Re: [PSES] Power Integrity Question
Yes and no. The coupling path was closing through the user PCB... John Woodgate wrote: That should be warned about in the data sheet. Internal EMC problems tend to be rare, which is good, but because they are rare, there should be warnings if they can occur. John Woodgate OOO-Own Opinions Only J M Woodgate and Associateswww.woodjohn.uk Rayleigh, Essex UK On 2018-04-09 13:19, Istvan Novak wrote: And examples can be even more strange: we had DC-DC converter modules failing to work properly because one of the converter's power pins feeding an internal linear regulator picked up noise from the same converter. Regards, Istvan Novak John Woodgate wrote: I agree. One particular point is keeping a trace connected to an inverting input very short, even if that means including a low-value 'stopper' resistor close to the chip. That point has quasi-infinite sensitivity but infinitesimal impedance only within the op-amp pass band. Above the pass-band, it is an antenna connected to a diode. And yes, it can pick up power rail noise. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk Rayleigh, Essex UK On 2018-04-09 04:27, Doug Smith wrote: Hi Ken and the group, Many analog circuits, as well as the analog parts of large ICs that you mention, do have response to GHz noise even 1 MHz unity gain opamps! Low frequency op amps can generate a DC offset on their inputs from GHz digital noise or radio signals, a common problem for the last 45 years since I first observed it. Power supply rejection of op amps goes to pot pretty quickly with frequency as well. High frequency effects therefore are important even to low speed analog circuits. In some ways, one must lay out the low frequency analog circuit using microwave techniques to keep RF noise at bay. The circuit features must be keep really small,, including the bypass capacitors being kept extremely close (< 100 mils) to the op amp. 45 years ago, faced with opamp problems from RF noise I developed some techniques for keeping the op amps happy. I discuss these in my upcoming course. Doug University of Oxford, Course Tutor Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org Web: http://www.dsmith.org -- - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 mailto:emc-p...@ieee.org>> 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 mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org>> David Heald mailto:dhe...@gmail.com>> - 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 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 Dougl
Re: [PSES] Power Integrity Question
That should be warned about in the data sheet. Internal EMC problems tend to be rare, which is good, but because they are rare, there should be warnings if they can occur. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk Rayleigh, Essex UK On 2018-04-09 13:19, Istvan Novak wrote: And examples can be even more strange: we had DC-DC converter modules failing to work properly because one of the converter's power pins feeding an internal linear regulator picked up noise from the same converter. Regards, Istvan Novak John Woodgate wrote: I agree. One particular point is keeping a trace connected to an inverting input very short, even if that means including a low-value 'stopper' resistor close to the chip. That point has quasi-infinite sensitivity but infinitesimal impedance only within the op-amp pass band. Above the pass-band, it is an antenna connected to a diode. And yes, it can pick up power rail noise. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk Rayleigh, Essex UK On 2018-04-09 04:27, Doug Smith wrote: Hi Ken and the group, Many analog circuits, as well as the analog parts of large ICs that you mention, do have response to GHz noise even 1 MHz unity gain opamps! Low frequency op amps can generate a DC offset on their inputs from GHz digital noise or radio signals, a common problem for the last 45 years since I first observed it. Power supply rejection of op amps goes to pot pretty quickly with frequency as well. High frequency effects therefore are important even to low speed analog circuits. In some ways, one must lay out the low frequency analog circuit using microwave techniques to keep RF noise at bay. The circuit features must be keep really small,, including the bypass capacitors being kept extremely close (< 100 mils) to the op amp. 45 years ago, faced with opamp problems from RF noise I developed some techniques for keeping the op amps happy. I discuss these in my upcoming course. Doug University of Oxford, Course Tutor Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org Web: http://www.dsmith.org -- - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Power Integrity Question
And examples can be even more strange: we had DC-DC converter modules failing to work properly because one of the converter's power pins feeding an internal linear regulator picked up noise from the same converter. Regards, Istvan Novak John Woodgate wrote: I agree. One particular point is keeping a trace connected to an inverting input very short, even if that means including a low-value 'stopper' resistor close to the chip. That point has quasi-infinite sensitivity but infinitesimal impedance only within the op-amp pass band. Above the pass-band, it is an antenna connected to a diode. And yes, it can pick up power rail noise. