MPQ8632D-6, MPQ8632D-12 ― 6A/12A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER

MPQ8632D-6_MPQ8632D-12 Rev. 1.01

www.MonolithicPower.com

21

3/9/2016

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)

V

V

1

(

I

F

V

L

IN

OUT

L

SW

OUT

−

×

Δ

×

=

(27)

current.

Choose an inductor that will not saturate under

the maximum inductor peak current. The peak

inductor current can be calculated as:

)

V

V

1

(

L

F

2

V

I

I

IN

OUT

SW

OUT

OUT

LP

−

×

×

×

+

=

(28)

Table 1 lists a few highly-recommended high-

efficiency inductors.

Table 1—Inductor Selection Guide

Part Number

Manufacturer

Inductance

(µH)

DCR

(mΩ)

Current

Rating (A)

Dimensions

L x W x H (mm

Switching

Frequency

(kHz)

744325072

Wurth

0.72

1.35

35

10.2 x 10.5 x 4.7

500

FDU1250C-1R0M

TOKO

1

1.72

31.3

13.3 x 12.1 x 5

500

FDA1055-1R5M

TOKO

1.5

2.8

24

11.6 x 10.8 x 5.5

500

744325180

Wurth

1.8

3.5

18

10.2 x 10.5 x 4.7

500

FDA1055-2R2M

TOKO

2.2

3.94

20.6

11.6 x 10.8 x 5.5

500

FDA1055-3R3M

TOKO

3.3

5.92

15.6

11.6 x 10.8 x 5.5

500

HC7-3R9-R

Cooper

3.9

7.9

10.6

13.8 x 13 x 5.5

500

Typical Design Parameter Tables

The following tables include recommended

component values for typical output voltages (1V,

2.5V, 3.3V) and switching frequency (500kHz).

Refer to Tables 2-3 for design cases without

external ramp compensation and Tables 4-5 for

design cases with external ramp compensation.

An external ramp is not needed when using high-

ESR

capacitors,

such

as

electrolytic

or

POSCAPs. Use an external ramp when using

low-ESR capacitors, such as ceramic capacitors.

For cases not listed in this datasheet, an excel

spreadsheet

provided

by

local

sales

representatives can assist with the calculations.

(V)

L

(μH)

R1

(kΩ)

R2

(kΩ)

R7

(kΩ)

1

1

13.3

20

357

2.5

2.2

63.4

20

887

3.3

3.3

91

20

1200

(V)

L

(μH)

R1

(kΩ)

R2

(kΩ)

R7

(kΩ)

1

0.72

13.3

20

357

2.5

1.5

63.4

20

887

3.3

1.8

91

20

1200

(V)

L

(μH)

R1

(kΩ)

R2

(kΩ)

R4

(kΩ)

C4

(pF)

R7

(kΩ)

1

1

13.7

20

750

220

357

2.5

2.2

66.5

20

1000

220

887

3.3

3.3

95.3

20

1200

220

1200

(V)

L

(μH)

R1

(kΩ)

R2

(kΩ)

R4

(kΩ)

C4

(pF)

R7

(kΩ)

1

0.72

13.7

20

750

220

357

2.5

1.5

66.5

20

1000

220

887

3.3

1.8

95.3

20

1200

220

1200