Device and method for detecting a voltage drop

A battery-operated electrical machine tool, including an anode connection and a cathode connection for electrical supply, and a device for detecting a voltage drop between the anode connection and the cathode connection, the battery-operated machine tool comprising:

• a control capacitor, of which the first electrode is connected to the anode connection and the second electrode is connected to the cathode connection;
• a measuring device, which is designed to output a discharge signal depending on a potential difference detected between the anode connection and the cathode connection, and a first threshold value for the potential difference on a discharge control line;
• a discharge circuit, which is connected to the discharge control line and is designed to discharge the control capacitor depending on the discharge signal;
• and
• a control device, which is designed to detect the voltage drop by evaluating the state of charge of the control capacitor;
• wherein the measuring device includes a first control switch having an input connected to the anode connection via a second voltage divider and wherein the first control switch connects the discharge control line to the cathode connection with low impedance when the input potential applied at the control input exceeds the first threshold value;
• wherein the first control switch is adapted to disconnect the discharge control line from the cathode connection when the input potential applied at the control input drops below the first threshold value.
• wherein the discharge circuit includes a second control switch including a control input connected to the discharge control line and which connects the first electrode of the control capacitor with low impedance to the second electrode of the control capacitor when the discharge control line is disconnected from the cathode connection;
• and
• wherein the control input of the second control switch is connected to the anode connection via a pull-up resistor.