On Tue, 26 Oct 2004 22:57:38 GMT, the renowned Joerg <notthisjoergsch@removethispacbell.net> wrote:> >Actually with an LMV431 you can make a really accurate yet cheap voltage >detector. This little part is under 20 cents. I really don't know why >brown-out/reset chips are so expensive. So I am just not using them in >my designs until that changes.They're not anymore. Now they are available for 25 cents or so, one reel quantity, with tightly guaranteed trigger voltage plus a reasonable time delay. I think that's a no-brainer if you need such a device. Adding the WDT pushes the price up, but most chips have a WDT in them these days. If it's really a safety-critical application I prefer to completely bypass the micro and drive critical outputs to a safe position directly with an external WDT of some kind. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
8051 reset circuit
Started by ●October 26, 2004
Reply by ●October 26, 20042004-10-26
Reply by ●October 26, 20042004-10-26
Hi Spehro,>>Actually with an LMV431 you can make a really accurate yet cheap voltage >>detector. This little part is under 20 cents. I really don't know why >>brown-out/reset chips are so expensive. So I am just not using them in >>my designs until that changes. >> >> > >They're not anymore. Now they are available for 25 cents or so, one >reel quantity, with tightly guaranteed trigger voltage plus a >reasonable time delay. I think that's a no-brainer if you need such a >device. >25 cents sounds like a good deal. Which one is that?>Adding the WDT pushes the price up, but most chips have a WDT in them >these days. If it's really a safety-critical application I prefer to >completely bypass the micro and drive critical outputs to a safe >position directly with an external WDT of some kind. > >That is the way to go. I also prefer that and this is where things such as the long CMOS binary counter chips come in handy. Sometimes just a Schmitt and some discretes will do. Regards, Joerg http://www.analogconsultants.com
Reply by ●October 26, 20042004-10-26
Spehro Pefhany wrote:> On Wed, 27 Oct 2004 00:42:14 GMT, the renowned Joerg > <notthisjoergsch@removethispacbell.net> wrote: > > >>Hi Spehro, >> >> >>>>Actually with an LMV431 you can make a really accurate yet cheap voltage >>>>detector. This little part is under 20 cents. I really don't know why >>>>brown-out/reset chips are so expensive. So I am just not using them in >>>>my designs until that changes. >>>> >>>> >>> >>>They're not anymore. Now they are available for 25 cents or so, one >>>reel quantity, with tightly guaranteed trigger voltage plus a >>>reasonable time delay. I think that's a no-brainer if you need such a >>>device. >>> >> >>25 cents sounds like a good deal. Which one is that? > > > National's versions of Microchip's parts.And also STm have entered this market, http://www.st.com/stonline/press/news/year2004/p1510m.htm Now the big analog players are there, prices should be more sensible, and most new uC releases have these Power Monitoring features inbuilt. -jg
Reply by ●October 26, 20042004-10-26
On Wed, 27 Oct 2004 00:42:14 GMT, the renowned Joerg <notthisjoergsch@removethispacbell.net> wrote:>Hi Spehro, > >>>Actually with an LMV431 you can make a really accurate yet cheap voltage >>>detector. This little part is under 20 cents. I really don't know why >>>brown-out/reset chips are so expensive. So I am just not using them in >>>my designs until that changes. >>> >>> >> >>They're not anymore. Now they are available for 25 cents or so, one >>reel quantity, with tightly guaranteed trigger voltage plus a >>reasonable time delay. I think that's a no-brainer if you need such a >>device. >> >25 cents sounds like a good deal. Which one is that?National's versions of Microchip's parts. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Reply by ●October 27, 20042004-10-27
