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" <cet...@cetest.nl> 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).
