Microstepping motor driver IC from Allegro offers built-in translator for easy operation


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The new A4992 from Allegro MicroSystems Europe is a single-chip microstepping motor driver with a built-in translator that simplifies operation by minimising the need for external control circuitry. The new device is targeted at the automotive and industrial markets, with end applications including automotive adaptive headlamp systems, idle bypass valve positioning, HVAC vent position systems, EGR valves and satellite, solar panel and CCTV positioning systems. The A4992 is designed to operate bipolar stepper motors in full, half, quarter and eighth step modes at up to 28 V. At power-on, the A4992 is configured to drive most small stepper motors with simple step and direction inputs. It operates over a supply voltage range from 3.5 to 50 V. The current regulator in the A4992 operates with fixed-frequency pulse-width modulation, and uses adaptive mixed current decay to reduce audible motor noise and increase step accuracy. The current in each phase of the motor is controlled through a DMOS full-bridge circuit using synchronous rectification to improve power dissipation. Internal circuits and timers prevent cross-conduction and shoot-through when switching between high-side and low-side drives. The outputs are protected from short circuits, and monitoring for low load current and stalled rotor detection is also included. Chip-level protection includes hot thermal warning, overtemperature shutdown, overvoltage indication and undervoltage lockout. An optional serial interface mode, using the step, direction and microstep select inputs, can be used to configure several motor control parameters as well as providing diagnostic feedback. The A4992KLPTR-T is supplied in a 20-pin TSSOP power package with an exposed thermal pad (package type LP). This package is lead (Pb) free with 100% matt-tin leadframe plating. Allegro MicroSystems