]

A

[

f

L

2

D

V

+

D

¿

I

=

I

SW

IN

OUT

pk

_

L

K

x

x

x

]

A

[

2

I

+

I

=

I

L

AVE

_

L

pk

_

L

'

OUT

IN

OUT

V

V

V

=

D

-

x

],

A

[

f

L

D

V

=

I

SW

IN

L

'

x

],

x

OUT

IN

V

V

=

'

D

A

[

D

¿

I

=

I

OUT

AVE

_

L

K

[A]

LM4510

SNVS533C – SEPTEMBER 2007 – REVISED MAY 2013

www.ti.com

Table 1. Suggested Component Values for Different Output Voltages

Output Voltage (V)

16

20.5

240

46.4

2.2

12

20.5

174

46.4

2.2

5

20.5

60.4

46.4

2.2

3.3

20.5

33

46.4

2.2

MAXIMUM OUTPUT CURRENT

When the output voltage is set at different level, it is important to know the maximum load capability. By first

(2)

INDUCTOR SELECTION

The larger value inductor makes lower peak inductor current and reduces stress on internal power NMOS.

On the other hand, the smaller value inductor has smaller outline, lower DCR and a higher current capacity.

Generally a 4.7

μH to 15 μH inductor is recommended.

The average inductor current is given by the following equation:

(3)

switching regulator.

Inductor DC current rating (40°C temperature rise) should be more than the average inductor current at worst

case.

ΔI Define

The inductor ripple current is given by the following equations:

(4)

Where D is the on-duty cycle of the switching regulator. A common choice is to set

The peak inductor current is given by the following equation:

(5)

12

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