MP2276

– 16V, 8A, HIGH EFFICIENCY, SYNC, STEP-DOWN CONVERTER

MP2276 Rev.1.0

www.MonolithicPower.com

19

3/22/2017

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Selecting the Inductor

The inductor supplies a constant current to the

output load while being driven by the switching

input voltage. A larger-value inductor results in

less ripple current and lower output ripple

voltage, but also has a larger physical size,

higher series resistance, and lower saturation

current. Generally, select an inductor value that

allows the inductor peak-to-peak ripple current

to be 30% to 40% of the maximum switch

current limit. Also design for a peak inductor

current that is below the maximum switch

current limit. Calculate the inductance value

with Equation (14):

)

V

V

1

(

I

F

V

L

IN

OUT

L

SW

OUT











(14)

Where

current.

Choose an inductor that will not saturate under

the maximum inductor peak current. The peak

inductor

current

can

be

calculated

with

Equation (15):

)

V

V

1

(

L

F

2

V

I

I

IN

OUT

SW

OUT

OUT

LP













(15)

PCB Layout Guidelines

Efficient

PCB

layout

is

critical for

stable

operation. For the best performance, refer to

Figure 7 and follow the guidelines below.

1. Place the input MLCC capacitors as close to

VIN and PGND as possible.

2. Place the major MLCC capacitors on the

same layer as the MP2276.

3. Maximize the VIN and PGND copper plane

to minimize parasitic impedance.

4. Place as many PGND vias as possible as

close

to

the

MP2276

as

possible

to

minimize both parasitic impedance and

thermal resistance.

5. Place a VCC decoupling capacitor close to

the device.

6. Connect AGND and PGND at the point of

the VCC capacitor's ground connection.

7. Place a BST capacitor as close to BST and

SW as possible.

8. Use a trace width of 20 mils or higher to

route the path.

9. Use a 1µF bootstrap capacitor.

SW

VOUT

VIN

PGND

SW

FREQ/

MODE

BST

SW

VIN

PGND

ILIM

EN

SS/TRK

PG

R1

R2

1

2

3

4

5

12

11

10

9

8

6

7

14

13

C6

1

2

3

4

5

12

10

9

8

6

7

14

13

11

C5

C3

VOUT

L1

Figure 7: Recommended Layout