Patent ID: 7940094

Claim:
A semiconductor device comprising: an external power supply detection circuit configured to detect that an external power supply is turned on and output a first detection signal; an internal power supply voltage generation circuit configured to generate an internal power supply voltage based on the external power supply; a reference voltage generation circuit configured to generate a first reference voltage in response to the first detection signal; a reference voltage detection circuit configured to detect that the first reference voltage reaches a given level and output a second detection signal; a bias voltage generation circuit configured to generate, in response to the second detection signal, a bias voltage to which a capacitive element is coupled as a load, based on a second reference voltage dependent on the first reference voltage; and a power supply voltage detection circuit configured to compare, in response to the second detection signal, the bias voltage with a third reference voltage dependent on one of an external power supply voltage and the internal power supply voltage, and output a start signal.