Light-To-Frequency Converter Offers High Sensitivity, Low Noise

May 10, 2004

Able to sense ultra-low light levels undetectable by most silicon-based sensors, the TAOS TSL237R light-to-frequency converter with a 5,000,000:1 dynamic range combines enhanced sensitivity with low dark-signal levels. This device senses...

Roger Allan

This device senses down to 0.00002 Lux and has typical dark frequency down to 0.1 Hz. It produces a square-wave output signal with 16-bit resolution and frequency proportional to light intensity. Also, it can be interfaced directly to a DSP or a microcontroller, eliminating the need for an analog-to-digital converter.

"When you convert directly from a current to a frequency, a data converter or an amplifier are not needed. This eliminates voltage offsets and nonlinearities," says Ray King, a medical marketing specialist at TAOS.

"This is a very ubiquitous device that opens up many new applications," says Carlo Strippoli, vice president for marketing and sales. He cited automotive sensors, color calibration of computer monitors, densitomers, medical pulse oximetry, laser printers, photography, lighting control, and industrial pollution monitoring among these applications.

"Key to the product's development is that it is designed to be stable with high levels of dark current at elevated temperatures," explains Jack Berlian, director of new product development. The TSL237R operates from −25°C to 70°C. "The fact that we're using a current source also makes it inherently a wide-dynamic-range part."

The TSL237R comes in a three-pin Side Looker package. It costs $1.67 each in 1000-piece quantities.

TAOS Inc.www.taosinc.com (972) 673-0759

About the Author

Roger Allan

Roger Allan is an electronics journalism veteran, and served as Electronic Design's Executive Editor for 15 of those years. He has covered just about every technology beat from semiconductors, components, packaging and power devices, to communications, test and measurement, automotive electronics, robotics, medical electronics, military electronics, robotics, and industrial electronics. His specialties include MEMS and nanoelectronics technologies. He is a contributor to the McGraw Hill Annual Encyclopedia of Science and Technology. He is also a Life Senior Member of the IEEE and holds a BSEE from New York University's School of Engineering and Science. Roger has worked for major electronics magazines besides Electronic Design, including the IEEE Spectrum, Electronics, EDN, Electronic Products, and the British New Scientist. He also has working experience in the electronics industry as a design engineer in filters, power supplies and control systems.

After his retirement from Electronic Design Magazine, He has been extensively contributing articles for Penton’s Electronic Design, Power Electronics Technology, Energy Efficiency and Technology (EE&T) and Microwaves RF Magazine, covering all of the aforementioned electronics segments as well as energy efficiency, harvesting and related technologies. He has also contributed articles to other electronics technology magazines worldwide.

He is a “jack of all trades and a master in leading-edge technologies” like MEMS, nanolectronics, autonomous vehicles, artificial intelligence, military electronics, biometrics, implantable medical devices, and energy harvesting and related technologies.