Patent ID: 7474143

Claim:
A voltage generator circuit comprising: a voltage generator activated by a reference voltage to generate an internal supply voltage that is an intermediate voltage between a high potential supply voltage and a low potential supply voltage; a reference voltage clamp circuit coupled to the voltage generator for clamping the reference voltage to a first voltage in response to a power-down signal to deactivate the voltage generator; an internal supply voltage clamp circuit coupled to the voltage generator for clamping the internal supply voltage to a second voltage; and a control circuit connected to the internal supply voltage clamp circuit for enabling the internal supply voltage clamp circuit after the voltage generator is deactivated in response to the power-down signal, wherein the control circuit compares the reference voltage with the first voltage in response to the power-down signal and enables the internal supply voltage clamp circuit when a potential difference between the reference voltage and the first voltage is equal to or smaller than a predetermined threshold value to prevent the voltage generator and the internal supply voltage clamp circuit from being enabled at the same time.