An I/O driving circuit is applied to provide a driving voltage to drive an electronic device coupled to an I/O pad. FIG. 1 is a block diagram illustrating a conventional I/O driving circuit. As depicted in FIG. 1, the I/O driving circuit 100 comprises a pre-driver 101 and a post driver 103. The pre-driver 101 provides a pre-driving function, which can be an operation for controlling the post driver 103. The post driver 103 is configured to generate the driving voltage V_d to the I/O pad 105.
However, the pre-driver 101 only operates at a single power domain, thus the I/O driving circuit 100 cannot meet requirements of different operating voltage for various standards. Also, the post driver 103 always comprises several PMOSFETs for providing the driving voltage. However, a conventional post driver always applies core devices, which comprises thin oxides, as the PMOSFETs. In such structure, the pre-driver 101 cannot operate between a wide operating voltage range, or the transistors may be broken by the control signals generated by the pre-driver.