[FAQ] HDC2080/HDC2010/HDC1080/HDC1010 - How does TI recommend doing practical testing of HDC based application end equipment?

A combination temperature/humidity chamber is highly recommended / needed for lab testing, usually employed during product development, characterization and validation of the end result. The temp/humidity chamber usually has temperature and humidity sensors and will display both values it reads internally – but these devices have their own accuracy variance specifications which typically would be wider than the accuracy/variance specifications of the devices that are to be measured. To overcome this problem, a high accuracy measurement device should be procured and deployed with the chamber, as these devices will have similar or tighter specifications and will allow best reference for DUT testing.

 Here are some reference links to this kind of lab equipment:

Temperature and Humidity Chamber: https://www.testequity.com/1007H-specs

Dew Point Mirror: http://www.rhs.com/product_473.php

Other measurement devices: https://www.rotronic.com/en-us/humidity-measurement-feuchtemessung-temperaturmessung/humidity-measurement-feuchte-messung.html/

For procedural details, from a high level, the chamber and the reference should be calibrated on a schedule and it, the reference sensors and the DUTs should be allowed to settle for sufficient time for both temperature and humidity, according to chamber user guide, after setting points for temperature and humidity, and before recording any device measurements to be used later.

This chamber vendor has a table with waiting times for temperature to temperature changes on page 6-1. https://www.testequity.com/UserFiles/documents/pdfs/1007H-420.pdf

For accurate temperature measurements, as mentioned above, humidity and temperature ovens are often used for testing of systems across temperature, but they are generally not a good tool for verifying temperature sensor accuracy. This is because temperature gradients within ovens can be on the order of a few a degrees, meaning that proximity of the temperature reference to the sensor must be considered. In fact, the temperature chamber vendor may even specify the expected or known gradient of the temperature chamber. The uniformity specification for one chamber familiar to TI is ±1°C or a total of 2°C, when measured at least 2" away from the chamber interior walls. These specifications are for an empty chamber. The addition of a test sample may affect the temperature uniformity. For example, an energized test sample will produce a higher temperature near the sample.  See page 5-2 here: https://www.testequity.com/UserFiles/documents/pdfs/1007H-420.pdf

 In some cases, even when very close, it is still possible that air currents within the oven can create the appearance of excessive temperature error between reference and sensor. For these reasons, the use of a stirred liquid(oil) bath is preferred for testing of temperature accuracy. The bath will be filled with a non-conductive thermal oil to allow the test fixture to be placed directly in the bath. A calibrated temperature reference should be included to compare to the device readings.

Example oil bath which has range of -40C to 110C:  https://us.flukecal.com/products/temperature-calibration/calibration-baths/standard-calibration-baths/7008-7040-7037-7012-70?quicktabs_product_details=2, this company also makes >0C only / high temp versions and refrigerated baths for very cold to 110C measurements. https://us.flukecal.com/products/temperature-calibration/calibration-baths/standard-calibration-baths