Semiconductor device with selectionable pads

Abstract: Semiconductor device comprising at least two pads (101, 102; 103, 104) for the input of external signals and/or for the output of signals from said semiconductor device, at least two uncoupling buffers (201, 202; 203, 204) each connected to each one of said pads, at least one multiplexer (10; 20) connected to said pads (101, 102; 103, 104) by means of said uncoupling buffers (201, 202; 203, 204) and at least one memory element (4; 5) suitable to generate a configuration signal (C ) operating on said multiplexer (10; 20) and said uncoupling buffers (201, 202; 203, 204) to selectively enable one or the other of said pads (101, 102; 103, 104).

Description: The present invention refers to a semiconductor device that is preset with a configuration of pads that are selectionable in relation to the user needs. The correct choice of the output pads and of the input pads has a fundamental importance in the design of a semiconductor device. This is even more important primarily in the design of memory devices and especially of Flash memory devices. In industrial production, in fact, Flash memory devices must be realised in the most versatile way to guarantee a wide market range, so that they are not made uniquely for a single customer but instead for different customers. On the other hand, for a single Flash memory device there are different physical arrangements of the input and output pins in order to meet the requirements of the various customers. A traditionally adopted technique for the configuration of input and output pads of the memory device consists in the utilisation of different final steps of the process with corresponding different maskings. Such process steps are diversified according to the different configurations of the output and input pads that one wants to give the memory device. It is essential that the various cases are analysed at a design stage so as to reduce the number of masks that are necessary. Such a technique shows substantial costs of production that are tied to the differentiation of the process steps and therefore of the masks that are called for by the different configurations inherent in a same memory device. In view of the state of the art described, object of the present invention is to present a semiconductor device that is readily adjustable to the different pad configurations required by the users. According to the present invention, such object is attained by means of a semiconductor device characterised in that it comprises at least two pads for the input of external signals and/or for the output of signals from said semiconductor device, at least two uncoupling buffers each connected to each one of said pads, at least one multiplexer connected to said pads by means of said uncoupling buffers and at least one memory element suitable to generate a configuration signal operating on said multiplexer and said uncoupling buffers to selectively enable one or the other of said pads. Owing to the present invention it is possible to realise a semiconductor device that allows to vary the configuration of the input and/or output pads and that minimises the production costs of the device. The characteristics and the advantages of the present invention will become evident from the following detailed description of an embodiment thereof, that is illustrated as a non limiting example in the enclosed drawing, in which: Figure 1 is a schematic view of a Flash memory element according to an embodiment of the present invention. With reference to Figure 1, there is shown a schematic view of a semiconductor device 1 according to the present invention. Said device comprises in it a Flash memory element M, two multiplexers 10, 20, two CAM (Contenet Adressable Memory) memory elements 4, 5, four buffers 210, 202, 203, 204, two input pads 101, 102 and two output pads 103, 104. An output signal OUT of the Flash memory M and the output signal C of the CAM memory 5 represent the input signals of the multiplexer 20. More precisely the output signal C of the CAM memory 5 represents a configuration bit that allows the multiplexer 20 to enable one or the other of the two pads 103, 104. In this way the output signal of the Flash memory is present only on one of the two pads 103, 104, thus obviating the problem of the differentiation of the processes and therefore of the masks according to the traditional technique. The pad 103 and the pad 104 are connected to the multiplexer 20 by means of buffers 203, 204, respectively buffer 203 for pad 103 and buffer 204 for pad 104. Such buffers 203, 204 serve the purpose to uncouple the multiplexer 20 from the output pads since the capacity of the pads is much higher that the capacity of the output terminal of the multiplexer. In input the buffers 203 and 204 too are provided with the same signal C coming from the CAM memory 5, which allows to disable one of the two pads, leaving the other one on, thus preventing a high consumption of the current coming from the power supply. The pad enabling and disabling operations are made after the "testing" stage of the product. According to the same Figure 1, the same configuration provided for the output of data signals from the Flash memory M is provided for the input of the data signals coming from the outside. To this purpose the semiconductor device 1 is provided with a second multiplexer 10, with a second CAM memory 4, with two additional buffers 201, 202 and with two additional pads 101, 102. The multiplexer 10 enables one or the other of the two pads 101, 102, respectively connected to the buffer 201, 202, by means of the configuration bit C coming from the CAM memory 4. The input signal of the enabled pad will become the input signal IN of the Flash memory M. In addition, the configuration bit coming from the CAM memory 4 is sent to pads 101, 102 in order to disable the pad that is not in operation.

Claims: Semiconductor device characterised in that it comprises at least two pads (101, 102; 103, 104) for the input of external signals and/or for the output of signals from said semiconductor device, at least two uncoupling buffers (201, 202; 203, 204) each connected to each one of said pads, at least one multiplexer (10; 20) connected to said pads (101, 102; 103, 104) by means of said uncoupling buffers (201, 202; 203, 204) and at least one memory element (4; 5) suitable to generate a configuration signal (C ) operating on said multiplexer (10; 20) and said uncoupling buffers (201, 202; 203, 204) to selectively enable one or the other of said pads (101, 102; 103, 104). Semiconductor device according to claim 1, characterised in that said pads (101, 102; 103, 104) are input and/or output terminals of a Flash memory (M). Semiconductor device according to claim 2, characterised in that said memory element (4; 5) is a CAM (Contenet Addressable Memory) memory.

Inventors: BARTOLI SIMONE, NAVA CLAUDIO, RUSSO ANTONIO, SALI MAURO, BARTOLI, SIMONE, NAVA, CLAUDIO, RUSSO, ANTONIO, SALI, MAURO
Applicants: ST MICROELECTRONICS SRL, STMICROELECTRONICS S.R.L.
Application year: 1999
Main classification: G11C7
IPC codes: G11C5, G11C7