Is there any way to use an LTSpice ".ic" command to make some node voltage equal to the supply voltage at the beginning of the simulation? Say I wanted to change the supply voltage and then have the initial condition voltage change automatically.
".ic V(my_node) = V(Vcc)" for example doesn't work.
I don't know if you can do this, but you can set an initial voltage as a parameter and use it both for the VCC supply and the initial condition.
I do this quite often.
Ah, I had the suspicion I was thinking about that one backwards...
You can't refer to the initial condition directly -- you have to use a .parm command to set a number, and then apply that number to both the .ic command and the power supply's voltage.
PSpice has IC2 which is a .IC between two nodes.
But I think...
.IC V(A,B)=0 would do what you want. ...Jim Thompson
Yep, that will work. I looked up "template" for IC2, it's...
.IC V(%+,%-)=@IC
The @IC just means the number you supplied. ...Jim Thompson
Kewl. I knew that not, but now I do.
You can also put a VPULSE into a SW to join nodes under DC conditions, then open it after some nano/microseconds. You also get the softness of the switch risetime helping convergence, if it's being finnicky. (DON'T set the switch for super fast and all that, you want it as slow as tolerable so it ramps open.)
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website:
i.e. use negative hysteresis (VH) to get a smooth differentiable curve.
Cheers
Phil Hobbs
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