The ADT14 is a temperature sensor and controller that generatesan output voltage proportional to temperature and provides fourtemperature trip points. The four trip points, or temperaturesetpoints, and their hysteresis are determined by voltage levels setby the user. An on-chip voltage reference provides an easy methodfor setting the temperature trip points.The ADT14 consists of a bandgap voltage reference combinedwith four matched comparators. The reference provides both atemperature-stable 2.5 V output, and a voltage proportional toabsolute temperature (VPTAT) which has a precise temperaturecoefficient of 5 mV/K = 5 mV/(°C +273.15). The VPTAT outputis nominally 1.49 V at +25°C. The comparators determinewhether the VPTAT output is above the voltages set up byexternal resistive dividers (temperature trip points) and generatean open-collector output signal when one of their respectivethresholds has been exceeded.Hysteresis is programmed by a user-selected voltage at the hysteresispin. This voltage adjusts the hysteresis current which isused to generate a hysteresis offset voltage. The comparator’snoninverting inputs are connected in parallel, which guaranteesthat there is no hysteresis overlap and eliminates erratic transitionsbetween adjacent trip zones.Using a proprietary thin-film resistor process in conjunctionwith production laser trimming, a temperature accuracy of ±3°Cat 25°C is guaranteed. The open-collector outputs are capableof sinking 5 mA, and provide TTL/CMOS logic compatibilitywith an external pull-up resistor. Operating from a single 5 Vsupply, the quiescent current is 600 mA max.The ADT14 is available in the 16-lead epoxy DIP and SO(small outline) packages.