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[LTSPICE] Too many Teravolts!

Greetings:

Notice how this circuit causes some major voltage spikes to gazillions of TV. When the alternate solver is used, no problem.

Also notice that if the entire right half of the circuit containing all the op-amps is deleted (it is presently not doing anything useful, so may be deleted) and solved with the default SPICE options, then the TV spikes don't occur.

Any explanations? Some sort of math routine glitch?

Thanks.

Good day!

The following circuit was originally authored by "Genome":

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Version 4 SHEET 1 2256 1332 WIRE -656 1072 -656 1024 WIRE -656 1200 -656 1152 WIRE -272 576 -272 0 WIRE -272 688 -272 656 WIRE -272 704 -272 688 WIRE -272 1104 -272 832 WIRE -272 1216 -272 1184 WIRE -272 1248 -272 1216 WIRE -112 1072 -144 1072 WIRE -112 1104 -112 1072 WIRE -112 1216 -272 1216 WIRE -112 1216 -112 1184 WIRE -80 1024 -656 1024 WIRE -80 1072 -112 1072 WIRE -32 480 -32 96 WIRE -32 688 -272 688 WIRE -32 688 -32 480 WIRE -32 832 -272 832 WIRE -32 864 -32 832 WIRE -32 976 -32 944 WIRE -32 1008 -32 976 WIRE -32 1216 -112 1216 WIRE -32 1216 -32 1088 WIRE 0 48 -64 48 WIRE 0 96 -32 96 WIRE 0 432 -64 432 WIRE 0 480 -32 480 WIRE 0 832 -32 832 WIRE 48 0 -272 0 WIRE 48 32 48 0 WIRE 48 128 48 112 WIRE 48 240 -64 240 WIRE 48 240 48 128 WIRE 48 272 48 240 WIRE 48 352 48 272 WIRE 48 400 48 352 WIRE 48 416 48 400 WIRE 48 512 48 496 WIRE 48 544 -64 544 WIRE 48 544 48 512 WIRE 48 576 48 544 WIRE 48 688 -32 688 WIRE 48 688 48 656 WIRE 64 976 -32 976 WIRE 64 1056 64 976 WIRE 80 272 48 272 WIRE 80 976 64 976 WIRE 160 0 48 0 WIRE 160 48 160 0 WIRE 160 128 48 128 WIRE 160 128 160 112 WIRE 160 400 48 400 WIRE 160 432 160 400 WIRE 160 512 48 512 WIRE 160 512 160 496 WIRE 192 176 -64 176 WIRE 192 272 160 272 WIRE 192 272 192 176 WIRE 208 976 192 976 WIRE 208 976 208 832 WIRE 224 976 208 976 WIRE 272 352 48 352 WIRE 272 416 272 352 WIRE 272 544 272 496 WIRE 272 688 48 688 WIRE 272 688 272 608 WIRE 288 272 192 272 WIRE 336 176 192 176 WIRE 352 976 336 976 WIRE 352 976 352 896 WIRE 368 976 352 976 WIRE 432 272 368 272 WIRE 448 416 448 352 WIRE 448 544 448 496 WIRE 448 688 272 688 WIRE 448 688 448 608 WIRE 512 832 208 832 WIRE 512 976 480 976 WIRE 576 176 400 176 WIRE 576 272 512 272 WIRE 576 272 576 176 WIRE 592 0 160 0 WIRE 592 48 592 0 WIRE 592 128 592 112 WIRE 592 432 592 400 WIRE 592 512 592 496 WIRE 608 272 576 272 WIRE 640 976 624 976 WIRE 640 1024 640 976 WIRE 656 1024 640 1024 WIRE 656 1056 64 1056 WIRE 720 0 592 0 WIRE 720 32 720 0 WIRE 720 128 592 128 WIRE 720 128 720 112 WIRE 720 240 720 128 WIRE 720 272 688 272 WIRE 720 272 720 240 WIRE 720 352 448 352 WIRE 720 352 720 272 WIRE 720 400 592 400 WIRE 720 400 720 352 WIRE 720 416 720 400 WIRE 720 512 592 512 WIRE 720 512 720 496 WIRE 720 544 720 512 WIRE 720 576 720 544 WIRE 720 688 448 688 WIRE 720 688 720 656 WIRE 784 1040 768 1040 WIRE 800 96 768 96 WIRE 800 480 768 480 WIRE 800 480 800 96 WIRE 800 688 720 688 WIRE 800 688 800 480 WIRE 832 0 720 0 WIRE 832 48 768 48 WIRE 832 