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LTspice
Nikos A.:
Hi everyone.
I am trying to learn some basics on TLspice and I cannot figure out what I am doing wrong. I am using a P-channel Mosfet, a voltage source and a load. When the voltage source (ig battery) is reversed the Mosfet should be OFF because of Vgs>0 isn't it?
Why I am measuring a negative voltage after the Mosfet and current passing through the load??
Thanks in advance
StillTrying:
I1 is probably producing its own voltage, replace I1 with a 60R.
Ian.M:
StillTrying beat me to it.
Don't use a current source as a load!!!
As he said, replace I1 with a 60 ohm resistor and it will all make sense.
I would also suggest putting V1 back the right way round then running a DC sweep with .dc V1 -12 12 instead of .tran 1ms, which will show you when the MOSFET's channel has enough gate voltage to take over from its body diode. (Not that simmed gate thresholds are to be trusted - there's far too much variation between batches of the same part.)
SiliconWizard:
To use a current source as a proper load in LTSpice, you can just tick the "active load" parameter in the current source parameters' dialog. It will act as you would expect. Very handy.
Zero999:
--- Quote from: SiliconWizard on October 22, 2019, 05:06:29 pm ---To use a current source as a proper load in LTSpice, you can just tick the "active load" parameter in the current source parameters' dialog. It will act as you would expect. Very handy.
--- End quote ---
Yes, right click the component and click advanced to get the active load parameter.
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