PWM Motor Driver offers overcurrent protection.

Press Release Summary:

Designed for PWM current control of bipolar microstepping motors, Model A3992 DMOS full-bridge motor driver is capable of continuous output currents to ±1.5 A and operating voltages to 50 V. Internal fixed off-time circuitry is programmed via serial interface to operate in slow, fast, and mixed decay modes. Load current level is set via serial port with two 6-bit linear DACs in conjunction with reference voltage. A3992 is supplied in 1.1 mm 24L eTSSOP package.

Original Press Release:

Allegro Announces New DMOS Microstepping PWM Motor Driver with Serial Interface and Over-Current Protecion

Worcester, MA, October 4, 2006 - Allegro announces a new DMOS full-bridge microstepping PWM motor driver to complement their existing serial controlled microstepping driver family. Targeted at the office automation and industrial markets, Allegro's A3992 solution offers several key features to include: over-current protection (OCP), synchronous rectification for low power dissipation, patented programmable mixed, fast and slow current decay modes and low on resistance DMOS outputs in a thermally efficient surface mount package.

Designed for Pulse Width Modulated (PWM) current control of bipolar microstepping stepper motors, the A3992 is capable of continuous output currents to ± 1.5 A and operating voltages to 50 V. Internal fixed off-time PWM current control timing circuitry can be programmed via the serial interface to operate in slow, fast and mixed decay modes.

The desired load current level is set via the serial port with two six bit linear DAC's in conjunction with a reference voltage. The six bits of control allow maximum flexibility in torque control for a variety of step methods, from microstepping to full step drive. Load current is set in 1.56% increments of the maximum value.

Synchronous Rectification circuitry allows the load current to flow through the low Rdson of the DMOS output driver during current decay. This feature will eliminate the need for external clamp diodes in most applications, saving cost and external component count, while minimizing power dissipation. Internal circuit protection includes thermal shutdown with hysteresis, under voltage lockout, over current and crossover current protection. Special power up sequencing is not required.

Allegro's A3992 is supplied in a low profile (1.1mm) 24L eTSSOP (suffix 'LP') with exposed power tab and a 24-lead plastic DIP with a copper batwing tab (suffix 'B'). The power tab is at ground potential and needs no electrical isolation. The A3992SLP-T is priced at $2.36 in quantities of 5,000 and has a 12-week typical lead-time to market.

About Allegro
Allegro MicroSystems, Inc. is a global leader in the development, manufacture and marketing of high-performance power integrated circuits and integrated Hall-effect magnetic sensors. Allegro's innovative, system-level solutions serve high-growth applications within the automotive, computer/office automation, industrial, consumer and communications markets, while our leading-edge product and processes reinforce our expertise in motor driver and power management technology. In addition, we also hold leading positions within printer, scanner, copier and portable device (e.g. cellular phones) applications. With more than 2,400 employees, Allegro is headquartered in Worcester, MA. Further information about Allegro can be found at

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