LM5100A: Pspice model

Hi Ohad,

What is your switching frequency?

What is the voltage level of the inputs?

Also, 18.7nF is very small for the bootstrap capacitor. I am not sure what FETs you are using but 100nF is likely a better size for the capacitor.

Can you provide a screenshot of the schematic?

Thanks,

Daniel W

Hi Daniel, 

The switching frequency of the PWM is about 60kHz,

I'm using the CSD18531:

the input voltages weren't high enough ... 

another question now is why does the HO pin gives a positive voltage both when is on and off? 

Yellow trace: 

Hi Ohad,

It appears that in the schematic HS is only connected to the bootstrap capacitor. It should also connect to the source of the high side FET. This will likely solve the HO always positive behavior.

Thanks,

Daniel W

When connecting HS to high side FET source simulation dose not work 

Hi Ohad,

Can you provide plots of the what part of the system is not working when HS is connected to the switch node?

Thanks,

Daniel W

Hi Daniel, 

here i connected HS to VSS, please see the Cayan trace:  

it is the voltage of the high side gate. 

Hello Ohad,

Daniel will get back to you early next week.

Thanks!

Aaron

Still i wasn't able to make this work... 

please come back to me on that one 

Hi Ohad,

It appears that the driver inputs are being exposed to negative voltages (-6V) which exceed the abs max. This may have some effect on the driver. Once this issue is fixed please provide an updated schematic and plots.

Thanks,

Daniel W

Hi Daniel, i took buth PWM inputs and added them DC voltage so now HI LI are positive. 

now im geeting the following error: 

 Can not re-define X_U15. X_U15 is either a system defined variable or has already been defined

any ideas?