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US 8,525,581 B2Granted
Power supply protection circuit and method
OwnerRobert Newton Rountreeinventor
Life of this patent
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Abstract
A method of protecting a power supply voltage in an integrated circuit is disclosed. The method includes storing charge in a charge reservoir capacitor (142), receiving a power supply sample voltage (140), and receiving a load power supply voltage (VDDL, 102). The power supply sample voltage is compared to the load power supply voltage (150). Charge is added from the charge reservoir capacitor (142) to the load power supply (VDDL) through transistor 126 and capacitor 144 in response to the step of comparing.
Claims19
A circuit, comprising:
- a first capacitor arranged to store a power supply sample voltage in response to a first power fail signal;
- a second capacitor arranged to provide a charge reservoir;
- a third capacitor having first and second terminals;
- a first transistor having a control terminal and a current path, and having a first terminal of the current path coupled to the second capacitor and a second terminal of the current path coupled to the first terminal of the third capacitor;
- a second transistor having a control terminal coupled to receive the first power fail signal and having a current path coupled between a power supply voltage terminal and the first capacitor;
- a third transistor having a control terminal coupled to receive the first power fail signal and having a current path coupled between the power supply voltage terminal and the first terminal of the first transistor;
- and
- a comparator circuit having a first input terminal coupled to the first capacitor and a second input terminal coupled to the second terminal of the third capacitor, and having an output terminal coupled to the control terminal of the first transistor.
5 more elements
A method of operating a power supply, comprising:
- storing charge in a charge reservoir capacitor;
- connecting a sample capacitor to a power supply terminal;
- detecting a power supply failure;
- disconnecting the sample capacitor from the power supply terminal, thereby storing a power supply sample voltage on the sample capacitor in response to the step of detecting;
- receiving a load power supply voltage;
- comparing the power supply sample voltage to the load power supply voltage after the step of disconnecting;
- and
- adding charge from the charge reservoir capacitor to the load power supply in response to the step of comparing.
5 more elements
A method, comprising:
- providing current flow to a sample capacitor from a power supply;
- discontinuing current flow to the sample capacitor from the power supply after the step of providing, thereby storing a sample voltage on the sample capacitor;
- storing charge in a charge reservoir capacitor;
- detecting a power supply voltage failure;
- comparing the sample voltage to a load power supply voltage after the step of detecting;
- and
- adding charge from the charge reservoir capacitor to the load power supply in response to the step of comparing.
4 more elements
Dependencies are inferred from the claim text.