DMOS Full-Bridge PWM Motor Driver Dissipates Little Power

Designed for PWM current control of dc motors, the A3959 DMOS, full-bridge motor driver can deliver output currents up to ±3A and operating voltages to 50V. The device employs synchronous rectification that lowers on-chip power dissipation by automatically turning on the output MOSFETs to prevent the internal body diodes from conducting. The internal, fixed off-time PWM control can be set to operate in either slow, fast or mixed-decay mode. Operating in the mixed-decay mode is said to reduce the high ripple current effects of fast decay and minimizes the limited bandwidth issues of of slow decay by adjusting the percent of off-time spent in each mode by use of a unique percent-fast-decay pin. Available in 24-lead plastic DIPs and 24-lead plastic SOIC packages, price is $2.27 each/1,000 with a 16-week lead time. ALLEGRO MICROSYSTEMS INC., Worcester, MA. (508) 853-5000.