indication signal n 5 vdo indicates that over voltage occurs the internal circuit 22 can raise the signal ip to a high level then the voltage difference between the node np 2 and the gate signal gt will reduce below a safe voltage difference e g breakdown voltage of the gate oxide of the transistor qb 2 and the reliability issue of the transistor qb 2 can be resolved surely the internal circuit 22 can perform other kinds of protection procedures with information provided by the indication signal n 5 vdo while implementing the disclosed circuits a comparison circuit with hysteretic characteristic such as a schmidt trigger with hysteretic characteristic can be adopted to implement the detector dtr the timer tmr is either a specific timer designed for the over voltage indicator 36 or a power on reset por circuit commonly used in ordinary i o circuit usually a chip or an ic has a por circuit for providing a power on reset signal to reflect the voltage levels of the operation bias voltages when a chip starts to power on with its operation bias voltages gradually rising above a predetermined level the por circuit in the chip starts timing a predetermined interval.