DUAL DMOS FULL-BRIDGE MICROSTEPPING
PWM MOTOR DRIVER
Designed for pulse-width modulated (PWM) current control of bipolar
microstepping stepper motors, the A3972SB is capable of continuous output
currents to ±1.5 A and operating voltages to 50 V. Internal fixed off-time
PWM current-control timing circuitry can be programmed via a serial interface
to operate in slow, fast, and mixed current-decay modes.
The desired load-current level is set via the serial port with two 6-bit linear
DACs in conjunction with a reference voltage. The six 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 the current decay. This
feature will eliminate the need for external clamp diodes in most applications,
saving cost and external component count, while minimizing power dissipation.
Internal circuit protection includes thermal shutdown with hysteresis,
transient-suppression diodes, and crossover-current protection. Special powerup
sequencing is not required.
The A3972SB is supplied in a 24-lead plastic DIP with a copper batwing
power tab. The power tab is at ground potential and needs no electrical
isolation. The lead (Pb) free version has 100% matte tin leadframe plating.