On Sat, 01 Jun 2013 16:53:30 -0700, John Larkin wrote:> My regulation requirement isn't tight... I'm just powering opamps. If the > voltage comes out too low, I can always go to a higher zener voltage; it's not a > potential disaster. > > Here's data on a 6.2 volt part: > > https://dl.dropboxusercontent.com/u/53724080/Parts/Diodes/MMBZ5234BL.pdfI spun it again, with a MMBZ5232BT (5.6V). My version, with more zener current, drops v(out) by 3uV at 5mA draw. Without the extra resistor, yours drops by 47mV.> If we wanted more current, it would be better > to change R2, since the voltage there is more constant.Lowering R2 instead increases zener current, but degrades regulation. .SUBCKT DI_MMBZ5232BT 1 2 * Terminals A K D1 1 2 DF DZ 3 1 DR VZ 2 3 3.14 .MODEL DF D ( IS=11.0p RS=31.2 N=1.10 + CJO=57.6p VJ=0.750 M=0.330 TT=50.1n ) .MODEL DR D ( IS=2.21f RS=7.11 N=3.00 ) .ENDS -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
low power, HV-in regulator with depletion mosfet
Started by ●June 1, 2013
Reply by ●June 2, 20132013-06-02
Reply by ●June 2, 20132013-06-02
On Sun, 02 Jun 2013 08:22:45 -0700, Fred Abse <excretatauris@invalid.invalid> wrote:>On Sat, 01 Jun 2013 11:37:50 -0700, John Larkin wrote: > >> On Sat, 01 Jun 2013 13:34:22 -0500, John Fields <jfields@austininstruments.com> >> wrote: >> >>>On Sat, 01 Jun 2013 10:52:53 -0700, John Larkin >>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>--- >>><Snipped LTspice circuit list.> >>> >>>And the elusive supertex.lib file, which LTspice declares is nowhere >>>to be found, is to be found, where??? >>> >>> >> >> It's in plain sight, hardly elusive. >> >> Try Google. Or Supertex.com. > >It consists of .MODELs, but each ends in an .ENDS. Syntax error. .MODELS >don't take .ENDS, that's for SUBCKTS, > >Fills up the SPICE error log with warnings. Get rid of the .ENDS >statements.I just dumped the Supertex file into the LT Spice lib\sub folder and it worked fine. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●June 2, 20132013-06-02
On Sun, 02 Jun 2013 08:22:46 -0700, Fred Abse <excretatauris@invalid.invalid> wrote:>On Sat, 01 Jun 2013 16:53:30 -0700, John Larkin wrote: > >> My regulation requirement isn't tight... I'm just powering opamps. If the >> voltage comes out too low, I can always go to a higher zener voltage; it's not a >> potential disaster. >> >> Here's data on a 6.2 volt part: >> >> https://dl.dropboxusercontent.com/u/53724080/Parts/Diodes/MMBZ5234BL.pdf > >I spun it again, with a MMBZ5232BT (5.6V). > >My version, with more zener current, drops v(out) by 3uV at 5mA draw.(Microvolts?) What happens to line regulation?>Without the extra resistor, yours drops by 47mV.I'm just powering opamps, so 50 mV of load regulation doesn't matter here. My sim shows 30 mv drop when the 10 mA current load step kicks in. The thing that wrecks regulation isn't the zener, it's R1, the current-limit resistor. That 30 mV step drops to 5 mV if R1 is changed to 1 ohm. What's annoying, in such a simple circuit, is that LT Spice will go compute-bound randomly, like when a part value is changed. The usual fix is to change the minimum time step from something arbitrary like 500 ns to 600 ns. Or back. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●June 2, 20132013-06-02
