Op-Amp Shunt Current Sensing With Voltage Divider Overvoltage Protection

The patent introduces an operational amplifier as an intermediary component between the shunt resistor and the microcontroller unit. This operational amplifier buffers the voltage signal from the shunt resistor, preventing direct exposure of the microcontroller to overvoltage conditions while enabling the use of cost-effective ground line operational amplifiers. The operational amplifier acts as a mediator that isolates and protects the sensitive microcontroller inputs from voltage spikes and overvoltage events in the power circuit.

The patent employs a ground line operational amplifier, which is a cost-effective alternative to expensive floating type operational amplifiers. While ground line operational amplifiers have limitations under overvoltage conditions, the patent compensates for this by using the operational amplifier in a buffered configuration with proper grounding, allowing reliable current measurement at a lower cost. This approach accepts the use of a less expensive component type while maintaining measurement reliability through proper circuit design.

The patent implements a dynamic voltage scaling approach using the operational amplifier circuitry. The circuit automatically adjusts the voltage level presented to the operational amplifier inputs based on the shunt resistor voltage, ensuring the amplifier operates within its optimal input range while maintaining the ability to detect a wide range of current values. This dynamic adjustment prevents overvoltage errors while preserving broad current detection capability.