Data protection device

摘要

The invention relates to a data protection device for protecting data in electronic circuits, particularly microprocessors, by detecting and early signalling of mains failure or mains undervoltage in the area of the power supply. The drop in the mains voltage is detected via an output A of the switched-mode power supply which is connected to a controlled system which represents a function of the input and output voltage. Signalling to the electronic circuit (2) is effected by a flip-flop (3) which is in series with a comparator circuit (4) and is driven by its output. For this purpose, the output (A) of the switched-mode power supply (1) is connected via a voltage divider to the non-inverting input of the comparator circuit (4) whilst the inverting input is connected to a reference point B which is set to the corresponding voltage level by a resistor (10) and a Zener diode (14). An undervoltage monitor (7) is used for detecting the operating range during the running-up of the supply voltage and switches the flip-flop back into its initial state. A battery (5) is used as additional time buffer and increases the safety of the circuit. <IMAGE>