Integrated stepper motor pre-driver enables quiet drive in industrial applications

September 16, 2013 // By Graham Prophet
Texas Instruments recently expanded its motor driver portfolio to include its first integrated stepper motor pre-driver. The DRV8711 is highly configurable with a best-in-class on-chip micro-stepping indexer, as well as stall detection, and advanced current regulation that easily and efficiently tunes any motor.

External MOSFETs control the stepper motor to provide minimum heat dissipation and 20% more scalable output current than the nearest competitor, allowing designers to customise their design. The stepper motor pre-driver is designed for industrial applications, including textile machinery, video surveillance, ATM machines, robotics, office automation equipment and stage lighting.

Features include;

Customisable driver stage: Gate drive supports up to 200 mA of source current per 400 mA of sink current with adjustable slew rate, dead-time and on-time to accommodate application requirements. The device drives external N-channel MOSFETs with a built-in charge pump to provide more design options and a cost-effective solution.

Smooth motion profile for higher performance: Spins a stepper motor with an integrated micro-stepping indexer capable of up to 1/256 micro-stepping. Adaptive blanking time and various current decay modes, including slow, fast, mixed and auto-mixed decay, achieve a smooth profile to optimise motor performance.

Internal and external stall-detect feature: Designers can easily detect stall conditions through internal stall detection, or process the optional back electromotive force (BEMF) output to detect stall conditions and take corrective action through the external controller. This allows the designer to minimise a disturbance from a motor stall.

Easy to use and highly configurable: SPI interface allows the customer to program the output current, micro-stepping mode, current decay mode and stall detection to reduce system complexity and simplify design compared to similar devices.

Robust, reliable and protected: The DRV8711's protection against motor over-current, pre-driver over-current, over temperature and under voltage fault conditions provides system protection, and enables system reliability and system robustness.

The DRV8711EVM (photo, above) is available to evaluate the motor pre-driver. This evaluation module (EVM) includes a low-power MSP430F2617 microcontroller (MCU) and external NexFET power MOSFETs. The EVM provides up to 52-V externally through the power header and a USB interface to communicate with the MSP430F2617 MCU through a graphical user interface (GUI). A stepper motor is also included to evaluate controller