Allegro A3953SB-T Full-bridge pwm motor driver Datasheet

Data Sheet
29319.8e
3953
FULL-BRIDGE PWM MOTOR DRIVER
16
LOAD
SUPPLY
2
15
OUTB
RC
3
14
MODE
GROUND
4
13
GROUND
12
GROUND
11
SENSE
BRAKE
1
REF
VBB
LOGIC
GROUND
5
LOGIC
SUPPLY
6
PHASE
7
ENABLE
8
VCC
VBB
10
OUTA
9
LOAD
SUPPLY
Dwg. PP-056
Note the A3953SB (DIP) and the A3953SLB
(SOIC) are electrically identical and share a
common terminal number assignment.
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage, VBB . . . . . . . . . . 50 V
Output Current, IOUT
(Continuous) . . . . . . . . . . . . . . ±1.3 A*
Logic Supply Voltage, VCC . . . . . . . . . 7.0 V
Logic/Reference Input Voltage Range,
VIN . . . . . . . . . . . -0.3 V to VCC + 0.3 V
Sense Voltage, VSENSE
(VCC = 5.0 V) . . . . . . . . . . . . . . . . 1.0 V
(VCC = 3.3 V) . . . . . . . . . . . . . . . . 0.4 V
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, and heat sinking.
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 the device’s thermal
shutdown circuitry. These conditions can be
tolerated but should be avoided.
Designed for bidirectional pulse-width modulated (PWM) current control
of inductive loads, the A3953S— is capable of continuous output currents to
±1.3 A and operating voltages to 50 V. Internal fixed off-time PWM currentcontrol 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 power-up sequencing is not
required.
With the ENABLE input held low, the PHASE input controls load current
polarity by selecting the appropriate source and sink driver pair. The MODE
input determines whether the PWM current-control circuitry operates in a slow
current-decay mode (only the selected source driver switching) or in a fast
current-decay mode (selected source and sink switching). 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.
A sleep mode is provided to reduce power consumption.
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 used to dynamically
brake brush dc motors.
The A3953S— is supplied in a choice of two power packages; a 16-pin
dual-in-line plastic package with copper heat-sink tabs, and a 16-pin plastic
SOIC with copper heat-sink tabs. For both package styles, the power tab is at
ground potential and needs no electrical isolation. Each package type is
available in a lead (Pb) free version (100% matte tin plated leadframe).
FEATURES
■
■
■
■
■
■
■
±1.3 A Continuous Output Current
50 V Output Voltage Rating
3 V to 5.5 V Logic Supply Voltage
Internal PWM Current Control
Saturated Sink Drivers (Below 1 A)
Fast and Slow Current-Decay Modes
Automotive Capable
■ Sleep (Low Current Consumption) Mode
■ Internal TransientSuppression Diodes
■ Internal ThermalShutdown Circuitry
■ Crossover-Current and
UVLO Protection
RθJT
RθJA
Package
Packing
(°C/W) (°C/W)
A3953SB-T
Yes
43
6
16-Pin DIP
25 per Tube
A3953SLB-T
Yes
43
6
16-Lead SOIC 47 per Tube
A3953SLBTR-T
Yes
67
6
16-Lead SOIC 1000 per reel
*Pb-based variants are being phased out of the product line. The variants cited in this
footnote are in production but have been determined to be LAST TIME BUY. This
classification indicates that sale of this device is currently restricted to existing
customer applications. The variants should not be purchased for new design
applications because obsolescence in the near future is probable. Samples are no
longer available. Status change: October 31, 2006. Deadline for receipt of LAST TIME
BUY orders: April 27, 2007. These variants include: A3953SB, A3953SLB, and
A3953SLBTR.
