Stepper driver ICs are easy to interface

Two new DMOS microstepping motor driver integrated circuits come with built-in translator circuitry and output ratings of 35V and 1.5 A (2A peak).

Allegro MicroSystems Europe has introduced two new DMOS microstepping motor driver integrated circuits with built-in translator circuitry and output ratings of 35V and 1.5A (2A peak).

The new A3983 and A3984 are designed to operate bipolar stepper motors in full-, half-, quarter-, eighth- (A3983) and sixteenth- (A3984) step modes.

The devices combine an easy-to-use step and direction interface with efficient high-current output and high-resolution microstepping control at a competitive price.

The low on-resistance means that all N-channel DMOS outputs are rated at up to 2A peak, whereas most competing products are limited to 1.5A.

The translator circuitry makes designs based on the A3983/84 very easy to implement and interface.

Simply inputting one pulse on the step input causes the motor to take one microstep.

There are no phase-sequence tables, high-frequency control lines or complex interfaces to program.

This simple, two-input step and direction interface makes the devices ideal for applications with multiple motors that would normally overload the I/O capacity of typical microprocessor controllers.

Internal synchronous rectification control circuitry is included in the A3983/84 to improve power dissipation during PWM operation.

The power dissipation savings (typically greater than 20%) lead to lower-temperature operation and eliminate the need for external Schottky diodes.

Competing devices with bipolar outputs cannot implement synchronous rectification.

The A3983/84 devices include a fixed-off-time PWM current regulator that will automatically switch to slow- or mixed-decay modes.

This patented current decay scheme results in reduced audible noise, increased step accuracy and reduced power dissipation.

Internal circuit protection includes thermal shutdown with hysteresis, undervoltage lockout and crossover current protection.

Special power-up sequencing is not required.

The A3983/84 devices are manufactured using Allegro's ABCD (Allegro bipolar/CMOS/DMOS) process, and are offered in an industry-standard 24-lead eTSSOP package with exposed thermal pad (suffix LP).

Measuring only 7.8 x 6.4mm, the device is one-third the size of its closest competitor.

A lead-free (Pb-free) version is available.

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