Electronics Forum / Design / July 2009

Suppose one has a "large" power plane. But the power plane, the vcc of
many components, is switched off many times per second.... at least at
3k but more like 30k. Will the plane have a large enough capacitance
to reduce effect's of switching off?

The plane connects to the anodes of many leds in a switching
configuration. There are several planes for each row of the led
matrix. The "planes" must switch fast enough to that the leds on the
current row are the only ones on. I saw they are planes because I am
dividing up the circuit board into rows and the rows are basically
like power planes as they are large and in one dimension cover the
entire board. It just occurred to me that with a corresponding ground
plane this might cause some big problems with fast switching.

For power planes you want the high capacitance but this will probably
adversely affect my circuit. I wanted the large size mainly to reduce
the heat dissipation in the case for large currents.

Anyone know what the approximate capacitance is for about 8inx1in
power plane on FR4?