A3973SLB-T Datasheet, PDF (1/10 Pages) Allegro MicroSystems – Dual DMOS Full-Bridge Microstepping PWM Motor Driver

A3973
Dual DMOS Full-Bridge Microstepping PWM Motor Driver
Features and Benefits
▪ ±1 A, 35 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
Packages:
Package B, 24-pin DIP with
two batwing power tabs
Not to scale
Package LB, 24 pin SOICW
with 4 fused leads
Description
Designed for pulse-width modulated (PWM) current control
of bipolar microstepping stepper motors, the A3973 is capable
of continuous output currents to ±1 A and operating voltages
to 35 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 eliminates 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 B package is a 24-lead DIP with two copper batwing power
tabs. The LB is a 24-lead SOICW with four internally fused
leads for enhanced power dissipation. These power tabs and
pins are at ground potential and need no electrical isolation.
The A3973 B and LB packages are electrically identical.
Pin-out Diagram
29319.34 Rev. 2
VCP 1
CP1 2
CP2 ₃
OUT 1B 4
LOAD
SUPPLY 1 ⁵ V BB1
GROUND 6
GROUND 7
SENSE 1 8
OUT 1A 99
STROBE 10
CLOCK 11
DATA 12
24 OSC
23 SLEEP
22 V REG
21 OUT 2B
20 ^LOAD
V BB2
SUPPLY 2
19 GROUND
18 GROUND
17 SENSE 2
16 OUT 2A
LOGIC
VDD 15 _SUPPLY
14 MUX
13 REF
Dwg. PP-069-3