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TPS659037: Using internal ADC for external temperature monitoring (using a NTC)

Patrick Ruf
Genius 4965 points
Part Number: TPS659037
Other Parts Discussed in Thread: TWL6032EVM

Hi,

Is there any example on how to measure a temperature with a NTC connected to GPAD_IN1 and a resistor to GPADC_VREF? A schematic is displayed on page 77 of the TPS659037 datasheet (slis165e). But there is no information concerning the values of the used resistors and NTC thermistor.

Thanks and best regards,
Patrick

  • 0
    TI__Genius 16410 points
    Hi Patrick,

    You will want to have a fixed resistor from GPADC_VREF to GPADC_IN1, then a fixed resistor and NTC thermistor in parallel from GPADC_IN1 to GND. This will create a variable resistor divider based on temperature. You should select the fixed resistors based on the thermistor resistance profile across temp, so that the GPADC input voltage is between 0.01V and 1.215V (range of GPADC_IN1). In practice, you'll want to select components that have a narrower range to give margin.

    For a reference circuit, you can look at the TWL6032EVM, it has a resistor/thermistor network on one channel for temperature measurement.

    Regards,
    Karl
  • 0 in reply to Karl Wallinger
    Genius 4965 points

    Hi Karl,

    Thanks for the link. This will be a good base for my own device selection and calculation of the device values.

    Best regards,
    Patrick