Why and How LOS and DOS registers are used?. I am getting 0xD0 value in fault register. why these bitsWhy and How LOS and DOS registers are used?. I am getting 0xD0 value in fault register. why these bits (1101 0000) are set in fault register AD2s1210 RDC

Why and How LOS and DOS registers are used?. I am getting 0xD0 value in fault register. why these bits (1101 0000) are set in fault register AD2s1210 RDC

  • Hello,

    If the fault register contains 0xD0 the faults that are reported are

    • Sine/cosine inputs clipped
    • Sine/cosine inputs below LOS threshold
    • Sine/cosine inputs exceed DOS mismatch threshold

    The AD2S1210 monitors the sine and cosine inputs from the resolver to determine if they are within the operating range as specified in the data sheet. The operating range should be considered from both a differential perspective, i.e. Sin - SinLo and Cos - CosLo and a single ended perspective.

    Clipping

    The clipping fault will be triggered if any of the resolver inputs, Sin, SinLo, Cos or CosLo are below 0.15V or greater than AVdd - 0.2V. To verify this you should look at the signals from a single ended perspective when the signals are at their maximum amplitude, 0 degrees for cosine signals and 90 degrees for sine signals. If the signals are clipping either the amplitude of the signals is too large or the biasing of the signals needs to be adjusted.

    LOS

    This is a differential specification. The sine and cosine signals when they are at their maximum amplitude should be > 2.3V for default settings. If the signals are lower than this you should look to increase the amplitude. If the signals are lower than the spec the part will continue to operate but the accuracy in the data sheet is not guaranteed.

    DOS mismatch

    If the difference between the amplitude of the sine signal when it is at its maximum and the cosine signal at its maximum. Amplitude mismatch is directly related to positional errors. The default setting for the fault indication is 380mV. So if the difference is greater than this a fault will trigger. 

    Additionally I would recommend you check the dc bias on the sin, sinlo, cos and coslo signals. For each signal pair the bias should be the same. 

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    Thank you,
    EZ Admin