JPS63193717A - Semiconductor device - Google Patents

Abstract

PURPOSE:To make the preparation of a protection circuit in a signal input system unnecessary and to reduce the area of a device, by constituting the protection circuit of the signal input system by using an inverter at the final stage of an output circuit in the output circuit of a nonuse data. CONSTITUTION:The protection circuit 8 is constituted by using the inverter 6 of the final stage in a nonuse state. Thus, by constituting the protection circuit 8 of an address input circuit 7 by using the inverter 6 of the final stage unnecessitated on an operation in a data input/output circuit, it is possible to remove the protection circuit provided in a conventional device and to reduce the area of the device. In such a case, the inverter 6 at the final stage is used as the protection circuit 8 of the address input circuit 7, but, it is also advisable to use it for another input system, for example, for the protection circuit of the data input circuit, by which the same effect is expected to be given.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to an input protection circuit thereof.

[Conventional technology]

FIGS. 1(a) and 1(b) are configuration diagrams showing the data output circuit section of a conventional semiconductor device equipped with a plurality of data output systems whose use or non-use is selected at the manufacturing stage. figure(
a) in Figure 1 when one data output signal is selected)
shows the case where four data output signals are selected, and the former has one more address input signal than the latter. In both figures, 1 is a data input circuit, 2 is a protection circuit for the data input circuit 1, and 2a is a data input terminal, to which the data input circuit 1 is connected via the protection circuit 2. 3
4 is a data output circuit, 4.6 is a final stage inverter of the data output circuit 3, and 4a is a data output terminal, to which the data output circuit 3 is connected via the final stage inverter 4. 6a is a data input/output terminal, to which the data input circuit 1 and the data output circuit 3 are connected via the final stage inverter 6. 7 is an address input circuit (decoder), 8 is a protection circuit for the address input circuit 7, and 8a is an address input terminal.

In such a conventional semiconductor device, each low input circuit 1.7 is provided with a dedicated protection circuit 2.8. In the case of FIG. 1(a), the final stage inverter 6 is disconnected from the circuit and is not in use.

[Problem that the invention seeks to solve]

As described above, conventional semiconductor devices have a problem in that each input circuit is provided with a dedicated protection circuit, resulting in an increase in device area.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a semiconductor device whose device area can be reduced by reducing the area occupied by the protection circuit.

[Means for solving problems]

In the semiconductor device according to the present invention, a protection circuit for a signal input system is constructed using a final stage inverter of an unused data output circuit.

[Effect]

In this invention, since the final stage inverter of the unused data output circuit is used to configure the protection circuit for the signal input system, there is no need to separately provide a protection circuit for the signal input system.
The device area can be reduced.

〔Example〕

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

FIG. 1+al shows a data output circuit section of a semiconductor device according to an embodiment of the present invention. This shows the case where this selection is made. In the figure, 1 to 4 degrees 2a, ja, 6a, 8a, 6
．． Reference numeral 7 is the same as in the conventional example, but in this embodiment, although not shown, a protection circuit 8 is constructed using a final stage inverter 6 which is in an unused state. Figure 2(a), (
b) is a circuit diagram specifically showing an example of its configuration, FIG. 2(a) shows an example of the final stage inverter 6 of the data output circuit, and FIG. A protection circuit 8 constructed as shown in FIG.

In a semiconductor device having such a configuration, the final stage inverter 6, which is no longer necessary for operation, is installed in the data and output circuits.
Since the protection circuit 8 of the address input circuit 7 is constructed using the above, the conventional protection circuit can be made unnecessary, and the device area can be reduced accordingly.

In the above embodiment, the final stage inverter 6 is used as the protection circuit 8 for the address input circuit 7, but it may also be used for other input systems, such as the protection circuit for the data input circuit, and the same effect can be obtained. play.

〔Effect of the invention〕

As described above, according to the semiconductor device of the present invention, the protection circuit for the signal input system is configured using the final stage inverter of the unused data output circuit, so that the protection circuit is separately provided for the signal input system. This has the effect of eliminating the need for this, reducing the area of the device, and making it possible to obtain the device at low cost.

[Brief explanation of the drawing]

FIG. 1 (al is a block diagram showing the data and output circuit sections of a semiconductor device according to an embodiment of the present invention and a conventional example; FIG. 1 (b)
) is a configuration diagram showing the data output circuit section when four data output signals are selected in the conventional example, and FIG. 2(a) is an unused data output circuit of a semiconductor device according to an embodiment of the present invention. 2 (bl is a diagram showing a protection circuit for an address input circuit configured using the final stage inverter. In the figure, 1... data input circuit, 3...・Data output circuit, 7... Address input circuit, 2, 8... Protection circuit, 4.6... Final stage inverter, 2m... Data input terminal, 4a... Data output terminal, 6a ...
Data input/output terminal, 8a...address input terminal. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) In a semiconductor device equipped with multiple data output systems whose use or non-use is selected at the manufacturing stage, a protection circuit for the signal input system is configured using an inverter at the final stage of the output circuit of the unused data output system. A semiconductor device characterized by: (2) The semiconductor device according to claim 1, wherein the signal input system protection circuit is a data input circuit protection circuit. (3) The semiconductor device according to claim 1, wherein the signal input system protection circuit is an address input circuit protection circuit.