5V, Step-Down,
Current-Mode PWM DC-DC Converters
MAX730A/MAX738A/MAX744A
FROM SHDN
R1
510k
SS CLAMP
SS
1M
±35%
C1
1.23V
MAX730A
MAX738A
MAX744A
Figure 2. Block Diagram of Soft-Start Circuitry
MAX730A +5.2V TO +11.0V
MAX738A/MAX744A +6.0V TO +16.0V
C2
1µF
C3
*
8
1
SHDN
V+
LX
7
D1
1N5817
R1
510k
L1
*
OUTPUT
+5V
C5
330pF
C4
*
PART
MAX730A
MAX738A
C6
0.01µF
MAX744A
OPTIONAL LOWPASS OUTPUT FILTER
L2
25µH
OUTPUT
C7
2.2µF
FILTER
OUTPUT
MAX730A
MAX738A
OUT 5
MAX744A
3
SS
GND
6
REF
2
CC
4
INPUT SUPPLY RANGE (V)
6.0 to 11.0
6.0 to 16.0
10.2 to 16.0
6.0 to 9.0
9.0 to 16.0
GUARANTEED OUTPUT CURRENT AT 5V (mA)
450
450
750
500
750
C1
0.1µF
*
SEE TABLE 2 FOR COMPONENT VALUES AND SUPPLIERS.
NOTE:
PIN NUMBERS REFER TO 8-PIN PACKAGES.
Figure 3. Standard +5V Step-Down Application Circuit
12
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
