Programmable proximity sensor utilising CMOS technology comprising temperature compensation and a variable switching point

摘要

There is disclosed an improved proximity sensor (100a - 100e), an a method of using same. A number of problems are identified in known sensors, eg ease of programmability, cost, operating power, operating voltage and accuracy. The invention therefore provides an inductive proximity sensor or switch (100a - 100e) comprising an Application Specific Integrated Circuit (ASIC) 10, and a plurality of external components. The ASIC 10 is implemented in CMOS technology, and has an oscillator, a switch point of the sensor/switch (100a - 100E) being predetermined by a selection of a bias voltage to a potential node of the oscillator. The apparatus also comprises a means for maintaining the output voltage of the oscillator, said means also comprising temperature compensation. Alternatively the bias voltage may be selected by means of a series of approximation steps. The functionality of the sensor may also be programmed by applying pre-determined voltages to a power supply input terminal.