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ADS8885: Can ADS8885 be run at 250 KSPS (16-bits)

Part Number: ADS8885
Other Parts Discussed in Thread: ADS8339

Hello I am using ADS8885 which is originally 18-bit 400ksps ADC, I have connected to my DSP using 3-wire mode without busy indicator.

Is it possible to acquire data at 250ksps@ 16-bit resolution, which is not integer multiples of 400ksps? 



  • Hello Rahul,

    Technically speaking yes, but this would not be a good use of the device.

    The device can run up to 400Ksps, thus it can support a sampling rate of 250ksps.

    As for the 16 bit resolution, I imagine this would mean you are not clocking out the last two bits, and proving a CONVST pulse without reading them out.

    If you do not need the higher resolution, this device has a 16 bit variant, the ADS8685, which is more economical.

    But from your previous post, which I am assuming is about the same issue, where you are using the ADS8339, also provides what you are looking for, unless the DSP you are using cannot support it?

    If you could you provide what your input source is, we can provide the best fitting ADC for your application.



  • Thanks for the prompt response Cynthia, 

    Solved the issue, yes I am pulling CONVST high after reading 16-bits. I am doing this to experiment with different sampling rates and ADCs for prototyping.

    Also, can you brief or guide me about what parameters will be affected, so I can research more about it. 


  • Rahul,

    Let us know if there is anything specific you are looking for.

    As for what will be affected, if you cut off the last two bits, you are now limiting the resolution of the device, the LSB size now is limited to 2*Vref/2^N = 2*2.5/2^16 = 76.3 uV. This will limit the SNR of the device, you will not be able to achieve the high 100dB of SNR offered by the device. Even with an ideal device, with a 16 bit device, best SNR is 98 dB.

    In general, the Data Converter Learning Center has some good material covering different aspects of the Signal Chain.

    Also, when you get deeper into your design, the Circuit Cookbook has different application solutions that might prove helpful.

    Regards, Cynthia

  • Thanks Cynthia I am aware about the Dynamic range and SNR.
    Thanks for the help. ADC ADS8885 is running perfectly well now.