Joseph Thomas

Noise issue during transitions between normal and low power modes

Discussion created by Joseph Thomas on May 31, 2006
Latest reply on Jun 12, 2006 by Joseph Thomas
I have an rf receiver attached to a 908qy1.  When I started, I was running in normal mode (no sleep) and I had some microprocessor based noise in the rf section.  Once those issues were resolved, I coded the "power reduction" scheme of waking via the auto-wakeup timer.  When I did that, I can see noise spikes every time the processor wakes and goes to sleep.  I assumed that these were from the transiet current draw, however, large caps to suppress any regulator lugging and a choke in the ground path did nothing to resolve.  Any help on explaining A) where is the noise comming from (conducted or radiated), and B) how do I get rid of it???  Any thing I can do in software??