A3979: Microstepping DMOS Driver with Translator

Description

The A3979 is a complete microstepping motor driver with built-in translator, designed as a pin-compatible replacement for the successful A3977, with enhanced microstepping (1/16 step) precision. It is designed to operate bipolar stepper motors in full-, half-, quarter-, and sixteenth-step modes, with an output drive capacity of up to 35 V and ±2.5 A. The A3979 includes a fixed off-time current regulator that has the ability to operate in Slow, Fast, or Mixed decay modes. This current-decay control scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation.

The translator is the key to the easy implementation of the A3979. It allows the simple input of one pulse on the STEP pin to drive the motor one microstep, which can be either a full step, half, quarter, or sixteenth, depending on the setting of the MS1 and MS2 logic inputs. There are no phase-sequence tables, high-frequency control lines, or complex interfaces to program. The A3979 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened.

Internal synchronous-rectification control circuitry is provided to improve power dissipation during PWM operation. Internal circuit protection includes: thermal shutdown with hysteresis, UVLO (undervoltage lockout), and crossover-current protection. Special power-on sequencing is not required.

The A3979 is supplied in a low-profile (maximum height ≤1.20 mm), 28-pin TSSOP with exposed thermal pad. The package is available in a lead (Pb) free version, with 100% matte tin leadframe plating.

Top Features

  • ±2.5 A, 35 V output rating
  • Low RDS(On) outputs: 0.28 Ω source, 0.22 Ω sink, typical
  • Automatic current decay mode detection/selection
  • 3.0 to 5.5 V logic supply voltage range
  • Slow, Fast or Mixed current decay modes
  • Home output
  • Synchronous rectification for low power dissipation
  • Internal UVLO and thermal shutdown circuitry
  • Crossover-current protection

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Compliant
Part Composition /
RoHS Data
Comments Samples Check Stock
A3979SLPTR-T 28-lead TSSOP -20°C to 85°C Yes View Data Contact your
local sales rep
Check
Distributor Stock
APEK3979SLP-01-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Check
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.

Packaging

The A3979 is supplied in a low-profile (maximum height ≤1.20 mm), 28-pin TSSOP with exposed thermal pad. The package is available in a lead (Pb) free version, with 100% matte tin leadframe plating.

LP TSSOP 28 pin