On Sun, 02 Jun 2013 09:18:11 -0400, Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:>John Larkin wrote: > >> On Sat, 01 Jun 2013 21:12:43 -0400, Jamie >> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote: >> >> >>>John Larkin wrote: >>> >>> >>>>On Sat, 1 Jun 2013 18:40:15 -0500, "Tim Williams" <tmoranwms@charter.net> wrote: >>>> >>>> >>>> >>>>>Quaint. I've been doing that for many years, and of course the circuit >>>>>dates back to any tube supply in existence. >>>> >>>> >>>>Never hurts to remember the old stuff. 6080s and VR tubes and like that. >>>> >>>> >>>> Two transistors give rather >>>> >>>> >>>>>poor performance (not much better than the tube circuit). A diff hardly >>>>>costs any board area. >>>>>http://webpages.charter.net/dawill/tmoranwms/Elec_Pulse1.gif >>>> >>>> >>>>18 parts vs 5! What is the 100 uH inductor for? >>>> >>>> >>>> >>>>>Of course, these days I'd just make the switcher right to begin with. I >>>>>have a few jellybean circuits I play with, which only require a few more >>>>>transistors than this. Or, God forbid, an IC. >>>> >>>> >>>>The only candidate I found was the LM317HV, which is a big TO-220. >>>> >>>> >>> >>>Looking at that Elec_Pulse1.gif, I wasn't aware that a 2N3904 could hold >>>back 120Volts on the collector? >>> >>> Last I checked, I think the V(brk)CEO was around 40. Vcbo a little >>>higher.. >>> >>> Oh well. >>> >>>Jamie >> >> >> It's probably one of those hand-selected avalanche situations. The HV is tuned >> with the pot, too. This circuit *wants* the 3904 to break down. >> >> The Zetex avalanche transistors are much more predictable, but expensive and >> relatively slow. >> >> > > Explaining it away as an intentional design decision shows a cover up. >Well seasoned engineers can and do make mistakes, too. > > > > JamieIt's an avalanche pulser. The whole point is to make the transistor over-voltage avalanche. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●June 2, 20132013-06-02
John Larkin wrote:> On Sun, 02 Jun 2013 08:22:45 -0700, Fred Abse <excretatauris@invalid.invalid> > wrote: > > >>On Sat, 01 Jun 2013 11:37:50 -0700, John Larkin wrote: >> >> >>>On Sat, 01 Jun 2013 13:34:22 -0500, John Fields <jfields@austininstruments.com> >>>wrote: >>> >>> >>>>On Sat, 01 Jun 2013 10:52:53 -0700, John Larkin >>>><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>--- >>>><Snipped LTspice circuit list.> >>>> >>>>And the elusive supertex.lib file, which LTspice declares is nowhere >>>>to be found, is to be found, where??? >>>> >>>> >>> >>>It's in plain sight, hardly elusive. >>> >>>Try Google. Or Supertex.com. >> >>It consists of .MODELs, but each ends in an .ENDS. Syntax error. .MODELS >>don't take .ENDS, that's for SUBCKTS, >> >>Fills up the SPICE error log with warnings. Get rid of the .ENDS >>statements. > > > I just dumped the Supertex file into the LT Spice lib\sub folder and it worked > fine. > >Works fine here, too. Would be nice if there was a way to have the lib file show up in the parts list instead of using a directive to include the .lib maybe there is and I am just not seeing it. Jamie
Reply by ●June 2, 20132013-06-02
On Sun, 02 Jun 2013 08:44:28 -0700, John Larkin wrote:> I just dumped the Supertex file into the LT Spice lib\sub folder and it worked > fine.So did I. It worked fine. Then I saw the Spice error log ;-) -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
Reply by ●June 2, 20132013-06-02
On Sun, 02 Jun 2013 08:20:49 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:>On Sat, 01 Jun 2013 10:52:53 -0700, John Larkin ><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote: > >Looks remarkably like... > > www.analog-innovations.com/SED/SingleLoopController_00056_MOD3.pdf > >dating back to October, 2012, which Larkin roundly criticized. > >Don't the same criticisms apply now ?>:-}Yes. The problem with your circuit was that the charge pump wouldn't work, which I pointed out and you subsequently realized. Your assumed Vrect waveform won't be available in a real-life offline power supply. You posted two unsuccessful circuits to solve the startup problem, and then declared that your third one works. But you never posted that one. Why not? -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●June 2, 20132013-06-02
