7.1 Overview

The DRV8886 device is an integrated motor-driver solution for bipolar stepper motors. The device integrates two N-channel power MOSFET H-bridges, integrated current sense and regulation circuitry, and a microstepping indexer. The DRV8886 device can be powered with a supply voltage from 8 to 37 V and is capable of providing an output current up to 3-A peak, 2-A full-scale, or 1.4-A root mean square (rms). The actual full-scale and rms current depends on the ambient temperature, supply voltage, and PCB thermal capability.

The DRV8886 device uses an integrated current-sense architecture which eliminates the need for two external power sense resistors. This architecture removes the power dissipated in the sense resistors by using a current mirror approach and using the internal power MOSFETs for current sensing. The current regulation set point is adjusted with a standard low-power resistor connected to the RREF pin. This features reduces external component cost, board PCB size, and system power consumption.

A simple STEP/DIR interface allows for an external controller to manage the direction and step rate of the stepper motor. The internal indexer can execute high-accuracy microstepping without requiring the external controller to manage the winding current level. The indexer is capable of full step, half step, and 1/4, 1/8, 1/16 microstepping. In addition to a standard half stepping mode, a non-circular half stepping mode is available for increased torque output at higher motor RPM.

The current regulation is configurable between several decay modes. The decay mode can be selected as a fixed slow, slow-mixed, or mixed decay current regulation scheme. The slow-mixed decay mode uses slow decay on increasing steps and mixed decay on decreasing steps.

An adaptive blanking time feature automatically scales the minimum drive time with output current level. This feature helps alleviate zero-crossing distortion by limiting the drive time at low-current steps.

A torque DAC feature allows the controller to scale the output current without needing to scale the RREF reference resistor. The torque DAC is accessed using a digital input pin which allows the controller to save system power by decreasing the motor current consumption when high output torque is not required.

A low-power sleep mode is included which allows the system to save power when not actively driving the motor.