3972
DUAL DMOS FULL-BRIDGE MICRO-
STEPPING 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.
VCP
CP1
CP2
OSC
23 SLEEP
24
1
2
3
4
VREG
22
OUT1B
LOAD
21 OUT2B
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.
LOAD
SUPPLY
20
5
6
7
8
SUPPLY
1
V
BB1
V
BB2
2
19
18
GROUND
GROUND
GROUND
GROUND
SENSE
1
SENSE
2
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.
17
16
9
9
OUT2A
LOGIC
OUT1A
STROBE
VDD
15
14
13
10
11
SUPPLY
MUX
CLOCK
Internal circuit protection includes thermal shutdown with hyster-
esis, transient-suppression diodes, and crossover-current protection.
Special power-up sequencing is not required.
REF
DATA 12
Dwg. PP-069-3
The A3972SB is supplied in a 24-lead plastic DIP with a copper
batwing power tab (suffix ‘B’). The power tab is at ground potential and
needs no electrical isolation.
ABSOLUTE MAXIMUM RATINGS
at TA = +25°C
Load Supply Voltage, VBB ................ 50 V
Output Current, IOUT ...................... 1.5 A
Logic Supply Voltage, VDD .............. 7.0 V
Logic Input Voltage Range,
VIN ................ -0.3 V to VDD + 0.3 V
Reference Voltage, VREF ..................... 3 V
Sense Voltage (dc), VS ................ 500 mV
Package Power Dissipation,
PD .......................................... 3.1 W
Operating Temperature Range,
TA .......................... -20°C to +85°C
Junction Temperature, TJ ............. +150°C
Storage Temperature Range,
FEATURES
I
1.5 A, 50 V Continuous Output Rating
I Low rDS(on) DMOS Output Drivers
I Optimized Microstepping via 6-Bit Linear DACs
I Programmable Mixed, Fast, and Slow Current-Decay Modes
I 4 MHz Internal Oscillator for Digital Timing
I Serial-Interface Controls Chip Functions
I Synchronous Rectification for Low Power Dissipation
I Internal UVLO and Thermal Shutdown Circuitry
I Crossover-Current Protection
TS ......................... -55°C to +150°C
I Precision 2 V Reference
Output current rating may be limited by duty
cycle, ambient temperature, and heat sinking.
Under any set of conditions, do not exceed the
specified current rating or a junction tempera-
ture of 150°C.
I Inputs Compatible with 3.3 V or 5 V Control Signals
I Sleep and Idle Modes
Always order by complete part number: A3972SB .