Power Electronics

Dual DMOS Full-Bridge Motor Driver and Dual Regulator

Allegro MicroSystems, Inc. announces a new integrated power IC that is designed to supply the motor driver and power supply requirements for office automation such as printers and scanners as well as industrial applications. Allegro's A3998 incorporates two high current, high performance, DMOS full-bridge outputs that are capable of 1.5 A at 50 V. Additionally, two power supply rails are provided for microprocessor or DSP supplies. A switching buck regulator steps the supply down to an adjustable low voltage output from 3.3 to 5 V. This voltage can be used to supply external 3.3 V or 5 V rails and also feeds back into the part supplying the adjustable, integrated linear regulator from 1 V to 2.5 V.

The A3998 serial port provides flexible configuration for the dual full-bridge motor driver. Two full-bridges can be programmed to control one stepper motor or two DC motors. Both bridges have integrated fixed off-time PWM current control with programmable decay mode selection. Maximum output current is set by an external VREF input voltage, sense resistor and serial port controlled four bit DAC for each bridge. The four bit non-linear DAC can be programmed to produce up to 16 current levels for full, half, 1/4, 1/8 and 1/16 microstep per step resolution in stepper motor configurations.

Internal circuit protection includes: thermal shutdown with hysteresis, under voltage lockout (UVLO), over current and crossover-current protection.

The A3998SETTR-T is priced at $2.63 in quantities of 1,000 and is supplied in a low profile, 32-contact QFN, 5 × 5 mm, 0.90 mm nominal height, with exposed thermal pad (suffix ET) package. The package is lead (Pb) free with 100% matte-tin leadframe plating.

Allegro Microsystems
Part Number: A3998

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