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ADS122C04: Protecting sensitive Analog Signals from EMI close to an Induction Heater

Tony Philip45
Intellectual 755 points
Part Number: ADS122C04

Hi,

In our product, we have a pan that is heated by an Induction heater. To weight the contents of this pan, we also have 4 3-Wire load sensors (of 10kg max weight) in a bridge configuration that is connected to a data converter (ADS122C04). Since the Induction heater and the sensitive load sensor are also within close proximity to each other, What are the best measure that we can take to shield the analog wires from Interference?

Also Is there anything we can add on the PCB board of the ADC that can help with this too?

Regards,

Tony  

  • 0
    TI__Guru** 113765 points

    HiTony,

    EMI/RFI are some of the most difficult aspects to treat to achieve a low noise design.    With bridge/load cell type designs the wiring is going to act as an antenna.  At the very least you will need to have twisted pair shielded wire that is properly terminated at the PCB. You may need something like a braided sheath that can be grounded at the PCB.  You could place the wires inside the sheath where the sheath will act as a Faraday cage around the wiring.  If possible, connecting the shielding to earth ground is best.  If this cannot be done, then I would suggest creating a ground ring around your PCB that is separate from the analog and digital grounds.

    When terminating at the PCB, you need to be very careful as any exposed wiring once outside the shield can pick up EMI and possibly defeat your shielding efforts.  So the connector used and the connection itself is very important.

    The main effort is to prevent the noise as much as possible from getting into the input where the ADS122C04 will gain the noise along with the signal.  As I just stated the wiring is the main source of picking up the noise.  However, there are a number of transients that may be involved as well.  These transients may exceed the absolute maximum ratings for the ADS122C04.  TVS and Schottky diodes are often used to limit the transient voltage, however these devices must be low leakage to prevent measurement error.

    I recently had a similar discussion that you may find helpful in the following post:

    https://e2e.ti.com/support/data-converters/f/73/t/791085

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Intellectual 755 points

    Thanks for that Bob!