Texas Instruments has introduced two new light-to-frequency converters that offer direct, high-resolution conversion of light intensity to a digital format.
The compact TSL235 is well-suited for portable applications such as cameras, hand-held diagnostic equipment and light meters. The TSL245 infrared converter is well-suited for applications such as paper detection, proximity detection and diagnostic equipment.
These devices, which interface directly to a microcontroller or DSP, combine a photodiode and current-to-frequency converter on a single chip. Both provide a simple way to process a wide dynamic range of light levels without external signal conditioning circuitry or A/D converters.
The TSL235 offers a high-performance, low-cost alternative to conventional discrete combinations of photodiodes, amplifiers and A/D converters. The device can be used in a variety of light measurement applications such as ambient light metering, transmittance of a fluid or other medium or surface reflectance. Other applications include lighting controls, display contrast adjustment, fluid turbidity/transmissivity measurement, color detection, flame monitoring and visual process control.
The TSL245 is optimized for near-infrared light sensing and incorporates an ambient light-blocking filter. This device is compatible with infrared sources with wavelengths ranging from 880nm to 940nm and is well-suited for transmissive or reflective measurement and detection applications such as object detection, fluid opacity and reflectometry.
Both devices are available now from Texas Instruments and its authorized distributors. Suggested resale price in 1,000-unit quantity.
TSL235 3-lead plastic side-looking package $1.75TSL245 3-lead plastic side-looking package $1.75
Features Benefits ----------------------------------------------------------------------------------- Light-to-digital Pulse-train output interfaces conversion directly to microcontroller or DSP ----------------------------------------------------------------------------------- Wide dynamic range 120dB with 500 kHz full-scale output ----------------------------------------------------------------------------------- Single-chip solution No external components required for operation ----------------------------------------------------------------------------------- Low-voltage operation 2.7-V to 5-V operation for battery-powered systems ----------------------------------------------------------------------------------- TTL-compatible output 50 percent duty cycle square wave with frequency directly proportional to light intensity on the photodiode ----------------------------------------------------------------------------------- Compact 3-lead clear (TSL235) or IR-transmissive (TSL245) plastic side-looking package
July - August 1995, vol. 12, no. 5
TI Home
Search
Semiconductor Home