JPH02259973A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To improve responsiveness by performing input/output by switching a bus and a signal by a change-over switch provided at an input/output interface with the outside or a part neighboring to the input/output interface. CONSTITUTION:The change-over switch 14 is provided neighboring to the input/ output interface 6, and connects either the signal of a functional block 3 or the bus 7 to the input/output interface 6. While the input/output of the signal between the functional block 3 and external equipment is performed, the change- over switch 14 is connected to a functional block 3 side. Therefore, the output capacity of the functional block 3 is mainly limited to only the input capacity of the input/output interface 6 when the signal is outputted from the functional block 3 considering wiring capacity, and also, the output capacity of the input/ output interface 6 when the signal is outputted from the functional block 3 considering wiring capacity, and also, the output capacity of the input/output interface 6 is mainly limited to only the input capacity of the functional block 3 when the signal is inputted to the functional block 3 such a way, it is possible to improve the responsiveness of a specific functional block 3 even when the wiring of the bus 7 is extend longer, and to reduce power consumption when the functional block 3 is operated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor integrated circuit, particularly a large-scale semiconductor integrated circuit having a bus. [Prior Art] FIG. In Figure 0, which is a block diagram showing the configuration of a large-scale semiconductor integrated circuit, (1) is a semiconductor integrated circuit, +21, (3), '(4) and (
5) is a functional block, (6) is an input/output interface with the outside, (7) is a bus, and (8) is a functional block (2).
(9) is a changeover switch for connection between function block (3) and bus (7), Q(I is for connection between function block (4) and bus (7)) Changeover switch, 0υ is changeover switch for connection between function block (5) and bus (7), (2) is input/output bus for connecting input/output interface (6) and external equipment, Q3 is changeover switch control It is a circuit.

Next, the operation will be explained. Functional blocks (2) to (5)
) to access an external device, the bus (7) is connected to the input/output interface (6 ) via input/output bus 02
leading to. Furthermore, when inputting a signal from the outside to one of the functional blocks (2) to (5), the meridian is opposite to the above.

[The espionage that invention attempts to solve]

Since the conventional semiconductor integrated circuit with a bus is configured as described above, when the functional block (3) accesses external equipment through the changeover switch t9), the input/output interface (6), and the input/output bus (6). When considering, first, if a signal is output from one functional block (3), the output capacity of functional block (3) is equal to the bus (7).
It is the sum of the wiring capacitance of and the input capacitance of the input/output interface (6). Further, when a signal is input to one functional block (3), the output capacitance of the input/output interface (6) is equal to the wiring capacitance of the bus (7) and the input capacitance of the functional block (3). The wiring capacity of the bus (7) increases as the scale of the integrated circuit increases and the wiring length of the bus (7) increases, which poses a problem in that it impairs responsiveness such as access time.0 This invention was developed in order to solve the above-mentioned problems, and its purpose is to improve the responsiveness of a specific functional block among a plurality of functional blocks.

[Means to solve the problem]

In the semiconductor integrated circuit according to the present invention, the signal line of a specific functional block is characterized by improved responsiveness.

A switch for switching between the above-mentioned specific signal line and the above-mentioned bus, which is separated from the buses used in other functional blocks and is provided at an input/output interface with the outside of the semiconductor integrated circuit, or at a through portion adjacent to the above-mentioned input/output interface. 4
1-1. so that it can be connected to external devices.

[Effect]

In the semiconductor integrated circuit according to the present invention, the wiring capacitance between a specific functional block and the input/output interface is not added to the wiring capacitance of other buses, resulting in a low capacitance.

〔Example〕

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

FIG. 1 is a block diagram of a large scale integrated circuit with a bus. In the figure, (1) to (8) and α1 to a1 are the same as those shown in the conventional example of FIG. 3, so their explanations will be omitted.

04 is a newly provided changeover switch. A specific functional block that requires responsiveness is now designated as functional block (3). The changeover switch α4 is provided adjacent to the input/output interface (6), and connects either the signal of the functional block (3) or the bus (7) to the input/output interface (6).

Next, the operation will be explained. Let us now consider a case where functional block (3) is inputting and outputting signals to and from an external device. At this time, the changeover switch α is the function block (
3) (11) Considering the wiring capacitance as in the conventional example shown in Fig. 3, first, when a signal is output from 1 functional block (3), the output capacitance of 1 functional block (3) is , the input capacity of the input/output interface (6) is only the input capacity of the input/output interface (6), and when a signal is input to one functional block (3), the output capacity of the input/output interface (6) is the input capacity of the functional block (3). Both of these effects are due to the fact that most of the bus (7) is separated by the changeover switch α4.Compared to the conventional example, the wiring capacitance is clearly reduced, and this effect is The size increases as the scale increases and the wiring length of the bus (7) increases.

In the above embodiment, the case where there is one specific functional block has been described, but the same effect can be obtained even when there is a plurality of functional blocks. FIG. 2 is a block diagram of a semiconductor device according to another embodiment of the present invention in which there are two specific functional blocks. In the figure, (1) to (8).

(11-(to) is the same as that shown in FIG. 1, so the explanation is omitted. (G) is a changeover switch. Changeover switch αQ is for function block (3) or (5) or bus ) can be switched.

[Effects of the Invention] As described above, according to the present invention, even if the scale of the semiconductor integrated circuit becomes large and the bus wiring becomes long.

The responsiveness of a specific functional block can be improved, and as an additional effect, the power consumption during operation of the functional block is reduced by the reduction in load capacity.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a semiconductor integrated circuit according to an embodiment of the present invention, FIG. 2 is a block diagram of a semiconductor integrated circuit according to another embodiment of the invention, and FIG. 3 is a block diagram of a conventional semiconductor integrated circuit. be. In the figure, (1) is a semiconductor integrated circuit, +2), (3
), (4) and (5) are functional blocks, (6) is an input/output interface, (7) is a bus, (8), Ql, αυ and Moe are switching units. Input/output bus. (to) is a changeover switch control circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] Multiple functional blocks use a bus, and the signal line of a specific functional block is independent of the bus and is connected to an external input/output block (hereinafter referred to as input/output interface) or adjacent to the input/output interface. A semiconductor integrated circuit, characterized in that input/output to/from the outside is performed by switching between the bus and the signal using a changeover switch provided in a portion of the semiconductor integrated circuit.