Then let¹s slightly rephrase the question. What sort of ripple causes problems? Is it dips - how much? Spikes again, how much? Let¹s confine this to digital logic. Analog is easier because there is defined power supply ripple rejection for parts plus the noise sources aren¹t high speed.
Ken Javor Phone: (256) 650-5261 From: John Woodgate <[email protected]> Date: Sun, 8 Apr 2018 08:09:47 +0100 To: Ken Javor <[email protected]>, <[email protected]> Subject: Re: [PSES] Power Integrity Question A specific target would typically be 'less than 1/3 of the value known to just provoke trouble'. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk <http://www.woodjohn.uk> Rayleigh, Essex UK On 2018-04-08 04:25, Ken Javor wrote: > Re: [PSES] Power Integrity Question If the answer to how much ripple is too > much, or how little ripple is good enough is in all cases, ³it depends,² then > does that mean that the pursuit of power integrity has a purely functional > pass/fail criteria; i.e., that the unit operates properly, as opposed to a > specific target on ripple level? > > Ken Javor > Phone: (256) 650-5261 > > > > > > From: John Woodgate <[email protected]> <mailto:[email protected]> > Date: Sat, 7 Apr 2018 17:58:36 +0100 > To: Ken Javor <[email protected]> > <mailto:[email protected]> , <[email protected]> > <mailto:[email protected]> > Subject: Re: [PSES] Power Integrity Question > > > > I don't think that there is a general rule that doesn't have so many > exceptions as to be useless. Even a 'simple' audio power amplifier can show > this. A conventional linear amplifier can have very good PSRR (power supply > rejection ratio) but a Class D amplifier has zero dB PSRR - none at all. > > > John Woodgate OOO-Own Opinions Only > J M Woodgate and Associates www.woodjohn.uk <http://www.woodjohn.uk> > <http://www.woodjohn.uk> > Rayleigh, Essex UK > > On 2018-04-07 17:41, Ken Javor wrote: > > > >> Power Integrity Question There are many learned books/papers/discussions on >> how to achieve proper power integrity by way of proper PCB layout and proper >> capacitor decoupling techniques, but what is the goal? I don't mean the >> functional goal, which is obvious, but rather what is the metric? Is it >> ripple voltage peak-to-peak, maximum excursion, minimum excursion, some rms >> value, or...? >> >> This question is decoupled from achieving PI for the purpose of controlling >> radiated emissions: just asking how close to pure unadulterated dc a dc rail >> must be in order to be considered properly functional. >> >> Understand the answer will be different for an analog rail vs. a digital >> one, and for different digital rails, but appreciate insight into what >> constitutes acceptable power quality for all dc rails used in a typical piece >> of electronics. >> >> Thank you, >> >> Ken Javor >> Phone: (256) 650-5261 >> >> >> - >> ---------------------------------------------------------------- >> >> >> This message is from the IEEE Product Safety Engineering Society emc-pstc >> discussion list. To post a message to the list, send your e-mail to >> <[email protected]> <mailto:[email protected]> >> >> >> All emc-pstc postings are archived and searchable on the web at: >> http://www.ieee-pses.org/emc-pstc.html >> >> >> Attachments are not permitted but the IEEE PSES Online Communities site at >> http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used >> formats), large files, etc. >> >> >> Website: http://www.ieee-pses.org/ >> Instructions: http://www.ieee-pses.org/list.html (including how to >> unsubscribe) <http://www.ieee-pses.org/list.html> >> List rules: http://www.ieee-pses.org/listrules.html >> >> >> For help, send mail to the list administrators: >> Scott Douglas <[email protected]> <mailto:[email protected]> >> Mike Cantwell <[email protected]> <mailto:[email protected]> >> >> >> For policy questions, send mail to: >> Jim Bacher <[email protected]> <mailto:[email protected]> >> David Heald <[email protected]> <mailto:[email protected]> >> >> > > > - > ---------------------------------------------------------------- > > > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to > <[email protected]> > > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
