JP2014143464A - Crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a crystal oscillator needs to be provided with a clock-loss detection circuit thereoutside because the crystal oscillator does not include clock-loss detection function means.SOLUTION: Crystal oscillation function means 1 for oscillating a clock signal to be reference and clock-loss detection function means 2 for detecting the loss of the clock signal from the crystal oscillation function means 1 are housed in a module 3, and the module 3 is provided with a power-supply pin 4, a ground pin 5, an output enable pin 6, a clock signal output pin 7, and a clock-loss signal output pin 8. By embedding the clock-loss detection function means 2, a crystal oscillator that allows improving reliability and reducing mounting area can be obtained.

Description

  The present invention relates to a crystal oscillator which is mounted on a substrate and supplies a clock signal, and more particularly to a crystal oscillator having a built-in clock loss detection function means.

The clock signal becomes the basis of an operation sequence in, for example, a microcomputer system, and a crystal oscillator is generally used as a generation source of such a clock signal.
However, the frequency reference signal generated by the crystal oscillator may be lost due to mechanical or other failures of the oscillator of the crystal oscillator, which greatly affects the reliability of the system.

  For this reason, in the conventional clock signal generation circuit, a clock loss detection circuit that detects the loss of the clock signal whose reference clock is fixed to “0” or “1” is separately provided in the crystal oscillator that is the source of the clock signal. The circuit configuration is divided between the crystal oscillator and the clock loss detection circuit. (For example, see Patent Document 1)

Japanese Patent Laid-Open No. 7-131342

Conventional crystal oscillators generally have only a power supply pin, a ground pin, an output enable pin, and a clock output pin, and it is necessary to provide a clock loss detection circuit for detecting a loss of a clock signal outside.
For this reason, when mounting a crystal oscillator on a board, it is necessary to supply the crystal oscillator and clock loss detection circuit with power supplied to each, and as the board is downsized, the mounting area and wiring area of parts are often used. There was a point. In addition, there is a problem that it is impossible to determine the presence or absence of clock output with a crystal oscillator alone.

  The present invention has been made to solve the above-mentioned problems, and by adding a clock loss detection function means, a mounting area and a wiring area are improved, and a crystal oscillator with improved reliability is obtained. It is for the purpose.

  A crystal oscillator according to the present invention includes a crystal oscillation function means for oscillating a reference clock signal and a clock loss detection function means for detecting a loss of the clock signal from the crystal oscillation function means in one module. Are provided with a power supply pin, a ground pin, an output enable pin, a clock signal output pin, and a clock loss signal output pin.

  According to the present invention, since the crystal oscillator function means and the clock loss detection function means are built in one crystal oscillator, the crystal oscillator and the clock loss detection circuit, which have conventionally been installed separately, are integrated into one component. I can do it. Therefore, when the crystal oscillator is mounted on the substrate, the mounting area and wiring area of components can be reduced, and the reliability is improved.

It is a circuit block diagram which shows the crystal oscillator of Embodiment 1 of this invention. It is a circuit block diagram which shows the crystal oscillator of Embodiment 2 of this invention. It is a circuit block diagram which shows the crystal oscillator of Embodiment 3 of this invention. It is a circuit block diagram which shows the crystal oscillator of Embodiment 4 of this invention. It is a circuit block diagram which shows the crystal oscillator of Embodiment 5 of this invention.

Embodiment 1 FIG.
Hereinafter, a crystal oscillator according to Embodiment 1 of the present invention will be described with reference to FIG.
In FIG. 1, a crystal oscillator 10 according to the present invention detects a loss of a clock signal from a crystal oscillation function means 1 that is a conventional general crystal oscillator that oscillates a reference clock signal. The clock loss detection function means 2 is built in one module 3 and stored.

  The module 3 includes a power supply pin 4 connected to a power supply, a ground pin 5 connected to the ground GND, an output enable (OE) pin 6 for controlling the clock output of the crystal oscillation function means 1, and a crystal. A clock signal output pin 7 for outputting a clock signal from the oscillation function means 1 and a clock loss signal output pin 8 for outputting a clock loss signal from the clock loss detection function means 2 are provided.

The power supply pin 4, the ground pin 5, the output enable pin 6, and the clock signal output pin 7 are connected to the crystal oscillation function means 1, and the power supply pin 4, the ground pin 5 and the clock loss signal output pin 8 are the clock loss detection function means 2. It is connected to the. A power supply is connected to the output enable pin 6 so that the clock signal is always permitted to be output from the crystal oscillation function means 1.
As described above, the crystal oscillator 10 of the present invention incorporates the crystal oscillation function means 1 and the clock loss detection function means 2, operates with the same power supply, and outputs both the clock signal and the clock loss signal. .

