The TMC389 coolStep™ is the first energy efficient high current, high precision, microstepping driver IC for 3-phase bipolar stepper motors
Using low resonance 3-phase stepper motors, smoothness at low speed can be increased significantly compared to a 2-phase stepper motor solution. The unique high resolution, sensorless load detection stallGuard2™ is also used for the world’s first integrated load dependent current control feature called coolStep™.The ability to read out the load and detect an overload makes the TMC389 an optimum choice for drives where a high reliability is desired at a low cost. With 3-phase motors the adapted spread Cycle 3p PWM automatic mixed decay chopper scheme ensures highest smoothness and best zero crossing performance.
The TMC389 can be driven with step and direction signals as well as by serial SPI™ interface and using the microPlyer x16 allows you to operate the motor with highest μStep smoothness reducing the input frequency divided by 16. A full set of protection and diagnostic features makes this device very rugged. It directly drives external MOSFETs for currents of up to 6A and this way it reaches highest energy efficiency and allows driving of a high motor current without cooling measures even at high environment temperatures.
The main features of the module are stallGuard2™ for sensorless load detection, coolStep™ for load dependent current control, save up to 80% energy and gain supreme smoothness. It also achieves the best current zero crossing performance, the best sine wave form and lowest power dissipation.

In addition there is full protection and diagnostics, standby and shutdown mode stall / load detection output and low power consumption via low RDS-ON power stage.

There is also an evaluation board which comes with the PC software which gives access to every function of the driver. It comes alongside a step and direction interface, a RS232 and a USB port. The TMC389-Eval is a complete ‘plug and play’ solution, additionally only a motor, a PC and a power supply are required!

Micromech is the UK and Eire distributor for these amazing products and if you would like to find out more click here or contact Stirling Morley on 01376 333333 or email

‘Affordable Automation’


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