gEDA-user: bypass caps

Stuart Brorson sdb at cloud9.net
Mon Aug 21 13:14:20 EDT 2006


> I put a copy here: http://www.delorie.com/pcb/m3a-exp-board.pcb

I looked at your board.  The 0603 position on teh back of the board
looks good.  One thing:  Why not put a couple of 10uF tantalum caps at
strategic positions along the PWR/GND busses?  Perhaps one at each
power connector, and one in the middle?  Or -- better -- 10uF at each
power conn, and then a 2.2uF on teh back side for each SOIC row pair?
You really want to have some bulk decoupling, and for a bus topology
like this it helps to distribute the capacitance rather than lumping
it in one place.

Don't forget to derate the Ta voltage by a factor of 3.  That is, if
your VCC is 5V, you need at least a 16V Ta cap for safety.

Stuart



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