Datasheet

L36
L35
MAXIMUM LOAD CURRENT (A)
4 5 6 7 8 9 10 12
1
2
3
4
5
6
7
8
9
10
20
30
40
50
60
70
80
90
100
L01
L02
L03
L04
L05
L06
L07
L08
L09
L10
L11
L12
L13
L14
L15
L16
L17
L18
L19
L20
L21
L22
L23
L24
L34
L33
L32
L25
L26
L27
L28
L29
L30
L31
L48
L47
L46
L45
L44
L37
L38
L39
L40
L41
L42
L43
E À T (V À Ps)
47 P
H
33 P
H
22 P
H
15
P
H
10 P
H
6
.
8
P
H
4
.
7
P
H
3
.
3
P
H
2
.
2
P
H
1
.
5
P
H
1
.
0
P
H
0
.
68
P
H
0
.47
P
H
0
.
33
PH
ET = (Vinmax ± V
OUT
) x
Vinmax
V
OUT
x
f
S
1000
(V x Ps)
LM3151, LM3152, LM3153
SNVS562G –SEPTEMBER 2008–REVISED MARCH 2011 www.ti.com
Design Guide
The design guide provides the equations required to design with the LM3151/2/3 SIMPLE SWITCHER Controller.
WEBENCH design tool can be used with or in place of this section for a more complete and simplified design
process.
1. Define Power Supply Operating Conditions
a. Maximum and Minimum DC Input voltage
b. Maximum Expected Load Current during normal operation
c. Target Switching Frequency
2. Determine which IC Controller to Use
The desired input voltage range will determine which version of the LM3151/2/3 controller will be chosen. The
higher switching frequency options allow for physically smaller inductors but efficiency may decrease.
3. Determine Inductor Required Using Figure 13
To use the nomograph below calculate the inductor volt-microsecond constant ET from the following formula:
where
• f
S
is in kHz units
The intersection of the Load Current and the Volt-microseconds lines on the chart below will determine which
inductors are capable for use in the design. The chart shows a sample of parts that can be used. The offline
calculator tools and WEBENCH will fully calculate the requirements for the components needed for the design.
Figure 13. Inductor Nomograph
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