PURPOSE: To adjust easily a resistance value by constituting a programmable register by connecting in parallel plural series circuits of an FET of normal-on, a resistance and a pre-arcing fuse.
CONSTITUTION: A programmable register is constituted by connecting in parallel plural series circuits of FETs Tr1∼Trn of normal-on, resistances R1∼Rn, and pre-arcing fuses f1∼fn. A voltage is applied to the gate of a transistor and it is turned off, and an optimum resistance value is detected by monitoring a resistance of between (a) and (b) by a computer. When an unnecessary resistance is determined, the transistor is turned off, and thereafter, a sufficient current by which a pre-arcing fuse fi is cut is made to flow between a terminal Ti and (b). In this way, write of a resistance value can be executed easily.
AKIYAMA TATSUO
TSURU KAZUO
ETSUNO YUTAKA
