MP2209 – 16V, 2A, 600KHz SYNCHRONOUS STEP-DOWN CONVERTER

MP2209 Rev. 1.01

www.MonolithicPower.com

11

7/11/2013

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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

electrolytic capacitor.

PCB Layout Guide

PCB layout is very important to achieve stable

operation. It is highly recommended to duplicate

EVB layout for optimum performance. If change

is necessary, please follow the guidelines as

follows. Here, the typical application circuit is

taken as an example to illustrate the layout rules

should be followed.

1) For MP2209, a PCB layout with >=4 layers is

recommended.

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

should be placed very close to the device with

short, direct and wide traces.

3)

Two

input

ceramic

capacitors

(2

x

(10μF~22μF)) are strongly recommended to be

placed on both sides of the MP2209DL package

and keep them as close as possible to the “IN”

and “GND” pins.

4) A RC (see the typical application circuit,

R4=10Ω, C4=1μF ceramic capacitor) low pass

filter is recommended for VCC supply. C4 must

be placed as close as possible to “VCC” pin and

“GND” pin.

5) The external feedback resistors shall be

placed next to the FB pin. Keep the FB trace as

short as possible.

6) Keep the switching node SW short and away

from the feedback network.

Top layer

Inner layer-1

Inner layer-2

Bottom layer

Figure 2―PCB Layout (Four Layers)