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ADS1246: AVSS Pin Characteristics

TI-CSC
Genius 13005 points
Part Number: ADS1246
Other Parts Discussed in Thread: LM7705, ADS124S06

Tool/software:

Hello E2E Experts,

Good day.

I am trying to use the Avss pin on the ADS1246 ADC to create a linear operation region that includes 0V. To do this I am trying to supply -100mV to the pin. There is not a lot of information in the datasheet that I can find to know the pin impedance or the output current from the pin during operation. I am hoping to use a resistor divider and a voltage regulator to supply the -100mV but without information about the pin impedance and supply current I am having trouble modeling the pin to create the appropriate resistor divider.

I am looking for more information about the pin's operation, and am open to advice on how to properly use the pin to create the desired behavior.

Regards,

TICSC

  • 0
    TI__Guru 52316 points

    Hi TI-CSC,

    I don't have any pin characteristic information to share right now. Is there any reason not to just use a true bipolar supply e.g. +/-2.5V, instead of biasing AVSS to -100mV? It sounds like there will be a negative supply rail in the system already, so why not just use this to bias AVSS directly?

    Alternatively, they can use something like LM7705 (https://www.ti.com/product/LM7705). This device provides a constant -0.232V signal and can be connected to AVSS to provide the small negative voltage required to be able to measure single-ended signals with this ADC

    Another option is to use the next generation version of this device, the ADS124S06. This ADC can measured single-ended signals with a unipolar supply.

    -Bryan