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ADS1278 + MUX timings

Other Parts Discussed in Thread: ADS1278

Hello,

I am using ADS1278 with a 16:8 multiplexer. How should I set the timing for mux switching related to ADC clock? I am using high resolution mode with 27MHz ADC clock. Mux has 6ns (max) switching time. I am planning to use 13.5MHz clock to switch the mux but how should it phase against the 27MHz ADC clock? When does the ADS1278 sample related to ADC clock?

Thanks in advance!

  • Hello Kalle,

    Thank you for your question and welcome to our forum! I'm sorry that we did not answer you sooner. I will offer my inputs below and I hope they can still be helpful:

    The ADS1278 modulator samples the input on the falling edge of the modulator clock. My main concern with your proposal is the latency of the digital filter, which would require 78 conversions to output fully-settled data after an input-transient in High-Resolution Mode, which amounts to 1.5ms. 

    Just to be sure I'm understanding correctly, were you planning to switch the MUX every 1/13.5MHz = 74.1ns? The data will not be settled within that time. 

    Best Regards,