A3951: Full-Bridge PWM Motor Driver

Data Sheet
29319.4‡
3951
FULL-BRIDGE PWM MOTOR DRIVER
A3951SB
NC
1
REF/BRAKE
2
RC
3
GROUND
4
VBB
16
LOAD
SUPPLY
15
OUTB
t
c
u
d
y
o
l
r
P On
d
e
e
c
u
it n ren
n
e
f
o
e
c
s rR
i
D o
F
14
GROUND
13
GROUND
12
GROUND
11
SENSE
LOGIC
GROUND
5
LOGIC
SUPPLY
6
PHASE
7
ENABLE
8
Designed for bidirectional pulse-width modulated current control
of inductive loads, the A3951SB and A3951SW are capable of
continuous output currents to ±2 A and operating voltages to 50 V.
Internal fixed off-time PWM current-control circuitry can be used to
regulate the maximum load current to a desired value. The peak load
current limit is set by the user’s selection of an input reference voltage
and external sensing resistor. The fixed off-time pulse duration is set
by a user-selected external RC timing network. Internal circuit
protection includes thermal shutdown with hysteresis, transient
suppression diodes, and crossover-current protection. Special powerup sequencing is not required. The A3951SB and A3951SW are
improved replacements for the UDN2953B and UDN2954W, respectively. For new system designs, the A3952SB/SEB/SLB/SW are
recommended.
With the ENABLE input held low, the PHASE input controls load
current polarity by selecting the appropriate source and sink driver
pair. A user-selectable blanking window prevents false triggering of
the PWM current control circuitry. With the ENABLE input held high,
all output drivers are disabled.
When a logic low is applied to the BRAKE input, the braking
function is enabled. This overrides ENABLE and PHASE to turn off
both source drivers and turn on both sink drivers. The brake function
can be safely used to dynamically brake brush dc motors.
The A3951SB is supplied in a 16-pin dual in-line plastic package
with copper heat-sink contact tabs. The lead configuration enables
easy attachment of a heat sink while fitting a standard printed wiring
board layout. The A3951SW, for higher package power dissipation
requirements, is supplied in a 12-pin single in-line power-tab package.
In either package style, the batwing/power tab is at ground potential
and needs no isolation.
VCC
VBB
10
OUTA
9
LOAD
SUPPLY
Dwg. PP-056-1
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage, VBB ................... 50 V
Output Current, IOUT
(tw ≤ 20 µs) .................................. ±3.5 A
(Continuous) ............................... ±2.0 A
Logic Supply Voltage, VCC .................. 7.0 V
Logic Input Voltage Range,
VIN ........................ -0.3 V to VCC + 0.3 V
Sense Voltage, VSENSE ........................ 1.5 V
Reference Voltage, VREF ....................... VCC
Package Power Dissipation,
PD ....................................... See Graph
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, heat sinking and/or forced
cooling. Under any set of conditions, do not
exceed the specified current rating or a junction
temperature of +150°C.
* Fault conditions that produce excessive junction
temperature will activate device thermal shutdown
circuitry. These conditions can be tolerated but
should be avoided.
FEATURES
■
■
■
■
■
■
■
■
±2 A Continuous Output Current Rating
50 V Output Voltage Rating
Internal PWM Current Control
Internal Transient-Suppression Diodes
Under-Voltage Lockout
Internal Thermal-Shutdown Circuitry
Crossover-Current Protection
Default Brake Current Limit
Always order by complete part number:
Part Number
A3951SB
A3951SW
Package
16-Pin DIP
12-Pin Power-Tab SIP
RθJA
43°C/W
36°C/W
RθJT
6.0°C/W
2.0°C/W
3951
FULL-BRIDGE
PWM MOTOR DRIVER
OUTB
OUTA
VBB
VCC
LOAD
SUPPLY
LOGIC
SUPPLY
FUNCTIONAL BLOCK DIAGRAM
PHASE
ENABLE
REF/ BRAKE
–
+
INPUT LOGIC
UVLO
& TSD
R
SENSE
Q
9R
S
BLANKING
1.5 V
RS
PWM LATCH
VCC
+ –
RC
VTH
R
GROUND
Dwg. FP-036-1
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
10
SUFFIX 'W',
R θJT = 2.0°C/W
8
SUFFIX 'B',
RθJT = 6.0°C/W
6
TRUTH TABLE
BRAKE ENABLE PHASE
4
SUFFIX 'W', R
θJA
θJA
50
H
H
X
Z
Z
Outputs Disabled
H
L
H
H
L
Forward
H
L
L
L
H
Reverse
L
X
X
L
L
Brake, See Note
75
100
TEMPERATURE IN °C
125
150
X = Irrelevant
Z = High Impedance (source and sink both off)
NOTE: Includes internal default Vsense level for over-current protection.
