Hi!
I am layouting a L297-based, chopped, unipolar stepper driver. The steppers are
rated 20A max, consequently, switching 10-20A into an inductive load creates
quite a bit of noise.
The problem I am seeing is not uncommon for chopped steppers, ie that the
chopper settles on a subharmonic of the switching frequency (20kHz) because of
crosstalk.
I have tried moving stuff around on the prototype board and looking at various
grounding strategies. I have separated AGND and DGND in the schematic and then
joined them, but that makes KICAD treat them together as a net. What should I
do? Put in a 0 ohm resistor where I join them to keep filled zones separate?
Any ideas, tips, pointers?
(Apologies if this appears multiple times as Yahoo seemed to have problems this
morning)
- Anders Gustafsson
Engineer, CNE6, ASE
Pedago, The Aaland Islands (N60 E20)
www.pedago.fi
phone +358 18 12060
mobile +358 40506 7099
fax +358 18 14060