Part Number
Pb-free*
3953
FULL-BRIDGE
PWM MOTOR DRIVER
6
VCC
10
15
LOAD
SUPPLY
OUTA
9
OUTB
LOGIC
SUPPLY
LOAD
SUPPLY
FUNCTIONAL BLOCK DIAGRAM
16
SLEEP &
STANDBY MODES
MODE 14
VBB
7
BRAKE
1
INPUT LOGIC
8
PWM LATCH
R
11
–
ENABLE
UVLO
& TSD
+
PHASE
SENSE
Q
S
BLANKING
GROUND
VCC
4
RS
RC
3
5
12
+ –
2
REF
RT
CT
13
GROUND
VTH
Dwg. FP-036-2A
TRUTH TABLE
BRAKE
ENABLE
PHASE
MODE
OUTA
OUTB
DESCRIPTION
H
H
X
H
Off
Off
Sleep Mode
H
H
X
L
Off
Off
Standby
H
L
H
H
H
L
Forward, Fast Current-Decay Mode
H
L
H
L
H
L
Forward, Slow Current-Decay Mode
H
L
L
H
L
H
Reverse, Fast Current-Decay Mode
H
L
L
L
L
H
Reverse, Slow Current-Decay Mode
L
X
X
H
L
L
Brake, Fast Current-Decay Mode
L
X
X
L
L
L
Brake, No Current Control
X = Irrelevant
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1995, 2000, 2005 Allegro MicroSystems, Inc.
ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS
3953
FULL-BRIDGE
PWM MOTOR DRIVER
5
RθJT = 6.0°C/W
4
3
SUFFIX 'B', R θJA = 43°C/W
2
1
SUFFIX 'LB', R θJA = 63°C/W
0
25
50
75
100
TEMPERATURE IN °C
125
150
Dwg. GP-049-2A
ELECTRICAL CHARACTERISTICS at TJ = 25˚C, VBB = 5 V to 50 V, VCC = 3.0 V to 5.5 V
(unless otherwise noted.)
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
VCC
—
50
V
Power Outputs
Load Supply Voltage Range
VBB
Operating, IOUT = ±1.3 A, L = 3 mH
Output Leakage Current
ICEX
VOUT = VBB
—
<1.0
50
µA
VOUT = 0 V
—
<-1.0
-50
µA
ISO
ISENSE - IOUT1, IOUT = 850 mA,
VSENSE = 0 V, VCC = 5 V
22
33
38
mA
VCE(SAT)
VSENSE = 0.4 V, VCC = 3.0 V:
Sense Current Offset
Output Saturation Voltage
BRAKE = H
Source Driver, IOUT = -0.85 A
—
1.0
1.1
V
(Forward/Reverse Mode)
Source Driver, IOUT = -1.3 A
—
1.7
1.9
V
Sink Driver, IOUT = 0.85 A
—
0.4
0.5
V
Sink Driver, IOUT = 1.3 A
—
1.1
1.3
V
Output Saturation Voltage
VCE(SAT)
VSENSE = 0.4 V, VCC = 3.0 V:
BRAKE = L
Sink Driver, IOUT = 0.85 A
—
1.0
1.2
V
(Brake Mode)
Sink Driver, IOUT = 1.3 A
—
1.3
1.5
V
IF = 0.85 A
—
1.2
1.4
V
IF = 1.3 A
—
1.4
1.6
V
Clamp Diode Forward Voltage
(Sink or Source)
VF
Continued next page…
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3
3953
FULL-BRIDGE
PWM MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TJ = 25˚C, VBB = 5 V to 50 V, VCC = 3.0 V to 5.5 V
(unless otherwise noted.)
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
CT = 680 pF, RT= 30 kΩ, VCC = 3.3 V
18.3
20.4
22.5
µs
Comparator Trip to Source Off,
IOUT = 25 mA
Comparator Trip to Source Off,
IOUT = 1.3 A
—
1.0
1.5
µs
—
1.8
2.6
µs
IRC Charge On to Source On,
IOUT = 25 mA
IRC Charge On to Source On,
IOUT = 1.3 A
—
0.4
0.7
µs
—
0.55
0.85
µs
VCC = 3.3 V, RT ≥ 12 kΩ, CT = 680 pF
0.8
1.4
1.9
µs
VCC = 5.0 V, RT ≥ 12 kΩ, CT = 470 pF
0.8
1.6
2.0
µs
ENABLE On to Source On
—
1.0
—
µs
ENABLE Off to Source Off
—
1.0
—
µs
ENABLE On to Sink On
—
1.0
—
µs
ENABLE Off to Sink Off (MODE = L)
—
0.8
—
µs
PHASE Change to Sink On
—
2.4
—
µs
PHASE Change to Sink Off
—
0.8
—
µs
PHASE Change to Source On
—
2.0
—
µs
PHASE Change to Source Off
—
1.7
—
µs
1 kΩ Load to 25 V, VBB = 50 V
0.3
1.5
3.0
µs
IOUT = 1.3 A
70
—
—
kHz
AC Timing
PWM RC Fixed Off-time
PWM Turn-Off Time
PWM Turn-On Time
PWM Minimum On Time
Propagation Delay Times
Crossover Dead Time
Maximum PWM Frequency
tOFF RC
tPWM(OFF)
tPWM(ON)
tON(min)
tpd
tCODT
fPWM(max)
IOUT = ±1.3 A, 50% to 90%:
Continued next page…
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3953
FULL-BRIDGE
PWM MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TJ = 25˚C, VBB = 5 V to 50 V, VCC = 3.0 V to 5.5 V
(unless otherwise noted. )
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
TJ
—
165
—
°C
∆TJ
—
8.0
—
°C
UVLO Enable Threshold
2.5
2.75
3.0
V
UVLO Hysteresis
0.12
0.17
0.25
V
Control Circuitry
Thermal Shutdown Temp.
