The LTC2063’s ultralow input offset voltage, low IOFFSET and IBIAS, and rail-to-rail input, provide precise current measurements over the entire range of 100µA to 250mA. Its 2µA maximum supply current enables the circuit to run on far less than 280µA supply current for most of its operating range. Along with LTC2063’s low supply voltage requirements, the low supply current allows it to be powered from a voltage reference with headroom to spare.