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HDC1000, how to use a heater?

Shinichi Inoue
Guru 21701 points
Other Parts Discussed in Thread: HDC1000, ENERGIA, HDC1080

Dear Specialists,

My customer is interested in HDC1000.

He has a question about the heater in device.

Could you advise me?

According to the datasheet page 9, the heater helps in reducing the accumulated offset after long exposure at high humidity conditions.

Could you give me an use case of heater about temperature, humidity and time. 

Before evaluation, he wants to know specific example of control sequence. 

And he wants to have a image of control.

Best regards,

Shinichi

ヒーターの使用条件について、高湿度状態に長く放置された場合と
　記載がありますが、具体的な使用条件等（実績など、例えば
　〇〇℃、〇〇%以上では〇時間ごとに必要）
　は御座いますでしょうか。

明確に時間が指定できないのは
　理解致しますが、例えばこのような環境では
　こういったシーケンスで動作させていた　というような実例や、
　だいたいの目安を開示頂けないでしょうか。

　当然評価は行っていくとしても、なんとなくの
　イメージを持っておきたいです。
  • 0
    Guru 21701 points

    Dear Specialists

    Does anyone reply above question.

    The customer wants to know how to use the heater device inside.

    Best regards,

    Shinichi 

  • 0 in reply to Shinichi Inoue
    TI__Intellectual 1960 points
    Dear Shinichi

    HDC1000 embedded heater is switched on only during the conversion time.
    To heat the device the bit nr. 13 in the register 0x02 has to be activate.
    To increase the heating power we suggest to increase the sampling frequency up to 200ms.

    It's difficult to provide information about the temperature increase (in the range of 1-2 degC) because are related to the PCB design and external condition (ventilation, humidity ect.)

    Best Regards
    Massimo
  • 0 in reply to Massimo Mascotto
    Guru 21701 points

    Dear Massimo

    Thank you for your reply.

    I'll send your suggestion to the customer.

    The customer is a beginner, so he wants to know how to design from the start.

    I appreciate your great help.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    TI__Intellectual 1960 points
    Than k you very much.

    Best Regards
    Massimo
  • 0 in reply to Massimo Mascotto
    TI__Genius 12865 points
    Hello Massimo,
    I am using the HDC1000 EVM and I broke the sensor part off in order to connect it to a CC3200EVM. I can enable the heater but it doesn't get above 32°C. What do you mean by increasing the sampling frequency, please?
    Here is my code (using Energia)
    Wire.beginTransmission(0x40); // transmit to device #40
    Wire.write(2); // set pointer
    Wire.write(0x3D); // enable heater
    Wire.write(0x00); //
    Wire.endTransmission(); // stop transmitting

    //for (k=0; k<200000; k++){
    Wire.beginTransmission(0x40); // transmit to device #40
    Wire.write(0); // trigger measurement; config default is 0x1000
    Wire.endTransmission(); // stop transmitting
    //}
    With the code above I see 26°C. If I remove the comments I get 32°C. What would be the max. temperature with this pcb and how to achieve it?

    Thanks and Best Regards,

    Hans-Günter
  • 0 in reply to Hans
    TI__Intellectual 1960 points

    Hi Hans

    In the HDC1000 the Heater is active only during the conversion time.

    Increasing the sampling rate and the resolution is the best way to increase the HDC1000 temperature.

    There is a limitation in the maximum amount of current that flow in the heater and based on the PCB design an increase in the range of 3 to 10 degC is expected.

    Big impact has the PCB design (thermal isolation) and the air flow.

    Regards

    Massimo 

  • 0 in reply to Massimo Mascotto
    TI__Genius 12865 points
    Hi Massimo,
    yes, I noticed that increasing the sampling rate will raise the temperature INDEPENDENT the setting of the heater enable bit.
    Is it possible to get a flow diagram which shows the correct way of using the heater, please?
    Any example source code available?

    Best Regards,

    Hans-Günter
  • 0 in reply to Hans
    TI__Intellectual 1960 points
    I Hans

    I'm going to prepare a app note to address your question.

    Best Regards
    Massimo
  • 0 in reply to Massimo Mascotto
    Prodigy 40 points
    Hello Massimo

    Is the app note available?

    In our application a high relative humidity is possible, therefore we plan to activate the heater periodically.

    Unfortunately we have no idea how long we should use the heater and which periode makes sense?

    Thanks in advance,

    Thomas
  • 0 in reply to Thomas Kaufmann88
    TI__Expert 5145 points

    Hi Thomas,
    Unfortunately the application note on the usage of the heater is not available yet.
    Sorry for the inconvenience.
    In any case, we suggest to activate the heater only in presence of condensation, and turn it off after the condensation disappears.
    The time you need to keep it activated depends on the sampling rate (bigger is the sampling rate, higher is the temperature increase, shorter is the time you need to keep it on), but also from the boundary conditions of your board (as for example PCB layout).
    Best regards,
    Carmine

  • 0 in reply to Carmine Iascone
    Prodigy 40 points

    Hi Carmine

    Thank you for the quick response!

    As said before in our application a high relative Humidity is possible.

    If I understand the datasheet correct following happens:

    - This high relative Humidity leads to an offset and a presence of condensation

    - This two effects leads to an measurement failure 

    At this point my problems starts, let's only take the offset problem for example: What can it do? Ok, I can activate the heater, but I don't know how long, because i don't know, after which time the offset will disappear. Is there any time value? For example after 10 minutes of heating the sensor works properly again? Or is there another way to solve this problem?

    Thanks in advance,

    Thomas 

  • 0 in reply to Carmine Iascone
    Prodigy 190 points

    Hello Carmine & Massimo,

    My application is a battery powered wireless sensor measuring humidity and temperature.

    I am using the HDC1080 device and I am struggling with condensation.

    About the application, in order to save battery power, a humidity and temperature measument is taken at every 80 seconds.

    After that, the device shuts down and only wakes up after another 80 seconds to do a new measument.

    In this post: e2e.ti.com/.../524867

    Carmine wrote "...The device is able to auto detect the condensation..."

    So how can the HDC1080 detect condensation?

    Besides, I've tried using the heater and that seems to help, but it consumes a lot more power.

    Thus, could you please clarify which is the best method to use the heater in order to still save battery?

    Thanks in advance.

    Gustavohdc1080_humidity_temp_log.xlsx