MP28127 – 1.25A, 5.5V SYNCHRONOUS STEP-DOWN SWITCHING REGULATOR

MP28127 Rev. 0.9

www.MonolithicPower.com

8

6/7/2010

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PCB Layout

The high current paths (GND, IN and SW) should

be placed very close to the device with short,

direct and wide traces. Two input ceramic

to be placed on both sides of MP28127DQ

package and keep them as close as possible to

“IN” and “GND” pins. If this placement is not

possible, a ceramic cap (10µF~47µF) must be

placed across PIN7-“IN”and PIN9-“GND” since

and good decoupling is needed to avoid any

interference issues.

The external feedback resistors should be placed

next to the FB pin.

Keep the switching node SW short and away

from the feedback network.

Please see the EV datasheet for the detailed

information.

Table 2—Suggested Surface Mount Inductors

Manufacturer

Part

Number

Inductance

(µH)

Max DCR

(mΩ)

Current Rating

(A)

Dimensions

L x W x H (mm3)

Wurth Electronics

744310055

0.55

4.5

14

7×6.9×3

744310095

0.95

7.4

11

7×6.9×3

TOKO

B1015AS-1R0N

1

11

6.9

8.4×8.3×4

Recommended Layout Pattern

SW

GND

L

EN

GND

SW

IN

POK

FB

GND

SW

IN

BS

Figure 2—Recommended Layout Pattern for QFN Package