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ADS7945: Remarkably good transition noise specification?

tony holt
Prodigy 200 points
Part Number: ADS7945
Other Parts Discussed in Thread: ADS9110, ADS9224R, ADS9234R,

The transistion noise spec is 25uV which is approx .04LSBs. This seems remarkably low for a 2MSPS 14bit convertor - it is better than many (most?) 18 bit converters such as the ADS9110 which are much more expensive.

So is this specification correct? Transistion noise is usually specified in LSBs so could the 25uV be a misprint - say 2.5LSBs? I hope not, as this could be ideal for my application!

Thanks, Tony H

PS. An alternative may be the ADS9234R, or even the ADS9224R, but the datasheets still have the transistion noise as TBD. Are there any ballpark figure avaliable if not the final specification value?

  • 0
    TI__Guru**** 175111 points
    Hi there poster!

    Our team of experts is enjoying a well deserved break this Thanksgiving Holiday with their family and friends. Our apologies for the delay in responding to your query, but we'll be back to it on Monday the 26th. Happy Thanksgiving everyone!
  • 0
    TI__Guru**** 175111 points
    Hi Tony,

    Sorry for the delay here. The transition noise on the ADS7945 is correct, no typo. We don't have final numbers for the ADS9224R yet, they will be published as soon as they are verified.
  • 0 in reply to Tom Hendrick
    Prodigy 200 points

    Thanks Tom. That's very good news - does that make it the lowest noise 14bit ADC on the market? (Of course a lot of datasheets don't specify transition noise).

    Also a bit odd that the ADS7945 noise spec is a maximum of 25uV which is unusual - noise specs seem to be almost always specified as typical, for good reason I presume as it would be expensive to test for noise levels in production. I can't think of any other ADC that specifies a maximum noise figure.

  • 0 in reply to tony holt
    TI__Guru**** 175111 points
    Hi Tony -

    I'm more into the actual application of parts rather than the marketing of them. I do know that min/max values drive production test time, which drives costs. Get some sample of the ADS7945 and try them out. I think you'll be happy with the performance of these parts.