sc4525d Semtech Corporation, sc4525d Datasheet - Page 6

• Manufacturer Part Number: sc4525d
• Description: 18v, 3a, 350khz Step-down Switching Regulator
• Manufacturer: Semtech Corporation

Block Diagram
© 2011 Semtech Corp.
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
Figure 3. Soft-start and Overload Hiccup Control Circuit
1V
1V
SHUTDOWN
SHUTDOWN
& THERMAL
& THERMAL
R
R
A1
A1
2.4mA
2.4mA
I C
I C
+
+
-
-
OSCILLATOR
OSCILLATOR
1.9V
1.9V
SLOPE
SLOPE
COMP
COMP
1.9V
1.9V
Figure 2. SC4525D Block Diagram
R
R
1.2V
1.2V
+
+
I D
I D
3.9mA
3.9mA
S
S
FAULT
FAULT
+
+
1V/2.15V
1V/2.15V
+
+
-
-
+
+
PWM
PWM
-
-
B4
B4
B1
B1
SOFT - START
SOFT - START
OVERLOAD
OVERLOAD
CONTROL
CONTROL
HICCUP
HICCUP
AND
AND
OC
OC
S
S
R
R
CLK
CLK
Q
Q
ILIM
ILIM
S
S
R
R
Q
Q
_
_
B2
B2
B3
B3
+
+
-
-
Q
Q
S
S
R
R
18mV
18mV
ISEN
ISEN
+
+
OC
OC
PWM
PWM
-
-
OVERLOAD
OVERLOAD
BST
BST
8
8
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GND
GND
SW
SW
IN
IN
2
2
4
4
1
1
3.53m W
3.53m W
TRANSISTOR
TRANSISTOR
SC4525D
POWER
POWER
6