176 576 176 WIRE 832 240 720 240 WIRE 832 432 768 432 WIRE 832 544 720 544 WIRE 928 896 352 896 WIRE 928 1008 928 896 WIRE 928 1040 896 1040 WIRE 928 1120 928 1040 WIRE 960 1040 928 1040 WIRE 960 1040 960 864 WIRE 992 832 624 832 WIRE 992 864 960 864 WIRE 992 1008 928 1008 WIRE 992 1040 960 1040 WIRE 1120 0 1088 0 WIRE 1120 176 1088 176 WIRE 1120 432 1088 432 WIRE 1120 544 1088 544 WIRE 1136 848 1104 848 WIRE 1136 1024 1104 1024 WIRE 1136 1120 928 1120 WIRE 1232 0 1200 0 WIRE 1232 80 1232 0 WIRE 1232 176 1200 176 WIRE 1232 176 1232 80 WIRE 1232 320 1232 208 WIRE 1232 352 1232 320 WIRE 1232 432 1200 432 WIRE 1232 512 1232 432 WIRE 1232 544 1200 544 WIRE 1232 576 1232 544 WIRE 1232 688 800 688 WIRE 1232 688 1232 656 WIRE 1264 0 1232 0 WIRE 1264 80 1232 80 WIRE 1264 176 1232 176 WIRE 1264 208 1232 208 WIRE 1264 432 1232 432 WIRE 1264 512 1232 512 WIRE 1264 544 1232 544 WIRE 1376 0 1344 0 WIRE 1376 80 1328 80 WIRE 1376 432 1344 432 WIRE 1376 528 1328 528 WIRE 1376 528 1376 432 WIRE 1408 432 1376 432 WIRE 1472 0 1440 0 WIRE 1472 80 1440 80 WIRE 1472 80 1472 0 WIRE 1472 192 1328 192 WIRE 1472 192 1472 80 WIRE 1504 0 1472 0 WIRE 1712 176 1680 176 WIRE 1712 208 1712 176 WIRE 1712 320 1232 320 WIRE 1712 320 1712 288 WIRE 1728 432 1696 432 WIRE 1728 544 1696 544 WIRE 1744 0 1680 0 WIRE 1744 176 1712 176 WIRE 1840 432 1808 432 WIRE 1840 512 1840 432 WIRE 1840 544 1808 544 WIRE 1840 576 1840 544 WIRE 1840 688 1232 688 WIRE 1840 688 1840 656 WIRE 1856 0 1824 0 WIRE 1856 80 1856 0 WIRE 1856 176 1824 176 WIRE 1856 176 1856 80 WIRE 1856 320 1712 320 WIRE 1856 320 1856 208 WIRE 1872 432 1840 432 WIRE 1872 512 1840 512 WIRE 1872 544 1840 544 WIRE 1888 0 1856 0 WIRE 1888 80 1856 80 WIRE 1888 176 1856 176 WIRE 1888 208 1856 208 WIRE 1984 432 1952 432 WIRE 1984 528 1936 528 WIRE 1984 528 1984 432 WIRE 2000 0 1968 0 WIRE 2000 80 1952 80 WIRE 2016 432 1984 432 WIRE 2096 0 2064 0 WIRE 2096 80 2064 80 WIRE 2096 80 2096 0 WIRE 2096 192 1952 192 WIRE 2096 192 2096 80 WIRE 2128 0 2096 0 FLAG -64 48 PHA IOPIN -64 48 In FLAG 832 48 PHB IOPIN 832 48 In FLAG -64 432 PHB IOPIN -64 432 In FLAG 832 432 PHA IOPIN 832 432 In FLAG -272 704 0 FLAG -64 240 PREA IOPIN -64 240 Out FLAG 832 240 PREB IOPIN 832 240 Out FLAG -64 176 POSTA IOPIN -64 176 Out FLAG 832 176 POSTB IOPIN 832 176 Out FLAG -64 544 ISNSA IOPIN -64 544 Out FLAG 832 544 ISNSB IOPIN 832 544 Out FLAG 1136 1120 DEAD IOPIN 1136 1120 Out FLAG -144 1072 VTRI IOPIN -144 1072 Out FLAG -272 1248 0 FLAG 0 832 +15 IOPIN 0 832 Out FLAG 1136 848 PHA IOPIN 1136 848 Out FLAG 1136 1024 PHB IOPIN 1136 1024 Out FLAG 1088 432 ISNSA IOPIN 1088 432 In FLAG 1088 544 ISNSB IOPIN 1088 544 In FLAG 1408 432 ISNS IOPIN 1408 432 Out FLAG 1088 0 ISNS IOPIN 1088 0 In FLAG 1504 0 IERR IOPIN 1504 0 Out FLAG 1232 352 0 FLAG 832 0 VBUS IOPIN 832 0 Out FLAG 1696 432 PREA IOPIN 1696 432 In FLAG 1696 544 PREB IOPIN 1696 544 In FLAG 2016 432 VFB IOPIN 2016 432 Out FLAG 1680 0 VFB IOPIN 1680 0 In FLAG 2128 0 IDEM IOPIN 2128 0 Out FLAG 1088 176 IDEM IOPIN 1088 176 In FLAG 1680 176 VDEM IOPIN 1680 176 Out FLAG -656 1200 0 SYMBOL sw 48 128 M180 WINDOW 0 40 65 Left 