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk Rayleigh, Essex UK On 2018-04-09 04:27, Doug Smith wrote: Hi Ken and the group, Many analog circuits, as well as the analog parts of large ICs that you mention, do have response to GHz noise even 1 MHz unity gain opamps! Low frequency op amps can generate a DC offset on their inputs from GHz digital noise or radio signals, a common problem for the last 45 years since I first observed it. Power supply rejection of op amps goes to pot pretty quickly with frequency as well. High frequency effects therefore are important even to low speed analog circuits. In some ways, one must lay out the low frequency analog circuit using microwave techniques to keep RF noise at bay. The circuit features must be keep really small,, including the bypass capacitors being kept extremely close (< 100 mils) to the op amp. 45 years ago, faced with opamp problems from RF noise I developed some techniques for keeping the op amps happy. I discuss these in my upcoming course. Doug University of Oxford, Course Tutor Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org Web: http://www.dsmith.org -- - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald: - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Power Integrity Question
I agree. One particular point is keeping a trace connected to an inverting input very short, even if that means including a low-value 'stopper' resistor close to the chip. That point has quasi-infinite sensitivity but infinitesimal impedance only within the op-amp pass band. Above the pass-band, it is an antenna connected to a diode. And yes, it can pick up power rail noise. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk Rayleigh, Essex UK On 2018-04-09 04:27, Doug Smith wrote: Hi Ken and the group, Many analog circuits, as well as the analog parts of large ICs that you mention, do have response to GHz noise even 1 MHz unity gain opamps! Low frequency op amps can generate a DC offset on their inputs from GHz digital noise or radio signals, a common problem for the last 45 years since I first observed it. Power supply rejection of op amps goes to pot pretty quickly with frequency as well. High frequency effects therefore are important even to low speed analog circuits. In some ways, one must lay out the low frequency analog circuit using microwave techniques to keep RF noise at bay. The circuit features must be keep really small,, including the bypass capacitors being kept extremely close (< 100 mils) to the op amp. 45 years ago, faced with opamp problems from RF noise I developed some techniques for keeping the op amps happy. I discuss these in my upcoming course. Doug University of Oxford, Course Tutor Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org Web: http://www.dsmith.org -- - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Power Integrity Question
Hi Ken and the group, Many analog circuits, as well as the analog parts of large ICs that you mention, do have response to GHz noise even 1 MHz unity gain opamps! Low frequency op amps can generate a DC offset on their inputs from GHz digital noise or radio signals, a common problem for the last 45 years since I first observed it. Power supply rejection of op amps goes to pot pretty quickly with frequency as well. High frequency effects therefore are important even to low speed analog circuits. In some ways, one must lay out the low frequency analog circuit using microwave techniques to keep RF noise at bay. The circuit features must be keep really small,, including the bypass capacitors being kept extremely close (< 100 mils) to the op amp. 45 years ago, faced with opamp problems from RF noise I developed some techniques for keeping the op amps happy. I discuss these in my upcoming course. Doug University of Oxford, Course Tutor Department for Continuing Education Oxford, Oxfordshire, United Kingdom -- Doug Smith P.O. Box 60941 Boulder City, NV 89006-0941 TEL/FAX: 702-570-6108/570-6013 Mobile: 408-858-4528 Email: d...@dsmith.org Web: http://www.dsmith.org -- On Sun, 8 Apr 2018 12:30:10 -0400, Istvan Novak wrote: Ken, Again, there is no generic answer, it depends on the circuit you feed. Generic low speed logic can be fairly tolerant to noise, but today's high-speed digital chips also have a lot of analog-like circuits: PLL, oscillators, SerDes drivers and receivers. Dependent on their construction, their tolerance to noise can be very different. If we are lucky, we get that requirement from the device's data sheet, so that we can decide about acceptable limits rail by rail and device by device. Dips usually dont kill a device, it may cause 'only' functional errors. A spike can cause damage to the chips, but only if it appears on the semiconductor itself. But we do not have direct access to the semiconductor to measure the voltage, and as opposed to signal integrity, where we can deembed the package and can reliably infer the waveform on the silicon from a waveform measured at the pin and from a package model, we almost never have a model for the power path of the package to do the same deembedding with power noise. Regards, Istvan Novak Ken Javor wrote: > Re: [PSES] Power Integrity Question Then let’s slightly rephrase the > question. What sort of ripple causes problems? Is it dips - how much? > Spikes – again, how much? Let’s confine this to digital logic. Analog > is easier because there is defined power supply ripple rejection for > parts plus the noise sources aren’t high speed. > > Ken Javor > Phone: (256) 650-5261 > > > > *From: *John Woodgate > *Date: *Sun, 8 Apr 2018 08:09:47 +0100 > *To: *Ken Javor , > > *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 > > 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, “it depends,” 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 > > *Date: *Sat, 7 Apr 2018 17:58:36 +0100 > *To: *Ken Javor > > , > > > *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 > > > 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
