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PGA450-Q1: PGA450-Q1 Internal Temperature Sensor

Part Number: PGA450-Q1

In the PGA450-Q1 has an internal temperature sensor when I am trying to access the internal temperature value initially its giving correct value.

Later sometimes the chip is giving constant junk values from the internal register, is the internal Temperature sensor is not reliable or any other issue

I am adding my code snippet here with please provide a feedback for the same 

/* In Default the temperature sensor is disabled, to enable the same we need to set the TS_DAC_EN = 1 & TS_DAC_MODE = 0 bits in TEMP_DAC_CTRL ESFR */

                                TEMP_DAC_CTRL = 0x01;

                                /* Delay for Approximately 1.4 ms */

                                for(Count = 0;Count <= 23000;Count++);/*1.4375 ms */

                                u8PGATemSenOutPut = TEMP_SENS;

                                 TEMP_DAC_CTRL = 0x00;

  • Hi Rakesh,

    How have you come to use a delay of 1.4ms?
    Your TEMP_DAC_CTRL update is correct for a temperature sensor reading.

    How much later after the device has been running does the device begin to return invalid data? At what point in your overall code are you running the temperature sensor measurement (i.e. prior to a burst, after the FIFO has filled, or else where)?

    Is the invalid temperature sensor data value consistently similar? If so, how much different (in degrees) is a bad value compared to a good value? Can you provide an example of good vs bad values?
  • Hi Akeem,

    The 1.4ms is from the device data sheet please refer 7.3.10 Temperature Sensor (PGA450-Q1)

    The PGA450-Q1 has an on-chip temperature sensor that provides a signed 8-bit 2s-complement output (MSB is
    the sign bit) with code 0 corresponding to 30°C. The temperature sensor has a typical gain of 1.75°C / code. The
    temperature sensor is disabled by default. The TS_DAC_EN bit in the TEMP_DAC_CTRL register must be set to
    enable the temperature sensor. The conversion time is typically 1.4 ms.

    I have changed the delay from 1.4 to 20ms for testing the same the readings are not consistant, in the error conditions the TEMP_SENS output shows as 0xFF

    With Regards,
    Rakesh Hegden
  • Hi Rakesh,

    Can you specify what the device is doing just prior to taking a temperature sensor reading? For instance, are you performing a burst/listen command prior to waiting 1.4ms to read the TEMP_SENS output?

    How much later (in minutes or hours) after the device has been running does the device begin to log faulty TEMP_SENS values?
    Is the time to occasional TEMP_SENS failure always the same? Is the faulty value always 0xFF?

    How many devices have you run this code on? How many occasionally output a faulty TEMP_SENS value?
  • Hi Akeem,
    I have put the device to do the temparature logging alone for every 3 seconds continuesly for 5 hrs in Evaluvation Board. the results are satisfactory got the logged data perfectly allright.
    after that it start inconsistance output.
    tried the same in our Application board it was in consistance for couple of minutes then it also started failing .
    i had put my device on continues test it samples the data ater every 35 seconds and found the device gives correct output very rarely less than 1%.
    i have found the same issue in 4 +1 devicess
    i have tested the board for 3 continues days and the result is total fail (pass rate is less than 1%)
    with regards,
    Rakesh Hegden
  • Hi Rakesh,
    Can you send us one of your datalogs (100~1000 datapoints) so that we can see the failing values, and occasional passing value?
    For the datalog you provide, are you at room temp (25°C)?
  • Discussion continued offline.