CD4060 Xtl Osc. Circuit
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From: Fred Bartoli on 16 Mar 2010 16:55 Joerg a �crit : > Jim Thompson wrote: >> On Sun, 14 Mar 2010 13:25:18 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> .... >> >> Wanna bet ?:-) >> > > With MEMS you could, lots of things are possible. But unlikely as good > as a real crystal. > Have a look at SiTime then... (SiT8102 for ex.) -- Thanks, Fred.
From: Joerg on 16 Mar 2010 17:24 Fred Bartoli wrote: > Joerg a �crit : >> Jim Thompson wrote: >>> On Sun, 14 Mar 2010 13:25:18 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> > ... >>> >>> Wanna bet ?:-) >>> >> >> With MEMS you could, lots of things are possible. But unlikely as good >> as a real crystal. >> > > Have a look at SiTime then... (SiT8102 for ex.) > Those are indeed pretty good. I'd have hoped for some phase noise plots in the datasheet but the jitter specs look nice: http://www.sitime.com/products/datasheets/sit8102/SiT8102LF-REV-1.08-03-12-09.pdf However, while they were announced over two years ago at $1 in qties they haven't made it into Digikey. That's usually a sign for a boutique product: http://www.nsti.org/press/PRshow.html?id=2342 Most of my clients prefer parts to be available at places like Digikey. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: petrus bitbyter on 16 Mar 2010 18:20 "Steve Upton" <steveupton(a)gerber.com> schreef in bericht news:4b9ad91d.1910484(a)news.tpg.com.au... >I have copied the CD4060 part of the CMOS synthesizer in the link > below to the letter, but it does not work. I am using a 12VDC SLA for > supply. It tries to start when I tease the caps, but then dies. > > I've spent hours tinkering to no avail. Can anyone see what is might > be going amiss? Or can anyone please provide a similar circuit that > works? > > http://www.redclifferadioclub.org.au/QRM/2006%2010%20-%20October%20QRM.pdf > > Steve Upton Well, there's the 4060, the crystal and the circuit. All of them may cause the problem. One CD4060 may differ from another. Although the internal circuit should be the same, they act different and has different specs depending on de manufacturer. If not driven to their limits they're usually compatible. Crystals are made in many types and qualities. You'd have the datasheet of the manufacturer to find out how that particular crystal should be applied. The external circuit depends on both components above. The circuit shown in QRM may be the best for the available components but is rather unusual. The 100k resistor for instance is too low. Seems that 100k is to high a load for the invertor. It should be 1M maybe even more. The capacitors depend on the crystal characteristics. If you don't have the datasheet you can try from 22pF upward to - let's say - 56pF. No reason to use different values for the two of them. When using 12V power supply a series resistor may be necessary to limit the current through the crystal. The 2k2 can be a little too high however. You can try 1k for instance but wait until all other maesures fail. petrus bitbyter
From: krw on 16 Mar 2010 19:30 On Tue, 16 Mar 2010 08:10:55 -0700, "JosephKK"<quiettechblue(a)yahoo.com> wrote: >On Sat, 13 Mar 2010 13:15:43 -0600, "krw(a)att.bizzzzzzzzzzzz" <krw(a)att.bizzzzzzzzzzzz> wrote: > >>On Sat, 13 Mar 2010 13:53:23 -0500, "Martin Riddle" <martin_rid(a)verizon.net> >>wrote: >> >>> >>> >>><krw(a)att.bizzzzzzzzzzzz> wrote in message >>>news:6qmnp598tm30hlmvgvdne65ps3msbb8q3r(a)4ax.com... >>>> On Sat, 13 Mar 2010 09:05:24 -0800, John Larkin >>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>>On Sat, 13 Mar 2010 08:42:27 -0800, Fred Abse >>>>><excretatauris(a)invalid.invalid> wrote: >>>>> >>>>>>On Fri, 12 Mar 2010 16:28:07 -0800, John Larkin wrote: >>>>>> >>>>>>> I never buy crystals for things like this. They have a high >>>>>>> probability of >>>>>>> not working, and you wind up fiddling with capacitors and such. >>>>>>> It's >>>>>>> easier to but a packaged, working crystal oscillator, already tuned >>>>>>> to a >>>>>>> couple PPM, guaranteed to oscillate, for $1.50 or thereabouts. >>>>>> >>>>>>Me, too. Amplifiers oscillate, oscillators don't ;-) >>>>> >>>>>We've just started using silicon oscillators, in SOT-23 sized >>>>>packages, for things where 1% is good enough. We're using one part >>>>>that's pin strappable for 8-4-2-1 MHz. >>>> >>>> A seven pin SOT-23? >>> >>>I think its this Linear part >>><http://cds.linear.com/docs/Datasheet/6900fa.pdf> >>>There are others tho. >> >>Neat (but sloppy - 1/5% to 2% error). That's a trinary input (1/10/100) in a >>SOT-23-5. John was suggesting 1-2-4-8 binary inputs. I've never seen a >>SOT-23-7. Up to six pins on a "SOT-23" I can understand, but where does the >>seventh pin go? > >As a quick guess, perhaps a thermal/power pad? SOT-23s with a power pad? I think we got the answer, though.
