No current sense resistor required for MOSFET switch protection
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From: Jim Thompson on 8 Apr 2010 13:04 On Thu, 8 Apr 2010 09:55:13 -0700 (PDT), "oparr(a)hotmail.com" <oparr(a)hotmail.com> wrote: >>He's cagey enough about >>it that either (a) he thinks it's a genuine crown jewel or (b) he >>doesn't want to get his tailfeathers singed by bragging about a kluge. > >I haven't the faintest idea as to what my "circuit" is being likened >to. This thread is a followup (sort of) to an earlier thread "High >side current monitor with latch" in which Joerg gives me some advice >(albeit old school) regarding MOSFET protection. > >After throughly investigating the characteristics of MOSFETs, it >dawned on me that they are probably the easiest of all transistors to >protect. It also dawned on me that others, including Joerg, were >probably aware ot this already but have decided to keep this to >themselves. Hence this thread. > >It is my opinion, based on both characteristics and test results, that >a MOSFET can be operated very close to its absolute maximum >thresholds, without damage, when used in conjunction with a single >small signal BJT. Not being one to ever give anything on a silver >platter (too expensive), that's about all you need to know from me. > >Furthermore, I'm convinced that "regulars" like Joerg etc. are the >ones who should be imparting this knowledge. I'm just an occasional >visitor and already a "John Fields" seems to be on the verge of "death >threats" over this. > >On Apr 8, 12:10�pm, Phil Hobbs ><pcdhSpamMeSensel...(a)electrooptical.net> wrote: >> I think you grossly overestimate your own competence. And I will maintain your competence rating at "Dubious" until you prove otherwise. It was probably a severe goof-up on my part to allow you thru my hotmail rejection filter, I perceived you initially as asking for help on a real technical question. Further observation proves you to be a blow-hard. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: oparr on 8 Apr 2010 13:15 >More likely an amateur with a silly circuit. Put your sour grapes to good use....A new exotic wine perhaps. On Apr 8, 11:48 am, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >
From: oparr on 8 Apr 2010 13:32 >It was probably a severe goof-up on my part to allow you thru my >hotmail rejection filter, I perceived you initially as asking for help >on a real technical question. How many "red herrings" do you have behind that cloak of yours? Unknown to Larkin and others, you're trying to keep a lid on this too. On Apr 8, 1:04 pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)On-My- Web-Site.com> wrote: >
From: Phil Hobbs on 8 Apr 2010 13:33 oparr(a)hotmail.com wrote: >> He's cagey enough about >> it that either (a) he thinks it's a genuine crown jewel or (b) he >> doesn't want to get his tailfeathers singed by bragging about a kluge. > > I haven't the faintest idea as to what my "circuit" is being likened > to. This thread is a followup (sort of) to an earlier thread "High > side current monitor with latch" in which Joerg gives me some advice > (albeit old school) regarding MOSFET protection. > > After throughly investigating the characteristics of MOSFETs, it > dawned on me that they are probably the easiest of all transistors to > protect. It also dawned on me that others, including Joerg, were > probably aware ot this already but have decided to keep this to > themselves. Hence this thread. > > It is my opinion, based on both characteristics and test results, that > a MOSFET can be operated very close to its absolute maximum > thresholds, without damage, when used in conjunction with a single > small signal BJT. Not being one to ever give anything on a silver > platter (too expensive), that's about all you need to know from me. > > Furthermore, I'm convinced that "regulars" like Joerg etc. are the > ones who should be imparting this knowledge. I'm just an occasional > visitor and already a "John Fields" seems to be on the verge of "death > threats" over this. I very much doubt that you have anything to worry about. Our pseudonymous mascot has survived despite his years of abusive misbehaviour, and nobody has put any arsenic in Phil Allison's tea, either, despite his being a one-man flame war. We're just a bit suspicious, though, due to the number of poseurs we get here, who go all mysterious on us and then start throwing--um--mud, to show how much smarter they are than we are. That doesn't actually wound anyone, but it does get tedious on the Nth repetition. Most of the time, when somebody posts a cute circuit, people are properly appreciative. Apart from a few private urination contests, such as Jim's & John's, most of us are pretty interested in circuits, and like it very much when somebody helps improve the SNR of the group. (Jim and John like circuits too, just not each other's so much.) So go ahead and post it. The pseud will say that back where he used to work, they did it with germanium point-contact diodes and that that was way better. Then Jan will tell you that he could do it with a PIC in 30 seconds, and that you're nothing but a neural net, but what can you do? As the cop said to Jack Nicholson at the end of 'Chinatown', "Forget it, Jake--it's Usenet.' Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Jim Thompson on 8 Apr 2010 15:09
On Thu, 8 Apr 2010 10:32:55 -0700 (PDT), "oparr(a)hotmail.com" <oparr(a)hotmail.com> wrote: >>It was probably a severe goof-up on my part to allow you thru my >>hotmail rejection filter, I perceived you initially as asking for help >>on a real technical question. > >How many "red herrings" do you have behind that cloak of yours? >Unknown to Larkin and others, you're trying to keep a lid on this too. > >On Apr 8, 1:04�pm, Jim Thompson <To-Email-Use-The-Envelope-I...(a)On-My- >Web-Site.com> wrote: >> You've presented nothing of substance to "keep a lid on". You nothing more than a severely egotistical jerk-off. I'll remove you from my hotmail whitelist, so don't bother to continue to jerk-off, I won't see your response. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy |