Temporary locking of an electronic circuit to protect data contained in the electronic circuit

摘要

A method and a circuit for protecting at least one piece of information contained in an electronic circuit by disabling at least one function of the circuit in case of detection of a number of abnormal operations greater than a threshold, in which the disabling of the function is temporary, of a duration independent from whether the circuit is powered or not.

主权项

1. A method, comprising:
detecting a number of abnormal operations of an electronic circuit; in response to the detected number of abnormal operations reaching a limit, setting a charge retention circuit to an active state which causes at least one circuit function to be disabled, the charge retention circuit including at least one first capacitive element having a leakage that discharges the first capacitive element to an inactive state at the end of a disabling period that is independent of whether power is applied to the electronic circuit; resetting the detected number of abnormal operations to an initial value in response to a condition where the state of the charge retention circuit is inactive and the detected number of abnormal operations is at the limit; and resetting the detected number of abnormal operations to the initial value following each normal operation of the electronic circuit, wherein the at least one first capacitive element has a first electrode connected to a floating node and wherein the charge retention circuit further comprises at least one second capacitive element having a first electrode connected to the floating node, the second capacitive element having larger capacitance and a smaller leakage than the first capacitive element, and a measurement circuit connected to the floating node to measure a residual charge of the floating node.