Circuit for monitoring of loads

A method for monitoring loads of a load circuit, in which a measuring resistor is disposed in the load circuit, comprising the steps of:

• producing a single reference current which is temperature dependent and voltage dependent, wherein the single reference current includes a voltage dependent and a voltage independent component;
• supplying the single reference current to a reference resistor, an input resistor, and a current comparator branch;
• inputting a measuring voltage drop of the measuring resistor by coupling the measuring resistor between a reference voltage terminal and a measuring voltage terminal to produce an input current through the input resistor to generate an input voltage drop while the single reference current flows through the reference resistor to produce a reference voltage drop;
• comparing the input voltage drop to the reference voltage drop by comparing the reference current to the input current;
• and
• producing a comparison output as an output voltage level at an output terminal.

A monitoring circuit for monitoring loads of a load circuit, with the monitoring circuit being connectable to at least one measuring resistor which is disposed in the load circuit and which has a corresponding measuring voltage drop, the monitoring circuit comprising:

• a reference current means for generating a single reference current which is temperature dependent and voltage dependent, wherein the single reference current includes a voltage dependent and a voltage independent component;
• at least one comparator means, connected to the reference current means, to receive the single reference current and connectable to the at least one measuring resistor to measure the corresponding measuring voltage drop, each comparator means including a reference branch having a reference voltage terminal, at least one input branch each having a measuring voltage terminal, and at least one comparator branch, each connected to the reference branch and to a respective input branch, and each comparator branch having an output terminal;
• a checking means, connected to the at least one comparator means, that terminates monitoring of the load when the value of the voltage at the reference voltage terminal falls below a minimum voltage value, said checking means including a voltage divider coupled in parallel to a plurality of switching transistors, wherein the minimum voltage value is set using the resistor values of the resistors in the voltage divider, and wherein the output terminals of the respective comparator branches are switched off by the switching transistors when the value of the voltage at the reference voltage terminal is less than the minimum voltage value;
• means for connecting each measuring resistor between the reference voltage terminal and a respective measuring voltage terminal of a respective input branch in order to generate a respective input current flowing through the respective input branch while the single reference current flows through the reference branch;
• wherein each comparator branch compares the respective input current with the single reference current, and outputs a respective output voltage level at a respective output terminal as a result of the comparison.