JPS63183684A - Semiconductor device - Google Patents

Abstract

PURPOSE:To simplify the constitution of a system by supplying directly code data to semiconductor devices, and discriminating whether its data itself has been selected or not, based on whether said data coincides with code data which is held by each device or not. CONSTITUTION:Semiconductor devices 24-27 are provided with code holding parts 28-31 for storing each different code data, respectively, and code deciding part 32-35 for comparing code data supplied through an address line 22 with code data stored in the holding parts 28-31. When the code data supplied through the address line 22 coincides with the code data stored in the holding parts 28-31, an activating signal is supplied to circuits 36-39 from the deciding parts 32-35. As a result, only the circuits 36-39 to which the activating signal has been supplied are activated, and to the data supplied through a data line 23, prescribed processing is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to a chip select circuit that determines whether a semiconductor device has been selected from a plurality of chips constituting a system.

[Conventional technology]

Conventionally, when selecting a semiconductor device in a system composed of multiple chips, as shown in FIG.
The chip selection semiconductor device 15 decodes an address signal sent from the central processing unit (hereinafter referred to as CPU) 12 via the address line 13, and sends it to a plurality of semiconductor devices 17 to 20, for example 17 via signal #16. This was done by supplying all selection signals. Since the integrated circuit of the semiconductor device 17 selected in this way is activated, even if the data code is commonly supplied from the CPU 12 to the semiconductor devices 17 to 20 via the data line 14, the semiconductor device 1111
Only No. 7 executes predetermined processing on the data code.

[Problem that the invention seeks to solve]

However, in the conventional system described above, in order to select one of the plurality of commonly wired semiconductor devices 17 to 20, a semiconductor device [k15] for chip selection is required, making the system's glue arrangement complicated. In addition to increasing the size of the system, the physical space of the system also became larger. So,
An object of the present invention is to simplify the configuration of a system composed of a plurality of chips.

[Means, operations, and effects for solving the problems] The present invention directly supplies code data to the semiconductor devices constituting the system, and performs self-control based on whether the code data matches the code data held by each device. The gist of the system is to determine whether or not it has been selected.The code holding section holds the code data in advance, and when the code data is supplied from the outside, the code discrimination section The code data held in the code holding section is compared with the code data held in the code holding section. If the comparison results match, it determines that it has been selected, activates the integrated circuit, and executes a predetermined attack. Therefore, even if data is supplied directly to a plurality of semiconductor devices by 1 m, only the proven circuit of the semiconductor device selected by the code data can be activated, and a separate semiconductor device for chip selection is provided. I have no mental image. By the way,
The system can be adapted to a t-phrase, and the physical space of the system can be reduced in size.

[Implementation fee]

FIG. 1 is a block diagram showing one embodiment of the present invention.
The address line 22 and data line 23 of the PU 21 are connected to a plurality of semiconductor devices 24 to 27 in a converging manner. The semiconductor devices 11t24 to 27 transfer the code data supplied via the code holding lines 28 to 31 storing different code data and the address line 22 to the code holding line 2.
It has code discrimination sections 32 to 35 that compare code data stored in address lines 8 to 31, and
The code data supplied through 2 is code 1 (
When the code data matches the code data stored in S28 to S31, an activation signal is supplied from the code determination sections 32 to 35 to the printing circuit P636 stamp 39. As a result, only the IA cap n integrated circuits 36 to 39 of activation number 18 are activated and predetermined processing is performed on the data supplied via the data line 23.

As shown in FIG. 3, the code holding section 28 and the code discriminating section 32 are constructed in a manner that the code holding section 28 has +4 programmable address holding circuits ff141 to ff44. The circuits 41 to 44 are n-channel stacked gate MOS transistors (hereinafter referred to as n-8n-
(referred to as 8G transistor) 45 and P channel type MOS
It has a transistor 46. n-8GMOS
) n-8Gn-8G transistor 45 based on the presence or absence of carrier injection into the 70-teinggut of the transistor 45.
switches to on or off state, n-8n-8G
If the transistor 45 is on, it is at a low level, i.e. “O
" is output. To load code data, for example, l-1, IJ, into the code holding unit 28 at 7n, a program voltage VPP is applied to the drain and gate of the n-8n-8G transistor of the programmable address holding circuit 42 and 44.
After applying the voltage VCC, the power supply voltage VCC is applied to the gates of the n-8GMOS) transistors of the programmable address holding circuits 41 to 44.

As a result, programmable address holding circuits 41 to 4
From 4 onwards, roJ, rxJ, rIJ, rIJ
When the code data I-1 and IJ are supplied through the address i22, each bit of the code data rx and lJ is output to the inverter 45°4.
Since n and 6 are inverted at 6, only the input of the NOR circuit 47 is all "
0'', NOR circuit 48 based on the output of this NOR circuit
The inverted output from the inverter 49 becomes the activation signal C8. On the other hand, rO, OJ,
``0.When IJ, rl, and OJ are supplied,
NOR circuits 52, 50, and 51 are selected respectively, but rlJ is selected from programmable address holding circuits 42 to 44.
Since n is the supply, the NOR circuit 47 outputs "1".
, 50 to 52, and no polarization or activation signal C8 is output. The NOR circuits 47, 48, 50, 51, 52 and the inverters 45, 46, 49 constitute the code discrimination section 32 as a whole.

In this way, in one embodiment, the data held in the code holding unit 28 can be rewritten, which facilitates system design.

The n-8GIldO8) transistor in one embodiment is an ultraviolet erasable EFROM, but an electrically rewritable non-volatile memory (E2FROM) or a fuse ROM may be used instead.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram of a conventional example, and FIG. 3 is an electric circuit diagram showing the detailed configuration of one embodiment. 28 to 31... Cord holding section, 32 to 35
......Code discrimination section, 36 to 39...
18 product circuit. Agent Patent Attorney Uchihara 12'. Figure 3

Claims (2)

[Claims] (1) In a semiconductor device comprising an integrated circuit and a chip select means for activating the integrated circuit in response to an instruction from the outside, the chip select means includes a code holding section that holds code data specifying the integrated circuit. . A semiconductor device comprising: a code discrimination section that compares code data supplied from the outside with code data held in the code holding section and activates the integrated circuit if the comparison results match. (2) The semiconductor device according to claim 1, wherein the code data held in the code holding section is rewritable.