RE: RE: EMC Circuit Board Design
The first thing I do when encountering board with too high emissions (small band) at an impair multitude of the metal box oscillator, is adding a resistor (chip) in series with it's output. Depending of the load this may vary form 22 - 150 Ohms. This alone helps often to bring a board in compliance. Any standard buffer will do the same. You know, if any metal can oscillator manufacturer wants to stand out to it's competitors, he has the rise time of it's output signal as most important parameter. Low rise time means high short circuit current. During each edge of the square wave this full value of short circuit current is allowed to flow, as the load is mainly capacitive. This is especially relevant on multi-layer boards where wiring has almost no inductance. >-Original Message- >From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf >Of Allen Tudor >Sent: Friday, January 21, 2000 5:38 PM >To: cet...@cetest.nl; emc-p...@majordomo.ieee.org; rehel...@mmm.com >Subject: Re: RE: EMC Circuit Board Design > > > >What do you recommend other than metal can oscillators in item 5 below? > >Allen Tudor, Compliance Engineer >PairGain Technologies tel: (919)875-3382 >6531 Meridien Drive fax: (919)876-1817 >Raleigh, NC 27616 email: >allen_tu...@pairgain.com > > >>>> "cetest" 01/21 9:50 AM >>> > >The most common mistakes carried out on PCB are: > > >1 Use 2-layer instead of multi-layer boards >2 Permit high F clocks to go trough long traces (> 4 Mhz) >3 Place connectors all over the surface instead of corner or edge >4 Let input and out lines of analog and power circuits run >unfiltered to the >cable >5 Use metal can oscillators (too high current drive) >6 Empty copper-fill grounded through thin traces (copper fill is of no use >to emi) >7 Create 2 different ground planes that will compete for "real emc ground". >8 > > >Regards, > >Gert Gremmen > >ce-test qualified testing > >== >http://www.cetest.nl >Do you know our >CE/E mark True type Font ? >http://www.cetest.nl/cettf.htm >== > > > > > > >>-Original Message- >>From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf >>Of rehel...@mmm.com >>Sent: Friday, January 21, 2000 1:48 PM >>To: emc-p...@majordomo.ieee.org >>Subject: EMC Circuit Board Design >> >> >> >> >> >>Dear List-Members, >> >>I am requesting information/opinions/etc. on the following: >> >>When circuit boards are designed, what are the common mistakes that the >>circuit board designers make regarding EMC (multi-layer boards in >>particular)? >> >>You can respond to me directly but I would prefer a response to >the list as >>I believe that the question is of interest to many on this list-server. In >>either event I will compile the responses and resend the >compilation later. >> >>Thanks for your time, >> >>Bob Heller >>3M Company >> >> >> >>- >>This message is coming from the emc-pstc discussion list. >>To cancel your subscription, send mail to majord...@ieee.org >>with the single line: "unsubscribe emc-pstc" (without the >>quotes). For help, send mail to ed.pr...@cubic.com, >>jim_bac...@monarch.com, ri...@sdd.hp.com, or >>roger.volgst...@compaq.com (the list administrators). >> >> > > > >- >This message is coming from the emc-pstc discussion list. >To cancel your subscription, send mail to majord...@ieee.org >with the single line: "unsubscribe emc-pstc" (without the >quotes). For help, send mail to ed.pr...@cubic.com, >jim_bac...@monarch.com, ri...@sdd.hp.com, or >roger.volgst...@compaq.com (the list administrators). > > > > >- >This message is coming from the emc-pstc discussion list. >To cancel your subscription, send mail to majord...@ieee.org >with the single line: "unsubscribe emc-pstc" (without the >quotes). For help, send mail to ed.pr...@cubic.com, >jim_bac...@monarch.com, ri...@sdd.hp.com, or >roger.volgst...@compaq.com (the list administrators). > > - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: RE: EMC Circuit Board Design
