Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
Subject: Re: LT SwitcherCAD Current Source Help
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Date: Thu, 12 Sep 2002 16:05:09 +0100
NNTP-Posting-Date: Thu, 12 Sep 2002 16:05:10 BST
"David Huhn" wrote in message
> I am a student working on a software model(in LT SwitcherCAD III) for
> motor driver and am trying to model the current chopping action of the
> FET driver IC that is going to be used.
> I am trying to do this with a voltage dependent current source. I
> read through the help and tried unsucessfully to come up with even a
> simple tests.
> Ideally, my current source would provide X amps if the voltage at the
> V_sense node is less than 3.4, and 0 amps if the voltage at the sense
> node is greater than 3.4.
> I apologize for the trivial nature of this question, but I would
> appreciate any suggestions on how to complete this model.
> Thank you for your time.
If you are modelling a fet you can do the obvious and use a fet!, or you
can use a voltage controlled switch, i.e.
.MODEL VSwitch SW(RON=0.1 ROFF=100Meg VT=3.4 VH=1m)
You can use this switch to switch the voltage to the VCCS if you put a
resistor across the VCCC inputs.
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.