JP2001345867A - Transmitting circuit for electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitting circuit for electronic equipment capable of suppressing low the power consumption of transmission line as a whole. SOLUTION: Concerning the transmitting circuit for electronic equipment provided with a differential driver 1 for signal transmission based on the EIA-422A standard, a differential receiver 2 for signal transmission based on the EIA-422A standard and positive signal and negative signal transmission lines 3 and 4 located between the driver 1 and the receiver 2 for respectively transmitting positive and negative signals, first and second terminal resistors 5 and 6 are serially connected to the positive signal transmission line 3, first and second terminal resistors 7 and 8 are serially connected to the negative signal transmission line 4, so that moreover the potential difference between the input terminals of the receiver 2 is made equal to or higher than ±200 mV.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission circuit for electronic equipment mounted on a battery-driven device such as an artificial satellite.

[0002]

2. Description of the Related Art A transmission circuit shown in FIG. 2 and a transmission circuit shown in FIG.
A-485 (American Electronic Industries Association) standard-compliant transmission circuit.

FIG. 2 shows a differential driver 1 for signal transmission conforming to EIA-422A (American Electronic Industries Association) standard,
A differential signal transmission receiver 2 conforming to the EIA-422A standard and a positive signal transmission path 3 and a negative signal transmission path 4 disposed between the driver 1 and the receiver 2 for transmitting a positive signal and a negative signal, respectively. It is provided between the positive signal transmission path 3 and the negative signal transmission path 4 and has a terminating resistor 9 connected in parallel to them.

FIG. 3 shows a differential driver 1 for signal transmission conforming to EIA-485 (American Electronic Industries Association) standard,
A differential receiver 2 for signal transmission conforming to the IA-485A standard, and a positive signal transmission line 3 and a negative signal transmission line 4 disposed between the driver 1 and the receiver 2 for transmitting a positive signal and a negative signal, respectively. And the signal transmission differential driver 13 is provided in parallel with the positive signal transmission path 3 and the negative signal transmission path 4.
And the differential receiver 12 for signal transmission, respectively,
A terminating resistor 1 is provided between the positive signal transmission path 3 and the negative signal transmission path 4.
0 and 11 are connected in parallel.

[0005] In the case of FIG. 2 or 3, the transmission signal is transmitted as a conversion into a positive signal and a negative signal by the driver 1, the difference between the positive and negative signals is obtained by the receiver 2, and the original signal mixed on the transmission line is obtained. A communication method called a differential method for removing noise other than the above is intended to improve communication reliability.

The terminating resistors 9, 10, 11 shown in FIG.
Is connected in parallel to the transmission path 3 and the transmission path 4, so that by adding a resistance value equivalent to the impedance of the transmission path 3 and the transmission path 4, signal reflection is prevented,
The effect of reducing signal distortion can be obtained.

[0007]

As described above, since the conventional electronic equipment is mounted on a battery drive device such as an artificial satellite, it is necessary to keep the power consumption low to maintain the life of the battery (device). . As described above, there are various places where measures are taken to reduce power consumption in electronic devices.When considering a transmission circuit as one of them, a transmission line standardized as described above is used. The initial purpose cannot be achieved simply by using it within the standard, and some solution is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a transmission circuit of an electronic device capable of suppressing the power consumption of the entire transmission line.

[0009]

In order to achieve the above object, an invention corresponding to claim 1 comprises a differential driver for signal transmission conforming to the EIA-422A standard and an EIA-422A.
Transmission of an electronic device provided with a differential receiver for signal transmission conforming to a standard, and provided with a positive signal transmission path and a negative signal transmission path for transmitting a positive signal and a negative signal, respectively, disposed between the driver and the receiver. In a circuit, at least one terminating resistor is connected in series to each of the positive signal transmission line and the negative signal transmission line, and an electronic device is configured such that a potential difference between input terminals on the receiver side becomes ± 200 mV or more. Transmission circuit.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram for explaining a first embodiment according to the present invention. That is, the embodiment uses the EI
A-422A standard compliant signal transmission differential driver 1
A differential receiver 2 for signal transmission conforming to the EIA-422A standard; a positive signal transmission path 3 and a negative signal transmission path disposed between the driver 1 and the receiver 2 for transmitting a positive signal and a negative signal, respectively. In a transmission circuit of an electronic device provided with a first signal transmission line, first and second terminating resistors are connected in series to a positive signal transmission line, and first and second terminating resistors are connected to both ends of a negative signal transmission line. And the second terminating resistors 7 and 8 are connected in series, and the potential difference between the input terminals of the receiver 2 is ± 2.
This is a transmission circuit of an electronic device provided with a voltage of 00 mV or more.

