Abstract: A technique of operating a processor subsystem masks interrupts to the processor subsystem during a power-down sequence of a processor of the processor subsystem. A boot vector for the processor of the processor subsystem is set. The boot vector provides an address associated with a saved processor state. A current state of the processor is saved to provide the saved processor state. The technique determines whether one or more first masked interrupts occurred during the saving of the current state of the processor. The processor that is to be powered-down is stopped when the one or more first masked interrupts did not occur during the saving of the current state of the processor. The technique also determines whether one or more second masked interrupts occurred following the saving of the current state of the processor. The processor is powered-down when the one or more second masked interrupts did not occur following the saving of the current state of the processor.

Abstract: A technique of operating a processor subsystem masks interrupts to the processor subsystem during a power-down sequence of a processor of the processor subsystem. A boot vector for the processor of the processor subsystem is set. The boot vector provides an address associated with a saved processor state. A current state of the processor is saved to provide the saved processor state. The technique determines whether one or more first masked interrupts occurred during the saving of the current state of the processor. The processor that is to be powered-down is stopped when the one or more first masked interrupts did not occur during the saving of the current state of the processor. The technique also determines whether one or more second masked interrupts occurred following the saving of the current state of the processor. The processor is powered-down when the one or more second masked interrupts did not occur following the saving of the current state of the processor.

Abstract: A method and apparatus for entering a low power mode is provided. In one embodiment, data processing system (10) has power control circuitry (52) which may be used to control power usage in data processing system (10). Power mode select circuitry (84) may be used to select a power mode. Depending upon the power mode selected, power control circuitry (52) may use a cascaded approach to selecting which portions of data processing system (10) will be powered down, and thus how deeply data processing system (10) will be powered down.

Abstract: An integrated circuit (10) includes a multiple voltage digital multiplexer circuit (30) for multiplexing digital signals provided at different supply voltage levels. In one form, the multiplexer (30) includes an analog multiplexer (32) for receiving the digital signals, a level shifter (40) coupled to the output of the analog multiplexer (32), and a supply voltage multiplexer (34) for providing one of various supply voltages used on the IC corresponding to the signals being multiplexed. A control circuit (38, 39) is used to control the input selection of the analog multiplexer (32) as well as the supply voltage multiplexer (34) for providing the correct supply voltage to the level shifter (40). This provides the ability to multiplex digital signals of differing voltage levels onto a single pad on the IC (10).