[SOLVED] LTspice simulation error for MAX16833 IC

[STHOTA]

Hello,

I'm working on IC MAX 16833 chip as an LED driver in LTspice simulation.
I was facing an error saying "Shorted voltage source: u1:vg2"
u1 is the pin name and there are no other pins like vg2 on the chip or anywhere on the board.
But the circuit was a weel established one already and all my connections were perfect.
If anyone could help me solve that error, I can run it.
Thanks for your help!!

 

[KlausST]

Hi,

u1 is the pin name

I assume U1 is the part name, not the pin name.

Why do you show us a meaningless snippet of your circuit and not the complete circuit?

Klaus

 

[mtwieg]

vg2 is a likely a voltage source in the model subcircuit. A full schematic would help.

 

[dick_freebird]

There is a vg2 inside the subcircuit definition that U2
refers to. This source has been shorted, perhaps by
some connection made to U2 (for example grounding
a pin that vg2 connects to, when its return is to GND
node already).

Run your finger down the subcircuit, follow vg2 nets
out to the top level and back around, the short is
not hiding but in plain sight if you look methodically.

 

[FvM]

The question is answered in a German forum discussion https://www.mikrocontroller.net/topic/416497

It's a problem of the model connecting SGND and PGND to SPICE GND node through 0 V source vg2, these nodes must be apparently floated. Very strange model design.

Ltspice questions should always append the design file and all non-standard models.

 

[STHOTA]

Hi,


I assume U1 is the part name, not the pin name.

Why do you show us a meaningless snippet of your circuit and not the complete circuit?

Klaus

------------------------

Thank you for replying. I got the help I needed from the snippet I have provided.

- - - Updated - - -

vg2 is a likely a voltage source in the model subcircuit. A full schematic would help.

Hey Mtwieg, Thanks for replying That is true!!

------------------------------------------------------------------------

There is a vg2 inside the subcircuit definition that U2
refers to. This source has been shorted, perhaps by
some connection made to U2 (for example grounding
a pin that vg2 connects to, when its return is to GND
node already).

Hey dick_freebird, That was right. Thanks for the help

--------------------------------------------------------------------------------------

The question is answered in a German forum discussion https://www.mikrocontroller.net/topic/416497

It's a problem of the model connecting SGND and PGND to SPICE GND node through 0 V source vg2, these nodes must be apparently floated. Very strange model design.

Ltspice questions should always append the design file and all non-standard models.

Hey FvM, we figured the same thing last evening. Thanks a lot for the help. It's true, the problem is with SGND and PGND to spice GND node. We connected small resistance between them to the ground, and it worked. Thanks again..

 

[andre_luis]

Hey FvM, we figured the same thing last evening. Thanks a lot for the help. It's true, the problem is with SGND and PGND to spice GND node. We connected small resistance between them to the ground, and it worked. Thanks again..

It is not rare to find problems with component models that attempt to reproduce the behavior of inner parts of an integrated circuit galvanically isolated from each other, but in this case unlike than what you did, I often couple with high-value resistors between their grounds, not low values; this is enough to avoid SPICE convergence issues with a negligible leakage current that would be not expected in normal operation.

 

[STHOTA]

It is not rare to find problems with component models that attempt to reproduce the behavior of inner parts of an integrated circuit galvanically isolated from each other, but in this case unlike than what you did, I often couple with high-value resistors between their grounds, not low values; this is enough to avoid SPICE convergence issues with a negligible leakage current that would be not expected in normal operation.

Sure. I will replace with high resistances and check..
Thank you