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BD9DA00MF

Datasheet

TSZ02201-0J2J0AB01940-1-2

© 2025 ROHM Co., Ltd. All rights reserved.

18.Mar.2025 Rev.001

www.rohm.com

TSZ22111 • 15 • 001

PCB Layout Design

PCB layout design for DC/DC converter is very important. The appropriate layout can avoid various problems concerning power

supply circuit. Figure 87 to Figure 89 show the current path in a buck DC/DC converter circuit. The Loop 1 in Figure 87 is a

current path when High-Side Switch is ON and Low-Side Switch is OFF, the Loop 2 in Figure 88 is when High-Side Switch is

OFF and Low-Side Switch is ON. The thick line in Figure 89 shows the difference between Loop1 and Loop2. The current in

thick line change sharply each time the switching element High-Side and Low-Side Switch change from OFF to ON, and vice

versa. These sharp changes induce a waveform with harmonics in this loop. Therefore, the loop area of thick line that is

consisted by input capacitor and IC should be as small as possible to minimize noise. For more details, refer to application note

of switching regulator series “PCB Layout Techniques of Buck Converter”.

Figure 87. Current Path when High-Side Switch = ON, Low-Side Switch = OFF

Figure 88. Current Path when High-Side Switch = OFF, Low-Side Switch = ON

Figure 89. Difference of Current and Critical Area in Layout

CIN

High-Side Switch

COUT

VOUT

L

VIN

Loop1

Low-Side Switch

GND

GND

CIN

COUT

VOUT

L

VIN

Loop2

High-Side Switch

Low-Side Switch

GND

GND

CIN

High-Side FET

COUT

VOUT

L

VIN

GND

GND

Low-Side FET