0 WINDOW 3 38 41 Left 0 SYMATTR InstName S1 SYMATTR Value MSW SYMBOL sw 720 128 R180 WINDOW 0 72 65 Left 0 WINDOW 3 44 40 Left 0 SYMATTR InstName S2 SYMATTR Value MSW SYMBOL sw 48 512 M180 WINDOW 0 41 67 Left 0 WINDOW 3 40 43 Left 0 SYMATTR InstName S3 SYMATTR Value MSW SYMBOL sw 720 512 R180 WINDOW 0 78 68 Left 0 WINDOW 3 51 44 Left 0 SYMATTR InstName S4 SYMATTR Value MSW SYMBOL ind 592 288 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 5 56 VBottom 0 SYMATTR InstName LFILTB SYMATTR Value 25 SYMBOL res 384 256 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName RLOAD SYMATTR Value 2R5 SYMBOL voltage -272 560 R0 WINDOW 0 37 43 Left 0 WINDOW 3 37 69 Left 0 SYMATTR InstName VBUS SYMATTR Value 80V SYMBOL diode 176 112 R180 WINDOW 0 -36 49 Left 0 WINDOW 3 -44 27 Left 0 SYMATTR InstName D1 SYMATTR Value DID SYMBOL diode 608 112 R180 WINDOW 0 49 49 Left 0 WINDOW 3 39 25 Left 0 SYMATTR InstName D2 SYMATTR Value DID SYMBOL diode 608 496 R180 WINDOW 0 44 53 Left 0 WINDOW 3 35 30 Left 0 SYMATTR InstName D4 SYMATTR Value DID SYMBOL diode 176 496 R180 WINDOW 0 -36 50 Left 0 WINDOW 3 -48 29 Left 0 SYMATTR InstName D3 SYMATTR Value DID SYMBOL res 704 560 R0 WINDOW 0 -62 40 Left 0 WINDOW 3 -64 65 Left 0 SYMATTR InstName R2 SYMATTR Value 0R1 SYMBOL res 32 560 R0 SYMATTR InstName R1 SYMATTR Value 0R1 SYMBOL Digital\\\\CD4000\\\\CD4070B 704 976 R0 WINDOW 0 -25 -8 Left 0 WINDOW 3 -27 14 Left 0 SYMATTR InstName U1 SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9 SYMBOL Digital\\\\CD4000\\\\CD4050B 128 912 R0 SYMATTR InstName U2 SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9 SYMBOL Digital\\\\CD4000\\\\CD4050B 272 912 R0 SYMATTR InstName U3 SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9 SYMBOL Digital\\\\CD4000\\\\CD4050B 416 912 R0 SYMATTR InstName U4 SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9 SYMBOL Digital\\\\CD4000\\\\CD4050B 560 912 R0 SYMATTR InstName U5 SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9 SYMBOL sw -32 1104 M180 WINDOW 0 -105 141 Left 0 WINDOW 3 -106 115 Left 0 SYMATTR InstName S5 SYMATTR Value COMP SYMBOL res -48 848 R0 SYMATTR InstName R3 SYMATTR Value 1K SYMBOL voltage -112 1088 R0 WINDOW 0 -93 58 Left 0 WINDOW 3 -62 181 Left 0 SYMATTR InstName VTRI SYMATTR Value PULSE(-1 1 0 4u 4u 0 8u) SYMBOL voltage -272 1088 R0 WINDOW 0 -90 46 Left 0 WINDOW 3 -89 70 Left 0 SYMATTR InstName VDD SYMATTR Value 15V SYMBOL Digital\\\\CD4000\\\\CD4049B 560 768 R0 SYMATTR InstName U6 SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9 SYMBOL Digital\\\\CD4000\\\\CD4049B 832 976 R0 SYMATTR InstName U7 SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9 SYMBOL Digital\\\\CD4000\\\\CD4081B 1040 784 R0 SYMATTR InstName U8 SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9 SYMBOL Digital\\\\CD4000\\\\CD4081B 1040 960 R0 SYMATTR InstName U9 SYMATTR SpiceLine VDD=15 SPEED=1.0 TRIPDT=5e-9 SYMBOL Opamps\\\\opamp 1296 464 R0 SYMATTR InstName IDIFF SYMBOL res 1216 416 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R6 SYMATTR Value 10K SYMBOL res 1360 416 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R7 