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ADS1298R: ADS1298R Sampling rate issue

Muhammed AbedElhadi
Prodigy 40 points
Part Number: ADS1298R

Hello TI team,
During the design verification we have countered issue with the sampling rate with one of he ADS1298R IC.

 We are working on 500 SPS, and one of the systems have failed on the sampling rate tests, it gives ~488[Hz] consistently, and we have checked the RDY signal and it really seems that the problem is with the ADS.
Any chance we can know what is the problem with this IC? according to the ADS datasheet, the internal oscillator (clock) accuracy is  +-0.5%., and we see that it is not the case here.

Our software is verified with another ADS IC and it seems to work well

.

Attaching screenshot for the RDY signal that shows that the sampling rate is ~488 [HZ].

10.24[msec]/5[pulses]=2.048[msec].
SR [Hz]=1000[ms]/2.048[msec]=488.28125[Hz]

Best Regards,

Muhammad

  • 0
    TI__Genius 11550 points

    Hi Muhammad,

    Thanks for the post. 

    The device's internal oscillator is tested during the production to ensure it meets the datasheet specification (+/-0.5% at 25C). Before we proceed to investigate the root cause, can you please verify the items below?

    1. Verify the internal clock oscillator frequency by setting CONFIG1.CLK_EN bit to 1 and measure the internal clock frequency on the CLK pin #37 with an oscilloscope.

    2. Is this the only ADS1298R device that you see the issue with the internal clock frequency out of specification?

    Thanks

    -TC