Aspects of the present disclosure provide for circuit. In at least some examples, the circuit includes a controller, a current source, a switch, and a digital-to-analog converter (DAC). The controller includes an analog-to-digital converter (ADC) having an input and an output, a first register, and a second register coupled to the output of the ADC. The switch is coupled between an output of the current source and a first node and has a control terminal coupled to the controller. The first node is coupled to the input of the ADC and is configured to couple to a resistor. The DAC has an input coupled to the controller and an output configured to couple to a battery.