JPS59160336A - Returning circuit - Google Patents

Abstract

PURPOSE:To eliminate the need for a relay and reduce power consumption and to reduce package area by utilizing switching transistors (TR) and constituting a return loop. CONSTITUTION:When an H-level signal is applied to a control input terminal 1, the switching TR1 and TR2 turn on and transmission signals supplied from terminals 4 and 6 are sent out from a terminal 3 to an in-use circuit which is not shown in a figure through the TR1 and TR2 and a transformer 2. In this case, switches SW1 and SW2 are placed on sides of a receiving transformer as shown in the figure, so a reception signal from a terminal is led to a reception output terminal 11 through a receiving transformer 9. On the other hand, when an L- level signal is applied to the control input terminal 1, the TR1 and TR2 turn off and the switches SW1 and SW2 are connected to sides of a terminal opposite to the states in the figure at the same time, returning the transmit signals which are applied to the terminals 4 and 6 to the reception output terminal 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a folding circuit that selectively sends a data signal to a transmission path and folds it back to a receiving output terminal through a switching operation of a transistor.

Conventionally, relays have been used in loop-back circuits that have both a communication mode in which an analog transmit data signal is sent to a transmission path and a received data signal is taken into a reception output terminal, and a mode in which the transmitted data signal is looped back to a reception output terminal. is provided. For this reason, there are disadvantages in that the power consumption is large and the mounting area is also large.

The present invention has been made to eliminate the above-mentioned drawbacks, and aims to provide a folding circuit that uses transistors, has low power consumption, a small mounting area, stable operation, and low cost. do.

The present invention comprises a switching transistor that is turned on and off in response to a control signal, and a first transistor set that is stacked vertically on the switching transistor and is activated under the control of a first monitor signal. , a switching transistor that turns on and off in response to the control signal, a set of transistors stacked vertically on this transistor and activated under the control of a second data signal, and the first and second transistors. a transmitting transformer that sends a difference signal between the first and second data signals to the transmitting path; and a receiving transformer that is controlled by the control signal and connects the receiving output terminal to the midpoint of the pair of transistors. and a switch that selectively connects to the output terminal of the output terminal.

Hereinafter, one embodiment of the present invention will be described based on the drawings. In the figure, 1 indicates a control signal input terminal, into which an H level or L level control signal is input. The control signal input terminal 1 is connected to a pair of NPN switching transistors Trt,
The switching transistor Trs connected to the base of Trz and the collector of Trz are connected to each other via the primary coil of the transmission transformer 2. Note that 3 is the end of the transmission line.

4 is a first data input terminal, to which the base of an NPN transistor Tr3 is connected, and this transistor Tri is a switching transistor Trs.
K is stacked vertically. Therefore, the switching transistor Trr and the transistor 'fr
s constitutes a first transistor set 5. Similarly, 6 is a second data input terminal, to which the base of an NPN transistor Tr4 is connected, and this transistor Tra is connected to a switching transistor Tr2.
are stacked vertically. switching transistor Tr
Two transistors Tr4 stacked vertically constitute a second transistor set 7. The collector of the transistor Tra is connected to the battery B via a resistor R1, and the collector of the transistor Tr< is also connected to the battery B via a resistor R2. Note that the battery B is connected to the tap of the transmitting transformer 2.

Reference numeral 8 indicates a receiving line end, which is connected to this output terminal 10 via a receiving transformer 9. 11 is a reception output terminal, which is switched by switches SW1. SW2 operation, transistor T+z
, connected to the data terminal 12 connected to the collector of Tra or the output terminal 1o of the receiving transformer 9.

First, when an H level control signal is applied to the control input terminal 1, the switching transistor Trs.

Both Trz become conductive. Also, transistor Tr3
generates a collector voltage in accordance with the first data signal, and transistor 'l'r4 generates a collector voltage in accordance with the second data signal, and switches both collector voltages to the primary coil of the transmitting transformer 2, respectively.・It is supplied through the transistors Trl and Trz, and the voltage difference between the collector voltages is sent out to the transmission path. On the other hand, at this time, the switches SWi and SW controlled by the H level control signal
2 is operatively switched to the output terminal 10 of the receiving transformer 9. The voltage applied to the receiving line end 8 therefore appears at the receiving output terminal 11. In this way, when the control signal is at H level, the difference signal between the first and second data signals is sent out to the transmission path, and the voltage at the reception line end 5 is output from the reception path to the reception output end 11. communication modes will be formed.

Next, when the control signal applied to the control input terminal 1 becomes L level, the switching transistors Trx, T
Both transistors Tr2 and Tr2 are in a non-conductive state.
The collector voltage of Tr4 is not applied to the transmitting transformer 2,
Therefore, there is no signal at the end of the transmission line. On the other hand, at this time, the switch S controlled by the L level control signal
W'+ and SW2 are switched in conjunction with the data terminal 12. Therefore, the voltage at the receiving line end 5 is not output to the receiving output end 11, and the voltage at the receiving line end 5 is not outputted to the receiving output end 11, and the voltage at the receiving line end 5 is not outputted to the receiving output end 11. Tr4
The collector voltage of
1Vc appears. t, b, when the control signal is at L level,
The transmission path is in a no-signal state, and the reception output terminal 11 has the first
and a second data signal will be returned.

In this embodiment, the switching transistor 'l
'r+, Tr2 is used, so it has the advantage of reducing power consumption, reducing the mounting area, and being stable in operation and inexpensive. In the above embodiment, all of the transistors 'l'r1 to T1m are of the NPN type, but they may be of the PNP type.

As explained above, since the folding circuit according to the present invention uses a switching transistor that operates in response to a control signal, it can reduce power consumption and the mounting area compared to conventional relays. It has the characteristics of being stable, offering improved performance, and being inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of a folding circuit according to the present invention. 1... Control signal input terminal 2... Transmission transformer 3.
...Transmission line end 4...First data input terminal 5.
...First transistor set 6...Second data input terminal 7...Second transistor set 8...Receiving line end 9...Receiving transformer 10...Output terminal of receiving transformer 11...Reception output terminal 12...Data terminal Trl, 'fr2...Switching transistor Tr31Tr4...Transistor B...Battery R1, R2 resistance SW+, SW2...
・Switch applicant: NEC Corporation Figure 1 W2

Claims (1)

[Claims] A switching device that operates on and off in response to a control signal.
A first transistor set consisting of a transistor and a transistor vertically stacked on this transistor and activated under control of a first data signal; a switching transistor that is turned on and off in response to the control signal; and this transistor. a second set of transistors configured of transistors stacked vertically and activated under the control of a second data signal; It consists of a transmitting transformer that sends a signal difference signal to a transmitting path, and a switch that is controlled by the control signal and selectively connects the receiving output terminal to the midpoint of the set of transistors and the output terminal of the receiving transformer. Folding circuit.