Dwg. GP-032A
2
DESCRIPTION
= 43°C/W
0
25
OUTB
= 38°C/W
2
SUFFIX 'B', R
OUTA
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1994, 2002 Allegro MicroSystems, Inc.
3951
FULL-BRIDGE
PWM MOTOR DRIVER
10
11
12
SENSE
9
NC
8
OUTA
RC
7
ENABLE
6
PHASE
5
LOGIC
SUPPLY
4
REF/ BRAKE
OUTB
3
LOAD
SUPPLY
2
LOAD
SUPPLY
1
GROUND
VCC
VBB
LOGIC
A3951SW
Dwg. PP-058-1
ELECTRICAL CHARACTERISTICS at TA = +25°C, VBB = 50 V, VCC = 5.0 V,
VREF = 2.0 V, VSENSE = 0 V, RC = 20 kΩ/1000 pF to Ground (unless noted otherwise).
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
VCC
–
50
V
Output Drivers
Load Supply Voltage Range
VBB
Operating, IOUT = ±2.0 A, L = 3 mH
Output Leakage Current
ICEX
VOUT = VBB
–
<1.0
50
µA
VOUT = 0 V
–
<-1.0
-50
µA
Source driver, IOUT = -0.5 A
–
0.9
1.2
V
Source driver, IOUT = -1.0 A
–
1.0
1.4
V
Source driver, IOUT = -2.0 A
–
1.2
1.8
V
Sink driver, IOUT = +0.5 A
–
0.9
1.2
V
Sink driver, IOUT = +1.0 A
–
1.0
1.4
V
Sink driver, IOUT = +2.0 A
–
1.3
1.8
V
IF = 0.5 A
–
1.0
1.4
V
IF = 1.0 A
–
1.1
1.6
V
IF = 2.0 A
–
1.4
2.0
V
Output Saturation Voltage
Clamp Diode Forward Voltage
VCE(SAT)
VF
(Source or Sink)
Load Supply Current
IBB(ON)
VENABLE = 0.8 V, VREF = 2.0 V
–
2.9
6.0
mA
(No Load)
IBB(OFF)
VENABLE = VREF = 2.0 V
–
3.1
6.5
mA
VBRAKE = 0.8 V
–
3.1
6.5
mA
IBB(BRAKE)
Continued next page …
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3
3951
FULL-BRIDGE
PWM MOTOR DRIVER
ELECTRICAL CHARACTERISTICS (Continued)
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
4.5
5.0
5.5
V
Control Logic
Logic Supply Voltage Range
VCC
Operating
Logic Input Voltage
VIN(1)
2.0
–
–
V
VIN(0)
–
–
0.8
V
IIN(1)
VIN = 2.0 V
–
<1.0
20
µA
IIN(0)
VIN = 0.8 V
–
<-2.0
-200
µA
Reference Voltage Range
VREF
Operating
2.0
–
VCC
V
Reference Input Current
IREF
2.0 V ≤ VREF ≤ VCC
25
40
55
µA
Logic Input Current
Reference Voltage Divider Ratio
–
VREF = 5 V
9.5
10.0
10.5
–
PWM RC Fixed Off Time
toff
CT = 1000 pF, RT = 20 kΩ
18
20
22
µs
PWM Minimum On Time
ton(min)
CT = 820 pF, RT ≥ 12 kΩ
–
1.7
3.0
µs
CT = 1200 pF, RT ≥ 12 kΩ
–
2.5
3.8
µs
ENABLE on to source driver on
–
2.9
–
µs
ENABLE off to source driver off
–
0.7
–
µs
ENABLE on to sink driver on
–
2.4
–
µs
ENABLE off to sink driver off
–
0.7
–
µs
PHASE change to source driver on
–
2.9
–
µs
PHASE change to source driver off
–
0.7
–
µs
PHASE change to sink driver on
–
2.4
–
µs
PHASE change to sink driver off
–
0.7
–
µs
–
0.8
1.5
µs
TJ
–
165
–
°C
∆TJ
–
15
–
°C
VCC(UVLO)
3.15
3.50
3.85
V
∆VCC(UVLO)
300
400
500
mV
Propagation Delay Time
tpd
tpd(pwm)
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
UVLO Disable Threshold
UVLO Hysteresis
IOUT = ±2.0 A, 50% EIN to 90% EOUT transition:
Comparator trip to sink driver off
Logic Supply Current
ICC(ON)
VENABLE = 0.8 V, VREF = 2.0 V
–
20
30
mA
(No Load)
ICC(OFF)
VENABLE = VREF = 2.0 V
–
12
18
mA
VREF = 0.8 V
–
26
40
mA
ICC(BRAKE)
NOTES: 1. Typical Data is for design information only.