From: krw on 16 Mar 2010 19:32
On Mon, 15 Mar 2010 21:09:42 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Mon, 15 Mar 2010 22:28:02 -0500, "krw(a)att.bizzzzzzzzzzzz" ><krw(a)att.bizzzzzzzzzzzz> wrote: > >>On Mon, 15 Mar 2010 18:01:19 -0700, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Mon, 15 Mar 2010 19:56:28 -0500, "krw(a)att.bizzzzzzzzzzzz" >>><krw(a)att.bizzzzzzzzzzzz> wrote: >>> >>>>On Mon, 15 Mar 2010 17:42:57 -0700, John Larkin >>>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>>On Mon, 15 Mar 2010 19:20:07 -0500, "krw(a)att.bizzzzzzzzzzzz" >>>>><krw(a)att.bizzzzzzzzzzzz> wrote: >>>>> >>>>>>On Mon, 15 Mar 2010 12:20:11 -0700, John Larkin >>>>>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>> >>>>>>>On Sat, 13 Mar 2010 12:37:57 -0600, "krw(a)att.bizzzzzzzzzzzz" >>>>>>><krw(a)att.bizzzzzzzzzzzz> wrote: >>>>>>> >>>>>>>>On Sat, 13 Mar 2010 09:05:24 -0800, John Larkin >>>>>>>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>> >>>>>>>>>On Sat, 13 Mar 2010 08:42:27 -0800, Fred Abse >>>>>>>>><excretatauris(a)invalid.invalid> wrote: >>>>>>>>> >>>>>>>>>>On Fri, 12 Mar 2010 16:28:07 -0800, John Larkin wrote: >>>>>>>>>> >>>>>>>>>>> I never buy crystals for things like this. They have a high probability of >>>>>>>>>>> not working, and you wind up fiddling with capacitors and such. It's >>>>>>>>>>> easier to but a packaged, working crystal oscillator, already tuned to a >>>>>>>>>>> couple PPM, guaranteed to oscillate, for $1.50 or thereabouts. >>>>>>>>>> >>>>>>>>>>Me, too. Amplifiers oscillate, oscillators don't ;-) >>>>>>>>> >>>>>>>>>We've just started using silicon oscillators, in SOT-23 sized >>>>>>>>>packages, for things where 1% is good enough. We're using one part >>>>>>>>>that's pin strappable for 8-4-2-1 MHz. >>>>>>>> >>>>>>>>A seven pin SOT-23? >>>>>>> >>>>>>>It's an LTC6930CMS8-8.00, in the MSOP8 package. It's basically an 8 >>>>>>>MHz oscillator with three pins that can be strapped to divide by 1 >>>>>>>through 128. >>>>>> >>>>>>That's a DFN, not SOT-23. >>>>> >>>>>We're buying the MSOP-8, as noted, which isn't a DFN. >>>>> >>>>>I did say "SOT-23 sized", which an MSOP8 pretty much is. I was at home >>>>>when I first mentioned the part and didn't have the exact LTC part >>>>>number handy. >>>>> >>>>> >>>>> D/QFNs suck, though sadly there isn't often much >>>>>>choice. Since it's only a binary selection it's not all that much use, >>>>>>either. >>>>>> >>>>>>>Frequency is +-0.09% at room temp, plenty good for UARTS >>>>>>>and most timing apps. >>>>>> >>>>>>Wrong frequency for a baud-rate-generator. If you have to add logic for the >>>>>>baud-rate-generator, the binary divider chain doesn't help much. >>>>> >>>>>We use it to clock uPs and FPGAs. They most always have an internal, >>>>>programmable PLL to bump the clock up to 20 or 100 or 240 MHz, >>>>>whatever works. We're currently doing a VME module that has 64 >>>>>(sixty-four!) latching relays on board, with an FPGA doing all the >>>>>logic. An 8 MHz silicon clock is fine for that. >>>> >>>>Which makes the divider redundant. My point. >>>> >>>>>We rarely use standalone chips like uarts. Most uPs have several these >>>>>days, and we can always plop more into an FPGA. >>>> >>>>Right, which is why I questioned your statement above. .1% isn't all that >>>>great. I can't remember when I didn't already have something in the system >>>>better than that. The fewer oscillators the better. >>> >>> >>>I guess daylight savings time has made a lot of people bitchy today. >> >>Bitchy? I just don't understand your reasoning. I usually do. > >OK, the reasoning is: > >A silicon oscillator in an MSOP-8 has advantages over a crystal >oscillator in lots of applications... cost, size, power consumption. >We are now using an 8 MHz part because it works in a number of >applications. We'll probably use others in the future, too. But it's a bit on the expensive side with a useless divider tacked on. |