How to avoid errors when specifying sensor products

There are three things designers/engineers should seek to do when specifying sensor products. These are: thermal hysteresis, board mounts that are moisture sensitive, and sensors that are A/D convertible.

The ability of the sensor to come back to the same output after a thermal change is called thermal hysteresis. Designers underestimate errors due to thermal hysteresis, such as after warming an outdoor system up from a cold night or taking a portable device outdoors from a warm vehicle in First Responder equipment. When designing, choose a sensor product where Total Error Band specifications are given and make sure this includes Thermal Hysteresis, or look for sensors where errors due to Thermal Hysteresis are explicitly specified as their own performance parameters.

When adhering to a board, select board mount sensors which are not robust due to the reflow soldering process or those that take days to stabilize after board mounting. Look for surface mount sensors which specify compliance to J-STD-020D.1 Moisture Sensitivity Level 1 such as Honeywell HSC/SSC TruStability pressure products.

It is a misnomer to assume digital sensors cost more money than analog sensors. In many cases, sensors include conversion to digital signals as part of their internal output compensation circuitry. In those cases, conversion back to an analog signal is actually less cost-effective.

Honeywell
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