13 2007 Semtech Corp. www.semtech.com
POWER MANAGEMENT
SC4521
Application Information (Cont.)
Design Example 3: 13V ~ 21V to 3.3V at 1A
C1
0.22u
SC4521
BST
1
IN
2
SW
3
GND
4
EN
5
FB
6
COMP
7
SS
8
R1
24.9k
R3
3.83k
C4
18n
C2
10u
D2
L1
10uH
C5
560p
V
I
V
o
=3.3V
C3
4.7u
R2
8.25k
D3
R0
0
Css
330n
Rss
200k
C1
0.22u
SC4521
BST
1
IN
2
SW
3
GND
4
EN
5
FB
6
COMP
7
SS
8
R1
24.9k
R3
3.83k
C4
18n
C2
10u
D2
L1
10uH
C5
560p
V
I
V
o
=3.3V
C3
4.7u
R2
8.25k
D3
R0
0
Css
330n
Rss
200k
Note: The bottom pad needs a big copper area to remove the heat.
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