Chuck: Yes, you are right! Low TC internal IC oscillator technology is available - since the early 80's. Since you have close contact within Microchip you should suggest they hire a sharp analog engineer (or get a cross-license) from a top analog IC house - like Analog Devices, Dallas Semiconductor, or Maxim. They have oscillators cells, like their bandgap references and charge transfer A/Ds, that give ppm performance over temperature. They know about die attach, packaging parameter shifts and how to trim with laser and e-squared trimming. Microchip may be too digitally inbred to know the proven production solutions are out there. - Wayne Foletta BMI - Saratoga, CA > ---------- > From: Mauro, Chuck[SMTP:Chuck.Mauro@KLA-TENCOR.COM] > Reply To: pic microcontroller discussion list > Sent: Tuesday, January 27, 1998 12:14 PM > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: Internal Oscillators > > Charles, > > Thanks for bringing this up Charles - I think it's a great topic. > > From my experience with working directly with Microchip, I'd say that > there is an excellent chance they will do this - eventually (measured, > unfortunately, in several years of time - but the success of the > 12CXXX > family already should have convinced them to offer such a version in > all > the PIC families). > > I designed a very high volume product around the 12C509 (millions of > units/yr., although, it hasn't shipped - yet -), and did EXTENSIVE lab > testing on the internal oscillator - it's a pretty rock-solid design. > I've even met with Microchip directly, and worked with the > manufacturing/test engineers to better characterize and fine tune our > oscillator requirements in our particular application. (BTW, don't > expect to ever be able to talk to these guys yourself unless you're an > incredibly large volume customer - and then only maybe...) I'm not > saying that they changed anything for us, but we had a much more > guarantee-able design after they "ran the numbers" for us (read: truly > characterized the oscillator through extensive wafer testing). > > I firmly support you in your appeal to Microchip to increase the > number > of devices that contain an internal RC oscillator. I think everyone > benefits. But - and everyone else out there should be aware of some > important issues when applying this particular feature of any PIC - > ESPECIALLY when it is first introduced to us (and even more > importantly > when devices are made available in "Engineering" type samples): > > 1) Any new chip they apply the internal oscillator technology to > needs > to be FULLY CHARACTERIZED by Microchip before I'd EVER use it. They > typically SIMULATE the design and release preliminary data sheets with > projected device characteristics... Things (osc. characteristics) > will > likely change after they build a few wafers and test for process > corners... For me, after they had performed serious wafer test, I > found > that the projected osc. characteristics became WORSE... But, > fortunately in my case, I was able to find a way around it. > > 2) Any of your designs need to seriously take into consideration: > > a) Temp range, > b) Typical Vdd operating point and range (especially supply > regulation). > c) +/- 3 sigma process variation (at least) of the chip. > > These parametrics will affect the oscillator frequency more than > anything else... > > 3) If you need to guarantee better than a 2.5%-3% tolerance on Fosc > over > ALL operating conditions, you're better off using a resonator or xtal, > because you're sure to see the corners of their process tolerances in > any kind of volume... > > > To more directly address your original points: > > 1) I saved about 25-30 cents [includes all costs] per widget by using > the internal RC osc. This includes all direct, indirect and typical > hidden costs (p.c. real estate needed, pick and place costs, component > stocking costs, improved reliability, etc.). Keep in mind that my > volume is (was) between 20-30 MM units/yr for a several year period. > Your savings will likely be even higher (perhaps as much as $1?). > > 2) My design was far more elegant because of the internal osc. > design... > > 3) And reliable... > > 4) I also needed all the I/O I could get in an 8 pin device. This is > the only way to maximize I/O capabilities of the 12CXXX family... > > 5) I also believed it may have helped in reducing my total RFI > emmision > signature for various reasons that I can't go into here... > > So, from a very real world example (sorry - can't disclose what the > widget is or does - due to one of those annoying proprietary/trade > secret clauses in an employee exit agreement), I can assure you the > internal RC osc. is a great way to go if you do not have strict > real-time timing issues. I suspect that a vast majority of > personal/hobby/non mission-critical PIC projects could probably get > away > with using this type of cost-improving oscillator. > > I just wish the folks at Microchip would consider using a better (more > temperature and voltage stable) internal osc. technology. I know for > a > fact that if they wanted to, they could tighten the tolerances to > under > 1%, and not necessarily at higher chip cost (I've researched the > various > fundamental methods, and it's quite doable). > > SO: HOW ABOUT IT MICROCHIP??? > > > Chuck Mauro > > > -----Original Message----- > > From: Charles Laforge [SMTP:cjoachim@HOTMAIL.COM] > > Sent: Tuesday, January 27, 1998 10:24 AM > > To: PICLIST@MITVMA.MIT.EDU > > Subject: Internal Oscillators > > > > Hi All > > > > I was wondering if anyone here (Microchip People?) know if Microchip > > plans to offer internal oscillators on devices other than the > > PIC12CXXX. > > Seems like logical thing to do. Probably bring the cost of many > > applications down, probably more reliable, simpler circuits..... I'm > > just looking for your opinions here... so give em to me... but not > too > > hard. > > > > Later > > > > Charles > > > > ______________________________________________________ > > Get Your Private, Free Email at http://www.hotmail.com >