> Even if I ran a 4000 right on the 12v, I wouldn't count on that 12v to > be very clean if it has motors running off it. Electrically braking a > motor with an H-bridge can spike the power rails.
> And a pic + regulator (sot-26 + sot-323)... Fast transients will go through the typical regulator as if it was not there at all. Some have better rejection ratios than others. A Depletion FET can be put before a regulator, driving the regulator's Vin, in a noisy environment, or where the regulator itself does not go as high as Vin. Drive its gate with the output of the regulator, it then becomes a variable resistor to absorb the transient, be sure to account for power dissipation, to keep the transient out of the regulator in the first place. SuperTex has an application note covering this, which Ixys copied sections of; "Depletion-Mode Power MOSFETs and Applications" by Abdus Sattar of Ixys. Ixys makes higher power Depletion FETs than SuperTex. _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
