Assessing energy requirements for a refreshed device
First Claim
1. A method comprising a step of determining a time interval over which a refresh device is subsequently maintainable in a self-refresh mode by an associated energy source, said interval comprising multiple charge decay and refresh cycles for the device, wherein the time interval of the determining step is determined in relation to an energy requirement value of the device obtained during device operation and an energy capacity value of the energy source.
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Abstract
Method and apparatus for assessing a time interval during which a refresh device can be maintained in a self-refresh mode by an associated energy source. The refresh device is initially operated in a self-refresh mode to maintain the device in a selected state. The time interval during which the refresh device can be subsequently maintained in the refresh mode is next determined in relation to an energy requirement value obtained during the self-refresh mode and an energy capacity value from the associated energy source. The energy capacity value is preferably obtained by fully discharging the associated energy source. Preferably, the refresh device is characterized as a dynamic random access memory (DRAM), and the associated energy source is characterized as a rechargeable backup battery. A selected test pattern is preferably written to the refresh device and maintained thereby during the self-refresh mode.
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Citations
17 Claims
- 1. A method comprising a step of determining a time interval over which a refresh device is subsequently maintainable in a self-refresh mode by an associated energy source, said interval comprising multiple charge decay and refresh cycles for the device, wherein the time interval of the determining step is determined in relation to an energy requirement value of the device obtained during device operation and an energy capacity value of the energy source.
- 10. An apparatus comprising a refresh device, an associated energy source and a control block adapted to determine a maximum interval over which the refresh device is subsequently maintainable in a self-refresh mode by the energy source, said interval beginning with device operation and ending when the refresh device can no longer supply sufficient charge to continue said self-refresh mode, the apparatus further comprising a current sense resistor coupled to the refresh device, wherein the control block determines an energy requirement value in relation to a voltage drop across said resistor and determines said interval in relation to the energy requirement value.
Specification