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PI352X-00 Datasheet, PDF (30/34 Pages) Vicor Corporation – 30VIN to 60VIN Cool-Power ZVS Buck Regulator
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Layout Guidelines
To optimize maximum efficiency and low noise performance
from a PI352x-00 design, layout considerations are necessary.
Reducing trace resistance and minimizing high current loop
returns along with proper component placement will contribute
to optimized performance.
A typical buck converter circuit is shown in Figure 62. The
potential areas of high parasitic inductance and resistance are the
circuit return paths, shown as LR below.
PI352x-00
VIN
CIN
COUT
VIN
CIN
COUT
Figure 62 — Typical Buck Regulator
The path between the COUT and CIN capacitors is of particular
importance since the AC currents are flowing through both of
them when Q1 is turned on. Figure 63, schematically, shows the
reduced trace length between input and output capacitors. The
shorter path lessens the effects that copper trace parasitics can
have on the PI352x-00 performance.
VIN
CIN
Figure 64 — Current flow: Q2 closed
Figure 65 illustrates the tight path between CIN and COUT
(and VIN and VOUT) for the high AC return current. The
PI352x-00 evaluation board uses a layout optimized for
performance in this way.
PGND
VS1
Inductor
ZVS-
VIN
Buck
SIP
VOUT
PGND
COUT
Figure 63 — Current flow: Q1 closed
When Q1 is on and Q2 is off, the majority of CIN’s current is used
to satisfy the output load and to recharge the COUT capacitors.
When Q1 is off and Q2 is on, the load current is supplied by the
inductor and the COUT capacitor as shown in Figure 64. During
this period CIN is also being recharged by the VIN. Minimizing CIN
loop inductance is important to reduce peak voltage excursions
when Q1 turns off. Also, the difference in area between the CIN
loop and COUT loop is vital to minimize switching and GND noise.
Figure 65 — Recommended layout for Optimized AC Current
within the SIP, Inductor, and Ceramic Input and
Output Capacitors
Cool-Power® ZVS Switching Regulators
Page 30 of 34
Rev 1.3
06/2017
vicorpower.com
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