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TIDM-LC-WATERMTR: TIDM-LC-WATERMTR the magnet is near the LC sensor problem

Part Number: TIDM-LC-WATERMTR

Hi

  As the water meter has a standard for anti-magnetic interference, our customer tested TI Two LC Sensors water meter TIDM-LC-WATERMTR referencd design (www.ti.com/.../TIDM-LC-WATERMTR) and found that when the magnet is near the LC sensor, the MCU counts The count will not increase when count 00→11), the customer would like to ask if there is any solution, whether it can be processed by software.

Thanks,

Andy

  • Hello Andy,

    I am looking into this and will provide some feedback shortly.

  • Hi Andy,

    There is not a way to resolve this in software. 

    To minimize the interference to static fields, you can use coils with low mu cores. Those do not saturate as easy. An air-coil without core would not saturate at all. E.g. you can use a pancake coil . You can also shield, using mu-metal. The other property of an permanemt magnet: it is a piece of metal that would allow eddie currents as well. This could mess up the calibration. 

    One common solution is to have a sensor coil that is not used for rotation detection. It has a high mu core and its purpose is to sense static field disturbances. Simply check for frq changes. Those will be timestamped whenever they change. This is then a tempersensor. The tempersensor can be used as an additional feature of the meter.

  • Hi Eddie,

         Thank you for your help, I will providing these information to customers refer.

    Andy