JPS636895Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an input/output sharing device in which input and output can be used as common terminals.

In recent years, with the development of electronic technology, there is a tendency for various circuits to be integrated. For example, in a circuit where the display output of an LED or the like is maintained by a signal from an input circuit made up of a non-lock type switch, it is necessary to provide one input terminal and one output terminal. be. in this case,
The most important issue is the number of terminals; the price of the IC changes significantly depending on the number of terminals, and if the number of terminals exceeds a certain number, it becomes impossible to configure the IC as a single IC. In particular, when a plurality of circuits are built-in, the number of terminals becomes extremely large.

Therefore, an object of the present invention is to provide an input/output sharing device in which the number of terminals is significantly reduced by sharing the input/output terminals. In order to achieve these objectives, this invention
a flip-flop, an input circuit externally connected to the set input of the flip-flop, an output circuit externally connected between the set input of the flip-flop and a power supply, and an output circuit connected between the set input of the flip-flop and ground; a switching transistor connected to have the output of the flip-flop as a base input, the flip-flop being activated in response to an input signal of the input circuit and controlled by the output of the flip-flop; This is to maintain the output level of the output circuit.

Hereinafter, it will be explained in detail using the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the input/output device according to the present invention, in which 1a to 1c have non-drop type switches 2a to 2c as external input circuits connected to the set input terminal S, respectively. A connected flip-flop. In this case, the reset input terminal R of each flip-flop 1a-1c is connected to the reset input terminal R of each flip-flop 1a-1c.
Switches 2a-2 as input circuits connected to
It is selectively connected so that the output of c is supplied. 3a to 3c are flip-flops 1a to 1c
These are light emitting diodes serving as external output circuits connected between the set input terminal of the power source +B and the power supply +B via resistors 4c. Reference numerals 5a to 5c are transistors connected to the cathode side of each light emitting diode, that is, between the input circuit line and the ground, and each transistor 5a to 5c is turned on by the reset output of the corresponding flip-flop 1a to 1c. It is configured as follows. Therefore, in the circuit configured in this way, switch 2
One end of a to 2c and the cathode of each light emitting diode 3a to 3c may be connected to a common input/output terminal for each pair.

In a circuit configured in this way, when the non-lock type switch 2a is turned on, for example, current flows through the path of power supply + B - resistor 4a - light emitting diode 3a - switch 2a - ground, and the light emitting diode 3a as an output circuit lights up. do. On the other hand, the flip-flop 1a is set by grounding the set input terminal S, and accordingly, the reset output becomes "L". As a result, the transistor 5a is turned on, and after the switch 2a is released and turned off, the current flowing through the light emitting diode 3a is allowed to flow through the transistor 5a, thereby maintaining the output level.

Next, for example, when switch 2b is turned on, flip-flop 1b is set at the same time as switch 2b is turned on, and flip-flop 1b is set.
Flip-flops 1a and 1c other than b are reset by the output of switch 2b, and the light emitting diode 3a
is turned off. When the flip-flop 1b is set, the reset output of the flip-flop 1b turns on the transistor 5b in the same way as in the case described above, and accordingly, the light-emitting diode 3b turns on.
remains lit, that is, the output continues to latch. Therefore, such an input/output device is extremely effective when used in, for example, a record size selection circuit of a record player.

FIG. 2 is a circuit diagram showing an embodiment in which the input/output device shown in FIG. 1 is constructed as a discrete unit, and the same parts as in FIG. 1 are designated by the same symbols. The difference between this figure and FIG. 1 is that a diode 6 for backflow prevention is connected between each reset input terminal of each flip-flop 1a to 1c and each switch 2a to 2c, and each flip-flop circuit 1a to 1c is The transistors 7 and 8 and resistors 9 to 12 respectively serve as transistors 7 and 8, and the transistors 5a to 5c for holding the output in FIG. This is the same as in FIG.

As explained above, according to the input/output sharing device according to the present invention, since the terminals connecting the input circuit and the output circuit can be shared, the reduction in the number of terminals can significantly reduce the cost of integration. In addition, it has various excellent effects such as being able to include more functions in one integrated device as the number of terminals is reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the input/output sharing device according to the present invention, and FIG. 2 is a circuit diagram showing an embodiment of the circuit shown in FIG. 1 in a discrete configuration. 1a-1c...Flip-flop, 2a-2c
...Switch, 3a-3c...Light-emitting diode,
4a-4c...Resistor, 5a-5c...Transistor, 6...Diode, 7,8...Transistor, 9-12...Resistor.

Claims (1)

[Scope of Claim for Utility Model Registration] A flip-flop, an input circuit externally connected to the set input of the flip-flop, an output circuit externally connected between the set input of the flip-flop and a power supply, and a set input circuit of the flip-flop. a switching transistor connected between an input and ground and connected to receive the output of the flip-flop as a base input; the flip-flop is activated in response to an input signal of the input circuit; An input/output shared device characterized in that the output level of the output circuit is maintained by the controlled switching transistor.