Light and proximity sensors work in a variety of light conditions for smart home devices

By Heather
Hamilton, contributing writer

Sensor solutions company ams recently introduced a series of new
sensors designed to optimize brightness for smart home devices. The devices
debuted at the Sensors Expo in San Jose at the end of June, and offer low power
and high sensitivity in a small package. Designed for consumer devices, the
release includes the TSL2540 and TSL2541 ambient light sensors, as well as the
TSL2740, which is a combined ambient light and proximity sensor. 

The sensors can detect ambient light at an intensity as low as a
few millilux. The sensors are designed to work in lighting conditions ranging
from bright sunlight to a dark room, and can automatically adjust LCD display
backlighting or indicator LEDs based on the brightness of the ambient light.



Each sensor has separate photopic ambient light and infrared light
sensing channels with interferometric IR and photopic filters deposited on the
silicon. The company said that the photopic channel approximates the way the
human eye responds to different levels of light and very dark attenuated

All three optical sensors are compact enough for consumer products
in a QFN package that measures 2 mm x 2 mm x .5 mm.  In addition, the TSL2541’s package is made
with a special dark compound that ensures the device is nearly undetectable
mounted under inked cover glass, said the company.

The TSL2740, which is also a proximity sensor, does so by
measuring reflected IR light that comes from an external LED. Because it is
also equipped with programmable proximity offset adjustability, it compensates
for crosstalk effects from the IR LED in relation to proximity events up to 10 cm.

All three sensors are available in production volumes at $0.44
(TSL2540/TSL2541) and $.046 (TSL2740) in quantities of 5,000. For a complete
list of specs, including data sheets, look here.