Abstract: A time-based digital temperature sensing system has a first oscillator which is temperature sensitive. The first oscillator has a temperature coefficient which allows the first oscillator to generate an output signal which varies linearly as a function of temperature. A second oscillator is provided and is used to generates a reference clock signal. The outputs from the first and the second oscillator are coupled to a timer. The timer has a clock input coupled to an output of the second oscillator and an enable input coupled to an output of the first oscillator. From these input signals, the timer generates a number indicative of a length of time the timer is enabled by the first oscillator. The number is proportional to a current temperature of a material that is being monitored by the temperature sensing system.

Abstract: A direct sensor interface (DSI) module which allows a microcontroller to directly interface to sensors having at least one of a resistive, capacitive, and/or current source characteristic. The DSI module is coupled directly to a sensor device, which could be a reference resistor, which generates a sensor current. A current mirroring circuit outputs a charging current proportional to the sensor current. A capacitive sensor and/or a capacitive device is coupled to the current mirroring circuit and generates a voltage when charged by the charging current. Using a comparator and a threshold voltage source, the time it takes the capacitive sensor and/or a capacitive device to ramp up from zero to the threshold voltage can be measured. The charging time is proportional to the sensor reading.