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Motor driver's built-in translator enables easy operation

Posted: 22 Sep 2006 ?? ?Print Version ?Bookmark and Share

Keywords:microstepping device? motor drivers? Allegro MicroSystems? A3987? motor driver?

Allegro MicroSystems has released a new microstepping motor driver with built-in translator for easy operation.

Targeted at the office automation and industrial markets, the A3987 augments existing motor drivers by offering 50V and 1.5A output drive capability. It operates bipolar stepper motors in full, half, quarter and sixteenth step modes, and includes a fixed off-time current regulator that operates in slow or mixed decay modes.

Allegro explained that the built-in translator is the key to the easy implementation of A3987. By inputting one pulse on the step input, the motor takes one microstep. No phase sequence tables, high frequency control lines or complex interfaces are needed to program. The device interface suits applications with complex P that is either unavailable or over-burdened.

The A3987 motor driver's chopping control automatically selects current decay mode such as slow or mixed. When a STEP signal occurs, the device determines if such results in a higher or lower current in each motor phase. If there is a higher current change, the decay mode is set to slow decay. And if the change is of a lower current, the decay mode is set to 30.1 percent fast decay. Such scheme results in reduced audible motor noise, increased step accuracy and reduced power dissipation, said Allegro. Additionally, internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. Internal circuit protection includes thermal shutdown with hysteresis, over current protection, under voltage lockout and crossover current protection. Special power up sequencing is not required.

The new A3987 is available in a low profile 1.1mm, 24L eTSSOP package with exposed power tab.

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