| 摘要 |
PURPOSE:To detect the use of a redundant bit as well as the position of a defective bit by applying the voltage higher than VCC to a part of an input terminal supplied from outside and checking the address input obtained when the current flowing to said input terminal is detected. CONSTITUTION:An input terminal 1 is kept under a high impedance state in a normal working mode. While the voltage higher than 8V is applied to the terminal 1 when the detection is desired for the position of a redundant bit. then a word line 10 is boosted up to the VCC level with selection of the redundant bit while MOS diodes 2-2'' are under a conduction state. Thus the gate of an MOSFET3 is charged through an MOSFET4, and this potential A is boosted by a signal which is set at a high level more slowly than a word line 6 by a boot capacity 5. Then the FET3 conducts, and a current flows to the VCC from the terminal 1. |
