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UCC27712-Q1: COM Pin over Shunt to GND

Volkmar Buckow
Prodigy 10 points
Part Number: UCC27712-Q1

Hello,

  the COM Pin of this driver is connected between IGBT Emitter and Shunt . the inductivity of the shunt is between 2nH and 4nH

the power supply and the input pins are connected to HV- Reference - the hin and lin signals are driven from a 5V µController directly.

with this schematic the LTSpice Model did not work - in my opinion there are some internal GND definitions - not referenced to the COM pin.

in 2 Parts we found defect LO output errors - the low side transistor has a low resistor  and it is not possible to switch on the IGBT with a high Signal .

is there a possibility to destroy internal parts because of the bouncing of the COM Pin depending from the di/dt  -  is there a limit of the allowed peak voltage ? 

Thanks for your help 

BR

  • 0
    TI__Mastermind 21675 points

    Hello Volkmar,

    There are a couple of comments to make regarding your description. Regarding the description of the simulation circuit. I have found that the gate driver spice models are structured to assume that the COM pin, or device ground reference, will be connected to the simulator ground reference. As a check, can you try the simulation with the COM pin connected to the simulator ground reference. Another possible issue may be that the ti spice models are confirmed and developed with the typical spice tools such as Pspice. Compatibility with LT spice cannot be guaranteed, and we really cannot support issues with that tool.

    When you mention in 2 parts you found defect LO output errors, was that actual physical parts on boards being tested? If so, when you connect the driver COM to a signal with high frequency noise, such as a shunt, there will be a high possibiliy of high ringing on the driver inputs relative to COM, since COM will have noise content.

    Confirm that the driver inputs to COM, do not violate the datasheet ratings, and do not have noise that can false trigger the driver outputs.

    Regards,