A2919: Dual Full-Bridge PWM Motor Driver

A2919
Dual Full-Bridge PWM Motor Driver
Discontinued Product
This device is no longer in production. The device should not be
purchased for new design applications. Samples are no longer available.
Date of status change: November 1, 2010
Recommended Substitutions:
For existing customer transition, and for new customers or new applications, contact Allegro Sales.
NOTE: For detailed information on purchasing options, contact your
local Allegro field applications engineer or sales representative.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan
for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The
information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use.
A2919
Dual Full-Bridge PWM Motor Driver
Features and Benefits
Description
▪ 750 mA continuous output current
▪ 45 V output sustaining voltage
▪ Internal clamp diodes
▪ Internal PWM current control
▪ Low output saturation voltage
▪ Internal thermal shutdown circuitry
▪ Half- or quarter-step operation of bipolar stepper motors
The A2919 motor driver is designed to drive both windings
of a bipolar stepper motor or bidirectionally control two DC
motors. Both bridges are capable of sustaining 45 V and include
internal pulse width modulation (PWM) control of the output
current to 750 mA. The outputs have been optimized for a low
output-saturation voltage drop (less than 1.8 V total source
plus sink at 500 mA).
For PWM current control, the maximum output current is
determined by the user’s selection of a reference voltage
and sensing resistor. Two logic-level inputs select output
current limits of 0%, 41%, 67%, or 100% of the maximum
level. A PHASE input to each bridge determines load current
direction.
Package: 24-pin SOIC with exposed
thermal tabs (suffix LB)
The bridges include both ground clamp and flyback diodes for
protection against inductive transients. Internally generated
delays prevent crossover currents when switching current
direction. Special power-up sequencing is not required. Thermal
protection circuitry disables the outputs if the chip temperature
exceeds safe operating limits.
Continued on the next page…
Not to scale
PWM Control Circuitry
LOAD SUPPLY
24 V
Channel 1
pin numbers
shown
BB
OUT 1B
17
14
OUT 1A
V REF1 10
16 E1
60 k7
w10
SENSE1 –
15
120 k7
RC
42 k7
I 01
ONE
SHOT
+
SOURCE
DISABLE
9 RC1
13
I 1 12
RS
CC
R
T
C
T
Dwg. EP-007-3
29319.21G
A2919
Dual Full-Bridge PWM Motor Driver
Description (continued)
The A2919 is supplied in a 24-pin surface-mountable SOICW with
heat sinkable tabs for improved power dissipation capabilities .
This batwing construction provides for maximum package power
dissipation in the smallest possible construction. The A2919 is
available for operation from -20°C to 85°C, and are also available
on special order for operation to +125°C.
Selection Guide
Part Number
Packing
A2919SLBTR-T
Package
1000 pieces per reel
24-pin SOICW with exposed thermal tabs
Absolute Maximum Ratings
Rating
Units
Logic Supply Voltage
Characteristic
Symbol
VCC
Notes
7.0
V
Logic Input Voltage Range
VIN
–0.3 to VCC+0.3
V
Motor Supply Voltage
VBB
45
V
Output Emitter Voltage
VE
1.5
V
Output Current
IOUT
Peak, tw ≤ 20 μs
±1.0
A
Continuous
±750
mA
Output current rating may be limited by duty cycle,
ambient temperature, and heat sinking. Under any
set of conditions, do not exceed the specified peak
current rating or a junction temperature of +150°C.
Package Power Dissipation
PD
See graph
Operating Ambient Temperature
TA
Range S
Maximum Junction Temperature
Storage Temperature
–
–
–20 to 85
ºC
TJ(max)
150
ºC
Tstg
–55 to 150
ºC
5
3
2
1
SUFFIX 'LB', R QJA = 55oC/W
25
50
75
100
TEMPERATURE IN oC
125
24
LOAD SUPPLY
23
OUT 2B
22
SENSE 2
I 12
2
PHASE 2
3
V REF 2
4
21
E2
RC 2
5
20
OUT 2A
GROUND
6
19
GROUND
GROUND
7
GIC SUPPLY
8
RC 1
99
V REF 1
10
PHASE 1
11
I 11
0
1
θ2
2
VBB
4
02
PWM 2
I
RQJT = 6.0oC/W
V CC
18
GROUND
17
OUT 1A
16
E1
15
SENSE 1
14
OUT 1B
13
I 01
1
12
θ1
PWM 1
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
Pin-out Diagram
150
Dwg. PP-047
Dwg. GP-049A
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A2919
Dual Full-Bridge PWM Motor Driver
ELECTRICAL CHARACTERISTICS at TA = +25°C, TJ 150°C, VBB = 45 V, VCC = 4.75 V to 5.25 V,
VREF = 5.0 V (unless otherwise noted).