Next, the operation of the crystal oscillator 10 will be described.
A power supply and a ground are connected to the power supply pin 4 and the ground pin 5, respectively, and the crystal oscillator 10 with built-in clock loss detection function means is turned on. Further, a power source is connected to the output enable (OE) pin 6 to make the output enable of the crystal oscillation function means 1 significant.
By doing so, the crystal oscillation function means 1 and the clock loss detection function means 2 incorporated in the crystal oscillator 10 are simultaneously supplied with power, and when the output enable of the crystal oscillation function means 1 becomes significant, the crystal oscillation function means 1 The function means 1 starts outputting a clock signal having a specified frequency and is taken out from the clock signal output pin 7. The clock loss detection function means 2 receives the clock signal output from the crystal oscillation function means 1 at the start of power supply, and monitors the presence or absence of the clock signal. If the clock signal is not output, the clock loss detection function means 2 A clock loss signal is output from the signal output pin 8.

As an example of the clock signal monitoring method in the clock loss detection function means 2, a clock loss signal is made involuntary for a certain period of time triggered by either or both of the rising edge and falling edge of the clock signal. Operate the loss signal significantly.
In this way, when the clock signal output from the crystal oscillation function means 1 is monitored and the supply of the clock signal is stopped, the clock loss signal becomes significant by the clock loss detection function means 2.

In the first embodiment, since the crystal oscillation function means 1 and the clock loss detection function means 2 are included in the crystal oscillator 10 with built-in clock loss detection function means, the crystal oscillator and the clock loss detection circuit are configured on the substrate. As a result, the mounting area can be reduced and the loss of the clock signal can be detected alone, so that a crystal oscillator with improved reliability can be obtained.

Embodiment 2. FIG.
Next, a crystal oscillator according to Embodiment 2 of the present invention will be described with reference to FIG.
In FIG. 2, a crystal oscillator 10 according to the present invention has a control circuit 20 connected to an output enable (OE) pin 6, and outputs from the control circuit 20 to both the crystal oscillation function means 1 and the clock loss detection function means 2. The enable signal can be input, and the clock signal output and the clock loss signal output can be controlled. Other configurations are the same as those of the first embodiment shown in FIG.

In the first embodiment, the case where the output is always permitted by connecting the output enable (OE) pin 6 for controlling the clock output to the power supply has been described, but the invention of the second embodiment is as shown in FIG. In addition, the crystal oscillation function means 1 and the clock loss detection function means 2 are controlled by a signal from the external control circuit 20.
When the output enable signal is not input to the clock loss detection function means 2, it is necessary to consider the significance of the clock loss signal output by the output enable input externally. However, as in the second embodiment, when the output enable signal input is added to the clock loss detection function means 2 and the clock signal output becomes invalid, the clock loss detection function means 2 is also invalidated.

  In the second embodiment, by adding an output enable signal monitoring function means to the clock loss detection function means 2 by the control circuit 20, even when output enable control is used, no additional circuit is required outside. I can do it.

Embodiment 3 FIG.
Next, a crystal oscillator according to Embodiment 3 of the present invention will be described with reference to FIG.
In FIG. 3, the crystal oscillator 10 according to the present invention is further provided with an enable (EN) pin 9 in the module 3 to have a 6-pin configuration. A control circuit 20 is connected to the output enable pin 6 and the enable pin 9 so that the clock output enable signal is input from the control circuit 20 to the crystal oscillation function means 1 and to the clock loss detection function means 2. The enable signal for controlling the validity or invalidity of the detection function means can be input. Other configurations are the same as those of the first embodiment shown in FIG.

  In the second embodiment, the case where the clock loss detection function means 2 is enabled or disabled by inputting the output enable signal has been described. However, in the third embodiment, as shown in FIG. In this system, an enable signal is input to the function means 2 to add a function means that can freely switch between valid and invalid of the clock loss detection function means 2.

  In the third embodiment, the control circuit 20 inputs an enable signal to the clock loss detection function means 2 and adds a valid / invalid switching function means of the clock loss detection function means 2, thereby providing a highly flexible output. A crystal oscillator having a function enable and clock loss detection function means can be obtained.

