Stepper drivers simplify peripheral circuitry

A range of unipolar two-phase stepper motor driver ICs is designed to simplify peripheral circuitry design and reduce space while maintaining high reliability.

The new SLA7070MPR Series from Allegro MicroSystems Europe is a range of unipolar two-phase stepper motor driver ICs designed to simplify peripheral circuitry design and reduce space while maintaining high reliability.

The SLA7070M Series provides a space-saving solution by including a built-in resistor for current sense and protection circuitry against load short-circuit or open-circuit operation.

A common interface signal with series pin compatibility simplifies peripheral circuitry design.

The built-in motor coil, short- and open-circuit protection, and varied output-current ratings (1, 1.5, 2 and 3A) all help to increase reliability.

The new devices use clock-in topology, with the ICs configured in a logic circuit that controls excitation switching and a D/A convertor.

As a result, driving a motor one way can be controlled with a single clock signal, making it possible to minimise the requirements for control-signal wiring and the load on the microcontroller.

The SLA7070M Series incorporates both full/half-step and microstepping device types.

Unlike conventional motor drivers, where the pin alignments are different between full and microstepping versions, the SLA7070M Series devices were designed with commonality in mind.

This means that pin alignments and interface specifications are compatible, making it easy for users to choose the most suitable part for their application.

The drivers operate from power-supply voltages between 10 and 44 V, and can be used with logic supply voltages of 3.3 or 5.5V.

They feature self-excitation PWM (pulsewidth modulated) current control with fixed off-time, which is automatically adjusted by the step reference current ratio to one of three levels.

A new built-in synchronous rectifying circuit provides lower loss during PWM "off" conditions, while a synchronous PWM chopping function prevents motor noise in the "hold" mode.

A "sleep" mode reduces the IC input current to minimise power consumption during standby conditions.

Applications include office automation, industrial control equipment, security systems and gaming machines: all areas where there is a requirement for compact, multifunctional control of multiple motors and motion controllers.

The devices are supplied in a ZIP-type 23-pin moulded package which has a high power dissipation and is easy to mount on a heatsink.

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