UC3844B, UC3845B, UC2844B, UC2845B
V
CC
V
in
V
CC
7(12)
V
ref
8(14)
R
T
2.5V
R
R
Internal
Bias
3.6V
Oscillator
C
T
4(7)
+ 1.0mA
36V
Reference
Regulator
V
CC
UVLO
+
−
V
ref
UVLO
+
−
(See
Text)
V
C
7(11)
Output
6(10)
Q1
S
Voltage
Feedback
Input 2(3)
Output/
Compensation 1(1)
2R
R
Error
Amplifier
R
1.0V
Current Sense
Comparator
GND
5(9)
Q
Power Ground
PWM
Latch
5(8)
Current Sense Input
3(5)
R
S
Pin numbers adjacent to terminals are for the 8−pin dual−in−line package.
Pin numbers in parenthesis are for the D suffix SOIC−14 package.
= Sink Only Positive True Logic
Figure 16. Representative Block Diagram
Capacitor C
T
Latch Set"
Input
Output/
Compensation
Current Sense
Input
Latch Reset"
Input
Output
Large R
T
/Small C
T
Small R
T
/Large C
T
Figure 17. Timing Diagram
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