Description
Designed for pulse-width modulated (PWM) current control
of bipolar microstepping stepper motors, the A3972 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 R
DS(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 power-up sequencing is not required.
The A3972SB is supplied in a 24-pin plastic DIP with two
batwing power tabs (suffix ‘B’). The power tabs are at ground
potential and need no electrical isolation. The device is lead
(Pb) free with 100% matte tin leadframe plating.
29319.33, Rev. D
Features and Benefits
▪ ±1.5 A, 50 V Continuous Output Rating
▪ Low R
DS(on)
DMOS Output Drivers
▪ Optimized Microstepping via 6-Bit Linear DACs
▪ Programmable Mixed, Fast, and Slow Current-Decay
Modes
▪ 4 MHz Internal Oscillator for Digital Timing
▪ Serial-Interface Controls Chip Functions
▪ Synchronous Rectification for Low Power Dissipation
▪ Internal UVLO and Thermal Shutdown Circuitry
▪ Crossover-Current Protection
▪ Precision 2 V Reference
▪ Inputs Compatible with 3.3 or 5 V Control Signals
▪ Sleep and Idle Modes
Package: 24-pin DIP with 4 fused leads
(suffix B)
Pin-out Diagram
Not to scale
A3972
Dual DMOS Full-Bridge Microstepping PWM Motor Driver
