Hi,

using the TI model of LF356 on LTspice v24.1.0 result in strange behaviour, DC output from OpAmp is over 18V when the supply voltages are +/- 15V.

In the "Component attribute editor" I've changed parameters for this version of LTspice, the original from the file area "LF356_test.zip" result in errors at simulation start.

I want to simulate a input circuit of an test equipment (Boonton 4200) that is oscillating at 93Hz square wave with amplitude near the supply coltages. I'm curious to see the Phase Margin of this differential stage with three LF356.

Clearly this pspice model is incompatible with this LTspice version, or there is a workaround possible to apply ?

Thanks, Stephano

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We can't help much unless you let us see more of what you are doing. Upload your .ASC file AND all the other files required to run the simulation, but not .RAW? and .LOG files or pictures,? in a ZIP archive to Files => Temp.

Go to the web page: /g/LTspice/topics. Click on Files in the list on the left. Then click on Temp. Then click on New Upload in the blue box at top left. Click on Upload File in the drop-down menu. Then send a message to tell us that you did that.

Hi,

using the TI model of LF356 on LTspice v24.1.0 result in strange behaviour, DC output from OpAmp is over 18V when the supply voltages are +/- 15V.

In the "Component attribute editor" I've changed parameters for this version of LTspice, the original from the file area "LF356_test.zip" result in errors at simulation start.

I want to simulate a input circuit of an test equipment (Boonton 4200) that is oscillating at 93Hz square wave with amplitude near the supply coltages. I'm curious to see the Phase Margin of this differential stage with three LF356.

Clearly this pspice model is incompatible with this LTspice version, or there is a workaround possible to apply ?

Thanks, Stephano

开云体育

using the TI model of LF356 on LTspice v24.1.0 result in strange behaviour, DC output from OpAmp is over 18V when the supply voltages are ± 15V.

In the "Component attribute editor" I've changed parameters for this version of LTspice, the original from the file area "LF356_test.zip" result in errors at simulation start.

I want to simulate a input circuit of an test equipment (Boonton 4200) that is oscillating at 93Hz square wave with amplitude near the supply coltages. I'm curious to see the Phase Margin of this differential stage with three LF356.

Clearly this pspice model is incompatible with this LTspice version, or there is a workaround possible to apply ?

I don't have version 24.1.0 installed, but with 24.1.5, the (Helmut's) original circuit stalled at 40% completion, but was correct up to that point. When I changed the rise and fall times of the source to 100n from 10n, it simulated perfectly. With version 25.0.12, the original unedited circuit had no problems. I also ran an input voltage sweep and saw the output clipped well inside the supply voltages.

The version 24.1.0 was quite short-lived because there were a number of problems with it. There have been many internal changes in the 24.1.x release. some of these have since been fixed, but others remain.

It may be that nobody can duplicate the problem you are having, but if you have changed anything in the schematic, you should upload it to Files > Temp, so more people can try. Did you change any of the Control Panel > SPICE settings from default? The Trtol parameter in 24.1 is different from 24.0 in the default state.

--
Regards,
Tony

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On 17/03/2025 11:40, Stephano via groups.io wrote:

using the TI model of LF356 on LTspice v24.1.0 result in strange behaviour, DC output from OpAmp is over 18V when the supply voltages are ± 15V.

In the "Component attribute editor" I've changed parameters for this version of LTspice, the original from the file area "LF356_test.zip" result in errors at simulation start.

I want to simulate a input circuit of an test equipment (Boonton 4200) that is oscillating at 93Hz square wave with amplitude near the supply coltages. I'm curious to see the Phase Margin of this differential stage with three LF356.

Clearly this pspice model is incompatible with this LTspice version, or there is a workaround possible to apply ?

I don't have version 24.1.0 installed, but with 24.1.5, the (Helmut's) original circuit stalled at 40% completion, but was correct up to that point. When I changed the rise and fall times of the source to 100n from 10n, it simulated perfectly. With version 25.0.12, the original unedited circuit had no problems. I also ran an input voltage sweep and saw the output clipped well inside the supply voltages.

The version 24.1.0 was quite short-lived because there were a number of problems with it. There have been many internal changes in the 24.1.x release. some of these have since been fixed, but others remain.

It may be that nobody can duplicate the problem you are having, but if you have changed anything in the schematic, you should upload it to Files > Temp, so more people can try. Did you change any of the Control Panel > SPICE settings from default? The Trtol parameter in 24.1 is different from 24.0 in the default state.

Adding ".options gshunt=1e-12 cshunt=1e-14" fixed the stalling at 40% issue with 24.1.5.

Thanks Tony and John,

LTspice v24.1.0 was installed automatically yesterday with the internal update. Today tried to update again and now installed new version 24.1.5

I've loaded the test simulation of LF356 and make sure to reset all settings, modified again the "Component attribute editor" to original setting for U2, applied the suggestions (rise/fall times and the option directive), now works perfectly... Thank you Tony!

Best regards, Stephano