JPS63274873A - Oscillation detection circuit - Google Patents

Abstract

PURPOSE:To obtain easy circuit constitution by deciding whether or not the integral value of the oscillation output of an oscillation circuit is within a reference voltage range, and inputting the decision result to a storage circuit. CONSTITUTION:The oscillation output 101 of the oscillation circuit 1 is passed through the parallel circuit of the series circuit of an inverter 2 and a resistance 3, and a capacitor 4 to become an integral signal 104, which is inputted to the inversion input terminal of a comparator 5 and an input terminal of a comparator 6. A reference potential 102 is supplied to the input terminal of the comparator 5 and a reference potential 103 is supplied to the inversion input terminal of the comparator 6. Here, when the output 101 is not outputted by the circuit 1, a fixed potential is supplied to the inverter 2 and its output is fixed at an H or L potential. The input potentials of the comparators 5 and 6 are not within the level ranges of the potentials 102 and 103 and one of the comparators 5 and 6 outputs an L potential. Consequently, the output 105 of an AND circuit 7 is an L potential, which is inputted to an FF circuit 8 together with a decision input signal 106; and a decision signal indicating that there is no oscillation output is outputted as an L potential through a terminal 54, so that the oscillation is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oscillation detection circuit, and more particularly to an oscillation detection circuit that detects the presence or absence of oscillation in an oscillation circuit.

[Conventional technology]

In general, oscillation circuits are widely used as clock generation sources in electronic devices, but it is extremely important to be able to arbitrarily monitor whether or not their operation is normal. For this purpose, a method is used to detect whether or not the operation of the oscillation circuit is normal, and to output a specific signal in the event of an abnormality.

Conventionally, in this type of oscillation detection circuit, a frequency counter 10 and a microcomputer 11 are provided in correspondence with the oscillation circuit 9, as an example of which is shown in FIG. In FIG. 3, the oscillation output of the oscillation circuit 9 is input to the frequency counter 10, and the frequency measurement data by the 0 frequency counter, which measures the frequency, is compared and verified with a preset frequency value in the microcomputer 11. , it is detected whether the oscillation circuit 9 is operating normally. The judgment signal from this detection is
It is output via terminal 55.

[Problem that the invention seeks to solve]

The above-mentioned conventional oscillation detection circuit inputs the oscillation output of the oscillation circuit to a frequency counter, transfers the frequency measurement data measured by the frequency counter to a microcomputer, and uses the microcomputer to determine whether the oscillation circuit is operating normally. The drawback is that it requires expensive equipment such as a frequency counter and a microcomputer to detect the presence or absence.

[Means for solving problems]

The oscillation detection circuit of the present invention includes an integration circuit that integrates the oscillation output of the oscillation circuit, a determination circuit that determines whether the output of the integration circuit is within two reference voltage ranges, and a memory that stores the determination results of the determination circuit. and a circuit to do so.

〔Example〕

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

FIG. 1 is a circuit diagram showing a main part of an embodiment of the present invention.

As shown in FIG. 1, this embodiment includes an inverter 2, a resistor 3, a capacitor 4, comparators 5 and 6, an AND circuit 7, a flip-flop circuit 8, corresponding to an oscillation circuit 1. It is equipped with

In FIG. 1, an oscillation output 101 of an oscillation circuit 1 is output as an integral signal 104 via a series circuit of an inverter 2 and a resistor 3, and a parallel circuit of a capacitor 4, and is output as an integral signal 104 between an inverting input terminal of a comparator 5 and an input of a comparator 6. input to the terminal. On the other hand, the input terminal of comparator 5 is terminal 5.
A reference potential 102 is supplied from the terminal 1, and a reference potential 103 is supplied from the terminal 52 to the inverting input terminal of the comparator 6.

When the oscillation circuit 1 is oscillating normally and the oscillation circuit output 101 is output as described above, the comparator 5
As shown in FIG. 2(b), the integral signal 104 input to the inverting input terminal of the comparator 6 and the input terminal of the comparator 6 is
Reference potential 102 (High potential) and reference potential 1103 (
Since it is within the level range of Lo potential), comparator 5
and 6 both output a high potential. The outputs of the comparators 5 and 6 are input to the AND circuit 7, but as mentioned above, when the oscillation output 1 is output from the oscillation circuit 1, the output 105 of the AND circuit 7 is the second output.
A high potential is output as shown in Figure (C).

The output 105 of the AND circuit 7 is input to the delay input terminal of the flip-flop circuit 8, is taken into the flip-flop circuit 8 by the judgment input signal 106 input from the terminal 53, and is output via the terminal 54 to determine whether there is an oscillation output. A determination signal is output. In this case, the judgment input signal 106 is a signal for setting a preliminary time until the oscillation circuit 1 enters a normal operating state after being switched on, and as shown in FIG. However, at the detection point that detects the presence or absence of oscillation, it becomes a low potential, and at this point, the output 105 of the AND circuit 7 becomes a low potential.
The signal is taken into the 17671 circuit 8, and a high potential determination signal is outputted via the terminal 54 in response to the presence of oscillation output from the oscillation circuit 1.

Further, when the oscillation output 101 is not output from the oscillation circuit 1, a fixed potential is applied to the inverter 2, and the output of the inverter 2 is fixed to the old gh potential or the Low potential. In this case, at the input stage of comparators 5 and 6, the input potentials are the reference potential 10102 (Hi potential) and the reference potential 1103 shown in FIG. 2(b).
(Lo potential) does not fall within the level range, and comparator 5
A low potential is always output from one of the comparators 6 and 6. Therefore, the output 105 of the AND circuit 7 is output at a low potential and is input to the delay input terminal of the flip-flop circuit 8. As in the previous case, the output 105 is the judgment input signal 106 input from the terminal 53.
is taken into the flip-flop circuit 8 via the terminal 5.
4, a determination signal indicating no oscillation output is output at a low potential.

It goes without saying that the flip-flop circuit 8 functions as a storage circuit for the determination result of whether or not there is an oscillation output.

〔Effect of the invention〕

As explained above, the present invention calculates the logical product of the comparison result between the oscillation output integral value of the oscillation circuit and a predetermined reference voltage, and stores the result in a predetermined storage circuit. The present invention has the advantage that it is possible to provide an oscillation detection circuit that does not require expensive equipment and is formed with an extremely simple circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the main parts of an embodiment of the present invention, FIGS. 2(a), (b) and (c) are operation signal waveform diagrams of each part in the embodiment, and FIG. 3 is a circuit diagram showing main parts of an embodiment of the present invention. , is a circuit diagram showing a main part of a conventional oscillation detection circuit. In the figure, 1.9... Oscillation circuit, 2... Inverter, 3... Resistor, 4... Capacitor, 5, 6...
Comparator, 7...AND circuit, 8...Flip-flop circuit, 10...Frequency counter, 11...
microcomputer. Rod l concave $ 3 sides

Claims (1)

[Claims] The method further comprises: an integrating circuit that integrates the oscillation output of the oscillator circuit, a determination circuit that determines whether the output of the integrating circuit is within two reference voltage ranges, and a circuit that stores the determination result of the determination circuit. Characteristic oscillation detection circuit.