Voltage source switching circuit at reduced voltage drop levels
AssigneeCalifornia Micro Devices Corporation
InventorsAnthony David Chan, Anthony Gerard Russell
Life of this patent
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Abstract
A voltage source switching circuit having switches capable of switching between different voltage sources with reduced voltage drop levels is disclosed. A selected one of the different voltage levels is output to a peripheral circuit or supplied to internal circuitry. In one embodiment, the switches are FET devices.
Claims20
A voltage source switch for outputting an output voltage corresponding to one of a first voltage source and a second voltage source, said voltage source switch comprising:
- a comparator for comparing voltages on the first and second voltage sources and producing first and second switch control signals, wherein said comparator includes at least:
- a hysteresis circuit that generates at least one hysteresis adjustment to resist improper switching following a switching action;
- and
- a blanking circuit that generates a blanking period wherein following a switching action said voltage source switch does not switch the output voltage during the blanking period;
- a first switch circuit that couples the first voltage source to the output voltage when the first switch control signal is at a first state and decouples the first voltage source from the output voltage when the first switch control signal is at a second state;
- and
- a second switch circuit that couples the second voltage source to the output voltage when the second switch control signal is at a first state and decouples the second voltage source from the output voltage when the second switch control signal is at a second state.
A voltage source switch for outputting an output voltage corresponding to one of a first voltage source and a second voltage source, said voltage source switch comprising:
- a comparator for comparing voltages on the first and second voltage sources and producing a comparator control signal, wherein said comparator includes at least:
- a hysteresis circuit that generates at least one hysteresis adjustment to resist improper switching following a switching action;
- and
- a blanking circuit that generates a blanking period wherein following a switching action said voltage source switch does not switch the output voltage during the blanking period;
- a charge pump system that receives the comparator control signal and generates first and second switch signals, at least one of the first and second switch signals having a voltage level that is increased in relation to the output voltage;
- a first switch circuit that couples the first voltage source to the output voltage when the first switch control signal is at a first state and decouples the first voltage source from the output voltage when the first switch control signal is at a second state;
- and
- a second switch circuit that couples the second voltage source to the output voltage when the second switch control signal is at a first state and decouples the second voltage source from the output voltage when the second switch control signal is at a second state.
A voltage source switch for outputting an output voltage corresponding to one of a first voltage source and a second voltage source, said voltage source switch comprising:
- a comparator for comparing voltages on the first and second voltage sources and producing a comparator control signal, wherein said comparator includes at least:
- a preference circuit that provides a switching preference to one of the first and second voltage sources;
- a hysteresis circuit that generates at least one hysteresis adjustment to resist improper switching following a switching action;
- and
- a blanking circuit that generates a blanking period wherein following a switching action said voltage source switch does not switch the output voltage during the blanking period;
- a charge pump system that receives the comparator control signal and generates first and second switch signals, at least one of the first and second switch signals having a voltage level that is increased in relation to the output voltage;
- a first switch circuit that couples the first voltage source to the output voltage when the first switch control signal is at a first state and decouples the first voltage source from the output voltage when the first switch control signal is at a second state;
- and
- a second switch circuit that couples the second voltage source to the output voltage when the second switch control signal is at a first state and decouples the second voltage source from the output voltage when the second switch control signal is at a second state.
Dependencies are inferred from the claim text.