Anordnung zum Erfassen des Stromes durch einen Meßwiderstand eines Laststromkreises

摘要

The invention relates to an arrangement for detecting the current by means of a precision resistor of a load current circuit. Said arrangement comprises an operational amplifier. The voltage drop at the precision resistor can be fed to said operational amplifier which emits an output signal at the output, whereby said signal is proportional to the detected current. Current measuring is made independent from the offset voltage of the operational amplifier by including the precision resistor in an additional voltage divider. A driving voltage for the operational amplifier can be picked up when the load current circuit is switched off. Said driving voltage is greater than the maximum offset voltage of the operational amplifier. The occurring output voltage of the operational amplifier is fed to a microcomputer which allocates said output voltage to the current value zero by the precision resistor. The driving voltage at the operational amplifier increases due to the voltage drop at the precision resistor when the load current circuit is closes. The microcomputer emits an output signal that is proportional to the voltage increase.