Smoke Detector

Overview

Across the most of the world’s regulations now require smoke detectors to be installed in homes, schools, public and commercial buildings. In addition to sounding an audible alarm when a fire breaks out, smoke detectors must also communicate an alarm notification to a remote control location, such as the local fire station. To detect smoke an LED inside the smoke sensor illuminates and measures the current corresponding to the amount of light output by a light receiving sensor. The current is converted to a voltage by an op-amp, and the voltage is read using an A/D converter. The LED inside the sensor illuminates at regular intervals controlled by a timer in order to reduce the power consumption by sampling the smoke volume intermittently.

Renesas’ 78K0/Kx2-L and R8C/Lx Super Low Power MCUs integrate on-chip the peripheral functions necessary for use in smoke detector design, making it possible to reduce the overall product size. Low-voltage operation contributes to extended battery life, which is essential for detectors that must operate over extended periods of time.