PCB Layout Guidelines
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. Use a multilayer board
whenever possible for better noise immunity and power
dissipation. Follow these guidelines for good PC board
layout:
1) Use a large contiguous copper plane under the
device package. Ensure that all heat-dissipating
components have adequate cooling. The bottom pad
of the devices must be soldered down to this copper
plane for effective heat dissipation and getting the full
power out of the devices. Use multiple vias or a single
large via in this plane for heat dissipation
2) Isolate the power components and high current path
from the sensitive analog circuitry. This is essential to
prevent any noise coupling into the analog signals.
3) Keep the high-current paths short, especially at the
ground terminals. This practice is essential for stable,
jitter-free operation. The high current path compris-
ing of input capacitor, high-side FET, inductor, and the
output capacitor should be as short as possible.
4) Keep the power traces and load connections short.
This practice is essential for high efciency. Use
thick copper PCBs (2oz vs. 1oz) to enhance full-load
efciency.
5) The analog signal lines should be routed away from
the high-frequency planes. This ensures integrity of
sensitive signals feeding back into the IC.
6) The ground connection for the analog and power
section should be close to the IC. This keeps the
ground current loops to a minimum. In cases where
only one ground is used, adequate isolation between
analog return signals and high-power signals must be
maintained.
www.maximintegrated.com
Maxim Integrated
│
17
MAX20002/MAX20003 36V, 220kHz to 2.2MHz, 2A/3A Fully
Integrated Step-Down Converters
with 15μA Operating Current
