Post by thread:[PIC]: Reset circuits

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 For using a prepackaged 4-pin reset generator, what would be a good part for PICs? - --Brendan -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPVsiTgVk8xtQuK+BEQL00QCgh8gFySshAutUV3njVlo1PL1K+c0AoMve BHBNbhPziOSeUt+ooZxMRUyH =By8F -----END PGP SIGNATURE----- -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

I've been using these with excellent results. They draw less than 40uA. The internal PIC BOR consumes over 600uA! http://canada.digikey.com/scripts/ca/dksus.dll?Detail?Ref=12269&Row=204536 Allan Brendan Moran wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > For using a prepackaged 4-pin reset generator, what would be a good part > for PICs? > > - --Brendan -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Brendan Moran wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > For using a prepackaged 4-pin reset generator, what would be a good part > for PICs? I've been using the MC34064 T0-92 part on my portable programmer. -- Best regards Tony mICros http://www.bubblesoftonline.com .....salesKILLspam@spam@bubblesoftonline.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

At 08:38 PM 8/14/02 -0700, you wrote: >For using a prepackaged 4-pin reset generator, what would be a good part >for PICs? Brendan, what do you mean by "4-pin"? Do you require an external reset switch or WDT? For an 3-pin reset generator (level detector + timer), Microchip's MCP809 (SMT, active low output) works nicely, uses little current and is small. http://www.microchip.com/download/lit/pline/analog/power/super/11194c.pdf Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speffKILLspaminterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 At 02:24 AM 15/08/2002 -0400, you wrote: {Quote hidden}>At 08:38 PM 8/14/02 -0700, you wrote: > > >>For using a prepackaged 4-pin reset generator, what would be a good part >>for PICs? > >Brendan, what do you mean by "4-pin"? Do you require an external reset >switch or WDT? > >For an 3-pin reset generator (level detector + timer), Microchip's >MCP809 (SMT, active low output) works nicely, uses little current and >is small. > >http://www.microchip.com/download/lit/pline/analog/power/super/11194c.pdf An external reset switch was the intention. I think I can get away without it, but it would be nicer to have it. - --Brendan -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPVtKUAVk8xtQuK+BEQKFOgCg9BVQdqc12JAjRyVdmazmFSoaUzsAoIP0 Dw7ErvAzHdA5atHk8kEzr2LF =Wepi -----END PGP SIGNATURE----- -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

>An external reset switch was the intention. I think I can get away without >it, but it would be nicer to have it. Maxim has the MAX638x series in SC70-4 package, you can also check out AD. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam.....interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

{Quote hidden}> -----Original Message----- > From: Spehro Pefhany [SMTP:EraseMEspeffspam_OUTTakeThisOuTINTERLOG.COM] > Sent: Thursday, August 15, 2002 7:24 AM > To: PICLISTspam_OUTMITVMA.MIT.EDU > Subject: Re: [PIC]: Reset circuits > > At 08:38 PM 8/14/02 -0700, you wrote: > > > >For using a prepackaged 4-pin reset generator, what would be a good part > >for PICs? > > Brendan, what do you mean by "4-pin"? Do you require an external reset > switch or WDT? > > For an 3-pin reset generator (level detector + timer), Microchip's > MCP809 (SMT, active low output) works nicely, uses little current and > is small. > > http://www.microchip.com/download/lit/pline/analog/power/super/11194c.pdf > > Best regards, > > Spehro Pefhany --"it's the network..." "The Journey is the > reward" > @spam@speffKILLspaminterlog.com Info for manufacturers: > http://www.trexon.com > Embedded software/hardware/analog Info for designers: > http://www.speff.com > 9/11 United we Stand > I don't suppose you know of any 3volt three pin reset generators that have an open collector output that can withstand the 13volts Vpp on a PIC? Seems like no-one makes such a beast. Regards Mike -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > I don't suppose you know of any 3volt three pin reset generators > that have an open collector output that can withstand the 13volts > Vpp on a PIC? Seems like no-one makes such a beast. I'd say don't worry about the open collector, and put a diode in series with the ouput. - --Brendan -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPVvY7wVk8xtQuK+BEQK1nQCcCiFRYm58LJzNqHORlN2h3pNs7dgAnRLt u4IToLKDeo5JNx09y4GAkQ+q =A6qg -----END PGP SIGNATURE----- -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Brendan Moran <KILLspambmoranKILLspamMILLENNIUM.CA> wrote: > > I don't suppose you know of any 3volt three pin reset generators > > that have an open collector output that can withstand the 13volts > > Vpp on a PIC? Seems like no-one makes such a beast. > > I'd say don't worry about the open collector, and put a diode in > series with the ouput. The reset generator still needs to withstand 13V if you don't want any current to flow in the diode when the anode is at Vpp. It's unlikely that a totem-pole device would meet this requirement with a 3V supply. -- Dave Tweed -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > Brendan Moran <RemoveMEbmoranTakeThisOuTMILLENNIUM.CA> wrote: > > > I don't suppose you know of any 3volt three pin reset > > > generators that have an open collector output that can > > > withstand the 13volts Vpp on a PIC? Seems like no-one makes > > > such a beast. > > > > I'd say don't worry about the open collector, and put a diode in > > series with the ouput. > > The reset generator still needs to withstand 13V if you don't want > any current to flow in the diode when the anode is at Vpp. It's > unlikely that a totem-pole device would meet this requirement with > a 3V supply. Erm... I think you missed the point. | Vpp Reset| | | Gen |---|>|---+---|PIC | | | That should be clearer. No need to withstand 13V. - --Brendan -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPVvpMAVk8xtQuK+BEQKYVgCglrPp6sdMpRz9+dKGlQ1AgGR+3UgAnilb OxlbN/bFr0in3/seLWeafQBX =tUMi -----END PGP SIGNATURE----- -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

