RTOS/HDC2080: Humidity sensor questions

Hi Hugo,

Please refer to my answers posted in the bullets below:

I'm not entirely sure if I understand the inquiry to question 1 and question 2, can you provide more information behind the questions?

3. How to process condensation problem? There is a heater that can be set by writing to a register field. The heater can be run briefly to remove or reduce any condensation that may develop on the device.

4. How to notes Layout placement? Please refer to the following document:
www.ti.com/.../snaa297

Best Regards,
Matt

1. Does must be outside chamber as below? If not, have any problems?

The illustrations shown are based on designs that allow water vapor to flow within the product enclosure for correct humidity readout.

2. If yes as Q1, How to design chamber size? Opening method? How to balance inside temp? This will all boil down to layout and heat sources generated from power hungry ICs.

3. What kind of opening model is popular application above figure? Figure A and B allow better air flow than C and D and are often used when designing applications.

4. About condensation problem, does steam condensation cause accuracy for temp and humidity? The device includes an internal heater that can be used to drive off or prevent condensation to maintain accurate readings.

5. What is testing humidity environment in your lab? How to decide accuracy for HDC solution? We test our products with a temperature and humidity chamber that ensures the accuracy described and guaranteed in the datasheet.

Hi Matt sir

1. Does must be outside chamber as below? If not, have any problems?

The illustrations shown are based on designs that allow water vapor to flow within the product enclosure for correct humidity readout.

2. If yes as Q1, How to design chamber size? Opening method? How to balance inside temp? This will all boil down to layout and heat sources generated from power hungry ICs.

3. What kind of opening model is popular application above figure? Figure A and B allow better air flow than C and D and are often used when designing applications.

4. About condensation problem, does steam condensation cause accuracy for temp and humidity? The device includes an internal heater that can be used to drive off or prevent condensation to maintain accurate readings.

5. What is testing humidity environment in your lab? How to decide accuracy for HDC solution? We test our products with a temperature and humidity chamber that ensures the accuracy described and guaranteed in the datasheet.

Howdy Hugo,

I see that you copied and paste the questions with answers, please let me know if this answers all your questions.

Best Regards,
Matt

Hi Hugo,

1. Relative Humidity relies on Temperature information, therefore you will need to ensure that the device is away from any heat sources in the form of thermal mass through heat conduction in the PCB, or hot ICs. Just to give you an example of how significantly temperature impacts humidity, 1C of temperature difference affects the RH reading by 4-5%RH.
2. Layout is very important in humidity sensing, as the sensor should be placed away from heat sources, and the opening of the enclosure should allow air to flow onto the humidity sensor.
3. No question was asked.
4. The internal heater can be invoked by writing to a register bit. It's important to note that the only function of the heater is to verify the functionality of the temperature sensor, and to drive or prevent condensation from developing on the exposed polymer.
5. We used a chilled mirror for reference, and use a humidity chamber for test.
6. All answers apply to both devices.