SLOSE70 December 2020 DRV8434S
The DRV8434S is an integrated motor-driver solution for bipolar stepper motors. The device provides the maximum integration by integrating two N-channel power MOSFET H-bridges, current sense resistors and regulation circuitry, and a microstepping indexer. The DRV8434S is capable of supporting wide supply voltage of 4.5 to 48 V. The device provides an output current up to 4-A peak, 2.5-A full-scale, or 1.8-A root mean square (rms). The actual full-scale and rms current depends on the ambient temperature, supply voltage, and PCB thermal capability.
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 DRV8434S 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. Along with this seamless, effortless automatic smart tune, DRV8434S also provides the traditional decay modes like slow-mixed and mixed decay as well.
A torque DAC feature allows the controller to scale the output current without needing to scale the VREF voltage reference. 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.
The device integrates a spread spectrum clocking feature for both the internal digital oscillator and internal charge pump. This feature minimizes the radiated emissions from the device. A low-power sleep mode is included which allows the system to save power when not actively driving the motor.