SC4525A Semtech Corporation, SC4525A Datasheet - Page 6

• Manufacturer Part Number: SC4525A
• Description: 28V 3A Step-Down Switching Regulator
• Manufacturer: Semtech Corporation

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Block Diagram
COMP
COMP
ROSC
ROSC
SS/EN
SS/EN
FB
FB
3
3
6
6
7
7
5
5
FAULT
FAULT
SS/EN
SS/EN
V1
V1
FREQUENCY
FREQUENCY
FOLDBACK
FOLDBACK
+
+
+
+
-
-
EA
EA
REFERENCE
REFERENCE
1V
1V
SHUTDOWN
SHUTDOWN
& THERMAL
& THERMAL
Figure 3. Soft-start and Overload Hiccup Control Circuit
R
R
I C
I C
2mA
2mA
A1
A1
OSCILLATOR
OSCILLATOR
+
+
1.9V
1.9V
-
-
1.9V
1.9V
SLOPE
SLOPE
COMP
COMP
1.23V
1.23V
R
R
I D
I D
3.5mA
3.5mA
Figure 2. SC4525A Block Diagram
+
+
1V/2.15V
1V/2.15V
FAULT
FAULT
S
S
+
+
-
-
B4
B4
+
+
B1
B1
+
+
-
-
PWM
PWM
SOFT-START
SOFT-START
OVERLOAD
OVERLOAD
CONTROL
CONTROL
HICCUP
HICCUP
AND
AND
OC
OC
CLK
CLK
S
S
R
R
Q
Q
S
S
R
R
Q
Q
_
_
B2
B2
B3
B3
ILIM
ILIM
Q
Q
S
S
R
R
+
+
-
-
20mV
20mV
ISEN
ISEN
OVERLOAD
OVERLOAD
OC
OC
PWM
PWM
+
+
-
-
BST
BST
8
8
GND
GND
SW
SW
IN
IN
2
2
1
1
4
4
TRANSISTOR
TRANSISTOR
POWER
POWER
4.1mW
4.1mW
SC4525A
6
1 1
1 1