The present subject matter refers to apparatus and methods for identifying a resistance level of a resistor. In an example, circuit configured to identify a resistor can include a plurality of current sources, each current source selectively coupled to the resistor to generate a resistor voltage, a comparator configured to compare the resistor voltage and a reference voltage, and to provide an output indicative of the comparison, and a controller configured to selectively couple a first one or more current sources of the plurality of current sources to the resistor, and to selectively couple a second one or more current sources of the plurality of current sources to the resistor in response to the output indicative of the comparison.