JP2748474B2 - Digital temperature compensated piezoelectric oscillator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital temperature compensated piezoelectric oscillator with reduced power consumption.

[Conventional technology]

As shown in FIG. 4, a conventional digital temperature-compensated piezoelectric oscillator includes a temperature-frequency conversion circuit 1 for converting a temperature into a frequency, a frequency counter circuit 2 for counting the output of the circuit 1, and a counter circuit 2 for counting the output of the circuit. , A microcomputer circuit 4 and a memory circuit 5 to which the output of the latch circuit 3 is input, and a second latch circuit 7 to which the output of the microcomputer circuit 4 is input. , And a digitally controlled piezoelectric oscillator 8 to which the output of the second latch circuit 7 is input.

With such a configuration, the frequency temperature characteristic A shown in FIG. 5 is compensated to obtain a stable frequency temperature characteristic B. 4th
In the figure, an ambient temperature is detected as a frequency by a temperature-frequency conversion circuit 1 such as an RC oscillator using a thermistor, counted by a frequency counter circuit 2, converted into a digital code, and connected to a microcomputer circuit via a latch circuit 3. 4 This microcomputer circuit 4
The memory and the memory circuit 5 previously store programs and constants for compensating the frequency temperature characteristics of the digitally controlled piezoelectric oscillator 8, and when the ambient temperature changes, the output digital code of the frequency counter 2 changes and the The computer circuit 4 calculates the compensation data and supplies it to the digitally controlled piezoelectric oscillator 8 via the latch circuit 7 to perform temperature compensation.

[Problems to be solved by the invention]

In the conventional digital temperature compensation type piezoelectric oscillator described above, the temperature compensation operation is performed continuously as shown in FIG. 6 (a) or intermittently as shown in FIG. 6 (b). Is common. When operated continuously as shown in FIG. 6 (a), large power consumption is required.
When performing an intermittent operation as shown in FIG. 6 (b), it is difficult to select a time during which the operation is not performed (off time). If the off time is too long, it becomes impossible to detect a temperature change, and if the off time is short. Has the disadvantage that power consumption is not reduced.

An object of the present invention is to eliminate such disadvantages and to turn on the power supply of the microcomputer circuit and the memory circuit only when the ambient temperature changes, and to perform a temperature compensation operation, without deteriorating the temperature detection resolution. Another object of the present invention is to provide a digital temperature-compensated piezoelectric oscillator with low power consumption.

[Means for solving the problem]

The configuration of the digital temperature compensated piezoelectric oscillator of the present invention includes a temperature-frequency conversion circuit that outputs a predetermined frequency corresponding to a detected temperature, a frequency counter circuit that counts a frequency from the conversion circuit, and an output of the frequency counter circuit. A first latch circuit for holding a value, a second latch circuit for inputting and holding an output of the first latch circuit, a microcomputer circuit for inputting signals from the first and second latch circuits, and A memory circuit, a third latch circuit that receives an output from the microcomputer circuit, a digitally controlled piezoelectric oscillator that receives an output of the third latch circuit, and outputs a predetermined oscillation frequency, A comparison circuit for comparing the output of the latch circuit with the output of the second latch circuit; Characterized in that it comprises a power switching device for switching the to supply power to the microcomputer circuit and a memory circuit can.

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of the present invention.
In this embodiment, a circuit 1 for converting a temperature into a frequency, a frequency counter circuit 2 for counting the frequency, a first latch circuit 3 for holding the output of the counter, and a micro-circuit having the output of the latch circuit 3 as an input. A computer circuit 4 and a memory circuit 5, a second latch circuit 6, a third latch circuit 7 receiving an output of the microcomputer circuit 4, and a digitally controlled piezoelectric oscillator 8 receiving an output of the latch circuit 7; A comparison circuit 9 for comparing respective outputs of the first latch circuit 3 and the second latch circuit 6, and a power supply switch for switching a power supply connection to the microcomputer circuit 4 and the memory circuit 5 by the output of the comparison circuit 9. Consists of 10 and 10. In this configuration, the current temperature detection result from the output of the temperature-frequency conversion circuit 1 and the temperature detection result immediately before are compared by a comparison circuit 9 and only when there is a difference between these detection results, the microcomputer circuit 4 and the memory Circuit 5
And a power supply is performed to perform a temperature compensation operation and supply a temperature compensation digital code to the third latch circuit 7. A temperature compensation digital code is supplied from the latch circuit 7 to the digital control piezoelectric oscillator 8 to perform a temperature compensation operation.

Further, when the comparison result between the current temperature detection result and the temperature detection result immediately before is the same, power is not supplied to the microcomputer circuit 4 and the memory circuit 5 and no power supply current flows. The latch circuit 7 holds the previously output temperature compensation digital code, and the digitally controlled piezoelectric oscillator 8 is controlled by the output of the latch circuit 7. Therefore, the temperature compensation operation of this embodiment is performed only when necessary, as shown in FIG.

FIG. 3 is a block diagram showing a second embodiment of the present invention. In the present embodiment, the output of the digitally controlled piezoelectric oscillator 8 in FIG. In this embodiment, the output frequency of the piezoelectric oscillator 8 is
The advantage is that the comparison accuracy of the comparison circuit 9 can be increased.

〔The invention's effect〕

As described above, the present invention turns on the power to the microcomputer circuit and the memory circuit only when it detects that the ambient temperature of the digital temperature-compensated piezoelectric oscillator has changed, and performs the temperature compensation operation. There is an effect that power consumption can be reduced without deteriorating the detection resolution.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
FIG. 3 is a block diagram of a second embodiment of the present invention, FIG. 4 is a block diagram of an example of a conventional digital temperature-compensated piezoelectric oscillator, and FIG. 5 is a diagram of FIG. FIG. 6A and FIG. 6B show frequency temperature characteristics before and after compensation.
FIG. 4 is a timing chart when the temperature compensation operation is performed continuously and intermittently in FIG. 1 temperature-frequency conversion circuit, 2 frequency counter circuit, 3, 6, 7 latch circuit, 4 microcomputer circuit, 5 memory circuit, 8 digital control piezoelectric oscillator, 9 Comparison circuit, 10 ... Power switch.

Claims (1)

(57) [Claims] 1. A temperature-frequency conversion circuit for outputting a predetermined frequency corresponding to a detected temperature, a frequency counter circuit for counting a frequency from the conversion circuit, and a first latch for holding an output value of the frequency counter circuit A second latch circuit for inputting and holding an output of the first latch circuit;
A microcomputer circuit and a memory circuit for inputting signals from the first and second latch circuits, and a third circuit for inputting an output from the microcomputer circuit.
, A digitally controlled piezoelectric oscillator that receives the output of the third latch circuit and outputs a predetermined oscillation frequency, and compares the output of the first latch circuit with the output of the second latch circuit. A digital temperature compensation type comprising: a comparison circuit; and a power supply switch that switches to supply power to the microcomputer circuit and the memory circuit when the output is equal to or more than a predetermined value according to the output of the comparison circuit. Piezoelectric oscillator.