8.2.2.2 Motor Current Trip Point

When the voltage on pin ISENSE exceeds VILIM (0.2 V), overcurrent is detected. The RSENSE resistor should be sized to set the desired ILIMIT level.

To set I_ILIMIT to 0.5 A, R_ISENSE = 0.2 V / 0.9 A = 0.22 Ω.

To prevent false trips, I_LIMIT must be higher than regular operating current. Motor current during start-up is typically much higher than steady-state spinning, because the initial load torque is higher, and the absence of back-EMF causes a higher voltage and extra current across the motor windings.

It can be beneficial to limit start-up current by using series inductors on the DRV8832-Q1 output, as that allows I_LIMIT to be lower, and it may decrease the system’s required bulk capacitance. Start-up current can also be limited by ramping the forward drive duty cycle.