Sensors for smart home devices optimise brightness in any condition

The new family delivers very high sensitivity when detecting ambient light at an intensity as low as a few millilux - the equivalent of a clear night sky with no moonlight.

With their wide range they operate effectively in lighting conditions ranging from bright sunlight to a dark room, and behind inked cover glass. The sensors enable automatic adjustment of LCD display backlighting or of indicator LEDs in response to changes in the brightness of the ambient light.

All three new optical sensors are offered in a miniature 2.0x2.0mm 0.5mm low profile QFN package which is small enough for compact consumer devices such as smart home assistants. The TSL2541’s package is made with a special dark compound which makes the device almost undetectable when mounted under inked cover glass.

The TSL2540,TSL2541 and TSL2740 are equipped with separate photopic ambient light and infrared light sensing channels made with interferometric IR and photopic filters deposited directly on the silicon. The photopic channel approximates the human eye’s response to light intensity under widely varying lighting conditions and through very dark attenuated materials. 

The TSL2740 performs proximity sensing by measuring reflected IR light emitted from an external LED. Programmable proximity offset adjustability compensates for crosstalk effects from the IR LED in relation to proximity events at a range of up to 10cm.

“Ambient light and proximity sensors are widely used today in smartphones and tablets. Thanks to the high sensitivity and package size of the new product family, ams addresses emerging market applications such as smart home devices, IoT hubs and consumer electronics. Flexible industrial design is a critical requirement for home devices, and the small form factor of this family of products makes them ideal for these applications,” said David Moon, Senior Marketing Manager for the Advanced Optical Solutions business at ams.

The TSL2540, TSL2541 and TSL2740 are available now in production volumes. Unit pricing is $0.44 for the TSL2540 and TSL2541 and $0.46 for the TSL2740 in an order quantity of 5,000 units.