A3955: Full-Bridge PWM Microstepping Motor Driver

Description

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: January 30, 2012. 

Recommended Substitutions: For existing customer transition, and for new customers or new applications, refer to the A4975.

The A3955 is designed to drive one winding of a bipolar stepper motor in a microstepping mode. The outputs are rated for continuous output currents to ±1.5 A and operating voltages to 50 V. Internal pulse width modulated (PWM) current control combined with an internal three-bit nonlinear digitalto- analog converter allows the motor current to be controlled in full-, half-, quarter-, or eighth-step (microstepping) modes. Nonlinear increments minimize the number of control lines necessary for microstepping. Microstepping provides increased step resolution, and reduces torque variations and resonance problems at low speed.

Internal circuitry determines whether the PWM current-control circuitry operates in a slow (recirculating) current-decay mode, fast (regenerative) current-decay mode, or in a mixed current-decay mode in which the off-time is divided into a period of fast current decay and with the remainder of the fixed off-time spent in slow current decay. The combination of user-selectable current-sensing resistor and reference voltage, digitally selected output current ratio; and slow, fast, or mixed current-decay modes provides users with a broad, variable range of motor control.

Internal circuit protection includes thermal shutdown with hysteresis, transient-suppression diodes, and crossover-current protection. Special power-up sequencing is not required.

The A3955 is supplied in a choice of two power packages; a 16-pin dual-in-line plastic package with copper heat-sink tabs (suffix ‘B’), and a 16-lead plastic SOIC with internally fused pins (suffix ‘LB’). For both package styles, the thermally enhanced pins are at ground potential and need no electrical isolation. Both packages are lead (Pb) free, with leadframe plating 100% matte tin.

Top Features

  • ±1.5 A continuous output current
  • 50 V output voltage rating
  • Internal PWM current control
  • 3-bit nonlinear DAC
  • Fast, mixed fast/slow, and slow current-decay modes
  • Internal transient-suppression diodes
  • Internal thermal shutdown circuitry
  • Crossover-current and UVLO protection

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Compliant
Part Composition /
RoHS Data
Comments Samples Check Stock
A3955SB-T 16-lead DIP -20°C to 85°C Yes View Data Discontinued Contact your
local sales rep
Check
Distributor Stock
A3955SLBTR-T 16-lead SOIC -20°C to 85°C Yes View Data Discontinued Contact your
local sales rep
Check
Distributor Stock

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Packaging

The A3955 is supplied in a choice of two power packages; a 16-pin dual-in-line plastic package with copper heat-sink tabs (suffix ‘B’), and a 16-lead plastic SOIC with internally fused pins (suffix ‘LB’). For both package styles, the thermally enhanced pins are at ground potential and need no electrical isolation. Both packages are lead (Pb) free, with leadframe plating 100% matte tin.

B and LP package combined

Design Support Tools

A3955 to A4975 Application Note