INPUT

CAPACITOR

OUTPUT

CAPACITOR

FEEDBACK

TRACE

VIN

VOUT

VCON

CAPACITOR

VREF

VIN

PGND

VOUT

SGND

FB

SGND CONNECTION TO

QUIET PGND PLANE

VCON

EN

RT

RESISTOR

RB

RESISTOR

HIGH di/dt LOOP

KEEP IT SMALL

PGND

LMZ10501

SNVS677D – MAY 2011 – REVISED MARCH 2013

www.ti.com

Board Layout Considerations

Figure 39. Example Top Layer Board Layout

The board layout of any DC-DC switching converter is critical for the optimal performance of the design. Bad

PCB layout design can disrupt the operation of an otherwise good schematic design. Even if the regulator still

converts the voltage properly, the board layout can mean the difference between passing or failing EMI

regulations. In a Buck converter, the most critical board layout path is between the input capacitor ground

terminal and the synchronous rectifier ground. The loop formed by the input capacitor and the power FETs is a

path for the high di/dt switching current during each switching period. This loop should always be kept as short

as possible when laying out a board for any Buck converter.

The LMZ10501 integrates the inductor and simplifies the DC-DC converter board layout. Refer to the example

layout in Figure 39. There are a few basic requirements to achieve a good LMZ10501 layout.

(pin 6) on the LMZ10501 are next to each other which makes the input capacitor placement simple.

4. Connect SGND to a quiet GND plane.

5. Provide enough PCB area for proper heatsinking. Refer to the Electrical Characteristics table for example

Refer to the evaluation board application note AN-2166 for a complete board layout example.

18

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