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ADS1248 single ended

Daniele Mereu
Prodigy 60 points
Other Parts Discussed in Thread: ADS1248

Hi all

I've a question about how to configure registers to do a measure on a single ended input of a ADS1248.

I've this configuration:

  • AIN0 - AIN1: first differential input
  • AIN2 - AIN3: second differential input
  • AIN4 - AIN5: third differential input
  • AIN6: first single ended input
  • AIN7: second single ended input

When I've to do a measure on the AIN6 or AIN7 inputs, how can I configure the mux0 register?

MUX0 register always wants a pin definition for the positive and the negative input but I only have the positive one.

Is there a way to tell to the ADS converter to measure the voltage from AIN6 and  the internal ground reference? If yes, which registers should I use?

Thanks

Daniele

  • 0
    TI__Guru* 92715 points

    Daniele,


    There isn't a way for the ADS1248 to internally connect the ground reference to the ADC in the way you are describing. While there are some other system monitoring options for the ADC to measure, you must select a positive and negative input for the multiplexer with the MUX0 register. In this way you may be able to make 7 single-ended measurements with the 8 analog input pins.

    However, note that if you use the one of the AINx channels for a ground input, the ground line may be outside the input range (AINx measurements need to be higher than AVSS-0.1V). Also note that if you choose your supply to be +2.5V for AVDD and -2.5V for AVSS, then the ground is within the input range and it is not a problem.


    Joseph Wu