Device for monitoring a predefined voltage

The invention concerns a device for monitoring a predefined voltage (UA) within a voltage tolerance range (UTU, UTO) using a comparator (2). According to the invention: A first and second voltage divider (12 and 14), for quantitatively lower and higher tolerance band values (UTU and UTO) respectively, are provided. The middle tap (16) of the first voltage divider (12) is connected firstly via a first decoupling diode (22) to a first reference voltage source (Uref1), and secondly to one of the two inputs (8, 34) of the comparator (2). The middle tap (26) of the second voltage divider (14) is connected via a second decoupling diode (32) to the other input (8, 34) of the comparator, which is connected via a resistor (36) to the first reference voltage source (Uref1). The two voltage dividers (12,14) are connected in parallel. One pole of the voltage dividers (12, 14) is connected to the predefined voltage (UA) to be monitored. The other pole is connected to a second reference voltage source (Uref2). In this way a simple device is produced, with which a voltage (UA) can be monitored for under-voltage and over-voltage, using a comparator.