Clock switching circuits and methods to select from multiple clock sources
First Claim
1. A method for switching between a plurality of clock sources comprising:
- receiving a select signal indicating selection of a clock source among the plurality of clock sources;
detecting an activity-status indication representing that the selected clock source is active or inactive;
generating an enable signal for the selected clock source responsive to receiving the select signal and detecting that the selected clock source is active;
in response to receiving a clock switch request instructing switching to the selected clock source and receiving the enable signal, updating a clock select input signal to indicate switching to the selected clock source; and
switching to the selected clock source in response to receiving the updated clock select input signal.
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Accused Products
Abstract
For use in systems having multiple potential clock sources, circuitry and methods are used for selecting from among multiple clock sources and for preventing switching to an inactive clock source. Such clock switching circuitry and methods are used to detect an activity-status indication of the clock sources, generate a selection based update-enable signal responsive to the detected activity-status indication of the selected clock source, update a clock select input signal in response to a clock switch request for switching to the selected clock source and based on the generated selection based update-enable signal, and control switching to the selected clock source based on the updated clock select input signal.
23 Citations
18 Claims
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1. A method for switching between a plurality of clock sources comprising:
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receiving a select signal indicating selection of a clock source among the plurality of clock sources; detecting an activity-status indication representing that the selected clock source is active or inactive; generating an enable signal for the selected clock source responsive to receiving the select signal and detecting that the selected clock source is active; in response to receiving a clock switch request instructing switching to the selected clock source and receiving the enable signal, updating a clock select input signal to indicate switching to the selected clock source; and switching to the selected clock source in response to receiving the updated clock select input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A circuit for switching between a plurality of clock sources comprising:
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detection circuitry configured to detect an activity-status indication representing that a selected clock source is active or inactive; update-enable circuitry configured to; receive a select signal indicating selection of the selected clock source; and generate an enable signal for the selected clock source responsive to receiving the select signal and detecting that the selected clock source is active; control circuitry configured to update a clock select input signal to indicate switching to the selected clock source responsive to receiving a clock switch request instructing switching to the selected clock source and receiving the enable signal; and switching circuitry configured to switch to the selected clock source in response to receiving the updated clock select input signal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification