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ADS1232 differential signal range at gain of 1 or 2

Jayaraj Anbalagan
Prodigy 30 points
Other Parts Discussed in Thread: ADS1232

Dear Sir,

     Thanks for your reply, previous reply (+24V load cell excitation).

Doubt:

   ADS1232, with a gain of 64 or 128, intake differential signal.

 With the gain selection of 1 or 2, will the ADS1232 intake differential signal?

If yes, what is the maximum differential voltage, is it 2.5V (for gain of 1) & 1.25V (for gain of 2)?

Kindly reply us,

   With regards,

Jayaraj.A

  • 0
    TI__Guru** 113765 points

    Hi Jayaraj,

    If you excite a load cell with 24V, then at the output of a balanced bridge (no load) you will see 1/2 of the excitation voltage (12V) with respect to ground.  You cannot simply measure the difference between the bridge outputs, but must also consider what voltage the bridge outputs are with respect to ground.  If the the ADS1232 is 5V AVDD, then when you connect the load cell you will damage the ADS1232 as the input exceeds the absolute maximum specifications (AVDD + 0.3V, maximum).

    The maximum voltage range that can be measured will be dependent on the reference voltage used.  The formula is shown on page 3 of the datasheet (+/-0.5Vref/Gain).  So if the reference voltage is 5V, then your calculations are correct.

    Usually 5V excitation is used with gain of 128.  The same voltage for excitation is used for the reference to limit noise and drift by making the measurement ratiometric.  This makes the balanced bridge at 2.5V relative to ground, which is well within the common mode input range of the ADS1232 inputs.

    Best regards,

    Bob B