MP2467 – 2.5A, 36V, 500KHz STEP-DOWN CONVERTER

MP2467 Rev. 1.1

www.MonolithicPower.com

11

1/25/2010

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Table 1—Inductor Selection Guide

Part Number

Inductance (µH)

Max DCR (Ω) Current Rating (A)

Dimensions

L x W x H (mm

Wurth Electronics

7447789002

2.2

0.019

4

7.3x7.3x3.2

7447789003

3.3

0.024

3.42

7.3x7.3x3.2

7447789004

4.7

0.033

2.9

7.3x7.3x3.2

744066100

10

0.035

3.6

10x10x3.8

744771115

15

0.025

3.75

12x12x6

744771122

22

0.031

3.37

12x12x6

TDK

RLF7030T-2R2

2.2

0.012

5.4

7.3x6.8x3.2

RLF7030T-3R3

3.3

0.02

4.1

7.3x6.8x3.2

RLF7030T-4R7

4.7

0.031

3.4

7.3x6.8x3.2

SLF10145T-100

10

0.0364

3

10.1x10.1x4.5

SLF12565T-150M4R2

15

0.0237

4.2

12.5x12.5x6.5

SLF12565T-220M3R5

22

0.0316

3.5

12.5x12.5x6.5

Toko

FDV0630-2R2M

2.2

0.021

5.3

7.7x7x3

FDV0630-3R3M

3.3

0.031

4.3

7.7x7x3

FDV0630-4R7M

4.7

0.049

3.3

7.7x7x3

919AS-100M

10

0.0265

4.3

10.3x10.3x4.5

919AS-160M

16

0.0492

3.3

10.3x10.3x4.5

919AS-220M

22

0.0776

3

10.3x10.3x4.5

Output Rectifier Diode

The output rectifier diode supplies the current to

the inductor when the high-side switch is off. To

reduce losses due to the diode forward voltage

and recovery times, use a Schottky diode.

Choose a diode whose maximum reverse

voltage rating is greater than the maximum

input voltage, and whose current rating is

greater than the maximum load current. Table 2

lists

example

Schottky

diodes

and

manufacturers.

Table 2—Diode Selection Guide

Diodes

Voltage/

Current

Rating

Manufacturer

B240A-13-F

40V, 2A

Diodes Inc.

B340A-13-F

40V, 3A

Diodes Inc.

CMSH2-40M

40V, 2A

Central Semi

CMSH3-40MA

40V, 3A

Central Semi

Input Capacitor

The input current to the step-down converter is

discontinuous, therefore a capacitor is required to

supply the AC current to the step-down converter

while maintaining the DC input voltage. Use low

ESR capacitors for the best performance. Ceramic

capacitors are preferred, but tantalum or low-ESR

electrolytic capacitors may also suffice.

Since the input capacitor (C1) absorbs the input

switching current it requires an adequate ripple

current rating. The RMS current in the input

capacitor can be estimated by:

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

×

−

×

=

IN

OUT

IN

OUT

LOAD

1

C

V

V

1

V

V

I

I

where:

2

I

I

LOAD

1