Applications Information
PC Board Layout Considerations
Careful PC board layout is critical to achieve clean and
stable operation. The switching power stage requires
particular attention. Follow these guidelines for good
PC board layout:
1) Place decoupling capacitors as close to the IC as
possible. Keep power ground plane (connected to
PGND) and signal ground plane (connected to
GND) separate.
2) Connect input and output capacitors to the power
ground plane; connect all other capacitors to the
signal ground plane.
3) Keep the high-current paths as short and wide as
possible. Keep the path of switching current short
and minimize the loop area formed by the high-side
MOSFET, the low-side MOSFET, and the input
capacitors. Avoid vias in the switching paths.
4) If possible, connect IN, LX, and PGND separately to
a large copper area to help cool the IC to further
improve efficiency and long-term reliability.
5) Ensure all feedback connections are short and
direct. Place the feedback resistors as close to the
IC as possible.
6) Route high-speed switching nodes away from sen-
sitive analog areas (FB, COMP).
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
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