Integrated circuit thermometer
AssigneeDallas Semiconductor Corporation
InventorsJames M. Douglass, Gary V. Zanders, Robert D. Lee
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Abstract
An integrated circuit temperature detector (thermometer) uses a temperature dependent oscillator to count up to a fixed number and thereby generate a time interval indicative of the temperature (a temperature-to-time converter). The time-to-number converter provides a numeric temperature output. Counting oscillations of a relatively temperature independent oscillator for the time interval may digitize the temperature measurement. Calibration and successive approximation iterations permit simple hardware to achieve good accuracy.
Claims13
A temperature detector, comprising:
- (a) a temperature-to-time first converter, said temperature-to-time first converter outputting a time interval with length depending upon an input temperature;
- (b) a time-to-number second converter, said time-to-number second converter with input coupled to receive said time interval outputted by said temperature-to-time first converter, said time-to-number second converter approximates a number version of said input temperature by fitting a linear model to said time interval and outputs said number version of said input temperature;
- (c) said temperature-to-time first converter including a first oscillator with a temperature dependent period coupled to a first counter for providing a temperature dependent time interval, said time interval for said first counter determined by the number of oscillations counted for a predetermined count;
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- (d) said time-to-number second converter including a second oscillator coupled to a time-to-number second counter, with said time-to-number second counter in response to said second oscillator input producing a digital number during said time interval of said first counter.
A thermometer embedded in a single integrated circuit, comprising:
- (a) delay circuitry to produce a signal delayed by a length of time corresponding to a temperature output sensed by a temperature sensor;
- (b) said delay circuitry including a first oscillator to generate oscillations at a first oscillation rate, said first oscillation rate having a sensitivity to temperature, and a first counter coupled to said first oscillator to count said oscillations for a predetermined count to determine said length of time;
- (c) timing circuitry coupled to receive said signal, said timing circuitry fits a linear mathematical model to said signal to generate a digital output corresponding to said temperature output;
- and
- (d) said timing circuitry including a second oscillator to generate oscillations at a second oscillation rate, said second oscillation rate having an insensitivity to temperature, and a second counter coupled to said first counter of said delay line circuitry to count said oscillations generated by said second oscillator to produce a digital number during said length of time determined by said first counter.
Dependencies are inferred from the claim text.