High-Precision Overcurrent Detection Using Metal Wire Resistance Sampling

This paper proposes a high-precision current limiting protection circuit utilizing the same metal-wire resistance sampling as the switching protection unit is proposed. The circuit achieves current detection through an integrated aluminum parasitic resistor, avoiding the introduction of additional on-resistance and power loss, and incorporates a self-zeroing amplifier to achieve high-precision current detection and overcurrent protection functions. In this paper, the design of the self-zeroing amplifier effectively compensates the effect of temperature drift and other non-ideal factors to ensure the accuracy of current detection. Meanwhile, a bandgap reference voltage circuit is designed to provide a comparison voltage that is not affected by temperature and supply voltage, which improves the comparison accuracy of the overcurrent detection circuit. Finally, this paper can set the circuit channel current limit size by external resistors of different resistance values. Simulation results show that the reference current generated by the bandgap reference circuit of this circuit varies up to 0.16%, the reference voltage accuracy of the current-limiting comparison circuit is 0.26%, and the current-limiting threshold accuracy varies up to 1.84%.