A voltage generation system for generating operating voltages for memory devices, especially non-volatile memories, from a single external high voltage source. In one embodiment, the system comprises an input terminal for receiving an external voltage, a charge pump for producing a first high voltage based on the external voltage to be higher than the external voltage, a first regulating circuit for regulating the first high voltage to a lower predetermined voltage, a second regulating circuit for generating a second high voltage based on the external voltage to be lower than the external voltage.