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Output Drivers (OUTA or OUTB)
Motor Supply Range
VBB
Operating
10
—
45
V
Output Leakage Current
ICEX
VOUT = VBB
—
< 1.0
50
μA
VOUT = 0
—
<-1.0
-50
μA
Output Sustaining Voltage
VCE(sus)
IOUT = ±750 mA, L = 3.0 mH
45 + VF
—
—
V
Output Saturation Voltage
VCE(SAT)
Sink Driver, IOUT = +500 mA
—
0.4
0.6
V
Sink Driver, IOUT = +750 mA
—
1.0
1.2
V
Source Driver, IOUT = -500 mA
—
1.0
1.2
V
Source Driver, IOUT = -750 mA
—
1.3
1.5
V
Clamp Diode Leakage Current
IR
VR = 45 V
—
< 1.0
50
μA
Clamp Diode Forward Voltage
VF
IF = 750 mA
—
1.6
2.0
V
IBB(ON)
Both Bridges ON, No Load
—
20
25
mA
IBB(OFF)
Both Bridges OFF
—
5.0
10
mA
VIN(1)
All inputs
2.4
—
—
V
VIN(0)
All inputs
—
—
0.8
V
IIN(1)
VIN = 2.4 V
—
<1.0
20
μA
VIN = 0.8 V
—
- 3.0
-200
μA
1.0
—
7.5
V
I0 = I1 = 0.8 V, VREF = 1.0 V to 7.5 V
9.5
10
10.5
—
I0 = 2.4 V, I1 = 0.8 V,
13.5
15
16.5
—
20.7
24.4
28.0
—
—
170
—
°C
Driver Supply Current
Control Logic
Input Voltage
Input Current
Reference Voltage Range
Current Limit Threshold
(at trip point)
VREF
VREF / VSENSE
VREF = 1.5 V to 7.5 V
I0 = 0.8 V, I1 = 2.4 V,
VREF = 1.5 V to 7.5 V
Thermal Shutdown Temperature
Total Logic Supply Current
Total Reference Current
Fixed Off-Time
TJ
ICC(ON)
I0 = I1 = 0.8 V, No Load
—
40
50
mA
ICC(OFF)
I0 = I1 = 2.4 V, No Load
—
10
12
mA
140
185
250
μA
—
46
—
μs
IREF1 + IREF2
toff
VREF1 = VREF2 = 7.5 V, I0 = I1 = 2.4 V
RT = 56 k, CT = 820 pF
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A2919
Dual Full-Bridge PWM Motor Driver
APPLICATIONS INFORMATION
PWM CURRENT CONTROL
The A2919 dual bridges are designed to drive both windings
of a bipolar stepper motor. Output current is sensed and
controlled independently in each bridge by an external
sense resistor (RS), internal comparator, and monostable
multivibrator.
When the bridge is turned ON, current increases in the motor
winding and flows through the external sense resistor until
the sense voltage (VS) reaches the level set at the comparator
input:
ITRIP = VREF/10 RS
The comparator then triggers the monostable, which turns off
the source driver of the bridge. The actual load current peak
will be slightly higher than the trip point (especially for lowinductance loads) because of the internal logic and switching
delays. This delay (td) is typically 2 μs. After turn-off, the
motor current decays, circulating through the ground-clamp
diode and sink transistor. The source driver off-time (and
therefore the magnitude of the current decrease) is determined
by the monostable external RC timing components, where
toff = RTCT within the range of 20 kΩ to 100 kΩ and
100 pF to 1000 pF.
The fixed off-time should be short enough to keep the current
chopping above the audible range (< 46 μs) and long enough
to properly regulate the current. Because only slow-decay
current control is available, short off times (< 10 μs) require
additional efforts to ensure proper current regulation. Factors
that can negatively affect the ability to properly regulate the
current when using short off times include: higher motorsupply voltage, light load, and longer than necessary blank
time.
PWM OUTPUT CURRENT WAVE FORM
V P HAS E
+
I OUT
0
–
I T R IP
td
toff
Dwg. WM-003-1A
LOAD CURRENT PATHS
V
BB
When the source driver is re-enabled, the winding current (the
sense voltage) is again allowed to rise to the comparator’s
threshold. This cycle repeats itself, maintaining the average
motor winding current at the desired level.
Loads with high distributed capacitances may cause current
spikes capable of tripping the comparator, resulting in
erroneous current control. An external RCCC time delay should
be used to delay the action of the comparator. Depending on
load type, many applications will not require these external
components (SENSE connected to E).
