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TINA/Spice/TPS54218: Clocking & EMI Scans

Go Bravos
Expert 6090 points
Part Number: TPS54218
Other Parts Discussed in Thread: TINA-TI

Tool/software: TINA-TI or Spice Models

Hi team,

Does the TPS54x18 family support being clocked from a spread spectrum modulated clock source?

 Are there any EMI scans from the TPS54x18 family? Conducted and radiated?

 The spice model in TINA shows significant input current spikes if you look at the current into the switcher.

Are these spikes real? For now I edited the exported txt file to match the data around it. I need it to see what the input filtering needs to be. This was with a 3 ohm load.

 In LT Spice the unencrypted model has like 80 -100A impulses for current so there is something really wrong there but it could be how I had to set it up.

Please let me know your thoughts.

Thank you.

  • 0
    TI__Guru**** 191445 points

    Go,

    You can modulate the clock frequency for TPS54x18 devices.  Generally there are 2 ways:time varying frequency external SYNC clock or time varying current injection into the RT/CLK pin with fixed RT set point resistor.  I do not believe the first type works with the pspice model though.

    We do not typically take EMI measurements as the EMI performance is greatly dependent on the end equipment.  We do not have any EMI data for that family of devices.  If we were to measure EMI, We would need to design a board specifically for that.  I doubt the standard EVM would fare very well.

    You cannot look at the input current in pspice.  I forget the exact details, but that particlar pin is not modeled as it would be in the actual circuit.  So you cannot for example measure efficiency in the pspice environment.  Also none of the parasitics are modeled so if you if you look at the SW node, you will see an ideal pulse train with no ringing or overshoot (a big source for EMI).  For any EMI evaluation, you will need to work with actual hardware