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ADS1194 internal Clock ( 2.048MHz ) with an error of 0.5% and dependent of temperature

David Aparisi
Prodigy 10 points

Hello,

We are developing a medical holter based on your ADS1194.

and we are watching that the internal clock (2.048MHz) have a variation of 0.5% more or less and this variation depends of temperature.

greater temperature -> lower frequency

Is it possible?

in normal use, the real frequency of this clock is 2.052MHz.

this variation of clock frequency generate a wrong sampling frequency.

How I solve this issue?

Thanks in advance,

  • 0
    TI__Mastermind 38745 points
    Hey David,

    If you look at page 5 of the datasheet, you can note that the internal oscillator has an accuracy of 0.5% at room temperature any up to 2% of tolerance from 0 - 70 degrees Centigrade. What you have measured looks to be expected behavior.

    Is your application highly dependent on sample time accuracy? The purpose of the DRDY output is to indicate when new data is available to the host which allows for the host's operation to remain asynchronous to the device.

    If exact time accuracy is required, you will have to provide an external clock that is either more accurate or synchronized to the host.

    Brian