RS
B R IDG E ON
S OUR C E OF F
ALL OF F
Dwg. E P -006-1
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A2919
Dual Full-Bridge PWM Motor Driver
LOGIC CONTROL OF OUTPUT CURRENT
GENERAL
Two logic level inputs (l0 and I1) allow digital selection of
the motor winding current at 100%, 67%, 41%, or 0% of the
maximum level per the table. The 0% output current condition
turns off all drivers in the bridge and can be used as an output
enable function.
The PHASE input to each bridge determines the direction
motor winding current flows. An internally generated deadtime
(approximately 2 μs) prevents crossover currents that can occur
when switching the PHASE input.
CURRENT-CONTROL TRUTH TABLE
l0
I1
Output Current
L
L
VREF/10 RS = 100% ITRIP
H
L
VREF/15 RS = 67% ITRIP
L
H
VREF/24.4 RS = 41% ITRIP
H
H
0
These logic level inputs greatly enhance the implementation of
μP-controlled drive formats.
During half-step operations, l0 and l1 allow the μP to control the
motor at a constant torque between all positions in an eight-step
sequence. This is accomplished by digitally selecting 100%
drive current when only one phase is on and 67% drive current
when two phases are on. Logic highs on both l0 and l1 turn off all
drivers to allow rapid current decay.
During quarter-step operation, I0 and I1 allow the μP to
control the motor position in a sixteen-step sequence. This is
accomplished by digitally selecting drive current as shown in the
table (for one quadrant of operation). Logic highs on both I0 and
I1 turn off all drivers to allow rapid current decay.
All four drivers in the bridge output can be turned off between
steps (l0 = l1 ž 2.4 V) resulting in a fast current decay through
the internal output clamp and flyback diodes. The fast current
decay is desirable in half-step and high-speed applications. The
PHASE, l0 , and I1 inputs float high.
Varying the reference voltage (VREF) provides continuous control
of the peak load current for micro-stepping applications.
Thermal protection circuitry turns off all drivers when the
junction temperature reaches +170°C. It is only intended
to protect the device from failures due to excessive junction
temperature and should not imply that output short circuits are
permitted. The output drivers are re-enabled when the junction
temperature cools to +145°C.
The A2919 output drivers are optimized for low output
saturation voltages—less than 1.8 V total (source plus sink) at
500 mA. Under normal operating conditions, when combined
with the excellent thermal properties of the batwing package
design, this allows continuous operation of both bridges
simultaneously at 500 mA.
The logic control inputs can also be used to select a reduced
current level (and reduced power dissipation) for ‘hold’
conditions and/or increased current (and available torque) for
start-up conditions.
QUARTER-STEPPING CURRENT CONTROL
Phase 1
Current Level
Phase 2
Current Level
100%
0%
100%
41%
67%
67%
41%
100%
0%
100%
TRUTH TABLE
PHASE
OUTA
OUTB
H
L
H
L
L
H
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
A2919
Dual Full-Bridge PWM Motor Driver
TYPICAL APPLICATION
STEPPER
MOTOR
V
BB
VBB
1
24
2
RC
CC
FROM
μP
3
20
6
19
7
18
8
17
56 kΩ
RT
PWM 2
θ2
θ1
FROM
μP
16
15
V
REF
14
11
12
820 pF
CT
CC
21
5
10
REF
22
2
4
99
V
RC
1
PWM 1
RS
+
RS
23
VCC
820 pF
13
+5 V
C
T
56 kΩ
RT
Dwg. EP-008B1
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
A2919
Dual Full-Bridge PWM Motor Driver
LB Package, 24-pin SOIC
15.40
4º
24
0.27
2.20
10.30
7.50
9.60
A
0.84
1
0.65
PCB Layout Reference View
2
1.27
0.25
16X
SEATING
PLANE
0.10 C
0.41
1.27
C
SEATING PLANE
GAUGE PLANE
2.65 MAX
0.20
All dimensions nominal, not for tooling use
Dimensions in millimeters
Pins 6 and 7, and 18 and 19 internally fused
(Reference JEDEC MS-013 AD)
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
A Terminal #1 mark area
B Reference pad layout (reference IPC SOIC127P1030X265-24M)
All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary
to meet application process requirements and PCB layout tolerances
Copyright ©1994-2008, Allegro MicroSystems, Inc.
The products described here are manufactured under one or more U.S. patents or U.S. patents pending.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the
information being relied upon is current.
Allegro’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the
failure of that life support device or system, or to affect the safety or effectiveness of that device or system.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use;
nor for any infringement of patents or other rights of third parties which may result from its use.
For the latest version of this document, visit our website:
www.allegromicro.com
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
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