Aspects of the disclosure provide for a circuit. In some examples, the circuit includes a first comparator, a second comparator, and a logic circuit. The first comparator includes a first input terminal coupled to a first node, a second input terminal coupled to a second node, and an output terminal. The second comparator includes a first input terminal coupled to the first node, a second input terminal coupled to a third node, and an output terminal. The logic circuit includes a first input terminal coupled to the output terminal of the first comparator, a second input terminal coupled to the output terminal of the second comparator, and an output terminal. The logic circuit is configured to determine a change in current over time based on analyzing an output signal of the first comparator and an output signal of the second comparator over a plurality of sequential cycles of operation.