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LTSPICE: startup

Greetings:

Wouldn't it be nice if SPICE allowed one to set the output voltage/current of independent sources for computing the operating point individually per source?

I realize LTSPICE has the "startup" option which can be a help, but sometimes I want only one source turned off while the others, like power supplies are left on. I find myself building klunky constructs such as a pulse source called "delay" which actuates switches to release desired sources after a specified time.

Also, the startup option in LTSPICE is limited to operating after 5us. Why the fixed time?

Is it possible to have a new option for indep. sources called "Vdelay" which sets the output voltage (speaking specifically here about V sources, of course) during the "Tdelay" period instead of having that output be set by "Vinitial"?

That would solve this problem in the most fine grained manner perhaps?

Thanks for comments.

Good day!

--
_____________________
Christopher R. Carlen
crobc@bogus-remove-me.sbcglobal.net
SuSE 9.1 Linux 2.6.5
Reply to
Chris Carlen
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Sno-o-o-ort ;-)

In PSpice...

STP(x) 1 if x>0.0, 0 if x

Reply to
Jim Thompson

I'm not surprised either.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Hello Chris,

So that Jim can't use LTSpice for his fast IC stuff ....?

Regards, Joerg

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Reply to
Joerg

----- Original Message ----- From: "Jim Thompson" Newsgroups: sci.electronics.cad Sent: Tuesday, May 17, 2005 11:46 PM Subject: Re: LTSPICE: startup

Hello Jim,

LTspice has a function u(x) which has the same definition as your STP(x). It can be used with B(ehavioral)-sources as well as with E-sources. Your example would then look like

V=V(1)*u(TIME-10ns)

or

with Epoly:

VALUE={V(1)*u(TIME-10ns)}

But as usual I am not surprised that LTspice also understands

V=V(1)*STP(TIME-10ns)

or with Epoly:

VALUE={V(1)*STP(TIME-10ns)}

Best regards, Helmut

Reply to
Helmut Sennewald

Undefined for x=0?

Reply to
Robert Baer

Pasted directly from the Reference Guide, but should be x >= 0

...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

That should suffice to meet my wishes. Thanks.

--
_______________________________________________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
crcarleRemoveThis@BOGUSsandia.gov
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Reply to
Chris Carlen

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