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Gain in ads1230

Shalini Singhal
Prodigy 10 points

Other Parts Discussed in Thread: ADS1230, ADS1232

I was using ads1230 for weighing scale.I noticed, adc full range is for 2 mv to 630mv. My referrence in 5 V. negative input of adc is connected to GND.

It shows PGA gain is 4.

I could not understand this. according to data sheet, PGA gain is 64 or 128. According to the connection of gain pin, it should be 128.

Please help.

BR,

Munish

 

  • 0
    TI__Guru** 113765 points

    Munish,

    The ADS1230 has a PGA and it is either 64 or 128 based on whether the GAIN pin is high or low.  If you have the GAIN pin set for 128, the full-scale input range will be +/- 19.5mV for the 5V reference.  I'm not sure how you are calculating the full-scale range, but you can not read 630mV.  Here is where I think your problem is in that you are trying to read a single ended input.  You can't do that as the PGA restricts you to a common mode input range of 1.5V from either rail for either AINP or AINN.

    The ADS1232 will allow you to measure single ended inputs at a gain of 1 or 2.

    Best regards,

    Bob B