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ADS1118: Temperature drift poor linearity

Chris Peng
Prodigy 560 points

Part Number: ADS1118

Hi team,

My customer Repower who make the BTS equipment using the ADS1118,

But they find the ADS1118 have poor temperature drift about 1mV/℃, and due to poor linearity and difficult to correct in software.

Do you have any good advice or another part with good temperature drift linearity to cover the problem?

  • 0
    TI__Guru 58981 points

    Hi Chris,

    Is there a specific offset drift target that the customer is looking for? If so, can you provide this value?

    Can the customer perform an offset or gain calibration to help improve performance? A periodic offset calibration will help remove the offset, which in turn removes the offset drift

    -Bryan

  • 0 in reply to Bryan Lizon86
    TI__Guru 58981 points

    Hi Chris,

    Also, how is the customer determining the temperature drift? The offset drift is specified as 0.002 LSB/C (typ), while the gain drift is 5 ppm/C (typ). At FSR = +/-2.048V, this is the equivalent of 0.125uV/C and 20.48uV/C, respectively. So the ADC drift cannot cause the 1mV/C drift that the customer is seeing.

    Additionally, The ADS1118 has a linearity (INL) spec of 1 LSB max, which means it should not even show up in the output code.

    I would guess that the issues the customer is having are coming from somewhere else in the circuit. Can you share a schematic?

    -Bryan

  • 0 in reply to Bryan Lizon86
    TI__Prodigy 560 points

    Hi Bryan,

    Thanks for your reply, my customer just find the 1mV/C in the test. i will ask the schematic and send you a e-mail. Thanks for your help~

  • 0 in reply to Chris Peng
    TI__Guru 58981 points

    Thanks Chris, I will wait for your offline feedback then.

    -Bryan