METHOD AND APPARATUS FOR POWER MANAGEMENT IN A MULTIFUNCTIONCONTROLLER WITH AN EMBEDDED MICRO-PROCESSOR

摘要

A method and apparatus for providing power management functions in a multifunction controller having an embedded microprocessor. An enter sleep mode indication is received in the microprocessor in the form of, for example, a command generated by a host central processing unit or an interrupt indicating a lac k of system activity for a predetermined period of time. The clock input to the microprocessor is switched from a first clock source to a second clock source in response to t he enter sleep mode indication. The main system supply may then be powered down by th e microprocessor. The first clock source is then turned off after expiration o f a first predetermined delay. The second clock is subsequently turned off after a second predetermined delay, to thereby place the system and the microprocessor into a sleep mode. While the system and microprocessor are in the sleep mode, an interrupt-handling portion of the microprocessor and a power control logic circuit remain powered off a low-current standby supply. Upon detection of a wake-up event, the second clock source is automatically started and applied to the microprocess or after a predetermined delay. The microprocessor can then process the wake-up event indicator, and if necessary power up the system and re-connect itself to the first clocksource.