CD4060 Xtl Osc. Circuit
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From: Joerg on 14 Mar 2010 17:13 Vladimir Vassilevsky wrote: > > > Joerg wrote: > >> Vladimir Vassilevsky wrote: >> >>> >>> >>> Joerg wrote: >>> >>>> Yup, a poly resistor is nice. But you can't put crystals on the chip >>>> :-) >>> >>> >>> Isn't it what Maxim does in their clock ICs ? >>> >> >> I never use Maxim parts. If you mean the former Dallas series 32kHz >> things those are modules that contain a tuning fork crystal. They may >> look like a chip but in reality it's modules. And my clients would >> probably have my head examined if I placed a timing clock oscillator >> that costs several Dollars :-) > > There are not too many choices when you need an RTC. Besides, some > Dallas/Maxim parts offer the ability to adjust the clock frequency > digitally, so you can phase lock it to external signal. That's not too > bad for few dollars. > If you can get any, that is. Key "Maxim" into the Digikey serch engine, then click on oscillators. All but two are zero stock. Now why does that not surprise me? If I needed a fancy RTC with phase-locking or other nifty add-ons I'd grab a uC. Much cheaper, and available. MSP430 comes to mind. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 14 Mar 2010 17:29 On Sun, 14 Mar 2010 13:34:49 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Jim Thompson wrote: >> On Sun, 14 Mar 2010 13:25:18 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> Jim Thompson wrote: >>>> On Sun, 14 Mar 2010 09:51:52 -0700, Joerg <invalid(a)invalid.invalid> >>>> wrote: >>>> >>>>> Jim Thompson wrote: >>>>>> On Sun, 14 Mar 2010 09:05:27 -0700, Joerg <invalid(a)invalid.invalid> >>>>>> wrote: >>>>>> >>>>>>> Jim Thompson wrote: >>>>> [...] >>>>> >>>>>>>> My rule of thumb, which seems to work with every inverter-style >>>>>>>> crystal oscillator I've ever tried: Use capacitors as recommended by >>>>>>>> the crystal specification... if it says 15pF, that means 30pF on EACH >>>>>>>> end to ground. Then choose the resistor based on 45� phase shift with >>>>>>>> the first capacitor (at the crystal frequency). >>>>>>>> >>>>>>> I am usually happy with around 1M. All it needs to do is to crank it >>>>>>> over. Kaaaa-chum-pah ... POOF ... vrooooom. Unless I must start it >>>>>>> really fast for some reason but that can require special kicker circuitry. >>>>>> Huh? You and I are talking two different resistors. I'm talking the >>>>>> series drive resistor; you're talking the DC loop resistor. >>>>>> >>>>> Ok, different thing. Mostly you can get away without although that's not >>>>> always the nice way of doing things. >>>>> >>>>> >>>>>> Which brings to mind... does the CD4060 have the DC loop resistor >>>>>> built-in? It would appear not. >>>>>> >>>>> AFAIR not. >>>>> >>>>> >>>>>> And I should pay closer attention to details :-( The OP has 100K >>>>>> there... needs to be 10-20Meg. >>>>>> >>>>> I usually go for 1M. >>>> CD series stuff doesn't have a lot of gm. But 1Meg is good for >>>> something like 74HCU04. >>>> >>> For the CD4060 they recommend even higher values, page 3: >>> >>> http://www.fairchildsemi.com/ds/CD%2FCD4060BC.pdf >> >> Didn't I say 10-20Meg ?:-) >>> >>>> DO NOT USE buffered inverters for crystal oscillators! >>>> >>> Depends on the frequency but generally yes, don't use those if you can >>> avoid it. >> >> Makes for lousy stability and possible non-starts. >> > >I never had those problems. But I also prefer non-buffered inverters for >that. > >>> >>>>> 10M may not work outdoors when humidity is high and >>>>> some condensation occurs. >>>> Mine are usually on-chip :-) >>>> >>> Yup, a poly resistor is nice. But you can't put crystals on the chip :-) >> >> Wanna bet ?:-) >> > >With MEMS you could, lots of things are possible. But unlikely as good >as a real crystal. You _can_ mount a membrane type crystal onto a chip, though, right now, we're mounting the crystal separately... hybrid board style. