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Original question:

TAS2780EVM: Evaluating V-Sense and I-sense

TAS2780EVM: TDM from External Development Kit, help on understanding I-sense values

Kessler Kerr
Prodigy 80 points
Part Number: TAS2780EVM
Other Parts Discussed in Thread: TAS2780, PUREPATHCONSOLE

Hello Audio Amp team,

I had a question regarding how to interpret the SDOUT data. My team is using the TAS2780EVM with PurepathConsole to configure the TAS2780EVM over I2C but have begun to stream audio data to the TAS2780EVM using an external development kit. My team also has the development kit set up to read back the SDOUT data. In Purepathconsole, the TAS2780 is configured for only the I-sense data now. Here is the PPC3 file we are using in the set up.

An initial test we removed the speaker from the output terminals expecting that the SDOUT would report 0A. Generally the readings we see are 0x0010 - 0x00F9 but we also get readings of 0xFF00. I wanted to confirm that a reading of 0x000 = 0A and 0xFFFF = 5A and that each LSB is about 77uA? Also what type of reading should we expect when we have the speaker disconnected? 

Our current set up only allows us to read/record the first SDOUT measurement. Could we expect bad data on the first measurement and if we read the next few measurements we would see measurements close to 0A?

Thank you,

Kessler 

  • +1
    TI__Mastermind 20805 points

    Hi Kessler, 

    There is some inherent non-linearities and noise in the I-sense. We certainly do not expect the data to be 0x0000 when the speaker is disconnected. 0x0010 - 0x00F9 seem reasonable. I am on travel at the moment, I can check this for you on Monday.

    However 0xFF00 does not seem correct.

    Kessler Kerr said:
    0x000 = 0A and 0xFFFF = 5A and that each LSB is about 77uA?

    Yes, correct.

    Kessler Kerr said:
    Our current set up only allows us to read/record the first SDOUT measurement

    is the value of 0xFF00 this first measurement? is this first measurement the first sample sent from SDOUT immediately after the device is powered on? I am not sure if this could be some erroneous measurement due to the device power on. you are not able to record the I-sense data for a short period of time?

    please share any details on when the measurement of 0xFF00 is coming - I will check it for you.

    Regards,
    Arthur

  • 0
    Prodigy 80 points

    Hi Arthur,

    I wanted to follow up and let you know we were able to resolve the readings once we read more of the SDOUT stream after power up. 

    Thanks,

    Kessler