SYMATTR Value 10K SYMBOL res 1216 528 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R8 SYMATTR Value 10K SYMBOL res 1216 560 R0 SYMATTR InstName R9 SYMATTR Value 10K SYMBOL Opamps\\\\opamp 1296 128 R0 SYMATTR InstName IERR SYMBOL res 1216 -16 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R10 SYMATTR Value 10K SYMBOL res 1360 -16 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R11 SYMATTR Value 15K SYMBOL cap 1440 -16 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C1 SYMATTR Value 10n SYMBOL res 1216 160 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R12 SYMATTR Value 10K SYMBOL diode 1264 96 R270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName D5 SYMATTR Value ZID SYMBOL diode 1440 64 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName D6 SYMATTR Value ZID SYMBOL Opamps\\\\opamp 1904 464 R0 SYMATTR InstName VDIFF SYMBOL res 1824 416 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R4 SYMATTR Value 1E6 SYMBOL res 1968 416 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R5 SYMATTR Value 10K SYMBOL res 1824 528 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R13 SYMATTR Value 1E6 SYMBOL res 1824 560 R0 SYMATTR InstName R14 SYMATTR Value 10K SYMBOL Opamps\\\\opamp 1920 128 R0 SYMATTR InstName VERR SYMBOL res 1840 -16 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R15 SYMATTR Value 10K SYMBOL res 1984 -16 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R16 SYMATTR Value 62K SYMBOL cap 2064 -16 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C2 SYMATTR Value 330p SYMBOL res 1840 160 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R17 SYMATTR Value 10K SYMBOL voltage 1712 192 R0 WINDOW 0 -101 59 Left 0 WINDOW 3 -101 87 Invisible 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName VDEM SYMATTR Value PULSE(0 0.4 0 10n 10n 500u 1m) SYMBOL diode 1888 96 R270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName D7 SYMATTR Value ZID SYMBOL diode 2064 64 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName D8 SYMATTR Value ZID SYMBOL voltage -656 1056 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value PULSE(-1 1 0 200u 10n 0 200u) SYMBOL res 256 400 R0 SYMATTR InstName R18 SYMATTR Value 1 SYMBOL res 432 400 R0 SYMATTR InstName R19 SYMATTR Value 1 SYMBOL cap 256 544 R0 SYMATTR InstName C3 SYMATTR Value 100p SYMBOL cap 432 544 R0 SYMATTR InstName C4 SYMATTR Value 100p SYMBOL ind 64 288 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 5 56 VBottom 0 SYMATTR InstName LFILTA SYMATTR Value 25 SYMBOL ind 416 288 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 5 56 VBottom 0 SYMATTR InstName L1 SYMATTR Value 250 SYMBOL cap 336 192 R270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName C5 SYMATTR Value 4.7 TEXT -280 744 Left 0 !.MODEL MSW SW(RON=10m ROFF=1E6 VT=5V VH=-2V) TEXT -280 768 Left 0 !.MODEL DID D(RON=10m) TEXT 24 1200 Left 0 !.tran 0 1.6m 1u uic TEXT 24 1176 Left 0 !.include Cd4000.lib TEXT 24 1128 Left 0 !.MODEL COMP SW(RON=10m ROFF=1E6 VT=0 VH=1m) TEXT 24 1152 Left 0 !.lib opamp.sub TEXT -280 792 Left 0 !.MODEL ZID D(RON=10m VREV=2)

