A3973
Dual DMOS Full-Bridge Microstepping PWM Motor Driver
Features and Benefits
Description
▪ ±1 A, 35 V Continuous Output Rating
▪ Low RDS(on) DMOS Output Drivers
▪ Optimized Microstepping via 6-Bit Linear DACs
Designed for pulse-width modulated (PWM) current control
of bipolar microstepping stepper motors, theA3973 is capable
of continuous output currents to ±1 A and operating voltages
▪ Programmable Mixed, Fast, and Slow Current Decay Modes to 35 V. Internal fixed off-time PWM current-control timing
▪ 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
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
flowthroughthelowRDS(on) oftheDMOSoutputdriverduring
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.
Packages:
Internal circuit protection includes thermal shutdown with
hysteresis,transient-suppressiondiodes,andcrossover-current
protection. Special power-up sequencing is not required.
Package B, 24-pin DIP with
two batwing power tabs
TheBpackageisa24-leadDIPwithtwocopperbatwingpower
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.
Package LB, 24 pin SOICW
with 4 fused leads
Not to scale
Pin-out Diagram
VCP
CP1
CP2
OSC
23 SLEEP
24
1
2
3
4
V
REG
22
OUT 1B
LOAD
21 OUT 2B
LOAD
SUPPLY 2
20
5
6
7
8
SUPPLY
1
V
BB1
V
BB2
19
18
GROUND
GROUND
GROUND
GROUND
SENSE
1
SENSE
2
17
16
9
9
OUT 2A
OUT 1A
STROBE
LOGIC
SUPPLY
V
DD
15
14
13
10
MUX
REF
CLOCK
DATA
11
12
Dwg. PP-069-3
29319.34 Rev. 2