A3998: Dual DMOS Full Bridge Motor Driver With Serial Port Control and Dual Regulators


Designed to provide the motor driver and power supply requirements for printers and office automation equipment. This integrated power IC incorporates two high current, high performance, full bridge outputs, 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 a low voltage output that is adjustable from 3.3 to 5 V. This voltage can be used to supply external 5 V rails, it also feeds back into the part and supplies the integrated linear regulator which is adjustable from 1 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 control with programmable decay mode selection.

The A3998 is supplied in a low profile, 32-contact QFN, 5 × 5 mm, 0.90 mm nominal height, with exposed thermal pad (suffix ET). The package is lead (Pb) free with 100% matte tin leadframe plating.

DISCONTINUED: This device is no longer in production. The device should not be purchased for new design applications. Samples are no longer available. Date of status change: December 28, 2019.

Recommended Substitutions: Contact Allegro Sales

Top Features

  • 3.3/5 V switching regulator
  • 1 to 2.5 V configurable linear regulator output
  • Dual DMOS full bridge: drive two DC motors or a single stepper motor
  • ±1.5 A, 50 V output rating per bridge
  • 4-bit microstepping capability
  • Serial port control
  • Configurable mixed, fast, and slow current decay
  • Synchronous rectification for low power dissipation
  • Internal UVLO and thermal shutdown circuitry
  • Crossover-current protection
  • OCP protection

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
A3998SETTR-T 32-lead QFN -20°C to 85°C Yes View Data Discontinued Contact your
local sales rep
Distributor Stock
APEK3998SET-01-T DEMO BOARD -20°C to 85°C No -- Discontinued Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.