MAX5986A MAXIM [Maxim Integrated Products], MAX5986A Datasheet - Page 15

• Manufacturer Part Number: MAX5986A
• Description: IEEE 802.3af-Compliant, High-Efficiency, Class 1,Powered Devices with Integrated DC-DC Converter
• Manufacturer: MAXIM [Maxim Integrated Products]

Careful PCB layout is critical to achieve clean and stable
operation. It is highly recommended to duplicate the
MAX5986A EV kit layout for optimum performance. If
deviation is necessary, follow these guidelines for good
PCB layout:
1) Connect input and output capacitors to the power
2) Place capacitors on V
3) Keep the high-current paths as short and wide as
Powered Devices with Integrated DC-DC Converter
ground plane; connect all other capacitors to the sig-
nal ground plane.
as possible to the IC and its corresponding pin using
direct traces. Keep power ground plane (connected
to PGND) and signal ground plane (connected to
GND) separate.
possible. Keep the path of switching current short
and minimize the loop area formed by LX, the output
capacitors, and the input capacitors.
IEEE 802.3af-Compliant, High-Efficiency, Class 1,
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DD
, V
CC
, AUX, V
PCB Layout
DRV
as close
4) Connect V
5) Ensure all feedback connections are short and direct.
6) Route high-speed switching nodes, such as LX, away
7) Place enough vias in the pad for the EP of the
MAX5986A/MAX5987A so that heat generated inside can
be effectively dissipated by the PCB copper. The recom-
mended spacing for the vias is 1mm to 1.2mm pitch. The
thermal vias should be plated (1oz copper) and have a
small barrel diameter (0.3mm to 0.33mm).
copper area to help cool the IC to further improve
efficiency and long-term reliability.
Place the feedback resistors and compensation com-
ponents as close as possible to the IC.
from sensitive analog areas (FB).
MAX5986A/MAX5987A
DD
, V
CC
, and PGND separately to a large