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ADS7067: Experience with ADS7067 Reset

Michael Scheil
Prodigy 20 points
Part Number: ADS7067
Other Parts Discussed in Thread: ADS7066

Tool/software:

Hi,
we're currently looking into the ADS7067. In the Datasheet it's mentioned that you can reset it with a reset bit and also by switching AVDD off and on again. (Content number 6.4.1 page 25) 

Meanwhile in the Absolute Maximum Ratings it says that the REF-Voltage and all Inputs shouldn't be greater then AVDD + 0.3. (Content number 5.1 page 5). 

Do you really have to shut down all these pins instead of the only mentioned AVDD or is it constructed to withstand a short reset and only for a long time without AVDD the part will be damaged?

Furthermore are there any known issues that will provocate the need of a reset? Like writing registers in a special kombination or any other known circumstances? 

Thanks in advance.

BR Michael

  • +1
    TI__Expert 4240 points

    Hello Michael! 

    Welcome to the E2E Forum! 

    That is actually a very good question actually!  Ideally, yes, powering everything off would be the safest approach to take, but for a power-on-reset (POR) it should be fine without since its for a short time.  If the power is expected to be off for a long time I would recommend powering-off/removing the external reference as well. 

    Reading the BOR bit in the System_Status register afterwards to confirm it was a successful reset is also recommended initially. 

    Could I ask for some information on the type of system the ADS7067 is going to be used? 

    I would say the ADS7067 is pretty robust, and no specific issues need to be mentioned that would require a full power reset.  Use case can help me confirm though.

    If you are planning to enable CRC there are a couple things I would like to mention: 

    1. There have been questions regarding how to know what mode (CRC enabled or not) if there is a power event.  Resetting the device and reconfiguring is probably the most straight forward approach. It's not a device issue, just a method that requires limited troubleshooting. 
    2. Since this device is in the same family as the ADS7066, in case there is any confusion or comparisons between datasheets, if CRC is enabled Daisy Chain will not be functional. if somehow there are multiple devices in daisy chain and CRC gets enabled on all devices (or past the 1st one), a full power reset will be needed on all devices after the 1st one to disable the CRC. 
      1. **The ADS7067 correctly states that Daisy Chain and CRC are not functional, but at the moment the ADS7066 datasheet is in the process of being updated. 

    Best regards, 

    Yolanda

  • 0 in reply to Yolanda Gonzalez
    Prodigy 20 points

    Hi Yolanda,

    thank you very much for your quick and detailed answer.

    The ADC will be used multiple times on a module for maritime purpose and should be able to run 24/7. A complete shutdown of only one or multiple ADCs for a longer time isn't a use-case.

    Can you guarantee that a short violation of the maximum ratings will not damage the part? If so can you name a timespan that would be valid? I need concrete answers for my boss.

    Daisy-Chain mode is currently not planned, but good to know and it makes sense, that it'll need a physical reset.

    Best regards,
    Michael