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HDC1080: humidity output constant at 0xFFFC

Part Number: HDC1080

Hi,

we are experiencing some problems with humidity output of the HDC1080 sensor. The sensors were working properly for more than a month. then the problems began. After a longer period of high humidity exposure (RH% at 80 - 85, 2-3 days), the sensors output went to 0xFFFC and it is stuck there. 

One of the problems might be our PCB. The HDC1080 is used as a substitute for a different sensor SI7020 (Silabs). We didn't change the PCB because our engineers thought they were pin to pin, but unfortunately it isn't so. In our case the pins 3,4 are connected to VDD (3V) and the DAP pad is connected to GND. Also the ceramic capacitor between VDD and GND in 1uF instead of 0.1 uF. Might this in any way affect the performance of the sensor or cause the problem we are experiencing?

Thanks in advance for your response. 

Primož

  • Hi,

    I forgot to add that the temperature output of the sensor is correct and responsive to the change of surrounding temperature.
  • Hello Primoz,
    The readings from the sensor points to a damaged humidity sensor. Ina addition to that the temperature is wrong, right?

    Please share the schematics with us. We can contact you privately if you prefer.

    Regards,
    Jose
  • The temperature reading is correct. We tested the sensor in a temperature  controlled chamber and it performed as expected with an avarage error of 0.2 deg. Celsius.

    I will send you the schematics in a couple of hours, because its 11pm in Slovenia and I'm not in my office at the moment.

    Thanks for the response, if you could contact me privately that  would be great.

    (primoz@termomer.com)

  • Hello Primoz,

    a correct temperature reading in combination with a zero or full scale humidity output points to a damaged sensor polymer. 

    We will release an application note early next week which contains information on handling the devices and avoiding damage to the sensing layer.

    I will email you to work with you on the schematics.