MPQ2451-5/33―36V, 2.2MHz, 0.6A, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED

MPQ2451-5/33 Rev 1.0

www.MonolithicPower.com

14

5/25/2016

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2016 MPS. All Rights Reserved.

Table 1: Inductor Selection Guide

Part Number

Inductance (µH)

Max DCR (

Ω) Current Rating (A)

Dimensions

L × W × H (mm

Wurth Electronics

7440430022

2.2

0.028

2.5

4.8×4.8×2.8

744043003

3.3

0.035

2.15

4.8×4.8×2.8

7447785004

4.7

0.078

2.4

5.9×6.2×3.2

TOKO

D63CB-#A916CY-2R0M

2.0

0.019

2.36

6.2×6.3×3.0

D62CB-#A916CY-3R3M

3.3

0.026

2.17

6.2×6.3×3.0

D62CB-#A916CY-4R7M

4.7

0.032

2.1

6.2×6.3×3.0

TDK

LTF5022T-2R2N3R2

2.2

0.04

3.2

5.2×5.0×2.2

LTF5022T-3R3N2R5

3.3

0.06

2.5

5.2×5.0×2.2

LTF5022T-4R7N2R0

4.7

0.081

2.0

5.2×5.0×2.2

COOPER BUSSMANN

SD25-2R2

2.2

0.031

2.8

5.2×5.2×2.5

SD25-3R3

3.3

0.038

2.21

5.2×5.2×2.5

SD25-4R7

4.7

0.047

1.83

5.2×5.2×2.5

The input capacitor (C1) can be electrolytic,

tantalum or ceramic. When using electrolytic or

tantalum capacitors, add a small, high quality

ceramic capacitor

—for example, 0.1μF—as close

to the IC as possible. When using ceramic

capacitors, make sure that they have enough

capacitance to provide

sufficient

charge to

prevent excessive voltage ripple at input. The

input voltage ripple caused by capacitance can

be estimated by:

























IN

OUT

IN

OUT

S

LOAD

IN

V

V

1

V

V

1

C

f

I

V

Output Capacitor

The output capacitor (C2) maintains the DC

output voltage. Ceramic, tantalum, or low ESR

electrolytic capacitors are recommended. Low

ESR capacitors are preferred to keep the output

voltage ripple low. The output voltage ripple can

be estimated by:











































2

C

f

8

1

R

V

V

1

L

f

V

V

S

ESR

IN

OUT

S

OUT

OUT

equivalent series resistance (ESR) value of the

output capacitor.

For ceramic capacitors, the impedance at the

switching

frequency

is

dominated

by

the

capacitance. The output voltage ripple is mainly

caused by the capacitance. For simplification, the

output voltage ripple can be estimated by:

























IN

OUT

2

S

OUT

OUT

V

V

1

2

C

L

f

8

V

ΔV

For tantalum or electrolytic capacitors, the ESR

dominates

the

impedance

at

the

switching

frequency. For simplification, the output ripple

can be approximated to:

ESR

IN

OUT

S

OUT

OUT

R

V

V

1

L

f

V

ΔV























The characteristics of the output capacitor also

affect the stability of the regulation system.