Patent attributes
A current shunt monitor (CSM) circuit for monitoring the current through a sense resistor. An analog circuit provides an analog output signal proportional to the voltage across the sense resistor. A power supply includes a fixed voltage power supply at a first voltage supply level and a floating power supply. The floating power supply operates at a second voltage supply level referenced from the voltage level on a voltage input and a floating ground. The voltage input varies from a voltage level above the first voltage supply level to a voltage level below the first voltage supply level, and the floating power supply provides power to the analog circuit at least when the voltage level of the voltage input is above the first voltage supply level. A crossover circuit switches power from the floating power to the fixed voltage power supply at the first voltage supply level upon detecting the voltage level on the voltage input proximate in value to the first voltage supply level.