On Sun, 02 Jun 2013 09:16:31 -0700, Fred Abse <excretatauris@invalid.invalid> wrote:>On Sun, 02 Jun 2013 08:44:28 -0700, John Larkin wrote: > >> I just dumped the Supertex file into the LT Spice lib\sub folder and it worked >> fine. > >So did I. It worked fine. > >Then I saw the Spice error log ;-)It's just whining. Ignore it. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●June 2, 20132013-06-02
On Sun, 02 Jun 2013 09:00:37 -0700, John Larkin wrote:> What happens to line regulation?11.499V at Vin=18V. 11.619 at Vin=50 That's with a MMBZ5232BT (5.6V nominal) zener. Zener current 0.35mA to 1.05mA over same input voltage range. What's annoying, in such a simple circuit, is that LT Spice will go compute-bound randomly, like when a part value is changed. The usual fix is to change the minimum time step from something arbitrary like 500 ns to 600 ns. Or back. All Spice does that. This particular example was happier at 10us than 1us. -- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
Reply by ●June 2, 20132013-06-02
John Larkin wrote:> On Sun, 02 Jun 2013 09:18:11 -0400, Jamie > <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote: > > >>John Larkin wrote: >> >> >>>On Sat, 01 Jun 2013 21:12:43 -0400, Jamie >>><jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote: >>> >>> >>> >>>>John Larkin wrote: >>>> >>>> >>>> >>>>>On Sat, 1 Jun 2013 18:40:15 -0500, "Tim Williams" <tmoranwms@charter.net> wrote: >>>>> >>>>> >>>>> >>>>> >>>>>>Quaint. I've been doing that for many years, and of course the circuit >>>>>>dates back to any tube supply in existence. >>>>> >>>>> >>>>>Never hurts to remember the old stuff. 6080s and VR tubes and like that. >>>>> >>>>> >>>>> Two transistors give rather >>>>> >>>>> >>>>> >>>>>>poor performance (not much better than the tube circuit). A diff hardly >>>>>>costs any board area. >>>>>>http://webpages.charter.net/dawill/tmoranwms/Elec_Pulse1.gif >>>>> >>>>> >>>>>18 parts vs 5! What is the 100 uH inductor for? >>>>> >>>>> >>>>> >>>>> >>>>>>Of course, these days I'd just make the switcher right to begin with. I >>>>>>have a few jellybean circuits I play with, which only require a few more >>>>>>transistors than this. Or, God forbid, an IC. >>>>> >>>>> >>>>>The only candidate I found was the LM317HV, which is a big TO-220. >>>>> >>>>> >>>> >>>>Looking at that Elec_Pulse1.gif, I wasn't aware that a 2N3904 could hold >>>>back 120Volts on the collector? >>>> >>>>Last I checked, I think the V(brk)CEO was around 40. Vcbo a little >>>>higher.. >>>> >>>>Oh well. >>>> >>>>Jamie >>> >>> >>>It's probably one of those hand-selected avalanche situations. The HV is tuned >>>with the pot, too. This circuit *wants* the 3904 to break down. >>> >>>The Zetex avalanche transistors are much more predictable, but expensive and >>>relatively slow. >>> >>> >> >> Explaining it away as an intentional design decision shows a cover up. >>Well seasoned engineers can and do make mistakes, too. >> >> >> >> Jamie > > > It's an avalanche pulser. The whole point is to make the transistor over-voltage > avalanche. > >yes, I see what it does, but I still say that is BAD! design.. I have not yet seen a transistor survive a lengthily life cycle avalanching either side, especially the emitter. Jamie
