High-precision overcurrent protection circuit for motor drive application

An overcurrent detection circuit for motor drive application is proposed and designed in this paper. The circuit utilizes the negative feedback clamp characteristics of operational amplifiers and off-chip high-resistance resistors to obtain an reference current with zero temperature coefficient current. This current flows through a small-size detection power mos transistor to generate a reference voltage used for motor driving over-current protection. The conduction voltage drop V_ds of the power transistor is transferred to a voltage on a sense resistor. The two voltages are compared, and the comparator flip point is the overcurrent point. The circuit is designed and simulated based on the 0.18μm MGN process. Simulation verification results show that under different PVT conditions, the overcurrent detection circuit has an accurate overcurrent point with error from -2.8% to +1.9%.