A3992 DMOS Dual, Full-Bridge Microstepping PWM Motor Driver

Designed for pulse width modulated (PWM) current control of bipolar microstepped stepper motors, the A3992 is capable of continuous output currents to 1.5 A and operating voltages to 50V. Internal fixed-off-time PWM current control timing circuitry can be programmed via the serial interface to operate in slow, fast, or mixed decay modes.

The desired load current level is set via the serial port with 2, 6-bit linear DACs in conjunction with a reference voltage. The 6 bits of control allow maximum flexibility in torque control for a variety of step methods, from microstepping to full-step drive. Load current is set in 1.56% increments of the maximum value.

Synchronous rectification circuitry allows the load current to flow through the low RDS(on) of the DMOS output driver during current decay. This feature eliminates the need for external clamp diodes in most applications, saving cost and external component count while minimizing power dissipation.

Internal circuit protection includes short-to-ground, shorted load, thermal shutdown with hysteresis, and crossover current protection. Special power-up sequencing is not required.

The A3992 is supplied in a thin profile (1.2 mm maximum height) 24-pin TSSOP (suffix LP) with an exposed thermal pad and a 24-pin plastic DIP with dual copper batwing tabs (suffix B). The exposed thermal pad on the LP is at ground potential and needs no electrical isolation. Both packages are lead-free with 100% matte tin leadframe plating.