasheet PDF下载

UC3844图片预览
型号: UC3844
PDF下载: 下载PDF文件 查看货源
内容描述: 高性能电流模式控制器 [HIGH PERFORMANCE CURRENT MODE CONTROLLERS]
分类和应用: 控制器
文件页数/大小: 14 页 / 380 K
品牌: MOTOROLA [ MOTOROLA ]
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UC3844, 45 UC2844, 45  
Figure 24. MOSFET Parasitic Oscillations  
Figure 25. Bipolar Transistor Drive  
V
I
CC  
B
V
in  
V
in  
7(12)  
+
0
+
5.0V  
ref  
Base Charge  
Removal  
+
+
C
1
+
7(11)  
6(10)  
5(8)  
R
Q1  
g
Q1  
T
6(1)  
S
Q
R
5(8)  
3(5)  
+
Comp/Latch  
3(5)  
R
R
S
S
The totem–pole output can furnish negative base current for enhanced  
Series gate resistor R will damp any high frequency parasitic oscillations  
g
causedbytheMOSFETinputcapacitanceandanyserieswiringinductance  
in the gate–source circuit.  
transistor turn–off, with the addition of capacitor C .  
1
Figure 26. Isolated MOSFET Drive  
Figure 27. Latched Shutdown  
V
V
CC  
in  
7(12)  
8(14)  
R
R
+
Isolation  
Boundary  
Bias  
5.0V  
ref  
+
+
V
Waveforms  
GS  
Q1  
+
Osc  
7(11)  
6(10)  
5(8)  
+
0
+
0
+
4(7)  
1.0mA  
2R  
T
+
50% DC  
V
25% DC  
S
EA  
– 1.4  
N
N
2(3)  
1(1)  
(pin 1)  
P
S
Q
I
=
R
R
pk  
+
3 R  
S
R
Comp/Latch  
3(5)  
C
N
S
R
S
N
p
2N  
3905  
MCR  
101  
5(9)  
2N  
3903  
The MCR101 SCR must be selected for a holding of less than 0.5 mA at  
. The simple two transistor circuit can be used in place of the SCR as  
T
A(min)  
shown. All resistors are 10 k.  
Figure 28. Error Amplifier Compensation  
From V  
O
From V  
O
2.5V  
+
2.5V  
+
R
i
1.0mA  
2R  
2(3)  
1.0mA  
2R  
+
R
p
2(3)  
R
+
i
EA  
R
C
d
I
R
EA  
f
R
C
R
I
R
d
f
R
C
p
1(1)  
1(1)  
5(9)  
R
8.8 k  
5(9)  
f
ErrorAmpcompensationcircuitforstabilizinganycurrent–modetopologyexcept  
for boost and flyback converters operating with continuous inductor current.  
Error Amp compensation circuit for stabilizing current–mode boost and flyback  
topologies operating with continuous inductor current.  
11  
MOTOROLA ANALOG IC DEVICE DATA