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PGA411-Q1: OUTA, OUTB Abnormal Question

Wayne Liu
Expert 8705 points
Part Number: PGA411-Q1


Hi,

When customer is testing the resolve with constant 7000rpm speed, sometimes the OUTA and OUTB frequency changes rapidly, check the waveform below please, could you please tell me what condition will cause this abnormal frequency and how to debug it? Thanks. 

  • 0
    TI__Expert 3435 points

    Hi,

    Can you ask the customer to plot AOUT to understand what is going on here?

    Is there any chance of the device transitioning into 10-bit mode? How is the BMODE0 connected to VIO or ground? Any noise on this pin can change the state of the device. 

    Regards

    Sharath.

  • 0 in reply to Sharath Vallamkonda
    TI__Expert 8705 points

    Hi Sharath,

    Thanks for your support. Below is the abnormal signal, the angle analog signal is not smooth. But not all the abnormal pulses are not smooth. Yellow is analog resolve signal, green is OSIN, blue is OUTA. 

     

     The AMODE is default high, if set it to low, the abnormal waveform above disappear, and it is smooth, it is normal. 

    Questions: 1.  This abnormal symptom only occurs in some type of resolver, why? 

    2. In what conditions we should use the accelerate mode ? Thanks. 

       

  • 0 in reply to Wayne Liu
    TI__Expert 3435 points

    Hi,

    Who is the customer?

    Please suggest the customer use DKI=DKP=5. Keep MKP at 2. Let me know if the problem solves.

    Please refer to Fig 3 to 7 of the datasheet to understand the PGA411 response for a step input. Customers can enable AMODE if the acceleration is expected in their application.

    Reards

    Sharath.