AN INTEGRATED ABSOLUTE TEMPERATURE SENSOR WITH SIGMA-DELTA A-D CONVERSION

A smart absolute temperature sensor is described, which provides a pulse-rate output and is highly suitable for communication with microprocessors. The temperature sensor generates an absolute temperature current as well as a reference current. Both signals are used in a sigma delta A-D converter, which provides a clock-synchronous pulse rate. This fully synchronized output signal offers important advantages over asynchronous signals, such as frequency or duty cycle. The last suffers from digital interference, which is often unrecognized. Smart sensors with on-chip digital processing or bus communication need synchronized A-D converters to prevent this problem.