John Doty wrote: > On Jun 16, 2007, at 5:43 PM, Randall Nortman wrote: I would think that 120Hz ripple on the input >> would not bother the thing, even if it's large ripple, so long as the >> voltage never drops below the minimum required to still enable a 5V >> output (i.e., about 8V). > > Depends on how much ripple on the output you can tolerate and how > fast the control loop is. The regulator acts as a lowpass filter, but > it will pass some ripple to the output. Know your requirements. Know > the specs of the stuff you're using. >
Yes, I would not be surprised if that TI controller cycling at 500KHz can be a low pass filter by changing it's pulse widths as the ripple varies. Its ripple response might have a shape like a one pole filter with 3db down lower than you think. The effect on the rectifier caps might be even worse -- more current draw when it sags -- sag further. Need to read its spec like John D. said. John Griessen _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
