SLVSCY9B August 2015 – July 2016 DRV8871
The DRV8871 device limits the output current based on a standard resistor attached to pin ILIM, according to this equation:
For example, if RILIM = 32 kΩ, the DRV8871 device limits motor current to 2 A no matter how much load torque is applied. The minimum allowed RILIM is 15 kΩ. System designers should always understand the min and max ITRIP, based on the RILIM resistor component tolerance and the DRV8871 specified VILIM range.
When ITRIP has been reached, the device enforces slow current decay by enabling both low-side FETs, and it does this for time tOFF (typically 25 µs).
After tOFF has elapsed, the output is re-enabled according to the two inputs INx. The drive time (tDRIVE) until reaching another ITRIP event heavily depends on the VM voltage, the motor’s back-EMF, and the motor’s inductance.