Return-Path: Received: (qmail 30160 invoked from network); 3 Jun 2003 13:42:18 -0000 Content-Transfer-Encoding: 8bit Received: from netmail01.services.quay.plus.net (212.159.14.219) by mailstore with SMTP; 3 Jun 2003 13:42:18 -0000 X-Priority: 3 Received: (qmail 17937 invoked by uid 10001); 3 Jun 2003 13:42:18 -0000 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by netmail01.services.quay.plus.net with SMTP; 3 Jun 2003 13:42:18 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 19NC2A-0002pH-Mo for rsgb_lf_group-outgoing@blacksheep.org; Tue, 03 Jun 2003 14:41:02 +0100 Received: from [147.197.200.9] (helo=hestia.herts.ac.uk) by post.thorcom.com with esmtp (Exim 4.14) id 19NC26-0002p8-Ey for rsgb_lf_group@blacksheep.org; Tue, 03 Jun 2003 14:40:58 +0100 Received: from gemini ([147.197.200.44] helo=gemini.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 19NBit-0005om-01 for rsgb_lf_group@blacksheep.org; Tue, 03 Jun 2003 14:21:07 +0100 Received: from [147.197.232.252] (helo=rsch-15.herts.ac.uk) by gemini.herts.ac.uk with esmtp (Exim 3.33 #1) id 19NAzn-0001Gs-00 for rsgb_lf_group@blacksheep.org; Tue, 03 Jun 2003 13:34:31 +0100 Message-ID: <5.1.0.14.0.20030603114630.00af0bf0@gemini.herts.ac.uk> X-Sender: mj9ar@gemini.herts.ac.uk X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Tue, 03 Jun 2003 13:34:29 +0100 To: rsgb_lf_group@blacksheep.org From: "James Moritz" In-reply-to: <000f01c32933$447cb400$4112f4cc@jsm> References: <5.2.0.9.0.20030602112216.02a65410@pop2.sympatico.ca> MIME-Version: 1.0 X-MailScanner: No Virus detected Subject: Re: LF: 4060 Divider Content-Type: text/plain; charset=us-ascii; format=flowed X-Spam-Status: No, hits=-22.9 required=5.0tests=EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES,REPLY_WITH_QUOTESversion=2.53 X-Spam-Checker-Version: SpamAssassin 2.53 (1.174.2.15-2003-03-30-exp) X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false At 11:17 02/06/2003 -0700, you wrote: >I would like to use the M74HC4060 as a 'divide-by-64' signal source. Can >anyone tell me the upper limit for xtals that this chip can handle? My xtal >will be on 8.750000; I fear that the upper limit may be around 4-6 MHz? > >Steve Dear Steve, LF Group According to the National Semiconductor data book, the 74HC4060 has a guaranteed minimum operating frequency of 30MHz at 5V supply. Over the 2 - 6V supply range, typical values are 6MHz and 35MHz respectively. The slower 4000 series CD4060 device operates over a wider voltage range - at 5V supply, guaranteed minumum frequency is 1.5MHz (4MHz typ); 10V, 4MHz (10MHz typ), 15V - 5MHz (12MHz typ). So it is a bit "iffy" for 8.75MHz, but it might be worth selecting a good one if, for example, you wanted everything to work from a 12V rail. These figures really relate to the divider part of the chip. As far as the crystal oscillator part goes, this depends a lot on the crystal and the external components, since the "oscillator" is just a CMOS inverter which provides gain (although the 74HC4060 inverter has been optimised for xtal osc use by increasing the output impedance). But experience shows that an xtal around 9MHz will be no problem for the 74HC device, and will almost certainly work with the 4000 series device too. For details of the oscillator section design, have a look at www.fairchildsemi.com/an/AN/AN-340.pdf Cheers, Jim Moritz 73 de M0BMU