Embodiment 4 FIG.
Next, a crystal oscillator according to a fourth embodiment of the present invention will be described with reference to FIG.
In FIG. 4, a crystal oscillator 10 according to the present invention houses a clock accuracy abnormality detection function means 11 in a module 3 and is provided with a clock accuracy abnormality detection pin 12. The clock signal is input to monitor the frequency accuracy of the clock signal. Other configurations are the same as those of the first embodiment shown in FIG.

In the first embodiment, the case where only the clock loss detection function means 2 is provided in the crystal oscillator 10 has been described. However, in the fourth embodiment, as shown in FIG. The clock accuracy abnormality detection pin 12 outputs a clock accuracy abnormality when the frequency accuracy of the clock signal output from the crystal oscillation function means 1 deviates from a specified numerical value.
By configuring in this way, it is possible to obtain a crystal oscillator having functional means for monitoring frequency accuracy.

Embodiment 5 FIG.
Next, a crystal oscillator according to a fifth embodiment of the present invention will be described with reference to FIG.
5, the crystal oscillator 10 according to the present invention houses the clock accuracy abnormality detection function means 11 in the module 3 and is provided with a clock accuracy abnormality detection pin 12 and a enable pin 13 connected to the clock accuracy abnormality detection function means 11. The control circuit 20 is connected to the output enable pin 6 and the two enable pins 9 and 13.
The clock output enable signal is input from the control circuit 20 to the crystal oscillation function means 1, and the clock loss detection function means 2 and the clock precision abnormality detection function means 11 are enabled to control the validity or invalidity of the clock precision abnormality detection function means. Each is capable of inputting signals. Other configurations are the same as those in FIG. 3 according to the third embodiment and FIG. 4 according to the fourth embodiment, and the same reference numerals are given and description thereof is omitted.

In the fifth embodiment, the clock signal output from the crystal oscillation function unit 1 is monitored by the clock loss detection function unit 2, and the frequency accuracy of the clock signal from the crystal oscillation function unit 1 is monitored by the clock accuracy abnormality detection function unit 11. At the same time, the clock loss detection function means 2 and the clock accuracy abnormality detection function means 11 can be switched between valid and invalid.
As described above, since the validity or invalidity of the clock loss detection function unit 2 and the clock accuracy abnormality detection function unit 11 can be controlled, a crystal oscillator capable of switching the validity or invalidity of a desired function unit can be obtained.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

1: crystal oscillation function means, 2: clock loss detection function means,
3: Module, 4: Power supply pin, 5: Ground pin,
6: Output enable pin, 7: Clock signal output pin,
8: Clock loss signal output pin, 9: Enable pin,
10: Crystal oscillator, 11: Clock accuracy abnormality detection function means,
12: Clock accuracy abnormality detection pin 13: Enable pin

Claims (7)

  The crystal oscillation function means for oscillating the reference clock signal and the clock loss detection function means for detecting the loss of the clock signal from the crystal oscillation function means are housed in one module, and the power supply pin, the ground pin, and the output are stored in the module. A crystal oscillator with an enable pin, clock signal output pin, and clock loss signal output pin.   The power supply pin, the ground pin, the output enable pin, and the clock signal output pin are connected to the crystal oscillation function means, and the power supply pin, the ground pin, and the clock loss signal output pin are connected to the clock loss detection function means. The crystal oscillator according to claim 1.   3. The crystal oscillator according to claim 1, wherein a power supply is connected to the output enable pin so as to always permit output of a clock signal.   3. The crystal oscillator according to claim 1, wherein a control circuit is connected to the output enable pin to control a clock signal output and a clock loss signal output.   The module is provided with an enable pin, a control circuit is connected to the output enable pin and the enable pin, and an input of a clock output enable signal is input from the control circuit to the crystal oscillation function means, and the clock loss detection 3. The crystal oscillator according to claim 1, wherein an enable signal for controlling validity or invalidity of the functional means can be input.   A clock accuracy abnormality detection function means is housed in the module, a clock accuracy abnormality detection pin is provided, a clock signal from the crystal oscillation function means is input to the clock accuracy abnormality detection function means, and the frequency accuracy of the clock signal The crystal oscillator according to claim 1, wherein the crystal oscillator is monitored.   The module includes a clock accuracy abnormality detection function means, a clock accuracy abnormality detection pin and an enable pin, a control circuit connected to the output enable pin and the enable pin, and the crystal oscillation function from the control circuit. The clock output enable signal can be input to the means, and the enable signal for controlling the validity or invalidity can be input to the clock loss detection function means and the clock accuracy abnormality detection function means, respectively. The crystal oscillator according to any one of the above.

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