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ADS1220: Power-up ramp timing question

Anders Torsein
Prodigy 110 points
Part Number: ADS1220
Other Parts Discussed in Thread: ADS1120

Hi,

I'm currently working with a new design that do use an TI ADS1220.

The data sheet SBAS501C (Revised  August 2016) chapter 10.2 states that "for proper device power-up over the entire temperature range, the Power-supply ramp rate must be monotonic and slower than 1 V per 50 us...".

I interpret the information in the thread "ADS1120 DRDY pin not going low after Power-up" as a too Quick supply voltage Power-up might lead to that the ADC internal oscillator not is activated.

Will there still be need for slow ramp time if temperature is kept stable at 26 *C (i.e. what do the data sheet "entire temperature range" imply)?

Is the voltage ramp timing still critical if an external frequency source is connected to the ADC CLK pin? 



Thanks in advance for clarification!

       best regards

               Anders T

  • 0
    TI__Guru** 113765 points

    Hi Anders,

    The full operating temperature range is -40 to 125 deg C for the ADS1220.  The startup issue is process and device dependent and not all ADS1220 devices will act the same way.  The startup recommendation is to ensure that in every application and system using any ADS1220 that the device will properly start up.  With fast start up ramps there is no certainty that the device will startup even at room temperature.

    If you use an external clock, there is no ramp requirement.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 110 points

    Thanks!

    The issue is closed.