low power, HV-in regulator with depletion mosfet

I just dumped the Supertex file into the LT Spice lib\sub folder and it worked fine.

not a

(Microvolts?)

What happens to line regulation?

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.

tuned

It's an avalanche pulser. The whole point is to make the transistor over-voltage avalanche.

So did I. It worked fine.

Then I saw the Spice error log ;-)

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

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?

worked

It's just whining. Ignore it.

--

John Larkin Highland Technology Inc

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

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.

worked

Never having had a wife, I can indulge in schadenfreude.

• .MODEL DN2540 NMOS (LEVEL=3 RS=1.05 NSUB=5.0E14

tuned

over-voltage

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

worked

I have much experience in that department with the wife!

Jamie

Take a look at ZTX415 datasheet, and Zetex app. note ANB8.

On Sun, 02 Jun 2013 12:18:42 -0400, Jamie wrote:

You mean like this?

Version 4 SHEET 1 1888 848 WIRE 768 -64 688 -64 WIRE 816 -64 768 -64 WIRE 144 48 -112 48 WIRE 208 48 144 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 144 304 144 48 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 144 528 144 384 WIRE 288 528 288 480 WIRE 288 528 144 528 WIRE 288 592 288 528 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 {V} 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 -186 4 Left 2 SYMATTR InstName D1 SYMATTR Value DI_MMBZ5232BT SYMATTR Description Diode SYMATTR Type diode SYMATTR Prefix X 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 2\u00b5 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) SYMBOL res 128 288 R0 SYMATTR InstName R6 SYMATTR Value 39k TEXT 928 544 Left 2 !.tran 0 20m 0 10u TEXT 904 440 Left 2 ;D100 +12 HV Regulator TEXT 920 488 Left 2 ;JL June 1 2013, Fred's mods. TEXT 1424 72 Left 2 ;Ilim test TEXT 424 344 Left 2 ;Quad R-pack TEXT -96 584 Left 2 !.SUBCKT DI_MMBZ5232BT 1 2\n* Terminals A K\nD1

--------------------------------------------------------- Plot File:

tuned

over-voltage

Most of the older Tek sampling scopes used an avalanche transistor to generate the sampling impulses, directly or through an SRD. The ones still around usually work, after trillions of avalanche events.

Some how that didn't intrigue me, nor what I asked.

Jamie

That should have been AN88.

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

$14 a pop from Digikey!

Also, could not find AN88 but did find AN8.