Re: AC 97
Darrell, Yes, we are also dealing with the AC 97 Codec. Our experience has been that it produces RF Emissions, but I would say that both common mode and differential mode noise contribute to the overall RF Emissions problem. I don't believe that you will solve the Emissions problem with components alone, you will need to look at your PCB layout in order to achieve the best EMC performance. I would take a look at the datasheet for this device; there is a layout diagram showing preferred grounding, and power feeds. This device creates an interesting situation since there are digital and analog partitions, that need to be supported by layout and component selection. I would also be interested in knowing other's EMC experience with this device. Regards, Scott Mee EMC Engineer Johnson Controls Inc. PH: 616.394.2565 EMAIL: scott@jci.com DLocke@advanced-input.c om To: emc-p...@majordomo.ieee.org Sent by: cc: owner-emc-pstc@majordomSubject: AC 97 o.ieee.org 02/22/02 11:11 AM Please respond to DLocke Esteemed Colleages; Has anyone had experience using Audio-Codec '97 (AC 97) topology with respect to EMC performance. It is commonly used in PC sound cards. We have a device that incorporates this technology for voice recognition and are seeing very high emissions between 100-600 MHz. The offending RF noise source appears to be entirely differential. Thanks Darrell Locke Advanced Input Devices --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: AC 97
Darrell: With respect to your radiated emissions dilemna, useful information would be the clock speeds, cable lengths, and worst-case mode of operation at which emissions are the highest. Generally, if you invoke the divide and conquer rule, it should be an easier matter pinpointing the dominant sources of emissions. Regards, Jeffrey W. Greilich EMC Technical Manager Automotive Systems Laboratory, Inc. 27200 Haggerty Road, Suite B-12 Farmington Hills, MI 48331 (248) 848-2771 (Office) --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: AC 97
The source may be differential, but common mode currents generally contribute much more to radiated emissions, especially with cables... It sounds like you have cable radiation (100MHz) as well as maybe slot radiation (600MHz)... Tell us more about your device's test setup... (i.e. chassis and cabling details)... Paul Hare e: ph...@pirus.com Compliance Engineer w: 978.206.9179 Pirus Networks f: 978.206.9199 43 Nagog Park c: 508.450.0376 Acton, MA 01720 i: www.pirus.com -Original Message- From: Darrell Locke [mailto:dlo...@advanced-input.com] Sent: Friday, February 22, 2002 11:12 AM To: emc-p...@majordomo.ieee.org Subject: AC 97 Esteemed Colleages; Has anyone had experience using Audio-Codec '97 (AC 97) topology with respect to EMC performance. It is commonly used in PC sound cards. We have a device that incorporates this technology for voice recognition and are seeing very high emissions between 100-600 MHz. The offending RF noise source appears to be entirely differential. Thanks Darrell Locke Advanced Input Devices --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