2. Each driver is tested separately.
3. Negative current is defined as coming out of (sourcing) the specified device terminal.
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3951
FULL-BRIDGE
PWM MOTOR DRIVER
FUNCTIONAL DESCRIPTION
INTERNAL PWM CURRENT CONTROL DURING
FORWARD AND REVERSE OPERATION
The A3951SB/SW contain a fixed off-time pulse-width
modulated (PWM) current-control circuit that can be used
to limit the load current to a desired value. The value of
the current limiting (ITRIP) is set by the selection of an
external current sensing resistor (RS) and reference input
voltage (VREF). The internal circuitry compares the
voltage across the external sense resistor to one tenth the
voltage on the REF input terminal, resulting in a function
approximated by
ITRIP = VREF/(10•RS).
In forward or reverse mode the current-control circuitry limits the load current. When the load current
reaches ITRIP, the comparator resets a latch to turn off the
selected sink driver. The load inductance causes the
current to recirculate through the source driver and
flyback diode (two-quadrant operation or slow decay).
See figure 1.
V
BB
RS
DRIVE CURRENT
RECIRCULATION
Dwg. EP-006-9
Figure 1 — Load-Current Paths
The user selects an external resistor (RT) and capacitor (CT) to determine the time period (toff = RT•CT) during
which the drivers remain disabled (see “RC Fixed OFF
Time” below). At the end of the RTCT interval, the drivers
are re-enabled allowing the load current to increase again.
The PWM cycle repeats, maintaining the load current at
the desired value (see figure 2).
www.allegromicro.com
ENABLE
I
TRIP
RC
LOAD
CURRENT
Dwg. WP-015-3
Figure 2 — Load-Current Waveform
INTERNAL PWM CURRENT CONTROL DURING
BRAKE MODE OPERATION
The brake circuit turns off both source drivers and
turns on both sink drivers. For dc motor applications, this
has the effect of shorting the motor’s back-EMF voltage,
resulting in current flow that brakes the motor dynamically.
However, if the back-EMF voltage is large and there is no
PWM current limiting, then the load current can increase to
a value that approaches a locked rotor condition. To limit
the current, when the ITRIP level is reached, the PWM
circuit disables the conducting sink driver. The energy
stored in the motor’s inductance is then discharged into
the load supply causing the motor current to decay.
As in the case of forward/reverse operation, the drivers
are re-enabled after a time given by toff = RT•CT (see “RC
Fixed Off Time” below). Depending on the back-EMF
voltage (proportional to the motor’s decreasing speed), the
load current again may increase to ITRIP. If so, the PWM
cycle will repeat, limiting the load current to the desired
value.
Brake Operation
During braking, the peak current limit defaults internally to a value approximated by
ITRIP = 1.5 V/RS.
In this mode, the value of RS determines the ITRIP value
independent of VREF. This is useful in applications with
differing run and brake currents and no practical method of
varying VREF.
5
3951
FULL-BRIDGE
PWM MOTOR DRIVER
Choosing a small value for RS essentially disables the
current limiting during braking. Therefore, care should be
taken to ensure that the motor’s current does not exceed
the absolute maximum ratings of the device. The braking
current can be measured by using an oscilloscope with a
current probe connected to one of the motor’s leads.
CAUTION: Because the kinetic energy stored in the
motor and load inertia is being converted into current,
which charges the VBB supply bulk capacitance (power
supply output and decoupling capacitance), care must be
taken to ensure the capacitance is sufficient to absorb the
energy without exceeding the voltage rating of any devices
connected to the motor supply.
RC Fixed Off Time
The internal PWM current control circuitry uses a one
shot to control the time the driver remains off. The one
shot time, toff (fixed off time), is determined by the selection
of an external resistor (RT) and capacitor (CT) connected in
parallel from the RC terminal to ground. The fixed off time,
over a range of values of CT = 820 pF to 1500 pF and RT =
12 kΩ to 100 kΩ, is approximated by
toff = RT•CT.
