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need help to find out 3.3V, 12-bit, bipolar input (+/-10V range) ADC

kiranraj deshaboina
Prodigy 30 points
Other Parts Discussed in Thread: ADS7808, ADS8634, ADS8638

Hello All,

I am looking for an ADC with the below features:

Bipolar input (+/-10V range)

12-bit resolution

100 KHz sampling rate

10 microsec throughput speed

and most importantly it should operate on a single 3.3V

In the existing design, the ADC used is ADS7808 which operates on single 5V supply. But in my new design, I want to use the 3.3V technology only. I also have +/-15V supplies on the board.

I am not able to find the ADC's which can operate on 3.3V and support bipolar input range of +/-10V with any manufacturers.

Please help me in finding the suitable ADC for my new design.

Many Thanks in advance,

Kiran

  • 0
    TI__Guru**** 168605 points

    Hi Kiran,

    Welcome to the e2e forum!

    Since you have +/-15V available, you might take a look at the ADS8634.  This is a four channel part that can accommodate your +/-10V input needs and can operate from 3.3V on both of its AVdd and DVdd rails.  It does require a bipolar supply (HVDD and HVSS) as well which can be up to +/-15V.  So, not exactly a single supply device, but it might suit your needs.

  • 0 in reply to Tom Hendrick
    Prodigy 30 points

    Hi Tom,

    Many thanks for the quick response.

    I did had a look at ADS8634 before i posted the query but what i found is the typical values for bipolar supply (HVDD and HVSS) are +/-10V only. If we supply the maximum voltages i.e, +/-15V to them, it might lead to problems. What do you think?

    Why the ADC's with +/-10V input range does not work on 3.3V supply? Do we need any extra circuitry?

    Also, can you please let me know what is the life of ADS8634/8638

    Thanks,

    Kiran

     

     

     

     

  • 0 in reply to kiranraj deshaboina
    TI__Guru**** 168605 points

    Hi again Kiran,

    Running the ADS8634 or ADS8638 with +/-15V applied to HVDD/HVSS will not cause you any problems.  By the life of the ADS8634, if you are referring to MTBF estimates, please check out this website:

    http://focus.ti.com/quality/docs/partnumsearch.tsp?templateId=5909&navigationId=11213&mtbfType=true

    If you are wondering if we're going to stop producing the part any time soon, the answer to that is 'No' - we generally do not obsolete parts unless we physically can't make them anymore.  I can't give you a great answer on why bipolar input devices are not single +3V supply compatible other than that there are come Si process related issues, we're working on that though. 

  • 0 in reply to Tom Hendrick
    Prodigy 30 points

    Hi Tom,

    Many Thanks for the information.

    The requirement of our client is that the components life which we are going to select in the new design has to be 10 years from now. I hope if i select ADS8634/8638 for my design, its life will be for 10 years.

    Also, Can you send me reference designs or applications notes related to ADS8634/8638 if any so that i can refer them when i need to build circuitry around the IC, please?

    Thanks again,

    Kiran

     

  • 0 in reply to kiranraj deshaboina
    TI__Guru**** 168605 points

    Hi Kiran,

    We have a number of devices in our portfolio that are still shipping after 20 years, so I don't have any reason to doubt that the ADS8634 and ADS8638 will still be shipping into 2023.  There is a schematic for the ADS8368EVM-PDK in the back of the users guide at this link that you can use for reference:

    http://www.ti.com/tool/ads8638evm-pdk