MAX8686
Single/Multiphase, Step-Down,
DC-DC Converter Delivers Up to 25A Per Phase
22 ______________________________________________________________________________________
Applications Information
PCB Layout Guidelines
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. The switching
power stage requires particular attention. Follow these
guidelines for good PCB layout:
1) Place IC decoupling capacitors as close to the IC
pins as possible. Separate the power and analog
ground planes. Place the input ceramic decoupling
capacitor directly across and as close as possible
to IN and PGND. This is to help contain the high
switching current within this small loop.
2) For output current greater than 10A, a four-layer
PCB is recommended. Pour an analog ground
plane in the second layer underneath the IC to min-
imize noise coupling.
3) Connect input and output capacitor to the PGND
plane and the VL capacitor to RTN. Connect all
analog signals to GND. The frequency-setting
capacitor should be connected to GFREQ.
4) Connect PGND, GND, and RTN at the return path
of the input bypass capacitor.
5) Signals shared by the master and slave (ILIM,
COMP, and FREQ) should not run close to switch-
ing signals.
6) Place the inductor current-sense resistor and
capacitor as close to the inductor as possible.
Make a Kelvin connection to minimize the effect of
PCB trace resistance.
7) Connect the exposed pad sections to the corre-
sponding IC pins and allow sufficient copper area
to help cooling the device.
8) Place the REFIN and compensation components
as close to the IC pins as possible.
9) Connect remote-sense input RS+ and RS- directly
to the load voltage regulation point and use Kelvin
connection for the two traces.
10) Refer to the MAX8686 Evaluation Kit for an exam-
ple layout.
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages
. Note that a “+”, “#”, or “-” in
the package code indicates RoHS status only. Package draw-
ings may show a different suffix character, but the drawing per-
tains to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
40 TQFN T4066M+1
21-0177
40 TQFN T4066MN+1
21-0177
