Claims
- 1. A system on a chip comprising:
a first power plane for powering a core logic portion of the system on a chip; a second power plane for powering selected analog circuitry of the system on a chip; clock generation circuitry for generating clocks for clocking operations of selected circuits of the system on the chip in response to a signal generated by an oscillator; and power control circuitry operable to:
in a first mode, switch-off power to the first and second power planes, the oscillator being enabled; and in a second mode, disable the clock generation circuitry and switch power to the first and second power planes, the oscillator being enabled.
- 2. The system on a chip of claim 1 wherein the selected analog circuitry comprises a phase-locked loop circuit.
- 3. The system on a chip of claim 1 wherein the selected analog circuitry comprises and analog to digital converter.
- 4. The system on a chip of claim 1 wherein the core logic comprises a microprocessor.
- 5. The system on a chip of claim 1 wherein the core logic comprises a digital signal processor.
- 6. The system on a chip of claim 1 and further comprising a third power plane for powering a pulse width modulation engine, the power control circuitry switching-off power to the third power plane in the first mode and switching power to the third power plane in the second mode.
- 7. The system on a chip of claim 4 wherein the control circuitry is further operable in a pause mode to pause execution instructions by the microprocessor, the power control circuitry switching power to the first and second power planes and the oscillator enabled during the pause mode.
- 8. The system on a chip of claim 1 wherein the power control circuitry is operable to generate a signal for transmission to an external switch for switching-off power to the selected ones of the power planes in the first mode.
- 9. A method of power control in a system on a chip including core logic powered by a first power plane, analog circuitry powered by a second power plane and clock generation circuitry for generating clocks for operating selected circuitry of the core logic in response to a clock signal generated by an oscillator comprising the steps of:
during a normal mode of operation, selectively powering the first and second power planes and running the oscillator; during a super stand-by mode, selectively terminating power to the first and second power planes and running the oscillator; and during a stand-by mode, selectively powering the first and second power planes, disabling the clock generation circuitry and running the oscillator.
- 10. The method of power control of claim 9 and further comprising the steps of:
entering the super-standby mode by setting a bit with a processor forming a portion of the core logic; and exiting the super-standby mode in response to a wake-up signal received from an external source.
- 11. The method of power control of claim 9 and further comprising the steps of:
entering the stand-by mode in response to a bit set with a processor forming a portion of the core logic; and exiting the stand-by mode in response to a signal received from an external source.
- 12. The method of power control of claim 9 wherein the core logic comprises a microprocessor and further comprising the steps of:
pausing execution of instructions by the microprocessor during a pause mode; and exiting the pause mode in response to an interrupt to the microprocessor.
- 13. The method of claim 9 wherein the clock generation circuitry comprises a phase-locked loop and said steps of enabling and disabling comprise the steps of powering-up and powering-down the phase-locked loop.
- 14. The method of claim 10 wherein said step of entering the super stand-by mode comprises the substeps of:
generating a signal within the system on a chip; and disabling an external power supply supplying the first and second power planes in response to the signal generated within the system on a chip.
- 15. A system on a chip comprising:
a microprocessor operating from a first bus and operating in response to a microprocessor clock; a digital signal processor operating from the first bus and operating in response to a DSP clock; a first power plane for providing power to said microprocessor and said digital signal processor; analog circuitry operating from a second bus coupled to the first bus by a bridge; a second power plane for providing power to said analog circuitry; and power control circuitry operable in a first stand-by mode decouple power from said first and second power planes and in a second stand-by mode to terminate generation said microprocessor and DSP clocks while maintaining power to said first and second power planes.
- 16. The system on a chip of claim 15 and further comprising a pulse width modulator operating from said second bus and a third power plane for powering said pulse width modulator, said power control circuitry further operable to decouple power from said third power plane in the first stand-by mode.
- 17. The system on a chip of claim 15 and further comprising a phase-locked loop operating from said second bus for generating said microprocessor and DSP clocks, said power control circuitry operable to power-down said phase-locked loop in the second stand-by mode.
- 18. The system on a chip of claim 15 wherein said microprocessor is operable to set a bit and enter a pause mode and exit said pause mode in response to an interrupt received on said first bus.
- 19. The system on a chip of claim 15 wherein the analog circuitry comprises a phase-locked loop and an analog to digital converter.
- 20. The system on a chip of claim 15 and further comprising a pad ring for driving input/output ports to selected circuitry of said system on a chip and a third power plane for powering said pad ring, said power control circuitry operable to decouple power from said third power plane during said first stand-by mode.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The following co-pending and co-assigned application contains related information and is hereby incorporated by reference:
[0002] Serial No. ______ (Attorney Docket No. 11 24-CA [2836-P124US]), by Luo and North entitled “A SYSTEM-ON-CHIP WITH SOFT CACHE AND SYSTEMS AND METHODS USING THE SAME”, filed ______, 200; and
[0003] Serial No. ______-(Attorney Docket No. 11 38-EPD [2836-P140US] by PIllay and Rao entitled “CIRCUITS AND METHODS FOR DEBUGGING AN EMBEDDED PROCESSOR AND SYSTEMS USING THE SAME”, filed March ______, 2001.