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TAD5242: THD+N vs current draw and early sample vs RTM

Luke Sakamoto
Intellectual 2345 points
Part Number: TAD5242
Other Parts Discussed in Thread: TAD5212, PCM5242,

Tool/software:

Hi team,

I have two questions.

1. THD+N curve

Below is the THD+N curve in differential config with 1.2kOhm impedance attached. You can see the increasing THD+N for higher imput amplitudes. 

Is there a way to improve this performance? What happens if you limit the current draw from the dac. for example, higher impedance.

2. Sample silicon vs RTM silicon

I know there was some improvements with sample die vs RTM.

Was pop noise one of the improvements? There was a claim in pop noise in early samples.

Thanks,

Luke

  • 0
    TI__Mastermind 32131 points

    Hi Luke,

    You  can't  improve the performance by much , the increase is not sensible and this performance is about the best you can expect.

    In general this device has better pop noise performance but the software version of the DAC  (TAD5212) has pop reduction adjustment and reg 0x06 is used for it.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    TI__Intellectual 2345 points

    Hi Arash,

    Thanks for the quick reply.

    Another question - 

    About the internal power supply. Can you explain what the digital power pin DREG is actually supplied to? Something like below block diagram was helpful in past generation (PCM5242) but it seems like there arent detailed pin description nor power supply section in new datasheets.

    Thanks,

    Luke

  • 0 in reply to Luke Sakamoto
    TI__Mastermind 32131 points

    Hi Luke,

    As you know , TAD5242 supports a single AVDD supply operation by integrating an on-chip digital regulator and DREG is the  on-chip regulator output for digital supply. So basically it is the output of the internal regulator that is used for digital section.

    Kind Regards,

    Arash

  • 0 in reply to Arash Loloee
    TI__Intellectual 2345 points

    Hi Arash,

    Thanks for the answer. I understand the internal regulater is supplying to the digital domain.

    My question is what parts are supplied by this power rail? For PCM5242, the supplied block were mentioned in the datasheet.

    For TAD5242, i think only below is available, but can you tell us how to know which block is which? This is important to build the power supply circuit.

    Thanks,

    Luke

  • 0 in reply to Luke Sakamoto
    TI__Mastermind 32131 points

    Hello, I am out of office and will check with System team on Monday . Thanks for your patience.

    Regards.

    Arash

  • 0 in reply to Arash Loloee
    TI__Mastermind 32131 points

    Luke, I have requested the system to provide the block diagram and copied you on the email.

    Once it is provided, I will come back  and add it to this post for future reference of other users.

    Regards,

    Arash