| 摘要 |
<p>PURPOSE:To enable the operation check after an assembly and to reduce the fall-out rate of shipped products by providing a write circuit and a read-out circuit of two system of different levels. CONSTITUTION:This circuit is a semiconductor storage circuit of an ultraviolet ray erasure PROM type by which a write processing can be executed only once, and has a write selecting circuit 5 for generating a first write voltage VPM1 for selecting one of plural write lines 4 and writing data to a selected memory cell 1 and a second write voltage VPM2 being lower than this first write voltage VPM1. In this case, when a switching signal is set to an active level, a second power supply voltage VPP2 of a write power source supply circuit 2, a second write voltage VPM2 of the write selecting circuit 5, and a second sense amplifying circuit 7B are selected by switching circuits 3A - 3C, an FET M1 becomes a write state of a low level of a voltage/current characteristic, and at the time of read-out, in a second sense amplifying circuit 7B, write or non-write is discriminated by a second threshold voltage VT2. In such a way, the inclusion of defectives in a shipped product can be reduced.</p> |
