Patent ID: 7536570

Claim:
A microcontroller unit (MCU) having a suspend mode of operation, comprising: a processing circuit for receiving digital information and processing said received digital information; timing circuitry for generating timing signals to the processing circuit during the suspend mode; a clock circuit for generating an internal system clock signal and receiving an external, asynchronous clock signal providing the timing for said timing circuit, wherein the system clock is independent of the asynchronous clock; and circuitry for controlling the selective application of the internal system clock signal and the asynchronous clock signal to the timing circuitry, the circuitry applying the internal system clock signal to the timing circuitry in at least an active mode of operation of the microcontroller unit responsive to at least one first control signal and applying the asynchronous clock signal to the timing circuitry in at least the suspend mode of operation of the microcontroller unit responsive to at least one suspend control signal.