| 摘要 |
<p>PURPOSE:To improve the reiability of fuse blowing operation by giving a threshold value for deciding that a fuse is not blown to a fuse which is in fear that it may vary to low resistance during long-peiod use. CONSTITUTION:The low resitance value of the resistance 35 of a control signal generating circuit 33 is set to >=10<8>OMEGA. Thus, the resistance value of the resistance 35 is set extremely high; if the blowing of the fuse 31 is incomplete during the blowing of the fuse 31 to maintain a connection in a stage of high resistance (generally, more than MOMEGA) and in case the reduction in resistance to be caused owing to a glow-back phenomenon during long-period use is in fear, a control signal led out from the connection point (c) of the fuse 31 and resistance 35 is held at an H level from the beginning of the blowing, i.e. when a connection in the high resistance state is made, a thereby deciding that the fuse is not blown. Consequently, a defective bit is remedied by a redundant circuit in the beginning of use, but the redundant circuit is switched to the original defective circuit during long-period use to prevent securely the defective bit from being reproduced.</p> |