On Thu, 15 Aug 2002, Dave Tweed wrote: >Brendan Moran <spamBeGonebmoranspamBeGoneMILLENNIUM.CA> wrote: >> > I don't suppose you know of any 3volt three pin reset generators >> > that have an open collector output that can withstand the 13volts >> > Vpp on a PIC? Seems like no-one makes such a beast. >> >> I'd say don't worry about the open collector, and put a diode in >> series with the ouput. > >The reset generator still needs to withstand 13V if you don't want any >current to flow in the diode when the anode is at Vpp. It's unlikely that a >totem-pole device would meet this requirement with a 3V supply. One could use an inexpensive NJFET with the gate wired to +Vcc, D and S between the reset chip and the PIC MCLR pin. Raising S (MCLR) a few volts above Vcc will close the JFET so the 13V won't reach the regulator. The reg would see at most a few volts more than Vcc (Vcc + Vg0). A resistor in the gate is mandatory for when the MCLR is pulled low (probably 1meg or larger but not really critical). Any JFET would work here. It should accept -Vgs >= -10V imho. Buying these in bulk should not impact on the project cost imho. An inexpensive MOSFET could also work here and eliminate the resistor but beware the reverse bulk diode. I've also thought of using a single CMOS schmitt (TCxxx) gate as reset driver/brownout detector. I've also though of using its output to power the PIC directly for when the MCLR pin is taken. Not tried. Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