Similarly, when a transition of the PHASE input occurs,
CT is discharged to near ground during the crossover delay
time (the crossover delay time is present to prevent
simultaneous conduction of the source and sink drivers).
After the crossover delay, CT is charged by an internal
current source of approximately 1 mA. The comparator
output remains blanked until the voltage on CT reaches
approximately 3.0 volts.
Similarly, when the device is disabled via the ENABLE
input, CT is discharged to near ground. When the device is
re-enabled, CT is charged by the internal current source.
The comparator output remains blanked until the voltage
on CT reaches approximately 3.0 V.
For most applications, the minimum recommended
value is CT = 820 pF ±5 %. This value ensures that the
blanking time is sufficient to avoid false trips of the comparator under normal operating conditions. For optimal
regulation of the load current, the above value for CT is
recommended and the value of RT can be sized to determine toff. For more information regarding load current
regulation, see below.
When the PWM latch is reset by the current comparator, the voltage on the RC terminal will begin to decay from
approximately 3 volts. When the voltage on the RC
terminal reaches approximately 1.1 volts, the PWM latch is
set, thereby re-enabling the driver.
LOAD CURRENT REGULATION WITH THE INTERNAL
PWM CURRENT-CONTROL CIRCUITRY
RC Blanking
Applications requiring a broader or full range (≈0% to
100%) should utilize the A3952S–, which are recommended for the improvements they bring to new designs.
In addition to determining the fixed off time of the
PWM control circuit, the CT component sets the comparator blanking time. This function blanks the output of the
comparator when the outputs are switched by the internal
current control circuitry (or by the PHASE, BRAKE, or
ENABLE inputs). The comparator output is blanked to
prevent false over-current detections due to reverse
recovery currents of the clamp diodes, and/or switching
transients related to distributed capacitance in the load.
During internal PWM operation, at the end of the off
time, the comparator’s output is blanked and CT begins to
be charged from approximately 1.1 V by an internal current
source of approximately 1 mA. The comparator output
remains blanked until the voltage on CT reaches approximately 3.0 volts.
6
During operation, the A3951S– have a lower limit to
the range of PWM current control. This directly relates to
the limitations imposed by the VREF input (2.0 V, minimum).
LOAD CURRENT REGULATION WITH EXTERNAL
PWM OF THE PHASE OR ENABLE INPUTS
The PHASE or ENABLE inputs can be pulse-width
modulated to regulate load current. Typical propagation
delays from the PHASE and ENABLE inputs to transitions
of the power outputs are specified in the electrical characteristics table. If the normal PWM current control is used,
then the comparator blanking function is active during
phase and enable transitions. This eliminates false
tripping of the over-current comparator caused by switching transients (see “RC Blanking” above).
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3951
FULL-BRIDGE
PWM MOTOR DRIVER
V
BB
between the duty cycle on the phase input and the average voltage applied to the motor is more linear than in the
case of ENABLE PWM control (which produces a discontinuous current at low current levels). See also, “DC Motor
Applications” below.
MISCELLANEOUS INFORMATION
RS
DRIVE CURRENT
RECIRCULATION
Dwg. EP-006-10
Figure 3 — Load-Current Paths
ENABLE Pulse-Width Modulation
Toggling the ENABLE input turns on and off the
selected source and sink drivers; the load inductance
causes the current to flow from ground to the load supply
via the ground clamp and flyback diodes (four-quadrant
operation or fast decay). See figure 3. When the device is
enabled, the internal current-control circuitry will be active
and can be used to limit the load current in the normal
internal PWM slow-decay or two-quadrant mode of operation.
An internally generated dead time prevents crossover
currents that can occur when switching phase or braking.
Thermal protection circuitry turns off all drivers should
the junction temperature reach 165°C (typical). This is
intended only to protect the device from failures due to
excessive junction temperatures and should not imply that
output short circuits are permitted. The hysteresis of the
thermal shutdown circuit is approximately 15°C.
If the internal current-control circuitry is not used; the
VREF terminal should be connected to VCC, the SENSE
terminal should be connected to ground, and the RC
terminal should be left floating (no connection).
An internal under-voltage lockout circuit prevents
simultaneous conduction of the outputs when the device is
powered up or powered down.