By connecting the terminating resistors 5, 6, 7, and 8 to the transmission lines 3 and 4 in series, signal reflection can be reduced and the resistance of the transmission lines 3 and 4 can be reduced. Since it is larger than the circuit, the power consumption of the transmission lines 3 and 4 can be suppressed low.

Here, the resistance values of the terminating resistors 5, 6, 7, and 8 will be described. To reduce the power consumption, the resistance values of the terminating resistors 5, 6, 7, and 8 may be increased, but a voltage drop occurs at both ends of the terminating resistors 5, 6, 7, and 8. Receiver 2 has a potential difference of ± 200 m between input terminals A ′ and B ′.
On the other hand, as the resistance values of the terminating resistors 5, 6, 7, and 8 increase, the individual voltage levels of the input terminals A 'and B' decrease. Conditions must be met at the same time.

On the other hand, in the circuits shown in FIGS. 2 and 3, it is possible to prevent signal reflection by the terminating resistors 9 and 11 and to reduce distortion of the signal waveform.
However, there is a drawback that the power consumption is large, and when low power consumption is considered for a transmission line, it cannot be used as it is.

That is, the terminating resistors 5, 6, 7, 8 in FIG.
Usually, a value matching the impedance of the transmission lines 3 and 4 connecting the driver 1 and the receiver 2 is used. In the embodiment of the present invention, however, the value is set to be high. By suppressing the distortion of the signal waveform due to the reflection within the limit value that the receiver 2 can receive, the power consumption of the entire transmission lines 3 and 4 can be suppressed as a result.

In the embodiment described above, the terminating resistors 5, 6
And those in which 7, 8 are connected in series to a positive signal transmission path and a negative signal transmission path, respectively, but those in which at least one terminating resistor is connected in series to each of the positive signal transmission path and the negative signal transmission path Needless to say, any configuration may be used. Of course, in this case, it is needless to say that the configuration is such that the potential difference between the input terminals of the receiver 2 becomes ± 200 mV or more.

In the embodiments of the present invention, a battery-driven device such as an artificial satellite has been described as a technical field to which the present invention pertains. However, the present invention is not limited to this, and any device that does not have strict requirements for fail-safe and the like can be applied. Needless to say.

[0018]

According to the present invention, at least one terminating resistor is connected in series to each of the positive signal transmission line and the negative signal transmission line, and the potential difference between the input terminals on the receiver side is ± 20.
Since the configuration is set to be 0 mV or more, it is possible to provide a transmission circuit of an electronic device that can reduce power consumption of a transmission path and reduce signal reflection.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating an embodiment of a transmission circuit of an electronic device of the present invention.

FIG. 2 is a circuit diagram illustrating one example of a transmission circuit of a conventional electronic device.

FIG. 3 is a circuit diagram for explaining another example of a transmission circuit of a conventional electronic device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Differential driver for signal transmission conforming to EIA-422A standard 2 ... Differential receiver for signal transmission conforming to EIA-422A standard 3 ... Positive signal transmission line 4 ... Negative signal transmission line 5, 6, 7, 8 ... Terminating resistor

Claims (1)

[Claims] 1. A differential driver for signal transmission conforming to the EIA-422A standard, a differential receiver for signal transmission conforming to the EIA-422A standard, and a positive signal and a negative signal disposed between the driver and the receiver. In a transmission circuit of an electronic device including a positive signal transmission path and a negative signal transmission path for transmitting signals, at least one terminating resistor is connected in series to each of the positive signal transmission path and the negative signal transmission path. A transmission circuit for the electronic device, wherein a potential difference between the input terminals on the receiver side is ± 200 mV or more.