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low power, HV-in regulator with depletion mosfet

Version 4 SHEET 1 1888 724 WIRE 768 -64 688 -64 WIRE 816 -64 768 -64 WIRE 208 48 -112 48 WIRE 352 48 304 48 WIRE 448 48 352 48 WIRE 688 48 688 -64 WIRE 688 48 528 48 WIRE 880 48 688 48 WIRE 1024 48 880 48 WIRE 1200 48 1024 48 WIRE 1392 48 1200 48 WIRE 1024 96 1024 48 WIRE 880 112 880 48 WIRE 1200 112 1200 48 WIRE 1392 112 1392 48 WIRE -112 160 -112 48 WIRE 1600 192 1440 192 WIRE 240 224 208 224 WIRE 288 224 288 96 WIRE 288 224 240 224 WIRE 448 224 288 224 WIRE 688 224 688 48 WIRE 688 224 528 224 WIRE 880 240 880 176 WIRE 1024 240 1024 176 WIRE 1200 240 1200 192 WIRE 1392 240 1392 208 WIRE 1600 240 1600 192 WIRE 688 272 688 224 WIRE -112 304 -112 240 WIRE 1600 352 1600 320 WIRE 288 384 288 224 WIRE 688 432 688 352 WIRE 688 432 352 432 WIRE 688 480 688 432 WIRE 288 592 288 480 WIRE 688 624 688 560 WIRE 288 704 288 656 FLAG -112 304 0 FLAG 288 704 0 FLAG 688 624 0 FLAG 880 240 0 FLAG 1024 240 0 FLAG 1200 240 0 FLAG 768 -64 OUT FLAG 240 224 GATE FLAG 352 48 SRC FLAG 1392 240 0 FLAG 1600 352 0 SYMBOL voltage -112 144 R0 WINDOW 0 58 41 Left 2 WINDOW 3 59 78 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 48 SYMBOL npn 352 384 M0 WINDOW 0 118 26 Left 2 WINDOW 3 94 68 Left 2 SYMATTR InstName Q1 SYMATTR Value 2N4401 SYMBOL zener 304 656 R180 WINDOW 0 -81 49 Left 2 WINDOW 3 -107 6 Left 2 SYMATTR InstName D1 SYMATTR Value DZ5.6 SYMATTR Description Diode SYMATTR Type diode SYMBOL res 432 64 R270 WINDOW 0 77 58 VTop 2 WINDOW 3 71 58 VBottom 2 SYMATTR InstName R1 SYMATTR Value 30 SYMBOL res 544 208 R90 WINDOW 0 71 56 VBottom 2 WINDOW 3 80 58 VTop 2 SYMATTR InstName R2 SYMATTR Value 10K SYMBOL res 704 368 R180 WINDOW 0 -56 70 Left 2 WINDOW 3 -62 34 Left 2 SYMATTR InstName R3 SYMATTR Value 10K SYMBOL res 704 576 R180 WINDOW 0 -59 76 Left 2 WINDOW 3 -67 40 Left 2 SYMATTR InstName R4 SYMATTR Value 10K SYMBOL res 1008 80 R0 WINDOW 0 61 42 Left 2 WINDOW 3 61 78 Left 2 SYMATTR InstName R5 SYMATTR Value 1K SYMBOL cap 864 112 R0 WINDOW 0 53 16 Left 2 WINDOW 3 55 50 Left 2 SYMATTR InstName C1 SYMATTR Value 2µ SYMBOL current 1200 112 R0 WINDOW 3 -123 -106 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value PULSE(0 5m 5m 1u 0 2m) SYMATTR InstName I1 SYMBOL nmos 208 96 R270 WINDOW 0 146 34 VRight 2 WINDOW 3 99 7 VRight 2 SYMATTR InstName M2 SYMATTR Value DN2540 SYMBOL nmos 1440 112 M0 WINDOW 0 -93 8 Left 2 WINDOW 3 -139 42 Left 2 SYMATTR InstName M1 SYMATTR Value FDS4072N3 SYMBOL voltage 1600 224 R0 WINDOW 0 -98 52 Left 2 WINDOW 3 -262 104 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V2 SYMATTR Value PULSE(0 10 10m 1u) TEXT -176 528 Left 2 !.tran 0 20m 0 1u TEXT 904 440 Left 2 ;D100 +12 HV Regulator TEXT 920 488 Left 2 ;JL June 1 2013 TEXT -376 624 Left 2 !.model DZ5.6 D(Vfwd=0.6 Ron=1 Roff=1G Vrev=5.6) TEXT -200 464 Left 2 !.include Supertex.lib TEXT 1424 72 Left 2 ;Ilim test TEXT 424 344 Left 2 ;Quad R-pack

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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 to
John Larkin
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Can you provide a link to Supertex.lib?

Reply to
bitrex

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And the elusive supertex.lib file, which LTspice declares is nowhere to be found, is to be found, where???

-- JF

Reply to
John Fields

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Just put that into C:\Program Files\LTC\SwCADIII\lib\sub. Then plop an nmos onto your schematic and change its name to DN2540.

Ixys/Claire has some depl fets, too.

--

John Larkin Highland Technology Inc

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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 to
John Larkin

It's in plain sight, hardly elusive.

Try Google. Or Supertex.com.

--

John Larkin Highland Technology Inc

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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 to
John Larkin
[LTSpice file]

Depletion mode FETs are really practical for such regulators because you don't need a boost supply and you also don't have to use an iffy p-channel LDO architecture. What occasionally happen is that someone says "But that can't work!" ... "It'll work, it's a depletion mode FET" ... "A WHAT? .. oh, aaaha!". Many folks think that other than JFETs depletion mode has gone the way of the dinosaurs. But it didn't.

