E-UC3843BD1 Datasheet, PDF (12/15 Pages) STMicroelectronics – HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER

UC2842B/3B/4B/5B - UC3842B/3B/4B/5B
Figure 24: Soft-Start Circuit
8
4
2
1MΩ
1
C
R
BIAS
R
5V_ref
+
-
OSC
+
+
-
EA
1mA
2R
R
S
Q
+
R
1V
-
5
D95IN354
Figure 25: Soft-Start and Error Amplifier Output Duty Cycle Clamp.
V_CC V_in
7
8
R
BIAS
R
5V_ref
+
-
4
OSC
+
2
R2
1
+
-
EA
1mA
V_Clamp
2R
-
+
R
1V
S
Q
R
Comp/Latch
5
C
R1 BC109
· V_CLAMP =
R₁
R₁ + R₂
where 0 <V_CLAMP <1V
I_pk(max) =
V_CLAMP
R_S
7
6
Q1
5
R_S
D95IN355
12/15