LT Spice universal opamp

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In universalopamp2, what does the "rail" parameter do?




--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
Am 02.03.2020 um 18:02 schrieb jlarkin@highlandsniptechnology.com:
In universalopamp2, what does the "rail" parameter do?
Click to expand...

Hello John,

rail=0 (default) means the maximum and minimum output voltages will be
the supply voltages.
If you set rail=2, the maximum output voltage will be the positive
supply voltage minus 2V and the minimum output voltage will be the
negative supply voltage plus 2V.

Best regards,
Helmut
 
On Mon, 2 Mar 2020 18:34:34 +0100, Helmut Sennewald
<helmutsennewald@t-online.de> wrote:

Am 02.03.2020 um 18:02 schrieb jlarkin@highlandsniptechnology.com:

In universalopamp2, what does the "rail" parameter do?


Hello John,

rail=0 (default) means the maximum and minimum output voltages will be
the supply voltages.
If you set rail=2, the maximum output voltage will be the positive
supply voltage minus 2V and the minimum output voltage will be the
negative supply voltage plus 2V.

Best regards,
Helmut
Click to expand...

OK, symmetric voltage limit. Thanks.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
onsdag den 4. marts 2020 kl. 00.17.03 UTC+1 skrev Joerg:
On 2020-03-02 09:38, jlarkin@highlandsniptechnology.com wrote:
On Mon, 2 Mar 2020 18:34:34 +0100, Helmut Sennewald
helmutsennewald@t-online.de> wrote:

Am 02.03.2020 um 18:02 schrieb jlarkin@highlandsniptechnology.com:

In universalopamp2, what does the "rail" parameter do?


Hello John,

rail=0 (default) means the maximum and minimum output voltages will be
the supply voltages.
If you set rail=2, the maximum output voltage will be the positive
supply voltage minus 2V and the minimum output voltage will be the
negative supply voltage plus 2V.

Best regards,
Helmut


OK, symmetric voltage limit. Thanks.


You could probably add a voltage source to its output, tap the feedback
off after that, and that way arrive at the asymmetrical limits of a real
opamp. With a defined Ri it might be even more realistic.
Click to expand...

why not add/subtract the voltage from the supply
 
On 2020-03-02 09:38, jlarkin@highlandsniptechnology.com wrote:
On Mon, 2 Mar 2020 18:34:34 +0100, Helmut Sennewald
helmutsennewald@t-online.de> wrote:

Am 02.03.2020 um 18:02 schrieb jlarkin@highlandsniptechnology.com:

In universalopamp2, what does the "rail" parameter do?


Hello John,

rail=0 (default) means the maximum and minimum output voltages will be
the supply voltages.
If you set rail=2, the maximum output voltage will be the positive
supply voltage minus 2V and the minimum output voltage will be the
negative supply voltage plus 2V.

Best regards,
Helmut


OK, symmetric voltage limit. Thanks.
Click to expand...

You could probably add a voltage source to its output, tap the feedback
off after that, and that way arrive at the asymmetrical limits of a real
opamp. With a defined Ri it might be even more realistic.

--
Regards, Joerg

http://www.analogconsultants.com/
 
On 2020-03-03 15:39, Lasse Langwadt Christensen wrote:
onsdag den 4. marts 2020 kl. 00.17.03 UTC+1 skrev Joerg:
On 2020-03-02 09:38, jlarkin@highlandsniptechnology.com wrote:
On Mon, 2 Mar 2020 18:34:34 +0100, Helmut Sennewald
helmutsennewald@t-online.de> wrote:

Am 02.03.2020 um 18:02 schrieb jlarkin@highlandsniptechnology.com:

In universalopamp2, what does the "rail" parameter do?


Hello John,

rail=0 (default) means the maximum and minimum output voltages will be
the supply voltages.
If you set rail=2, the maximum output voltage will be the positive
supply voltage minus 2V and the minimum output voltage will be the
negative supply voltage plus 2V.

Best regards,
Helmut


OK, symmetric voltage limit. Thanks.


You could probably add a voltage source to its output, tap the feedback
off after that, and that way arrive at the asymmetrical limits of a real
opamp. With a defined Ri it might be even more realistic.


why not add/subtract the voltage from the supply
Click to expand...

You could do that as well but then if you want to make it more realistic
(with an Ri) that Ri could affect some innards of the opamp model.
Unless the model is strictly behavioral where it might not matter.

--
Regards, Joerg

http://www.analogconsultants.com/
 
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