Check the CPC series, less expensive. Infineon also has nice ones but with EU companies one must keep an eye on the supply situation.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Another cool thing is that the NPN's collector resistor is bootstrapped. More gain, better line regulation. I was going to use an LM317HV, but it's a klunky TO-220 and is more expensive. I'd have to stand it up unsupported, use an uptight heat sink for support, or bolt it down flat. All ugly.

Nice. CPC3703 is similar to the Supertex part but cheaper.

Clare makes nice SSRs too. I've characterized some for mosfet destruction limits, which was tedious. I wish there were some good fully-protected opto SSRs.

--

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 to
John Larkin

You have zener diodes that are happy regulating with ~100 microamps zener current?

I tried it with a BZX84C5V6 model. I'd be happier to see 39K from supply to D1 cathode, to maintain a reasonable zener current.

I haven't checked the model for accuracy (yet), but,according to Fairchild's datasheet, that zener has a slope around 400 ohms at 1mA.

Other than that, it shows promise.

.MODEL BZX84C5V6 D IS=2.6665E-18

+N=.82284 +RS=.51617 +IKF=11.760E-3 +CJO=137.10E-12 +M=.34532 +VJ=.72637 +ISR=1.2666E-9 +BV=5.7078 +IBV=.35715 +TT=78.483E-9 
--
"For a successful technology, reality must take precedence  
over public relations, for nature cannot be fooled." 
                                       (Richard Feynman)
Reply to
Fred Abse

Quaint. I've been doing that for many years, and of course the circuit dates back to any tube supply in existence. Two transistors give rather poor performance (not much better than the tube circuit). A diff hardly costs any board area.

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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.

Tim

-- Deep Friar: a very philosophical monk. Website:

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"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

Reply to
Tim Williams

The higher voltages have pretty steep slopes. I've run 9 volt zeners at a few microamps.

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:

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My supply can range from 18 to 50. If we wanted more current, it would be better to change R2, since the voltage there is more constant. But I want to use a 10K r-pack, since I use them elsewhere on the board. R-packs are great, unless you paint yourself into a corner with them.

I like its simpliciy. It current limits and regulates and it just takes five small cheap surface-mount parts; C1 is just the various bypass caps. Loop compensation? We don't need no stinkin' loop compensation.

--

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 to
John Larkin

Never hurts to remember the old stuff. 6080s and VR tubes and like that.

Two transistors give rather

18 parts vs 5! What is the 100 uH inductor for?

The only candidate I found was the LM317HV, which is a big TO-220.

--

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 to
John Larkin

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

Reply to
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.

--

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 to
John Larkin

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

Keeping the risetime out of the regulator. Seems like the cap is on the wrong side, which may be the case. Superfluous I'm sure. You recognize the last section, of course.

Tim

--
Deep Friar: a very philosophical monk. 
Website: http://seventransistorlabs.com
Reply to
Tim Williams

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

I find they regularly handle 80-100. 2N4401s also, but they don't do the avalanche pulse thing (at least as easily). Not that I would operate them under such conditions, for, say, linear amplification (for which you might achieve negative hFE, like the germanium of old!), or switching (where the storage and 2nd breakdown will toast it anyway).

The PNP CCS in that Cdss test rig I posted about last week, it's only rated for 160V or so, but tonight I've just taken it up to 220 without a problem.

Measuring the test rig, with a very low capacitance device (a BFQ225, only rated for 100V, but it breaks down around 150), it seems to have a constant 60pF capacitance, independent of voltage (at least, down to -65Vce, apparently).

One thing that surprises me about BJTs versus MOSFETs: the capacitance is small and relatively constant. Ancient DMOS have relatively constant capacitance, but they're also an order of magnitude worse in performance than modern devices.

Hand-made test equipment is hardly production material, but of all the transistors I've tested (2N3904s, 2N2369s, and a few RF types), if a single unit will achieve pulse breakdown, it's characteristic of the type, not just that particular unit.

I've used TO-92s from various manufacturers, and SOT-23s from several (i.e., MMBT), with the same results.

RF types may be useful at lower voltages. I found a 2SA1206 or something (I'm sure that's the wrong number), 30V 50mA 2GHz PNP sort of thing, which made nice pulses at 60V. Beats me if higher voltage types can be convinced of doing the same.

Avalanche pulsing even works on a solderless breadboard, where the absolute worst risetime I was able to create was 4ns, half of which was the scope anyway. '3904s are slower than '2369s, but not by much, and still faster than the Zetex ones.

Tim

--
Deep Friar: a very philosophical monk. 
Website: http://seventransistorlabs.com
Reply to
Tim Williams

Explaining it away as an intentional design decision shows a cover up. Well seasoned engineers can and do make mistakes, too.

Jamie

Reply to
Jamie

tuned

It's not "explaining it away", it is the entire point of the circuit, which you missed.

--

John Devereux
Reply to
John Devereux

tuned

Zetex makes some really good components.

Reply to
DecadentLinuxUserNumeroUno

Looks remarkably like...

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dating back to October, 2012, which Larkin roundly criticized.

Don't the same criticisms apply now ?>:-}

[snip] Trimmed for brevity, find full asc listing at...

From: John Larkin Newsgroups: sci.electronics.design Subject: low power, HV-in regulator with depletion mosfet Date: Sat, 01 Jun 2013 10:52:53 -0700 Message-ID:

...Jim Thompson

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Reply to
Jim Thompson

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.

--
"For a successful technology, reality must take precedence  
over public relations, for nature cannot be fooled." 
                                       (Richard Feynman)
Reply to
Fred Abse

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