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: Jim Thompson on 14 Mar 2010 17:31 On Sun, 14 Mar 2010 14:13:57 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Vladimir Vassilevsky wrote: >> >> >> Joerg wrote: >> >>> Vladimir Vassilevsky wrote: >>> >>>> >>>> >>>> Joerg wrote: >>>> >>>>> Yup, a poly resistor is nice. But you can't put crystals on the chip >>>>> :-) >>>> >>>> >>>> Isn't it what Maxim does in their clock ICs ? >>>> >>> >>> I never use Maxim parts. If you mean the former Dallas series 32kHz >>> things those are modules that contain a tuning fork crystal. They may >>> look like a chip but in reality it's modules. And my clients would >>> probably have my head examined if I placed a timing clock oscillator >>> that costs several Dollars :-) >> >> There are not too many choices when you need an RTC. Besides, some >> Dallas/Maxim parts offer the ability to adjust the clock frequency >> digitally, so you can phase lock it to external signal. That's not too >> bad for few dollars. >> > >If you can get any, that is. Key "Maxim" into the Digikey serch engine, >then click on oscillators. All but two are zero stock. Now why does that >not surprise me? > >If I needed a fancy RTC with phase-locking or other nifty add-ons I'd >grab a uC. Much cheaper, and available. MSP430 comes to mind. I find it so incongruous... Joerg is designing medical electronics with _cheap_ components :-( ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: Vladimir Vassilevsky on 14 Mar 2010 17:48 Joerg wrote: > Vladimir Vassilevsky wrote: > >> Joerg wrote: >> >>> Vladimir Vassilevsky wrote: >>> >>>> >>>> >>>> Joerg wrote: >>>> >>>>> Yup, a poly resistor is nice. But you can't put crystals on the >>>>> chip :-) >>>> >>>> >>>> >>>> Isn't it what Maxim does in their clock ICs ? >>>> >>> >>> I never use Maxim parts. If you mean the former Dallas series 32kHz >>> things those are modules that contain a tuning fork crystal. They may >>> look like a chip but in reality it's modules. And my clients would >>> probably have my head examined if I placed a timing clock oscillator >>> that costs several Dollars :-) >> >> >> There are not too many choices when you need an RTC. Besides, some >> Dallas/Maxim parts offer the ability to adjust the clock frequency >> digitally, so you can phase lock it to external signal. That's not too >> bad for few dollars. >> > > If you can get any, that is. Key "Maxim" into the Digikey serch engine, > then click on oscillators. All but two are zero stock. Now why does that > not surprise me? I am not great fan of Maxim as I had burned with them before like everybody else. However you must be fair to them: "Items in stock: Yes" "You have selected 60 items, spanning 3 pages" > If I needed a fancy RTC with phase-locking or other nifty add-ons I'd > grab a uC. Much cheaper, and available. MSP430 comes to mind. My customers will eat me alive if I design in yet another programmable device. Especially as a DAC, a temperature sensor and some sort of clock adjustment circuitry will be required as well. MCU will drain somewhat x10 standby battery power compared to what is required for a pure RTC. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
From: krw on 14 Mar 2010 18:17
On Sun, 14 Mar 2010 14:13:57 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Vladimir Vassilevsky wrote: >> >> >> Joerg wrote: >> >>> Vladimir Vassilevsky wrote: >>> >>>> >>>> >>>> Joerg wrote: >>>> >>>>> Yup, a poly resistor is nice. But you can't put crystals on the chip >>>>> :-) >>>> >>>> >>>> Isn't it what Maxim does in their clock ICs ? >>>> >>> >>> I never use Maxim parts. If you mean the former Dallas series 32kHz >>> things those are modules that contain a tuning fork crystal. They may >>> look like a chip but in reality it's modules. And my clients would >>> probably have my head examined if I placed a timing clock oscillator >>> that costs several Dollars :-) >> >> There are not too many choices when you need an RTC. Besides, some >> Dallas/Maxim parts offer the ability to adjust the clock frequency >> digitally, so you can phase lock it to external signal. That's not too >> bad for few dollars. >> > >If you can get any, that is. Key "Maxim" into the Digikey serch engine, >then click on oscillators. All but two are zero stock. Now why does that >not surprise me? ....but Maxim has promised us that they've changed! I laughed at one of the Disties when they told me that recently. No, I'm not interested in Maxim, either. We do use one of their RS422 transceivers. Why, I have no idea. There are cheaper parts around, and from far more reliable suppliers. >If I needed a fancy RTC with phase-locking or other nifty add-ons I'd >grab a uC. Much cheaper, and available. MSP430 comes to mind. |