| 摘要 |
PURPOSE:To discriminate the use or disuse of an internal redundancy circuit simply in a short time by checking the electric output state of an internal detecting circuit through an external pin. CONSTITUTION:Fixed voltage VIN is applied between a chip select input pin (connected to an input terminal 26) and a VDD power supply pin (connected to a power supply terminal 25) for the memory integrated circuit to be checked from an external power supply. When the fuse of the detecting circuit 27 in the memory integrated circuit is broken previously, currents do not flow in the input pin; when the fuse is not broken, fixed currents determined by a characteristic curve flow in. Accordingly, the non-broken or broken state of the fuse of the detecting circuit 27, the disuse or use state of a spare memory circuit 20, can be discriminated by detecting the presence of currents flowing in the input pin from the outside by a proper means. |
