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29319.33a
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.
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
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.
of the DMOS output driver during the current decay. This
DS(on)
Data Sheet
ABSOLUTE MAXIMUM RATINGS
= +25°C
at T
A
Load Supply Voltage, VBB................ 50 V
Output Current, I
Logic Supply Voltage, VDD.............. 7.0 V
Logic Input Voltage Range,
VIN................ -0.3 V to V
Reference Voltage, 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,
TS......................... -55°C to +150°C
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 temperature of 150°C.
...................... ±1.5 A
OUT
DD
..................... 3 V
REF
+ 0.3 V
FEATURES
■ ±1.5 A, 50 V Continuous Output Rating
■ Low r
■ 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 V or 5 V Control Signals
■ Sleep and Idle Modes
Always order by complete part number:
Part Number Pb-Free Packing
A3972SB — 15 pieces/tube
A3972SB-T Yes 15 pieces/tube
DMOS Output Drivers
DS(on)
3972
DUAL DMOS FULL-BRIDGE
MICROSTEPPING PWM MOTOR DRIVER
FUNCTIONAL BLOCK DIAGRAM
LOGIC
SUPPLY
CLOCK
DATA
STROBE
SLEEP
V
MUX
OSC
15
DD
14
24
11
12
10
23
OSCILATOR
OSC SELECT/
DIVIDER
SERIAL
PORT
2 V
UVLO AND
FAULT
DETECT
6-BIT
LINEAR
DAC
6
6
2 V
REGULATOR
BANDGAP
+-
PROGRAMMABLE
PWM TIMER
FIXED-OFF
BLANK
MIXED DECAY
CONTROL
LOGIC
PHASE 1/2
SYNC. RECT. MODE
SYNC. RECT. DISABLE
MODE 1/2
PROGRAMMABLE
PWM TIMER
FIXED-OFF
BLANK
MIXED DECAY
SENSE
1
V
22
GATE
DRIVE
0.22 µF
REG
V
CP
0.22 µF
3
CP1CP2
2
CHARGE PUMP
DMOS H-BRIDGE
DMOS H-BRIDGE
1
5
9
4
8
20
16
21
V
CP
V
BB1
OUT
1A
OUT
1B
SENSE
V
BB2
OUT
2A
OUT
2B
1
0.1 µF
0.22 µF
LOAD
SUPPLY
2
REF
13
Dwg. FP-050-1
BUFFER
6-BIT
LINEAR
DAC
+-
GROUND
6
18
7
19
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 2000, Allegro MicroSystems, Inc.
17
SENSE
2
0.1
µ
F
3972
DUAL DMOS FULL-BRIDGE
MICROSTEPPING PWM MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = +25°C, VBB = 50 V, VDD = 5.0 V, VS = 0.5 V,
f
< 50 kHz (unless otherwise noted).
PWM
Limits
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Load Supply Voltage Range V
Logic Supply Voltage Range V
Load Supply Current I
Logic Supply Current I
Output Drivers
Output Leakage Current I
Output On Resistance r
DS(on)
Body Diode Forward Voltage V
BB
DD
BB
DD
DSS
Operating 15 — 50 V
During sleep mode 0 — 50 V
Operating 4.5 5.0 5.5 V
f
< 50 kHz — — 8.0 mA
PWM
Operating, outputs disabled — — 6.0 mA
Sleep or idle mode — — 20 µA
f
< 50 kHz — — 12 mA
PWM
Outputs off — — 10 mA
Idle mode (D0 = 1, D18 = 0) — — 1.5 mA
Sleep mode — — 100 µA
V
= V
OUT
V
OUT
Source driver, I
Sink driver, I
F
Source diode, IF = 1.5 A — — 1.2 V
BB
= 0 V — <-1.0 -50 µA
= –1.5 A — 0.5 0.55 Ω
OUT
= 1.5 A — 0.315 0.35 Ω
OUT
— <1.0 50 µA
Sink diode, IF = 1.5 A — — 1.2 V
Control Logic
Logic Input Voltage V
Logic Input Current I
OSC Input Frequency Range f
V
I
IN(1)
IN(0)
IN(1)
IN(0)
OSC
VIN = 2.0 V — <1.0 20 µA
V
= 0.8 V — <-2.0 -20 µA
IN
Divide by one 2.5 — 6.0 MHz
2.0 — — V
——0.8 V
(D0 =1, D13 = 0, D14 = 1)
OSC Input Duty Cycle — 40 — 60 %
Input Hysterisis ∆V
IN
0.20 — 0.40 V
continued next page ...
www.allegromicro.com
3
3972
DUAL DMOS FULL-BRIDGE
MICROSTEPPING PWM MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = +25°C, VBB = 50 V, VDD = 5.0 V, VS = 0.5 V,
f
< 50 kHz (unless otherwise noted).
PWM
Limits
Characteristics Symbol Test Conditions Min. Typ. Max. Units
Control Logic (continued)
Internal Oscillator f
DAC Accuracy (total error) E
Reference Input Voltage Range V
REF(EXT)
Reference Buffer Offset V
Reference Divider Ratio V
REF/VS
Reference Input Current I
Internal Reference Voltage V
REF(INT)
Gain (Gm) Error (note 3) E
Comparator Input Offset Voltage V
Propagation Delay Times t
OSC
OS
REF
G
IO
pd
OSC shorted to ground 3.0 4.0 5.0 MHz
R
= 51 kΩ 3.4 4.0 4.6 MHz
OSC
T
Relative to DAC reference buffer
— ±1/2 — LSB
output, D0 = 0, D17 = 0
0.5 — 2.6 V
— ±10 — mV
D0 = 0, D18 = 0 — 8.0 — —
D0 = 0, D18 = 1 — 4.0 — —
V
= 2.0 V — — ±0.5 µA
REF
1.94 2.0 2.06 V
D0 = 0, D17 = 0,
D18 = 0, DAC = 63 — 0 ±6%
D18 = 0, DAC = 31 — 0 ±9%
D18 = 1, DAC = 63 — 0 ±6%
D18 = 1, DAC = 15 — 0 ±10 %
V
= 0 V — ±5.0 — mV
REF
50% to 90%:
PWM change to source on 500 800 1200 ns
PWM change to source off 50 150 350 ns
PWM change to sink on 500 800 1200 ns
Crossover Dead Time t
Thermal Shutdown Temperature T
Thermal Shutdown Hysteresis ∆T
UVLO Enable Threshold V
UVLO Hysteresis ∆V
dt
J
J
UVLO
UVLO
NOTES: 1. Typical Data is for design information only.
2. Negative current is defined as coming out of (sourcing) the specified device terminal.
3. EG = [(V
/Range) – VS]/(V
REF
/Range).
REF
4
PWM change to sink off 50 150 350 ns
300 700 900 ns
— 165 — °C
—15— °C
Increasing V
DD
3.9 4.2 4.45 V
0.05 0.10 — V
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
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