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ADS5400: Reset/sync waveform

Part Number: ADS5400

Hi,

Figure 1 of the datasheet states that "RESET can be a single pulse, low-to-high step or repetitive pulse input signal". I want to also make sure whether an evenly divided version of CLKIN signal fed into the RESET input is also valid condition for synchronizing CLKOUT dividers across multiple ADS5400s. For example, could you confirm that the attached waveform fed into the parts (RESET signal is edge-aligned divided-by-4 version of CLKIN) would result in proper CLKOUT alignment on every part with SYNCOUT pulse every 4 samples.

 
Best regards.
  • Hi KJ,

    No, this is not valid. This is a periodic RESET signal. In the current configuration, your RESET is latched on two sequential falling edges of the clock. This will result in two sequential SYNCOUT pulses repeating every 4 samples.

    To achieve what you are asking for, RESET should only be high for one clock transition and then low for 3 as in the below image. This will result in the SYNCOUT occuring every 4th sample.

    Be sure to note the 7 CLK latency of N is the same as the latency between SYNCOUT and the latched RESET.

    Regards, Chase

  • Hi Chase,

    thank you for the answer,

    1) regarding only CLKOUT dividers, will waveform in my original post correctly align them between multiple ADS5400s?

    (Assuming I'm ok with SYNCOUT for multiple times, when RESET is latched in high state,
    but will CLKOUT stay in the same phase for all parts after the first RESET period and initial alignment).

    2) Or maybe RESET=CLKIN/2 is a better idea to just align the dividers?

    Best regards

  • Hi KJ,

    If you are only wanting to align the data once after power up, any width pulse is sufficient. The periodic signal is just to maintain that the phases are aligned throughout data capture. Any CLKOUT/N where N is an even integer should be sufficient and allow the timing to workout. CLKOUT/2 or CLKOUT/4 will be fine.

    Regards, Chase