I am not sure on the current datasheet for PIC 16C series but if your concern is about slow rise time for Vdd and brownout here are some ideas: BOR is perfect for sudden sags in the power line. As for slow rise time in the power line I would use an external circuitry to POWER the PIC when the right voltage is available. Regards, John ________________________________ From: Dwayne Reid To: pic microcontroller discussion list =20 Sent: Friday, December 14, 2012 5:21 AM Subject: [PIC] How reliable is PIC10F322? =20 Good day to all. I need advice and thought that I would tap the collective wisdom that=20 is the PIClist. I've been designing with PIC micro-controllers since the 16C54 and=20 16C71 days and am intimately familiar with the failure modes that can=20 occur if Vdd rise time is too slow or if the PIC is powered down,=20 then back up without allowing Vdd to collapse all the way down to=20 zero volts.=A0 Specifically, a PIC can hang with outputs asserted in an=20 unsafe manner for a particular project - and the PIC will NOT respond=20 to an external MCLR reset command. Because of these legacy problems, every design that has safety=20 requirements that I've done with PIC controllers has an external=20 watchdog timer and power supervisor controller.=A0 We use the Xicor=20 X5043 most of the time but I have used other devices as well. The extra cost of the Xicor chip is easily absorbed by the higher=20 margins that these projects command. However, PIC micro-controllers have evolved significantly over the=20 past ten years or so and I no longer have a feel about how sensitive=20 the newer part numbers are to those two problem scenarios. I *do* have first-hand experience with those kinds of failures with=20 the old 16c73 / 74 parts.=A0 We have been building gas catalytic oven=20 controllers since the late '80s using the PIC 16C series of chips and=20 have never, ever been able to cause an unsafe condition after we=20 added the Xicor watchdog chip along with some other watchdog /=20 lockout circuitry. Because we did have those bad experiences way back then, every design=20 that we've done since then that involves potentially hazardous or=20 safety issues always has some form of external watchdog and=20 supervisor system on the board. Now I'm doing a redesign of a tiny heater that is intended for use in=20 hazardous locations (Class 1 Div 2).=A0 This is a tiny block of epoxy=20 that is mounted to a simple aluminum heat-sink and turns ON if the=20 ambient temperature drops below 0C.=A0 It has an on-board temperature=20 sensor that also regulates if the temperature should exceed 55C and a=20 hardware temperature cutout that actuates if the internal temperature=20 ever exceeds 110C. The current design is completely analog and works very=20 well.=A0 However, there are some nice things that I could do with this=20 unit if it had some intelligence.=A0 Size is an issue, so I'm looking=20 at using the PIC10F322 in the SOT23-6 package. However, the PIC replaces most of the analog control circuitry and,=20 in particular, the on-board temp sensor that is intended to keep the=20 internal temperature of the heater to less than 55C.=A0 I don't have=20 either the room or the budget for an external watchdog and am now=20 wondering if the need for that watchdog has gone away. I'm not worried about a catastrophic electronic failure - the heater=20 will still have the high-temperature cutout that operates if the=20 internal temperature gets too high.=A0 But what I want to ensure is=20 that the PIC isn't going to hang in either a 'heater OFF' or a=20 'heater ON' state and not recover because it is hung. I'm asking if anyone has ever had a situation where a modern 10F /=20 12F / 16F PIC has ever hung because of either slow Vdd rise time or=20 having Vdd collapse to the 0.6V - 0.8V region, then return to=20 normal.=A0 Or, for that matter, any occasion of a PIC hanging in an=20 unrecoverable state due to explained or unexplained circumstances. Its going to cost us somewhere between $5K - $10K to get=20 certification on this new design and I'd *really* not spend that kind=20 of money, then find that I have a show-stopper problem relating to=20 the PIC controller.=A0 Unfortunately, this is one of those chicken and=20 egg problems - I can't ship these heaters into their target=20 environment without certification and I can't be certain that they=20 won't fail until they are in their target environment (really crappy power)= .. Many thanks! dwayne --=20 Dwayne Reid=A0 Trinity Electronics Systems Ltd=A0 =A0 Edmonton, AB, CANADA (780) 489-3199 voice=A0 =A0 =A0 =A0 =A0 (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .