A new Fahrenheit temperature sensor

A monolithic integrated circuit which provides an output voltage scaled proportionally to the Fahrenheit temperature without requiring the user to subtract a large constant offset is described. An advantage of this circuit is that the gain is inherently calibrated (e.g. to /spl plusmn/10.00 mV//spl deg/F) by simply trimming the offset error at room temperature. This behavior is shown to be a predictable function of the inherent bandgap voltage of silicon, +1.220 V. The circuit has been designed to permit trimming of accuracy (gain and offset) by blowing metal links and by the familiar Zener gap technique. The sensor achieves a typical accuracy of /spl plusmn/0.5/spl deg/F at room temperature, and /spl plusmn/1.0/spl deg/F over a rated temperature range from -50/spl deg/F to +300/spl deg/F, without any requirement for laser trimming. The practical limitation on accuracy is the production testing of devices under conditions of precisely known temperature. Applications circuits are also presented to show where this new sensor has advantages in accuracy and convenience over present sensors.