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TMS320F28374S: Inquire for 3.3V & 1.2V Power Supply

Benjamin Zhou
Expert 4000 points

Part Number: TMS320F28374S

Hi Team,

  My Customer used TMS320F2837s in solar inverter application, and while at night, the power supply of 3.3V(VDDIO/VDD3VFL/VDDA) would be 1V(low than startup), and power supply of 1.2V is 0v, the external monitor device output 0V to XRS pin; but according to the datasheet, which required “The supplies should ramp to full rail within 10ms”. Also while in day time, the 3.3V power supply will be start up from 1V.

  Will it affect to the reliability of TMS320F28374s or not at upper situation?

   update the waveform as attached file.  expect for your reply, thanks.

 

Best Regards

BenjaminTMS320F28374s Power Supply Issue.docx

  • 0
    TI__Guru 60865 points
    Hi Benjamin,

    This situation would directly go against the datasheet recommendation that you quoted, so it should be avoided if possible. If this is a product under development, some solutions would be:

    Use voltage regulators with enables, and tie the enables to the supervisor output to ensure that the power rails are only applied when the voltage levels are appropriate.

    Alternately, you may be able to gate the power rails with a FET where the FET is turned on by your supervisor.

    If this is a product in production, we can investigate the exact mechanism the datasheet advisory is looking to avoid, but in general we usually can't provide a quantitative risk/reliability assessment for operating outside of datasheet recommendations.
  • 0 in reply to Devin Cottier
    TI__Expert 4000 points

    Hi Devin,
       Clarify the issue with customer, and understand that the cause of power supply issue:  while in night, the Solar inverter still connect to the PV panel and the AC grid, and both of the PV panel and AC grid still exist,   so the F28374s ADC input still got the voltage from the sampling circuit, which will affect the VDDIO&VDDA via the diode.

      So the power supply can't be pull down to 0v while the solar inverter implemented in night.  Customer is very concern for the remaining voltage in power supply, could you kindly help on below items customer concerns:

      

    if the power supply still get some remaining voltage (not zero, typical 400mV);

    1. Customer want to understand that which risk will be implement to F28374s?

    2. And how the power supply remaining voltage to affect the F28374s?

    3. What’s the minimum remaining voltage for the power supply? 0.3v or less? Is there any documents descript the power supply remaining voltage?

    TMS320F28374s ADC Remaining voltage issue.docx

     

    Best Regards

    Benjamin