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BQ500511A: Please explain more details about FOD_CAL, and ralationship between FOD_CAL and FOD_THR

Part Number: BQ500511A

 

hello,

Could you please explain more details about FOD_CAL,  and ralationship between FOD_CAL and FOD_THR

  • FOD_THR (FOF Threshold) -- is the level that an FOD fault will be set, two external resistor are used to set this level.
    FOD_CAL (FOD Calibration) -- will compensate the calculated loss curve for and load dependent effects, similar to slop compensation.

    Also see:
    Data Sheet Section 7.3.4 --- Foreign Object Detection and FOD Calibration
    FAQ section of this forum -- bqTESLA TX FOD and PMOD – Short Introduction

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

  • In reply to Bill Johns:

    1. I checked BQ500511A, there isn't PMOD function, so how does it deal with Parasitic Metal Object?
    2. I'd like to know more further about when and how to tune FOD_CAL parameter ? and the relationship between FOD_CAl with FOD_THR as well.
  • In reply to xiaoyan Yun:

    Hello

    1.)  I checked BQ500511A, there isn't PMOD function, so how does it deal with Parasitic Metal Object? -- Bill J-PMOD is only used on WPC 1.0 RX, they are obsolete and the support for them is not required.

    2.)  I'd like to know more further about when and how to tune FOD_CAL parameter ? and the relationship between FOD_CAl with FOD_THR as well.

    Bill J -- FOD calibration will used the AVID FOD RX (see below link).  This is a precision receiver with all losses accounted for.  The loss calculated by the TX is read thru I2C bus using bqSTUDIO, with EV2400 see EVM User's Guide for bq50002A.   The loss value is "Calculated Parasitic Loss", plot this value across 0mW to 5W of load, it should be flat.  If it is not use FOD_CAL value to adjust.

    See:

    www.avid-tech.com

    http://www.avid-tech.com/product/qi-fod-receiver-v1-1/

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

  • In reply to Bill Johns:

    Hi,

    Thanks for your explanation. 

    I suppose our HW is different with EVM, so I have to tune FOD_CAL parameter ( divided voltage resistor ) to get better performance for "load depandent loss"

    Could you please let me know how to tune these 2 divided voltage resistor?

    The resistor location on EMV is R22 and R26.  EVM document name is "bq50002A Wireless Power TX EVM"  Thank you!