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ADS1246 vs ADS1118 for Thermocouple

1985518
Prodigy 100 points
Other Parts Discussed in Thread: ADS1246, ADS1118, ADS1247, TMP102, TMP112, INA333

Can the ADS1246 be used for accurate, high resolution thermocouple measurements?  The data sheet mentions that the PGA can be set to 128:1 and that it has an on-board temperature sensor, but I cannot seem to find any information regarding its accuracy.

I would like to read high resolution data from Type-E thermocouples, but the ADS1118 doesn't quite provide the resolution I am looking for.  It seems like the ADS1246 provides for much greater resolution, has more flexibility from the PGA, and can sample at a higher rate.

Thanks!

  • 0
    TI__Guru 55466 points

    Hi,

    The ADS1118 internal temperature sensor is high accuracy and is optimal to perform temperature measurements necessary for accurate cold junction compensation.

    The ADS1247/8 devices are optimal and often used to measure a thermocouples with high accuracy, but in general, they require an external high accuracy temperature sensor for cold junction compensation. The system monitor/internal temperature sensor of the ADS1247/8 is intended for coarse system temperature measurements.   A typical application of the internal temperature sensor of the ADS1247/8 will be to detect large temperature changes (in order of 10C) in the device to trigger a calibration.

    The TMP112/TMP102 low power temperature sensor is often used together with the ADS1247/8 performing thermocouple measurements with cold junction compensation.  Other possibilities include using an RTD or thermistor for cold junction compensation.

    The ADS1246 is also used for thermocouple measurements but it does not have an internal voltage reference built in.   The ADS1247-8 version includes an internal 2.048V voltage reference.

    Another option may be to use the ADS1118 with an external Instrumentation amplifier for additional gain. A possibility is the INA333,

    Best Regards,

    Luis