Capacitor power source tamper protection and reliability test
AssigneeCypress Semiconductor Corporation
InventorsSrikanth Reddy Tiyyagura, David Still, Jayant Ashokkumar, David G Wright
Life of this patent
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Abstract
A verification circuit for a capacitor power supply measures at least two voltages across the terminals of the capacitor at two points in time, the two points in time defining a time interval dT. A change in voltage dV over the time interval dT is determined. An operation powered by the capacitor is initiated, or not, by deriving from the time interval dT and/or the voltage change dV, a total required time or a total required voltage for completing the operation, and comparing the total required time or total required voltage to a pre-determined necessary total time or predetermined necessary total voltage, respectively (a “time interval test”).
Claims21
A verification circuit for a capacitor power supply, comprising:
- (a) logic to measure at least two voltages across the terminals of the capacitor at two points in time, the two points in time defining a time interval dT;
- (b) logic to determine a change in voltage dV over the time interval dT, the change in voltage defined by the two voltages that are measured;
- and
- (c) logic to determine whether to initiate an operation powered by the capacitor, by deriving a total required time or a total required voltage for completing the operation from the time interval dT and/or the voltage change dV, and comparing the total required time or total required voltage to a pre-determined necessary total time or predetermined necessary total voltage, respectively, for completing the operation;
- wherein the acts performed in (a)-(c) are collectively a “time interval test”.
A method for verifying a capacitor power supply, comprising:
- (a) measuring at least two voltages across the terminals of the capacitor at two points in time, the two points in time defining a time interval dT;
- (b) determining a change in voltage dV over the time interval dT, the change in voltage defined by the two voltages that are measured;
- and
- (c) determining whether to initiate an operation powered by the capacitor, by deriving a total required time or a total required voltage for completing the operation from the time interval dT or the voltage change dV respectively, and comparing the total required time or total required voltage to a pre-determined necessary total time or predetermined necessary total voltage, respectively, for completing the operation;
- wherein the acts performed in (a)-(c) are collectively a “time interval test”.
An memory system including a primary power supply and a backup capacitor power supply, comprising:
- a controller;
- an nvSRAM;
- and
- (a) logic to measure at least two voltages across the terminals of the capacitor at two points in time, the two points in time defining a time interval dT;
- (b) logic to determine a change in voltage dV over the time interval dT, the change in voltage defined by the two voltages that are measured;
- and
- (c) logic to determine whether to initiate an autostore operation on the nvSRAM, the autostore operation powered by the capacitor, the determination to initiate the autostore operation made by deriving a total required time or a total required voltage for completing the autostore operation from the time interval dT or the voltage change dV, respectively, and comparing the total required time or total required voltage to a pre-determined necessary total time or predetermined necessary total voltage, respectively, for completing the autostore operation;
- wherein the acts performed in (a)-(c) are collectively a “time interval test”.
Dependencies are inferred from the claim text.