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ADS124S06: increase in consumption current because of Capacitor to REFCOM

EDSON ABREU
Prodigy 140 points
Part Number: ADS124S06

Hi,

According to datasheet of ADS124S06 (page 6) we need to connect a 1-μF to 47-μF capacitor to REFCOM if the internal voltage reference is enabled.

My problem is that if this capacitor is placed, the consuption current increse about 25mA. I checked the hardware and firmware but i haven't found the problem yet.

Without the capacitor it works well.

Any suggestions to try to solve the problem or can I leave like this without the capacitor?

Thanks

Edson

  • 0
    TI__Guru** 113765 points

    Hi Edson,

    If you use the internal reference you need to use the capacitor for stability reasons. Without it most likely you will see an oscillation and a loss of accuracy.

    With the cap installed you will see some current draw while the cap charges. This should charge quickly and would not draw 25mA continuously. Can you give more detail on how you are measuring the current and where the current is being measured? Can you share your schematic with me?

    Is REFCOM connected to AVSS (see how the reference cap is connected in Figures 118 and 119 on page 96 of the ADS124S06 datasheet)? Does the increase in current occur with the cap installed, but even if the reference not enabled or turned on?

    Best regards,
    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 140 points
    Hi Bob,

    I'm doing some testing of the circuit I mentioned and the in other parts of the product and then I'm going to make some measures of what's going on. And I already noticed that the layout does not according to application note. As soon as possible, I'll sending the results of my tests and conclusions.