ENABLE
APPLICATIONS NOTES
Current Sensing
The actual peak load current (IOUTP) will be greater
than the calculated value of ITRIP due to delays in the turn
off of the drivers. The amount of overshoot can be approximated as
I TRIP
LOAD
CURRENT
IOUTP ≈
Dwg. WP-015-4
Figure 4 — ENABLE PWM Load-Current Waveform
PHASE Pulse-Width Modulation
Toggling the PHASE terminal determines/controls
which sink/source pair is enabled, producing a load current
that varies with the duty cycle and remains continuous at
all times. This can have added benefits in bidirectional
brush dc servo motor applications as the transfer function
www.allegromicro.com
(VBB – ((ITRIP • RLOAD) + VBEMF)) • tpd(pwm)
LLOAD
where VBB is the load/motor supply voltage, VBEMF is the
back-EMF voltage of the load, RLOAD and LLOAD are the
resistance and inductance of the load respectively, and
tpd(pwm) is the propagation delay as specified in the electrical
characteristics table.
The reference terminal has an equivalent input resistance of 50 kΩ ±30%. This should be taken into account
when determining the impedance of the external circuit
that sets the reference voltage value.
7
3951
FULL-BRIDGE
PWM MOTOR DRIVER
To minimize current-sensing inaccuracies caused by
ground trace I•R drops, the current-sensing resistor should
have a separate return to the ground terminal of the
device. For low-value sense resistors, the I•R drops in the
PCB can be significant and should be taken into account.
The use of sockets should be avoided as contact resistance can cause variations in the effective value of RS.
Larger values of RS reduce the aforementioned effects
but can result in excessive heating and power loss in the
sense resistor. The selected value of RS must not result in
the SENSE terminal absolute maximum voltage rating
being exceeded. The recommended value of RS is in the
range of
RS = (0.375 to 1.125)/ITRIP.
Thermal Considerations
For the most reliable operation, it is recommended that
the maximum junction temperature be kept as low as
practical, preferably below 125°C. The junction temperature can be measured by attaching a thermocouple to the
power tab/batwing of the device and measuring the tab
temperature, TT. The junction temperature then can be
approximated as
TJ ≈ TT + (2 • VF • IOUT • RΘJT)
where VF is the clamp diode forward voltage and can be
determined from the electrical specification table for the
given level of IOUT. The value for RΘJT is given in the
package thermal resistance table for the appropriate
package.
The power dissipation of the batwing package can be
improved by approximately 20% by adding a section of
printed circuit board copper (typically 6 to 18 square
centimeters) connected to the batwing terminals of the
device.
The thermal performance in applications with high load
currents and/or high duty cycles can be improved by
adding external diodes in parallel with the internal diodes.
In internal PWM applications, only the two top-side
(flyback) diodes need be added. For external PHASE or
ENABLE input PWM applications, four external diodes
should be added for maximum junction temperature
reduction.
PCB Layout
The load supply terminal, VBB, should be decoupled
(>47 µF electrolytic and 0.1 µF ceramic capacitors are
8
recommended) as close to the device as is physically
practical. To minimize the effect of system ground I•R
drops on the logic and reference input signals, the system
ground should have a low-resistance return to the load
supply voltage.
See also “Current Sensing” and “Thermal Considerations” above.
Fixed Off-Time Selection
With increasing values of toff, switching losses decrease, low-level load-current regulation improves, EMI is
reduced, the PWM frequency will decrease, and ripple
current will increase. The value of toff can be chosen for
optimization of these parameters. For applications where
audible noise is a concern, typical values of toff are chosen
to be in the range of 15 to 35 µs.
DC Motor Applications
In closed-loop systems, the speed of a dc motor can
be controlled by PWM of the PHASE or ENABLE inputs, or
by varying the REF input voltage (VREF). In digital systems
(microprocessor controlled), PWM of the PHASE or
ENABLE input is used typically thus avoiding the need to
generate a variable analog voltage reference. In this case,
a dc voltage on the REF input is used typically to limit the
maximum load current.
In dc servo applications that require accurate positioning at low or zero speed, PWM of the PHASE input is
selected typically. This simplifies the servo-control loop
because the transfer function between the duty cycle on
the PHASE input and the average voltage applied to the
motor is more linear than in the case of ENABLE PWM
control (which produces a discontinuous current at lowcurrent levels).