Re: [PSES] Power Integrity Question
Ken, Again, there is no generic answer, it depends on the circuit you feed. Generic low speed logic can be fairly tolerant to noise, but today's high-speed digital chips also have a lot of analog-like circuits: PLL, oscillators, SerDes drivers and receivers. Dependent on their construction, their tolerance to noise can be very different. If we are lucky, we get that requirement from the device's data sheet, so that we can decide about acceptable limits rail by rail and device by device. Dips usually dont kill a device, it may cause 'only' functional errors. A spike can cause damage to the chips, but only if it appears on the semiconductor itself. But we do not have direct access to the semiconductor to measure the voltage, and as opposed to signal integrity, where we can deembed the package and can reliably infer the waveform on the silicon from a waveform measured at the pin and from a package model, we almost never have a model for the power path of the package to do the same deembedding with power noise. Regards, Istvan Novak Ken Javor wrote: Re: [PSES] Power Integrity Question Then let’s slightly rephrase the question. What sort of ripple causes problems? Is it dips - how much? Spikes – again, how much? Let’s confine this to digital logic. Analog is easier because there is defined power supply ripple rejection for parts plus the noise sources aren’t high speed. Ken Javor Phone: (256) 650-5261 *From: *John Woodgate *Date: *Sun, 8 Apr 2018 08:09:47 +0100 *To: *Ken Javor , *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> <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, “it depends,” 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 <mailto:j...@woodjohn.uk> <mailto:j...@woodjohn.uk> *Date: *Sat, 7 Apr 2018 17:58:36 +0100 *To: *Ken Javor <mailto:ken.ja...@emccompliance.com> <mailto:ken.ja...@emccompliance.com> , <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> *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> <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 <mailto:emc-p...@ieee.org> <mailto:emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://w
Re: [PSES] Power Integrity Question
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 Date: Sun, 8 Apr 2018 08:09:47 +0100 To: Ken Javor , 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 <mailto:j...@woodjohn.uk> > Date: Sat, 7 Apr 2018 17:58:36 +0100 > To: Ken Javor > <mailto:ken.ja...@emccompliance.com> , > <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> > 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 >> <mailto:emc-p...@ieee.org> >> >> >> 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 <mailto:sdoug...@ieee.org> >> Mike Cantwell <mailto:mcantw...@ieee.org> >> >> >> For policy questions, send mail to: >> Jim Bacher <mailto:j.bac...@ieee.org> >> David Heald <mailto:dhe...@gmail.com> >> >> > > > - > > > > 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 > > > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc
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 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, “it depends,” 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 *Date: *Sat, 7 Apr 2018 17:58:36 +0100 *To: *Ken Javor , *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 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> <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 Mike Cantwell For policy questions, send mail to: Jim Bacher David Heald - 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 mailto:emc-p...@ieee.org>> 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 mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org>> David Heald mailto:dhe...@gmail.com>> - 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 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 t
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 Date: Sat, 7 Apr 2018 17:58:36 +0100 To: Ken Javor , 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> 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 > > > > 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 > Mike Cantwell > > > For policy questions, send mail to: > Jim Bacher > David Heald > - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Power Integrity Question
Hi Ken, Good question, and as you already suspect, there is no clear, generic answer (and for the same reason there is no such thing as typical electronics). Having practiced this art for decades, and teaching courses (up to five days in length) on the subject, the best we can do is to explain all possible factors that eventually the responsible designer has to take into account. You will find pieces of the answer in various books and on the publications posted on my website, for instance http://www.electrical-integrity.com/Paper_download_files/Ansoft_EMI_Workshop_SUN_for_22Aug07_v2.pdf Regards, Istvan Novak 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 mailto:emc-p...@ieee.org>> 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 mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org>> David Heald mailto:dhe...@gmail.com>> - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Power Integrity Question
I don't think that there is a general rule that doesn'thave 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 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 mailto:emc-p...@ieee.org>> 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 mailto:sdoug...@ieee.org>> Mike Cantwell mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher mailto:j.bac...@ieee.org>> David Heald mailto:dhe...@gmail.com>> - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
