Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
2005-02-22
2005-02-22
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
Reexamination Certificate
active
06859011
ABSTRACT:
A method for controlling the charging and discharging phases of a backup capacitor for a data storage medium has the step where the backup capacitor is first discharged to a defined voltage level before it is charged. The capacitor is discharged using a constant current. This ensures that the charging current for the backup capacitor cannot be used to identify what the charge-state of the capacitor was before discharging. Therefore, it is no longer possible to infer the currents that flowed during security-related arithmetic operations in a data processing unit. In one advantageous circuit configuration, a constant current source is formed by a current-mirror circuit, and a comparator is used to compare the voltage on the backup capacitor with a bandgap reference.
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Tscheternigg Siegfried
Wedel Armin
Greenberg Laurence A.
Infineon - Technologies AG
Mayback Gregory L.
Stemer Werner H.
Tibbits Pia
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