MP2905- 3V to 28V INPUT, HYSTERETIC SYNCHRONOUS STEP-DOWN CONTROLLER

MP2905 Rev. 0.91

www.monolithicpower.com

14

4/18/2011

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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 these

guidelines:

1) Keep the path of switching current short and

minimize the loop area formed by Input cap,

high-side MOSFET and low-side MOSFET.

2) IC

bypass

ceramic

capacitors

are

suggested to be put close to the IN Pin.

3) Ensure all feedback connections are short

and direct. Place the feedback resistors as

close to the chip as possible.

4) Route SW away from sensitive analog

areas such as FB.

5) Connect IN, SW, and especially GND

respectively to a large copper area to

improve chip thermal performance and long

term reliability.

6) It is suggested to add the snubber circuit

across the high side MOSFET (IN pin and

SW pin) so as to reduce the SW spike.

7) If output current is higher than 10A,

recommend to use a four layers PCB, and

pour ground in mid layer.

Figure 5—MP2905 Application Circuit