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Voltage Reference warmup and long term drift

I am designing a 12V battery powered data logger that will be sampling every 15 minutes.  I am currently using the LTC2408 ADC with the ADR4550 reference.  I am removing power from the ADC and the voltage reference in between samples to save power.  I have a few questions.

1) How will constant power cycling effect the voltage reference? 

2) How long should the voltage reference be powered on to stabilize?

3) Will only powering the voltage reference for 10 seconds every 15 minutes reduce the long term drift?  Normally 1000 hours is 42 days, but in my scenario it would take 10.3 years for the voltage reference to be on for 1000 hours.  Would this improve the long term drift or would powering the voltage reference on and off cause other issues?

Thanks,

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  • Hi Thomas,

    1) Constant power cycling will not affect ADR4550. For more information regarding this please see page 

    2) The ADR4550 will settle down after 160us. This can be seen at the specification table, labelled as Turn On Settling Time. Or you could also see the voltage reference response in Figure 71.

    3) No. Long term drift will work the same way power up or down.

    Regards,
    Mon

  • Thank you for answering my questions.  This helps alot. 

    I am surprised at #3.  I would think that most parts have been sitting on a shelf for several months, so they would be past the 1000 hours that long term drift is most dramatic.  Is that true or does the soldering process cause the process to begin? 

  • Hi Thomas,

    The ELD and LTD test are done after the unit is soldered to the board. And most of this drift are due to mechanical/physical stress applied to the package due to different temperature reaction of different material.

    Regards,

    Mon

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