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DRV421: DRV421 degauss function, how it works?

Part Number: DRV421

Hello Team,

One of my customer wants to understand, how degauss function in DRV421 works?

Is there a literature to explain the same?

Regards,

Mahendra

  • Hi Mahendra,

    Javier is still on vacations. He will get back to you next week.
  • Mahendra,
    For starters, section 7.3.8 of the DRV421 data sheet does describe the demagnetization feature to some extent. Is there some more specific information they are looking for?
  • Hello All,

     

    The reason we like to know about the closed loop degauss circuit is, we are facing problem with degauss function which is not working properly as temperature increases.

    At room temperature the degauss function is proper and it is giving alternating demagnetization current to demagnetize the core, as temperature increases the demagnetization function is not working properly, instead of demagnetizing the core this function magnetize the core. We like to understand this behavior is due to parameter change with temperature which is affecting the closed loop degauss function or due to IC.

     

    Following snaps provides more information about our problem.

    Demagnetization waveforms at 25degC. (Proper demagnetization)

    Yellow  - Current through the compensation coil, (Current = Measured Voltage / 40)

    Pink – Vcomp1

    Blue – Vcomp2

     

    Demagnetization waveforms at 70degC. (Improper demagnetization due to missing alternating currents)

     

      

    Demagnetization waveforms at 70degC. (Magnetization due to current in one direction)

     

    Only core change we observed is the increase in DC resistance of the coil with temperature, to compensate that we tried following options by reducing the resistance of the external shunt resistance, reducing the number of turns in compensation coils and changed the difference mode settings by RS1 and RS0 resistors. But we faced the same issue for all the changes.

     

    We are using Nickel- Iron core and the resistance of compensation coil is 67Ohm at 25degC and 85Ohm at 100degC.

     

    Regards,

    Manikandan.M

  • Manikandan,

    I am currently looking into this. I will keep you updated on any progress or questions I may have during my investigation.

    Regards,

    Javier