We design oscillators out of discrete components to meet the minimum drive requirements. If a can oscillator is used, RC terminations and power filtering is usually required to keep the harmonics from flowing into other ciruits. Regards, Wolf Josenhans "Allen Tudor" on 01/21/2000 10:38:09 AM Please respond to "Allen Tudor" Sent by: "Allen Tudor" To: cet...@cetest.nl, emc-p...@majordomo.ieee.org, rehel...@mmm.com cc:(Wolfgang Josenhans/MW/US/3Com) Subject: Re: RE: EMC Circuit Board Design What do you recommend other than metal can oscillators in item 5 below? Allen Tudor, Compliance Engineer PairGain Technologies tel: (919)875-3382 6531 Meridien Drive fax: (919)876-1817 Raleigh, NC 27616 email: allen_tu...@pairgain.com >>> "cetest" 01/21 9:50 AM >>> The most common mistakes carried out on PCB are: 1 Use 2-layer instead of multi-layer boards 2 Permit high F clocks to go trough long traces (> 4 Mhz) 3 Place connectors all over the surface instead of corner or edge 4 Let input and out lines of analog and power circuits run unfiltered to the cable 5 Use metal can oscillators (too high current drive) 6 Empty copper-fill grounded through thin traces (copper fill is of no use to emi) 7 Create 2 different ground planes that will compete for "real emc ground". 8 Regards, Gert Gremmen ce-test qualified testing == http://www.cetest.nl Do you know our CE/E mark True type Font ? http://www.cetest.nl/cettf.htm == >-Original Message- >From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf >Of rehel...@mmm.com >Sent: Friday, January 21, 2000 1:48 PM >To: emc-p...@majordomo.ieee.org >Subject: EMC Circuit Board Design > > > > > >Dear List-Members, > >I am requesting information/opinions/etc. on the following: > >When circuit boards are designed, what are the common mistakes that the >circuit board designers make regarding EMC (multi-layer boards in >particular)? > >You can respond to me directly but I would prefer a response to the list as >I believe that the question is of interest to many on this list-server. In >either event I will compile the responses and resend the compilation later. > >Thanks for your time, > >Bob Heller >3M Company > > > >- >This message is coming from the emc-pstc discussion list. >To cancel your subscription, send mail to majord...@ieee.org >with the single line: "unsubscribe emc-pstc" (without the >quotes). For help, send mail to ed.pr...@cubic.com, >jim_bac...@monarch.com, ri...@sdd.hp.com, or >roger.volgst...@compaq.com (the list administrators). > > - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: RE: EMC Circuit Board Design
What do you recommend other than metal can oscillators in item 5 below? Allen Tudor, Compliance Engineer PairGain Technologies tel: (919)875-3382 6531 Meridien Drive fax: (919)876-1817 Raleigh, NC 27616 email: allen_tu...@pairgain.com >>> "cetest" 01/21 9:50 AM >>> The most common mistakes carried out on PCB are: 1 Use 2-layer instead of multi-layer boards 2 Permit high F clocks to go trough long traces (> 4 Mhz) 3 Place connectors all over the surface instead of corner or edge 4 Let input and out lines of analog and power circuits run unfiltered to the cable 5 Use metal can oscillators (too high current drive) 6 Empty copper-fill grounded through thin traces (copper fill is of no use to emi) 7 Create 2 different ground planes that will compete for "real emc ground". 8 Regards, Gert Gremmen ce-test qualified testing == http://www.cetest.nl Do you know our CE/E mark True type Font ? http://www.cetest.nl/cettf.htm == >-Original Message- >From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf >Of rehel...@mmm.com >Sent: Friday, January 21, 2000 1:48 PM >To: emc-p...@majordomo.ieee.org >Subject: EMC Circuit Board Design > > > > > >Dear List-Members, > >I am requesting information/opinions/etc. on the following: > >When circuit boards are designed, what are the common mistakes that the >circuit board designers make regarding EMC (multi-layer boards in >particular)? > >You can respond to me directly but I would prefer a response to the list as >I believe that the question is of interest to many on this list-server. In >either event I will compile the responses and resend the compilation later. > >Thanks for your time, > >Bob Heller >3M Company > > > >- >This message is coming from the emc-pstc discussion list. >To cancel your subscription, send mail to majord...@ieee.org >with the single line: "unsubscribe emc-pstc" (without the >quotes). For help, send mail to ed.pr...@cubic.com, >jim_bac...@monarch.com, ri...@sdd.hp.com, or >roger.volgst...@compaq.com (the list administrators). > > - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
