• Resolved

LMP8480: Vsense calculation

Part Number: LMP8480

Hi Team,

If VCC is 5V, how to calculate the Vsense?

Does it Vsense = 5V / Av ? 

Besides, if VCC below 16V, the internal 14V LDO will not work. Am I right?

regards,

Johnson

  • Hello Johnson,

    Thanks for using our forum. It is a holiday for TI employees in the United States today. Our next business day is on Monday (11/26), starting at 8 a.m. mountain standard time. We will get back to you with a response to your issue on that day.

    Best Regards,

    Patrick Simmons, TI Sensing Products Applications Support

    Getting Started with Current Sensing Video Training Series

    TI makes no warranties and assumes no liability for applications assistance or customer product design. You are fully responsible for all design decisions and engineering with regard to your products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning your designs.

  • In reply to Patrick Simmons:

    Hello Johnson,

    Vsense at the max load or the max current value you want to measure is (5V-0.25V)/Gain. From that you can calculate the needed Rshunt and Vsense will then be Rshunt * ILoad. Yes at a VCC below 14V, the LDO will not be used.

    Best Regards,

    Patrick Simmons, TI Sensing Products Applications Support

    Getting Started with Current Sensing Video Training Series

    TI makes no warranties and assumes no liability for applications assistance or customer product design. You are fully responsible for all design decisions and engineering with regard to your products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning your designs.

  • In reply to Patrick Simmons:

    Hi Patrick,

    what is the 0.25V? Why VCC need to minus 0.25V? 

    Besides, what is VOMAX? It has 0.5V max for VOMAX, how to interpret it?

     

  • In reply to Johnson Cheah:

    Hello Johnson,

    I was referencing the following section, which is related to the VOMAX specification you saw.

    VOMAX in the above paragraph was assumed to be 250mV.  At worst it will to be 0.5V.  VOMAX is the difference between the supply and the device maximum output.  If you want a good understanding of why this exists, I think these precision lab videos are a good source: link1, link2link 3.  Although these linked videos pertain to the amplifier groups products, the information is still relevant to current sensors.

    Best Regards,

    Patrick Simmons, TI Sensing Products Applications Support

    Getting Started with Current Sensing Video Training Series

    TI makes no warranties and assumes no liability for applications assistance or customer product design. You are fully responsible for all design decisions and engineering with regard to your products, including decisions relating to application of TI products. By providing technical information, TI does not intend to offer or provide engineering services or advice concerning your designs.