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  • TI Thinks Resolved

ADS7854: Can I run the ADS7854 with AVDD = 3.3V?

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Part Number: ADS7854

I'm designing a battery operated medical device and I would like to run the ADS7854 with AVDD = DVDD = 3.3V and an external reference of 2.5V on pins REFIO_A / B. The datasheet specs AVDD at 4.5V min. Initial testing all looks good. Are there any technical reasons that would prevent AVDD = 3.3V?  

  • Hi user4053363,

    When using the device in 2xVREF mode with external reference of 2.5V, the minimum AVDD supply allowed is 5V. This is necessary since the AVDD can not be less than the expected input voltage, where the full-scale range of ±2xVREF or ±5V. This is the technical reason for the ±2xVREF range.

    The device also requires a minimum AVDD of 4.5V for the ±1xVREF range. I will need to verify with design, however, I believe there will be linearity degradation when applying AVDD < 4.5V when the device is set up with VREF=2.5V and ±1xVREF range.

    Many Thanks,

    Luis Chioye

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