Post by thread:16C57 resonator problems

We have been experiencing some high failure rates with resonators and the 16C57. We are using 3 different manufacturer's and have experienced failure rates in the order of 2.5 to 10 %. Some of these are intermittant. Someone had mentioned to me that this issue came up in the past on this list. Any ideas? Roger

At 10:23 AM 6/30/98 -0400, you wrote: >We have been experiencing some high failure rates with resonators and >the >16C57. We are using 3 different manufacturer's and have experienced >failure rates in the order of 2.5 to 10 %. Some of these are >intermittant. Someone had mentioned to me that this issue came up in >the past >on this list. What speed resonators are you using? 20 MHz PIC is not reliable using a resonator. Also, are you using a resonator with internal capacitors? Ê Todd Peterson Ê E-Lab Digital Engineering, Inc. Ê (816) 257-9954 Ê Embedded Control & Integrated Circuit Solutions... Ê <http://www.elabinc.com/>http://www.elabinc.com -> NEW: EDE702 OEM Serial to LCD Interface IC <- (Production Quantity version of our popular EDE700 IC)

I am using the ZTT-20.00MX part from ECS Inc. with complete success. I have assembled about 50 devices using the 16C57 with this resonator and have yet to have a single failure. Digi-Key part# X909-ND Calvin {Quote hidden}>At 10:23 AM 6/30/98 -0400, you wrote: >>We have been experiencing some high failure rates with resonators and >>the >>16C57. We are using 3 different manufacturer's and have experienced >>failure rates in the order of 2.5 to 10 %. Some of these are >>intermittant. Someone had mentioned to me that this issue came up in >>the past >>on this list. > >What speed resonators are you using? 20 MHz PIC is not reliable using a >resonator. Also, are you using a resonator with internal capacitors? > > Todd Peterson > E-Lab Digital Engineering, Inc. > (816) 257-9954 > Embedded Control & Integrated Circuit Solutions... > <http://www.elabinc.com/>http://www.elabinc.com > >-> NEW: EDE702 OEM Serial to LCD Interface IC <- >(Production Quantity version of our popular EDE700 IC)

Calvin wrote: >I am using the ZTT-20.00MX part from ECS Inc. with complete success. I have >assembled about 50 devices using the 16C57 with this resonator and have yet >to have a single failure. > >Digi-Key part# X909-ND I'm surprised at this - I had a lot of problems with this part on a 16C73A (and ended up going to a ZTA with external caps) because the built in capacitors of the ZTT (30 pF) were too much for the PICMicro at this speed. I Just looked at the 16C5x datasheet and it it indcates that for ceramic resonators (up to 16 MHz), 10 pF caps are required (and this was born out by my experience with the 16C73A). To the original requester, why don't you float the centre pin of the resonator (ie disconnect it from ground) and wire in some caps and see what happens? myke PICLite has been upgraded! Check out version 2.00a at: http://www.myke.com/piclite PICLite now includes a Macro Processor that allows structured programming language constructs ("if/else/end", "while/end" and "for/end"). Look in on the life of the Rabitte family in Dublin; Roddy Doyle's "Barrytown Trilogy" in the Book Room this week, http://www.myke.com/Book_Room

Roger said: >We have been experiencing some high failure rates with resonators and >the >16C57. We are using 3 different manufacturer's and have experienced >failure rates in the order of 2.5 to 10 %. Some of these are >intermittant. Someone had mentioned to me that this issue came up in >the past >on this list. > >Any ideas? > Roger: We have recently had some resonator problems which appear to be due to moisture penetration of the case during post-soldering cleanup. It can seem to be intermittent. Also, make sure that your PC boards are CLEAN. Flux residue trapped under a crystal or resonator can also cause problems which, again, can appear to be intermittent depending on the humidity. On a board that works OK, breathe heavily on the area that has the resonator. If it quits, that's a clue. On a board that doesn't work due to a suspected resonator problem, use a heat gun to heat up the resonator. If it starts working, maybe you've got moisture problems. If it's interior, it may stop working again after a day or so. Hope this is helpful, Reg Neale

I tried several resonators with internal capacitors on a 16c74a. The only ones I could get to work reliably at 16 MHz were those from uRata Erie. We've probably got over 1,000 units out now with those and no problems. Others (Integrity and the ones whose name I can't remember, but Mouser or Digikey sells them) wouldn't oscillate in up to 50% of the units. I talked with the manufacturers. Each said that if it worked in their sampe circuit with a cmos inverter the resonator was fine. The problem was with our circuit (which consists of just the 16c74a!). uRata actually tests the resonators with a variety of chips. When I talked with them they were still evaluating them with PICs, but I went ahead and tried them anyway. Never a problem. Harold On Tue, 30 Jun 1998 10:23:32 -0400 Roger Morella <spam_OUTrjmTakeThisOuTBUFFNET.NET> writes: {Quote hidden}>We have been experiencing some high failure rates with resonators and >the >16C57. We are using 3 different manufacturer's and have experienced >failure rates in the order of 2.5 to 10 %. Some of these are >intermittant. Someone had mentioned to me that this issue came up in >the past >on this list. > >Any ideas? > >Roger > _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]