The DRV8849 is an integrated motor-driver solution for driving two bipolar stepper motors. The device provides the maximum integration by integrating four N-channel power MOSFET H-bridges, current sense resistors and regulation circuitry, and one microstepping indexer for each stepper. The DRV8849 is capable of supporting wide supply voltage of 4.5 to 38 V. The device provides an output current up to 2.5-A peak, 1.5-A full-scale, or 1.1-A root mean square (rms) on each output. The actual full-scale and rms current depends on the ambient temperature, supply voltage, and PCB thermal capability.

The DRV8849 uses an integrated current-sense architecture which eliminates the need for four external power sense resistors, hence saving significant board space, BOM cost, design efforts and reduces significant power consumption. 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 by the voltage at the VREF pins.

A simple STEP/DIR interface allows for an external controller to manage the direction and step rate of the stepper motor. The internal microstepping indexer can execute high-accuracy micro-stepping 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, 1/32, 1/64, 1/128, and 1/256 microstepping. High microstepping contributes to significant audible noise reduction and smooth motion. In addition to a standard half stepping mode, a noncircular half stepping mode is available for increased torque output at higher motor RPM.

Stepper motor drivers need to re-circulate the winding current by implementing several types of decay modes, like slow decay, mixed decay and fast decay. The DRV8426 comes with smart tune decay modes. The smart tune is an innovative decay mechanism that automatically adjusts for optimal current regulation performance agnostic of voltage, motor speed, variation and aging effects. Smart tune Ripple Control uses a variable off-time, ripple current control scheme to minimize distortion of the motor winding current. Smart tune Dynamic Decay uses a fixed off-time, dynamic fast decay percentage scheme to minimize distortion of the motor winding current while minimizing frequency content and significantly reducing design efforts.

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