WPMDH1100601 / 171010601
MagI3C Power Module
VDRM – Variable Step Down Regulator Module
LAYOUT RECOMMENDATION
PCB layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance of a DC-DC
converter and surrounding circuitry by contributing to EMI, ground bounce and resistive voltage drop in the traces. These
can send erroneous signals to the DC-DC converter resulting in poor regulation or instability. A good layout can be
implemented by following simple design rules.
1: Minimize the area of switched current loops.
VIN
VOUT
VOUT
VIN
High
di/dt
CIN
COUT
Power Module
PGND
Loop 2
Loop 1
GND
GND
The target is to identify the paths in the system that have discontinuous current flow. They are the most critical ones
because they act as an antenna and cause observable high frequency noise (EMI). The easiest approach to find the critical
paths is to draw the high current loops during both switching cycles and identify the sections which do not overlap. They are
the ones where no continuous current flows and high di/dt is observed. Loop1 is the current path during the ON-time of the
high-side MOSFET. Loop2 is the current path during the OFF-time of the high-side MOSFET.
1
7
6
VIN
VOUT
VIN
VOUT
Module
RFBT
FB
AGND
COUT
CIN
PGND
RFBB
EP
4
GND
GND
Based on those considerations, the path of the input capacitor CIN is the most critical one to generate high frequency noise
on VIN. Therefore place CIN as close as possible to the MagI³C power module VIN and PGND exposed pad EP. This will
minimize the high di/dt area and reduce radiated EMI. Additionally, grounding for both the input and output capacitor should
consist of a localized top side plane that connects to the PGND exposed pad.
we-online.com
Würth Elektronik eiSos GmbH & Co. KG – Data Sheet Rev. 1.0
© September 2017
39/54
WURTH [ WURTH ELEKTRONIK GMBH & CO. KG, GERMANY. ]
