(a) to utilize CMOSs in safety applications with countermeasures against self-oscillation in the case of input open-failure, which can be solved by adding a capacitor and metal shield to the CMOS input,
b) to introduce a specific relay output circuit by transformers which enables the provision of high power output, transforming CMOS output signal, with constant voltage to relays and having band-pass filter characteristics, which are determined by energies for relay drive and by the transformer input current,
(c) to provide the on-delay T1 and off-delay T2 by capacitors and regulation ICs, which generate appropriate delays even in the malfunction situations by a cascaded drive circuit design