Hi Jim, Hi Spehro,>> National's versions of Microchip's parts. > > > And also STm have entered this market, > http://www.st.com/stonline/press/news/year2004/p1510m.htm > > Now the big analog players are there, prices should be more sensible, > and most new uC releases have these Power Monitoring features inbuilt.Thanks to both of you. I didn't know they entered the 25c range by now. I couldn't find the LM3700 this low but I am sure it is possible. The STM706 is fixed 5V so it's not that useful. Now I just wish ST had a better web site where one can quickly find a part against a budget price. In a few years this issue should be behind us when all uCs have on board BOR features that work well. Regards, Joerg http://www.analogconsultants.com
Reply by ●October 27, 20042004-10-27
On Wed, 27 Oct 2004 18:31:28 GMT, the renowned Joerg <notthisjoergsch@removethispacbell.net> wrote:>Hi Jim, Hi Spehro, > >>> National's versions of Microchip's parts. >> >> >> And also STm have entered this market, >> http://www.st.com/stonline/press/news/year2004/p1510m.htm >> >> Now the big analog players are there, prices should be more sensible, >> and most new uC releases have these Power Monitoring features inbuilt. > >Thanks to both of you. I didn't know they entered the 25c range by now. >I couldn't find the LM3700 this low but I am sure it is possible.The LM809/MCP809 (note that the pinout is different) is/are cheaper but don't have the /NMI output.>STM706 is fixed 5V so it's not that useful. Now I just wish ST had a >better web site where one can quickly find a part against a budget price. > >In a few years this issue should be behind us when all uCs have on board >BOR features that work well.I'm almost afraid to ask Jim how it's going... Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Reply by ●October 27, 20042004-10-27
Hi Spehro,>The LM809/MCP809 (note that the pinout is different) is/are cheaper >but don't have the /NMI output. > >That is a nice chip. Only fixed voltages but the versions come in sufficient granularity. Doesn't beat the discrete solution if there is a 1.2V reference for other purposes, but it does if there isn't.>>STM706 is fixed 5V so it's not that useful. Now I just wish ST had a >>better web site where one can quickly find a part against a budget price. >> >>In a few years this issue should be behind us when all uCs have on board >>BOR features that work well. >> >> > >I'm almost afraid to ask Jim how it's going... > >Jim Thompson? Did he design some of these? Regards, Joerg http://www.analogconsultants.com
Reply by ●October 27, 20042004-10-27
Joerg wrote:> Thanks to both of you. I didn't know they entered the 25c range by now. > I couldn't find the LM3700 this low but I am sure it is possible. The > STM706 is fixed 5V so it's not that useful. Now I just wish ST had a > better web site where one can quickly find a part against a budget price.If ST's web site drivs you to distraction, a better web portal is OnSemi's - eg http://www.onsemi.com/site/products/summary/0,4450,NCP300,00.html?tax=694 Shows Reel prices of 14.2c, and appx 500nA operate - apps also show how to use these as low-ish power oscillators, like a new '555.... -jg
Reply by ●October 27, 20042004-10-27
On Thu, 28 Oct 2004 09:44:29 +1300, the renowned Jim Granville <no.spam@designtools.co.nz> wrote:>Joerg wrote: >> Thanks to both of you. I didn't know they entered the 25c range by now. >> I couldn't find the LM3700 this low but I am sure it is possible. The >> STM706 is fixed 5V so it's not that useful. Now I just wish ST had a >> better web site where one can quickly find a part against a budget price. > >If ST's web site drivs you to distraction, a better web portal is >OnSemi's - eg > >http://www.onsemi.com/site/products/summary/0,4450,NCP300,00.html?tax=694 > >Shows Reel prices of 14.2c, and appx 500nA operate - apps also show how >to use these as low-ish power oscillators, like a new '555.... >-jgThese lack the timer feature, however. They are just voltage detectors. The 0.5uA consumption is very nice. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Reply by ●October 27, 20042004-10-27
edaudio2000@yahoo.co.uk (ted) wrote: ...>know the 8051 has an internal WDT circuit, but this is in addition as >the reset signal is needed elsewhere). >.. Hmm, 1) your 8051 has an internal WDT 2) you reserved an output pin (to hush the WD) Why not shake this pin by the micro right after a reset? Essentially making it function as the circuit you asked for. Joop
