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ADS1292: ADS1292 ISSUE

Jaimanoj Jayaraman
Intellectual 570 points
Part Number: ADS1292


Hi ,

We are using ADS1292 and we could be able to get ADC O/P(voltage) for the positive ADC I/P voltage successfully. No issue in reading positive voltage from ADC.

Our requirement is to measure the input voltage both positive and negative but we couldn't read appropriate negative voltage. We are getting wrong values.

Configuration:

We are using Channel2 and Channel1. Channel2 is for other purpose. This requirement is for channel1.

VrefP- 4.033

VrefN- Gnd

ADC I/P - Differential voltage of IN1P and IN1N

Our Register settings: [Note - Our project in not ECG]

CH1SET - 0x10 , RLD_SENS - 0x2C , LOFF_SENS - 0x0F , LOFF_STAT - 0x48, CONFIG1=0x02 ,CONFIG2=0xF8


Issue Faced:

If we provide negative input to ADC and we couldn't correct output from ADC. I summarized some of the values for your reference.

ADC-I/P   ADC-O/P

-4.285    0.00055288
-4.285    0.00055288
-4.285    0.00055423
-4.285    0.00055423
-0.483   -0.0006115
-0.378   -0.0006173
-0.29      -0.0006187
-0.208   -0.0006201
-0.03      -0.0006278

We require your advise on reading negative voltages. Please suggest on priority.

Regards

  • 0
    TI__Mastermind 38745 points
    Hello Jaimanoj,

    What are the power supplies provided to the device? The ADS1292 is capable of measuring negative voltages where IN1P < IN1N, but neither IN1P nor IN1N can be outside of the power supply rails. Equation 6 in the datasheet shows the limits of the input signals as they relate to the power supplies. To measure a negative voltage, you can set IN1N to (AVDD+AVSS)/2 and then make AVSS + 0.2V < IN1P < IN1N (assuming a gain of 1).

    Regards,
    Brian Pisani