of the present invention an esd protection circuit whole chip is surrounded by the esd bus 301 which serves as the common connection among each esd protection cell of each separate power supply moreover the esd bus 301 is not applied any external voltage the first voltage selector 305 of the first esd protection cell 315 will compare the voltage of the first power 303 and the voltage of the esd bus 301 then outputs the higher voltage as the output of the first voltage selector 305 in other words if the voltage of the first power 303 is higher than the voltage of the esd bus 301 the voltage of the first power 303 will be the output of the first voltage selector 305 similarly the operational principle of the second voltage selector 325 of the second esd protection cell 335 and the operational principle of the third voltage selector 345 of the third esd protection cell 355 are same as the principle of the first voltage selector 305 above otherwise referring to fig6 which shows that a simple circuit diagram of a voltage selector when the first voltage 240 is higher than the second voltage 250 the first transistor 270 is turned on and the second transistor 280 is inactive so that the first voltage 240 is outputted from the voltage selector 290 to the output.