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ADS1232 in weight scale

Jeff Wang100039
Intellectual 3000 points

Other Parts Discussed in Thread: ADS1232

Hi,

load cell rated output 1.3mV/V,  5V excitation. request : 200000 counts.

ADS1232 Gain 128, adc full scale range 39.1mV, utillzed ADC range: 5*1.3/39.1=16.6%,  potential counts: 2785017

ADS1232 AVDD=5V, Vref=5V, data rat=10sps. Gain =128, noise-free bits=18.4,    16.6% will lose about 2.4bit, customer can get noise fee bits 16.  throght software average can get one more bit(16+1=17),  so 100000counts is possible.

Any way to get 200000 counts?

thank you.

 

  • 0
    TI__Guru** 113765 points

    Hi Jeff,

    When looking at the numbers you want to resolve 200000 counts of 6.5mV or 32.5nV.  The converter itself has 110nV of noise.  Even 100000 is difficult because of layout constraints, external noise, drift, etc..

    We are working on some new devices that may be available sometime next year.  So about the only thing you can do is increase the input range for the ADS1232.  This will either require a low noise external amplifier, or an increase in excitation voltage.  The second option requires that the input voltage is within the common mode input range.  In either case you will lose the ratiometric measurement which will again increase the noise.

    Best regards,

    Bob B