On Thu, 15 Aug 2002 09:38:09 -0700, you wrote: >-----BEGIN PGP SIGNED MESSAGE----- >Hash: SHA1 > >> I don't suppose you know of any 3volt three pin reset generators >> that have an open collector output that can withstand the 13volts >> Vpp on a PIC? Seems like no-one makes such a beast. I normally just put 2K2 or so in series with the reset chip to protect it from Vpp. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Brendan Moran <TakeThisOuTbmoranEraseMEspam_OUTMILLENNIUM.CA> wrote: {Quote hidden}> I wrote: > > Brendan Moran <RemoveMEbmoranTakeThisOuTMILLENNIUM.CA> wrote: > > > > I don't suppose you know of any 3volt three pin reset > > > > generators that have an open collector output that can > > > > withstand the 13volts Vpp on a PIC? Seems like no-one makes > > > > such a beast. > > > > > > I'd say don't worry about the open collector, and put a diode in > > > series with the ouput. > > > > The reset generator still needs to withstand 13V if you don't want > > any current to flow in the diode when the anode is at Vpp. It's > > unlikely that a totem-pole device would meet this requirement with > > a 3V supply. > > Erm... I think you missed the point. > > | Vpp > Reset| | | > Gen |---|>|---+---|PIC > | | > | > > That should be clearer. No need to withstand 13V. Ah. I naturally assumed that since the OP wanted an open-collector driver, he wanted to sink current from the reset pin, not source current to it. -- Dave Tweed -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > Ah. I naturally assumed that since the OP wanted an open-collector > driver, he wanted to sink current from the reset pin, not source > current to it. Fair enough. In that case, a single P-channel FET attached to the reset generator should do the trick nicely. -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPVw8mgVk8xtQuK+BEQKPlwCfWGDxg08SvD+YX/gen65zv9K6mHgAoMG1 5kRhov1REnYSPy7/JACHcY55 =ILi2 -----END PGP SIGNATURE----- -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> -----Original Message----- > From: Brendan Moran [SMTP:bmoranEraseME.....MILLENNIUM.CA] > Sent: Thursday, August 15, 2002 5:38 PM > To: EraseMEPICLISTMITVMA.MIT.EDU > Subject: Re: [PIC]: Reset circuits > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > > I don't suppose you know of any 3volt three pin reset generators > > that have an open collector output that can withstand the 13volts > > Vpp on a PIC? Seems like no-one makes such a beast. > > I'd say don't worry about the open collector, and put a diode in > series with the ouput. > And a pull down resistor. This is what we have done in the past but our board space is often so tight that even a couple of extra tiny surface mount components can make things awkward. Also the MCLR voltage thresholds preclude the use of a cheap silicon diode at 3.3volts or below, you have to use a (more expensive) Schottky diode. Regards Mike -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> -----Original Message----- > From: Mike Harrison [SMTP:RemoveMEmikeEraseMEEraseMEwhitewing.co.uk] > Sent: Thursday, August 15, 2002 9:59 PM > To: RemoveMEPICLISTspam_OUTKILLspamMITVMA.MIT.EDU > Subject: Re: [PIC]: Reset circuits > > On Thu, 15 Aug 2002 09:38:09 -0700, you wrote: > > >-----BEGIN PGP SIGNED MESSAGE----- > >Hash: SHA1 > > > >> I don't suppose you know of any 3volt three pin reset generators > >> that have an open collector output that can withstand the 13volts > >> Vpp on a PIC? Seems like no-one makes such a beast. > I normally just put 2K2 or so in series with the reset chip to protect > it from Vpp. > > We discussed this in the office at the time, and while the general thoughts were that it would work, I get an uncomfortable feeling driving 13 volts (albeit current limited) back into the output. Probably just me being silly, Mike -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

{Quote hidden}> -----Original Message----- > From: Brendan Moran [SMTP:RemoveMEbmoranTakeThisOuTspamMILLENNIUM.CA] > Sent: Thursday, August 15, 2002 5:38 PM > To: EraseMEPICLISTspamspamBeGoneMITVMA.MIT.EDU > Subject: Re: [PIC]: Reset circuits > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > > I don't suppose you know of any 3volt three pin reset generators > > that have an open collector output that can withstand the 13volts > > Vpp on a PIC? Seems like no-one makes such a beast. > > I'd say don't worry about the open collector, and put a diode in > series with the ouput. > > - --Brendan > > -----BEGIN PGP SIGNATURE----- > Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> > > iQA/AwUBPVvY7wVk8xtQuK+BEQK1nQCcCiFRYm58LJzNqHORlN2h3pNs7dgAnRLt > u4IToLKDeo5JNx09y4GAkQ+q > =A6qg > -----END PGP SIGNATURE----- > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

>Erm... I think you missed the point. > > | Vpp >Reset| | | >Gen |---|>|---+---|PIC > | | > | > >That should be clearer. No need to withstand 13V. How is this going to reset the PIC ???? -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

On Thu, 15 Aug 2002, Brendan Moran wrote: >Erm... I think you missed the point. > > | Vpp >Reset| | | >Gen |---|>|---+---|PIC > | | > | > >That should be clearer. No need to withstand 13V. That won't work easily. You need a pulldown on MCLR and pullup on the output of the o.c. reset generator. and that makes the diode critical because Vih on MCLR is Vdd-0.4V. Peter -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.