| 摘要 |
<p>PURPOSE:To easily control a semiconductor memory by uniting a fuse element, an information read circuit and a high voltage detection circuit into one body with the same semiconductor chip. CONSTITUTION:The fuse is disconnected by impressing voltage between the pads 2, 3 of a wafer provided with an EPROM, and data for classifying an access time version is written. After a test, the data is erased by ultraviolet ray irradiation, and it is sealed in a package. At the time of the read of the classification information, 12V is impressed to the inverse of OE pad 8, and a buffer 5 is activated through the high voltage detection circuit 7, and the output of an FF 4 is outputted from the pad 6. In the case of the chip of access time 200ns, the fuse 1 is disconnected, and since the input of the FF 4 is floated, 'L' is outputted at the time of the read. The FF 4 is constituted in CMOS constitution, and there is no power consumption. In the case of the chip of 250ms, the fuse is in an ON state, and the output of the FF 4 is 'H', and the output of the pad 6 too comes to be 'H'. Since performance information is written electrically in the chip previously at the time of a wafer test, and it can be evaluated by reading it from an external part after sealing, it is easy to control.</p> |
