MPQ4462 – 3.5A, 4MHz, 36V, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED

MPQ4462 Rev. 1.11

www.MonolithicPower.com

17

7/17/2013

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PCB LAYOUT GUIDE

PCB layout is very important for system stability.

It is highly recommended to duplicate EVB

layout for optimum performance.

If change is necessary, please follow these

guidelines and take Figure 6 for reference.

1) Keep the path of switching current short

and minimize the loop area formed by input

capacitor, high-side MOSFET and external

switching diode. Place ceramic bypass

capacitors close to the VIN Pin.

2) Make all feedback connections short and

direct. Try to run the feedback trace as far

from the inductor and noisy power traces

as possible. If possible run the feedback

trace on the opposite PCB side to the

inductor with a ground plane separating the

two.

3) Place

the

feedback

resistors

and

compensation components as close to the

chip as possible. Do not place the

compensation components close to or

under high dv/dt SW node, or inside the

high di/dt power loop. If you have to do so,

the proper ground plane must be in place to

isolate those.

4) Connect VIN, SW, and especially GND

respectively to large copper areas to cool

the chip to improve thermal performance

and long-term reliability. To help to improve

the thermal conduction at high frequencies,

add a grid of thermal vias under the

exposed pad. Use small vias (15mil barrel

diameter) so that the hole fills up during the

plating process and improve thermal

conduction. Larger vias can cause solder

wicking during the reflow process. A pitch

(distance between the centers) of 40mil

between thermal vias is typical.

5) Place the input decoupling capacitor, catch

diode and the MPQ4462 (VIN, SW and

PGND) as close as possible, with traces

that are very short and fairly wide. This can

help to greatly reduce the voltage spike on

SW node, and lower the EMI noise level as

well.

6) Please refer to the layout example on

EVQ4460 datasheet.

C1

C3

R2

R1

L1

C4

C2

D1

VIN

EN

FREQ

GND

BST

SW

FB

COMP

EN

R5

R6

R3

R4

Figure 6: Typical Application Circuit