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ADS1234: voltage reference and analog input

Yakov Heifetz
Prodigy 20 points
Part Number: ADS1234

Tool/software:

I'm using the ADS1234 to measure a bridge.
The reference voltage is 2.5V. If I use a GAIN of 64, what will be the maximum voltage that the ADC can read?
Is the calculation 0.5Vref/64?

Second question: Since the component operates in a two's complement configuration, will the maximum readable voltage be Vref/2?
Is there a way to bypass the two's complement format?

  • 0
    TI__Mastermind 43000 points

    Hello Yakov,

    I will follow-up with answers tomorrow.  Thanks!

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    TI__Mastermind 43000 points

    Hello Yakov,

    Yes, you are correct.  The maximum differential voltage that can be read will be 0.5*2.5/64 = 19.53125mV and the minimum differential voltage will be -19.53125mV.

    Yes, with GAIN=1, the maximum differential voltage will be Vref/2.  Using Vref=2.5, this will be +1.25V. 

    Since the ADC can read both positive and negative differential voltages, the data is always encoded as two's complement.  There is no way to change the data encoding to straight binary.

    Regards,
    Keith