--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarleRemoveThis@BOGUSsandia.gov
NOTE, delete texts: "RemoveThis" and "BOGUS" from email address to reply.
Reply to
Chris Carlen
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[snip]

I thought that fixing inductors was a built-in "feature" of LTspice that Mikey cited repeatedly as one of the reasons that LTspice is faster than PSpice?

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.
Reply to
Jim Thompson

of

may

spikes

Oh..... bum, perhaps you might mention this one to Mike. Mind you it's probably not his problem but some Windows/News transfer snafu or somesuch.

There have been occasions when pasting text files into newsreaders where some of the characters go wayward and when things get cut and pasted a bit more something else happens..... the Greek u seems to be a favourite one.

Values get spumed on.

Yes, I've seen the teravolt/amp thing before, not just in LTspice. And if I'm interested I start to mess about with series and parallel impedances to try and tame them.

Spice, not that I know f*ck, finds an answer. If the answer satisfies the question then it is right. Simple as that. Perhaps there is or should be some way of setting up a box that says 'More than this amps/volts, bugger off and try again'.

DNA

DNA

Reply to
Endoscope

----- Original Message ----- From: "Chris Carlen" Newsgroups: sci.electronics.cad Sent: Tuesday, April 19, 2005 11:14 PM Subject: [LTSPICE] Too many Teravolts!

Hello Chris, I had a hard time with your circuit. I first tried with the usual SPICE parameters, but this hasn't really helped.

After that I looked to your component values.

Lfilta: 25 Henry Lfiltb: 25 Henry L1: 250 Henry C5: 4 Farad

What real word circuit contains an ideal 250H coil or an ideal capacitor with 4 Farad?

Please add the following parasitics by clicking the right mouse button over the appopriate component. A dialog will pop up.

Lfilta: Parallel Resistance: 1e7 Lfiltb: Parallel Resistance: 1e7 L1: Parallel Resistance: 1e7 C5: Serial Resistance: 0.01

The simulation will then run with the normal and the Alternate solver. There are also no more "super spikes".

My learning from this: Add a little bit loss to circuit elements if they have such extreme values of ideal inductance and capacitance. This helps to make it better solveable for any (LT-)SPICE engine. Your real parts will have decades more loss than I have added in your example.

Best regards, Helmut

Reply to
Helmut Sennewald

"Jim Thompson" schrieb im Newsbeitrag news: snipped-for-privacy@4ax.com...

Hello Jim

Yes there is damping(very small series resistance), but it is very light. It can be overwritten of course. Any automatic guess has to be very carefully choosen so that it doesn't have impact on the the accuracy of a simulation.

Best regards, Helmut

Reply to
Helmut Sennewald

"Helmut Sennewald" schrieb im Newsbeitrag news:d4bv7u$gru$00$ snipped-for-privacy@news.t-online.com...

Sorry, it's a very very high parallel resistance.

Reply to
Helmut Sennewald

Thanks for the reply!

Oh, I use 250H coils and 4F caps all the time. The surface mount ones. Air core inductors and silver mica caps too. ;-)

Seriously, the component values are just bungled by the cut and paste. This seems to happen a lot. The values should be 25uH, 250uH, 4uF.

Yes.

Good day!

--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarleRemoveThis@BOGUSsandia.gov
NOTE, delete texts: "RemoveThis" and "BOGUS" from email address to reply.
Reply to
Chris Carlen

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