Tiny Proximity Detector Integrates IR Emitter and Detector

Vishay Semiconductors has created an interesting reflectance proximity detector (VCNL4000) that includes an infrared (IR) LED and a photodetector. A second sensor in the same package measures ambient light with a spectral response close to that of a human eye.  The proximity detector, which measures 4-by-4 mm, can detect an object out to about 20 cm.  Vishay noted possible uses for the new device in smart phones, digital cameras, tabled PCs, and other devices.  Other ideas: hands-free light-dimmer controls, pet-door openers, kid detectors around hot stoves, industrial-safety apparatus, microwave oven controllers, and so on.

The proximity sensor lets engineers program the IR LED drive current from as little as 10 mA up to 200 mA in 10-mA steps. And they also can program the sample rate from one to as many as 250 samples/second. Internal signal-processing circuits reject 100- and 120-Hz flicker “noise” from electrical lights. By modulating the IR LED at one of four carrier frequencies, the sensor also rejects DC light levels that other types of sensors might respond to.

To help engineers and product-designers learn about the new sensor, Vishay offers a small USB “stick” demonstration unit and software that lets you view sensor output, adjust the values in programmable registers, turn compensation on or off, change low-pass filter settings, and so on.  The sensor chip uses an I2C interface, which simplifies communications with other devices. For kit information, visit: www.vishay.com/docs/83395/vcnl4000_demo_kit.pdf. Digi-Key, Mouser, and Newark will have development kits in stock by 21 May 2011.

The evaluation-and-test board comes with a “VCNL4000 Evaluation kit” CD-ROM that provides kit instructions (27 pages), an installation guide, and a detailed 12-page application note, “Designing VCNL4000 into an Application.” The latter supplies a lot of good electrical- and mechanical-engineering and design information and a software flow chart. You will find the 12-page app note at: www.vishay.com/docs/83372/vcnl4000.pdf.

For a complete sensor data sheet, visit:  www.vishay.com/docs/83798/vcnl4000.pdf.

I plan a hands-on review of this sensor and kit so stand by for the results. –Jon Titus