Elmos rain/light/tunnel sensor with high reliability and low system costs

With its E527.04 module, Elmos presents an RLT-IC (rain/light/tunnel sensor) that can be used to control an optical sensor unit in automotive windshield wiper systems or in industrial camera and window systems.

The IC has two embedded LED drivers, which can be controlled with up to 40mA to produce stimuli. These currents are perfectly adequate for reliable rain detection using the Elmos technology and are below the current consumption of other infrared-based solutions. The LED drivers are controlled by the slew rate (rate of voltage rise). A special, high-sensitivity input stage allows the processing of a diode input signal without total reflection of the transmit signal, which ensures reliable detection of rain, water droplets and condensed precipitation. By eliminating the total reflection, smaller sensor form factors are possible in order to save space or extend the range of functions.

Thanks to the HALIOS®-SD (Sigma Delta) measurement, the system achieves a very high degree of robustness against environmental influences, such as sunlight, any type of flickering light, aging and dirt. It also offers the best sensitivity available in the market for improved rain classification. The IC has 4 additional input channels for logarithmically amplified ambient light measurements. Communication via a 3-wire or 4-wire SPI interface enables fast and flexible transmission.

Due to the integration density and the very high robustness, only a few external components are necessary. This lowers the cost of the overall system while maintaining high performance. The device is qualified according to AEC-Q100 and is delivered in the QFN20L4 package.

For more information, application notes and samples, please write an email to sales@elmos.com with the subject “E527.04“, visit our website www.elmos.com or go directly to www.halios.de or call us on +49 231 7549 100.