Sensor IC gives accurate RH and temperature

November 12, 2016 // By Graham Prophet
The ams' ENS210 sensor module features temperature measurement accuracy of ±0.2°C over the entire range 0°C to 70°C; the device also outputs relative humidity measurements on its I²C interface, enabling, ams says, portable and connected smart home devices to improve performance and implement new features.

The ENS210 provides a digital temperature output in Kelvin, and relative humidity measurements as a digital output accurate to a maximum ±3.5%. Shipped to customers as a calibrated unit, the sensor requires no trimming on the production line. It provides its digital outputs over an I²C interface, eliminating the need for signal processing by the host device’s applications processor or microcontroller.

Housed in a moulded plastic surface-mount package measuring 2 x 2 x 0.75 mm, the ENS210 is small enough to be accommodated in smart phones and wearable devices including fitness monitoring wristbands.

Drawing 40 nA in stand-by mode and 7.1 µA in active measurement mode (averaged, sampling at 1 Hz), the ENS210 operates from a wide input voltage range of 1.71V-3.6V. Temperature sensing, the company discloses, is by an optimised band-gap/current mirror detector; RH is measured as the capacitance presented by a membrane over the silicon device surface.

In wearable devices, the ENS210’s readings of relative humidity and ambient temperature may be used to enhance the accuracy and reliability of measurements of physical activity that are highly dependent on environmental conditions. It can also be used to add sophisticated automation or performance-enhancement features to thermostats and to connected home appliances such as air conditioning and purifiers systems, refrigerators, clothes dryers, microwave ovens, kitchen air extractors and weather stations.

The device may also be used alongside the ams CCS811 or CCS801 gas sensor ICs, which measure volatile organic compounds (VOCs) in ambient air, to provide a complete system solution for indoor air quality monitoring. ams provides application software and a development board to enable OEMs to integrate the ams environmental sensor solutions rapidly into end product designs.

The ENS210 is priced at $1.90 (100).

An evaluation board for the ENS210 is available from the ams ICdirect online store.