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about HDC1080 power consumption

Other Parts Discussed in Thread: HDC1080

Hi Dear experts,

We have an opp DIN HDC1080 in ZTE project, and ZTE care about the power consumption of the device. Check the datasheet, it lists the supply current and heater current, i don't quite understand. Could you please explain?

thanks very much!

Joyce

  • Hi Joyce,

    As reported in the datasheet, the heater is a feature of the HDC1080 humidity sensor that can be used for the self-test of the sensor or to drive condensation off from the sensing element. It consists in an integrated resistive element that when is passed through by current, it begins to dissipate power, increasing the temperature measured by the sensor of about 1.5 to 2deg. It is also able, due to the temperature increase, to evaporate the condensation water, if this is deposited on the sensing element

    In any case, in the normal operation, the heater is switched off, so the average power consumption of the HDC1080 is very low and strongly depends on the sampling frequency: as example, as reported in the datasheet, the average current consumption in case of a 1 measurement for second,of both RH and T at 11 bit resolution, is only 1.3 μA

    Only in the case the customer want to use the heater, he needs to switch on it, setting to '1' the bit [13] in configuration register 0x02. Only at that point it starts to consume 7.2mA.

    Please consider that the heater is passed through by current only during the conversion time. It means that the temperature increase is related to the sampling frequency. The temperature increase is also strongly related the PCB design.

    I will reach you to your email address to better understand the details of this opportunity with your customer, in the meantime please let me know should you have any question or need further infomarmation

    Best regards,

    Carmine

  • Hello,

    I am also trying to get my head around the power consumption values for my application, but can't figure it out. Ideally if I could get a figure for the average current when waking up and measuring and measurement time I could figure out the new average for my application.

    I'm estimating that I would take a measurement once every 10 - 20 minutes, but I'm not certain yet.

  • Hi Craig,

    let me try to do an example based on your application:

    IDD during RH measurement = 190uA (typ.);

    IDD during T measurement = 160uA (typ.);

    IDD in sleep mode = 100nA;

    Considering RH at 14 bit of accuracy + T at 14 bit of accuracy the conversion time are:

    RHCT = 6.50msec;

    TEMPCT = 6.35msec;

    If you read data every 10 minutes = 600 seconds = 600000msec, your average power consumption is:

    ((Idd RH * RHct) + (Idd T * Tct) + (600000 - RHct - TEMPct)*Idd SLEEP)  / 600000 = ((190*6.50 + 160*6.35) + (600000-6.5-6.35))/600000 = 103.75nA typ.


    Please, let me know if this example is clear enough.

    Best regards,

    Carmine

  • Very clear, thank you!