JPH0591148A - Signal interruption detection circuit - Google Patents

Abstract

PURPOSE:To provide the signal interruption detection circuit in which large scale integration is attained and miniaturization is executed through the configuration of a digital logic circuit. CONSTITUTION:The circuit is provided with a pulse counter circuit counting an inputted monitored signal pulse S3 within a monitor interval period based on the monitor interval signal from an interval generating circuit 1 generating a signal interrupt detection interval signal S2 and with a discrimination circuit discriminating the result of count by the pulse count circuit for each monitor interval period and outputting signal interruption detection information S6, and the pulse counter circuit and the discrimination circuit are respectively made up of flip-flop circuits 2A, 3A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal disconnection detection circuit which can be constituted by a logic circuit.

[0002]

2. Description of the Related Art A conventional signal loss detection circuit comprises a monitored signal detection circuit 10 and an identification circuit 11, as shown in FIG.
The monitored signal detection circuit 10 is composed of an analog circuit using a time constant circuit composed of a resistor and a capacitor.

In this signal disconnection detection circuit, as shown in the timing chart of FIG. 5, it is confirmed that the monitored signal pulse U1 does not exist within the monitored interval defined by the time constants of the resistor and the capacitor in the monitored signal detection circuit 10. To detect. When the monitored signal U1 is present, the monitored signal detection circuit 10 outputs a high-level (“H”) detection signal U2, and when the monitored signal U1 is not detected due to a signal disconnection, the detection signal U2 is a monitoring interval. During this period, the voltage gradually approaches the low level (“L”), and then outputs “L”.
The discrimination circuit 11 discriminates that the output signal from the monitored signal detection circuit 10 has become “L”, and outputs the “L” signal loss detection signal U3 indicating the signal loss at this time. When the output signal is "H" normally, the signal disconnection detection signal U3 outputs "H".

[0004]

In the above-mentioned conventional signal loss detection circuit, since the monitored signal detection circuit 10 is composed of an analog circuit using a resistor and a capacitor,
There is a problem that miniaturization cannot be achieved because an LSI (large-scale integrated circuit) cannot be formed and circuit components must be externally attached.

The present invention has been proposed in order to solve the problems of the prior art as described above, and provides a signal loss detection circuit which can be made into an LSI and can be miniaturized by being constituted by a digital logic circuit. The purpose is to

[0006]

In order to achieve this object, a signal loss detection circuit according to the present invention includes an interval generation circuit for generating a monitoring interval signal for signal loss detection,
Based on the monitoring interval signal from this interval generation circuit, a pulse counting circuit that counts the input monitored signal pulses within the monitoring interval section, and the counting result of this pulse counting circuit is determined for each monitoring interval section,
The configuration includes a determination circuit that outputs signal loss detection information, and the favorable or pulse counting circuit and the determination circuit are configured by flip-flop circuits.

[0007]

According to the above configuration, when the pulse counting circuit does not count the monitored signal pulses at all in the monitoring interval section, the determination circuit provides the signal disconnection detection information based on the counting result of the pulse counting circuit. Can be output. Since the interval generation circuit, the pulse counting circuit, and the determination circuit can be configured by logic circuits, the signal disconnection detection circuit can be integrated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the signal loss detection circuit according to the present invention will be described in detail below with reference to the drawings. The block diagram of FIG. 1 shows the basic configuration of this signal disconnection detection circuit. In the figure, the interval generation circuit 1 generates a monitoring interval signal S2 from the input signal S1 and outputs it to the pulse counting circuit 2, and also outputs a signal S5 having the same cycle as the interval signal S2 to the determination circuit 3. The pulse counting circuit 2 counts the monitored signal pulses S3 within the monitoring interval signal interval based on the input monitoring interval signal S2, and outputs a detection signal S4 as the counting result to the determination circuit 3. The determination circuit 3 checks the state of the detection signal S4 for each monitoring interval section and outputs the signal disconnection detection information S6.

Next, a specific signal break detection circuit shown in FIG. 2 will be described. In this signal break detection circuit, the pulse counting circuit 2 is composed of the simplest D-type flip-flop circuit 2A, and the determination circuit 3 is also composed of the flip-flop circuit 3A. In the figure, the interval generation circuit 1 divides the input signal S1 to generate a monitoring interval signal S2 as shown in the timing chart of FIG. 2 and outputs it to the flip-flop circuit 2A. The cycle determination signal S5 is output to the flip-flop circuit 3A.

In the flip-flop circuit 2A constituting the pulse counting circuit 2, when the monitoring interval signal S2 is input, initialization is performed in intervals when the interval signal S2 is "L". "H" is always input to the data terminal of the flip-flop circuit 2A, and if at least one pulse of the monitored signal S3 is input within the interval section after initialization, the flip-flop circuit 2
A outputs a detection signal S4 of "H" indicating normality. On the other hand, when the monitored signal S3 is not input at all in the interval section after the initialization, the detection signal S4 of "L" indicating the signal disconnection is output.

In the flip-flop circuit 3A which constitutes the judgment circuit 3, the detection signal S4 immediately before being initialized by the monitoring interval signal S2 is judged by inputting the judgment signal S5. The information S6 is output, and when the signal disconnection is determined, the "L" signal disconnection detection information S6 is output.

The present invention is not limited to the above-described embodiments, but various modifications can be made within the scope of the invention.

[0013]

As described above, according to the present invention, the signal disconnection detection circuit, which was conventionally composed of an analog circuit, can be composed of a digital logic circuit.
It has become possible to implement the I-type, and the mounting circuit can be downsized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a signal loss detection circuit according to the present invention.

FIG. 2 is a block diagram showing an example of a specific signal loss detection circuit.

FIG. 3 is a timing chart showing an operation of the signal loss detection circuit of FIG.

FIG. 4 is a block diagram showing a conventional signal loss detection circuit.

FIG. 5 is a timing chart showing the operation of a conventional signal loss detection circuit.

[Explanation of symbols]

 1 Interval Generation Circuit 2 Pulse Generation Circuit 2A Flip-Flop Circuit 3 Judgment Circuit 3A Flip-Flop Circuit S1 Input Signal S2 Monitoring Interval Signal S3 Monitored Signal S4 Detection Signal S5 Judgment Signal S6 Signal Loss Detection Information

Claims (2)

[Claims] 1. An interval generation circuit for generating a monitoring interval signal for signal loss detection, and a pulse counting for counting an input monitored signal pulse in a monitoring interval section based on the monitoring interval signal from the interval generation circuit. A signal loss detection circuit comprising: a circuit; and a determination circuit that determines the counting result of the pulse counting circuit for each monitoring interval section and outputs signal loss detection information. 2. The signal disconnection judging circuit according to claim 1, wherein the pulse counting circuit and the judging circuit are constituted by a flip-flop circuit.