MP2227 – 24V, 3A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER

MP2227 Rev. 1.1

www.MonolithicPower.com

12

11/21/2011

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Table 2—Suggested Surface Mount Inductors

Manufacturer

Part Number

Inductance

(μH)

Max DCR

(mΩ)

Current Rating

(A)

Dimensions

L x W x H (mm

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

Output Capacitor Selection

The output capacitor keeps output voltage ripple

small and ensures regulation loop stable. The

output capacitor impedance shall be low at the

switching frequency. Ceramic capacitors with

X5R or X7R dielectrics are recommended. If

electrolytic capacitor is used, pay attention to

output ripple voltage, extra heating, and the

selection of feedback resistor R1 (refer to “Output

Voltage Setting” section) due to large ESR of

approximately:

OUT

IN

OUT

OUT

IN

OSC

OSC

Vx(V

V

)

1

V

x(ESR

)

V xf

xL

8xf

xC3







PC Board Layout

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

be placed very close to the device with short,

direct and wide traces. A 0.1μF-1μF ceramic is

recommended for VCC supply. C5 must be

placed as close as possible to “VCC” pin and

“GND” pin. The external feedback resistors shall

be placed next to the FB pin. Keep the switching

node SW short and away from the feedback

network. Please see EV2227EQ datasheet for

detailed info.