| 摘要 |
A voltage level shifting circuit for an integrated circuit system having an internal low voltage power supply (VCCL) and an external high voltage power supply (VCCH) is disclosed, the voltage level shifting circuit comprises a pair of cross coupled PMOS transistors connected to the VCCH, a NMOS transistor with a source connected to a ground (VSS) and a gate connected to a first signal swinging between the VCCL and the VSS, and a switching device coupled between a drain of one of the pair of PMOS transistors and a drain of the NMOS transistor, wherein the pair of PMOS transistors are high voltage transistors and the switching device is off when the VCCL is below a predetermined voltage level, and the switching device is on when the VCCL is above the predetermined voltage level.
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