Infineon Technologies Ag

Siegfried Tscheternigg

Armin Wedel

Robert Allinger

Susanne Gamperl

EEPROM memory matrix in which column lines are alternatively used as detector lines. A precharge voltage is applied to selected detector lines together with the relevant column line in each case before read-out of the memory columns. If a detector line loses its precharge level during the read-out of the memory cells, light incidence is assumed and a corresponding alarm function is triggered. Preferably column lines adjacent to the column lines that are respectively selected for the data transmission are connected as detector lines.

EEPROM memory matrix and method for safeguarding an EEPROM memory matrix

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.

Method for controlling the charging and discharging phases of a backup capacitor and a circuit configuration for carrying out the method

A circuit configuration for detecting a functional disturbance has a first and a second differential amplifier. The outputs of the differential amplifiers are connected to the inputs of a gate. One input of the differential amplifiers is in each case connected to a reference potential terminal. The respective other input of the first and second differential amplifiers is connected to a monitoring means, which responds in the event of a change in the supply voltage at a supply potential terminal of the circuit configuration.

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Vilgertshofen, Germany

Siegfried Tscheternigg