With bidirectional dc servo motors, the PHASE terminal can be used for mechanical direction control. Similar
to when braking the motor dynamically, abrupt changes in
the direction of a rotating motor produce a current generated by the back EMF. The current generated will depend
on the mode of operation. If the internal two-quadrant
slow-decay PWM current-control circuitry is used, the
maximum load current generated can be approximated by
ILOAD = VBEMF/RLOAD where VBEMF is proportional to the
motor’s speed. If external four-quadrant fast-decay
ENABLE PWM current-control is used, then the maximum
load current generated can be approximated by
ILOAD = (VBEMF + VBB)/RLOAD
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3951
FULL-BRIDGE
PWM MOTOR DRIVER
V
+5 V
See also, the section on brake operation under
“Functional Description”, above.
25 kΩ
820 pF
BRAKE
1
16
VBB
2
15
3
14
4
+
CAUTION: When the direction of the motor is changed
abruptly, the kinetic energy stored in the motor and load
inertia will be converted into current that charges the VBB
supply bulk capacitance (power supply output and
decoupling capacitance). Care must be taken to ensure
the capacitance is sufficient to absorb the energy without
exceeding the voltage rating of any devices connected to
the motor supply.
BB
47 µF
13
LOGIC
5
6
12
VCC
11
7
PHASE
ENABLE
0.5 Ω
For both cases, care must be taken to ensure that the
maximum current ratings of the device are not exceeded.
The load current will limit at a value
ILOAD = VREF/(10•RS).
10
VBB
8
9
Stepper Motor Applications
Dwg. EP-047-1
The A3951SB and A3951SW may be used for
bidrectional control of bipolar stepper motors with continuous output currents to 2 A and peak start-up currents as
high as 3.5 A.
Typical DC Servo Motor Application
VBB
+5 V
9
REF2
0.5 Ω
8
PHASE1
6
7
6
7
V
5
VCC
0.5 Ω
ENABLE 1
4
LOGIC
5
V
REF1
ENABLE 2
820 pF
10
11
2
25 kΩ
4
LOGIC
9
3
PHASE2
VCC
8
VBB
VBB
3
10
2
11
12
47 µF
1
+
1
12
25 kΩ
820 pF
Dwg. EP-048-1
Typical Bipolar Stepper Motor Application
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9
3951
FULL-BRIDGE
PWM MOTOR DRIVER
A3951SB
Dimensions in Inches
(controlling dimensions)
16
0.020
0.008
9
NOTE 4
0.430
MAX
0.280
0.240
0.300
BSC
1
0.070
0.045
0.100
0.775
0.735
8
0.005
BSC
MIN
0.210
MAX
0.015
0.150
0.115
MIN
0.022
0.014
Dwg. MA-001-17A in
Dimensions in Millimeters
(for reference only)
16
0.508
0.204
9
NOTE 4
10.92
MAX
7.11
6.10
7.62
BSC
1
1.77
1.15
2.54
19.68
18.67
8
0.13
BSC
MIN
5.33
MAX
0.39
3.81
2.93
MIN
0.558
0.356
Dwg. MA-001-17A mm
NOTES: 1. Leads 1, 8, 9, and 16 may be half leads at vendor’s option.
2. Lead thickness is measured at seating plane or below.
3. Lead spacing tolerance is non-cumulative.
4. Webbed lead frame. Leads indicated are internally one piece.
5. Exact body and lead configuration at vendor’s option within limits shown.
10
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3951
FULL-BRIDGE
PWM MOTOR DRIVER
A3951SW
Dimensions in Inches
(controlling dimensions)
0.180
1.260
1.240
0.020
MAX
0.775
0.765
0.245
0.225
0.055
0.045
0.155
ø
0.145
0.140
0.570
0.540
0.365
INDEX
AREA
0.065
0.035
0.135
0.100
0.290 MIN
1
0.030
0.020
12
0.023
0.018
0.100
±0.010
0.080
0.070
Dwg. MP-007 in
Dimensions in Millimeters
(for reference only)
32.00
31.49
0.51
4.57
MAX
19.69
19.45
6.22
5.71
1.40
1.14
3.94
ø
3.68
3.56
9.27
INDEX
AREA
1.65
0.89
3.43
2.54
7.36 MIN
1
0.76
0.51
12
2.54
±0.254
NOTES: 1. Lead thickness is measured at seating plane or below.
2. Lead spacing tolerance is non-cumulative.
3. Exact body and lead configuration at vendor’s option within limits shown.
4. Lead gauge plane is 0.030” (0.762 mm) below seating plane.
www.allegromicro.com
14.48
13.71
0.59
0.45
2.03
1.77
Dwg. MP-007 mm
11
3951
FULL-BRIDGE
PWM MOTOR DRIVER
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 products are not authorized for use as critical components
in life-support devices or systems without express written approval.
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.
12
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
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