Thermal Shutdown Hysteresis
Logic Supply Current
ICC(ON)
VENABLE = 0.8 V, VBRAKE = 2.0 V
—
42
50
mA
ICC(OFF)
VENABLE = 2.0 V, VMODE = 0.8 V
—
12
15
mA
ICC(Brake)
VBRAKE = 0.8 V
—
42
50
mA
ICC(Sleep)
VENABLE = VMODE = VBRAKE = 2.0 V
—
500
800
µA
Motor Supply Current
IBB(ON)
VENABLE = 0.8 V
—
2.5
4.0
mA
(No Load)
IBB(OFF)
VENABLE = 2.0 V, VMODE = 0.8 V
—
1.0
50
µA
IBB(Brake)
VBRAKE = 0.8 V
—
1.0
50
µA
IBB(Sleep)
VENABLE = VMODE = 2.0 V
—
1.0
50
µA
Operating
3.0
5.0
5.5
V
Logic Supply Voltage Range
VCC
Logic Input Voltage
VIN(1)
2.0
—
—
V
VIN(0)
—
—
0.8
V
Logic Input Current
VSENSE Voltage Range
IIN(1)
VIN = 2.0 V
—
<1.0
20
µA
IIN(0)
VIN = 0.8 V
—
<-2.0
-200
µA
VSENSE(3.3)
VCC = 3.0 V to 3.6 V
0
—
0.4
V
VSENSE(5.0)
VCC = 4.5 V to 5.5 V
0
—
1.0
V
Reference Input Current
IREF
VREF = 0 V to 1 V
—
—
±5.0
µA
Comparator Input Offset Volt.
VIO
VREF = 0 V
—
±2.0
±5.0
mV
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5
3953
FULL-BRIDGE
PWM MOTOR DRIVER
FUNCTIONAL DESCRIPTION
Internal PWM Current Control During Forward and
Reverse Operation. The A3953S— contains a fixed offtime pulse-width modulated (PWM) current-control circuit
that can be used to limit the load current to a desired
value. The peak 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 the voltage on the reference input terminal
(REF) resulting in a transconductance function approximated by:
VREF
ITRIP ≈
– ISO
RS
The user selects an external resistor (RT) and capacitor (CT) to determine the time period (tOFF = RT x CT)
during which the drivers remain disabled (see “RC Fixed
Off-Time” below). At the end of the RC interval, the
drivers are enabled allowing the load current to increase
again. The PWM cycle repeats, maintaining the peak
load current at the desired value (see figure 2).
Figure 2
Fast and Slow Current-Decay Waveforms
ENABLE
MODE
where ISO is the offset due to base drive current.
I TRIP
RC
In forward or reverse mode the current-control circuitry limits the load current as follows: when the load
current reaches ITRIP, the comparator resets a latch that
turns off the selected source driver or selected sink and
source driver pair depending on whether the device is
operating in slow or fast current-decay mode, respectively.
In slow current-decay mode, the selected source
driver is disabled; the load inductance causes the current
to recirculate through the sink driver and ground clamp
diode. In fast current-decay mode, the selected sink and
source driver pair are disabled; the load inductance
causes the current to flow from ground to the load supply
via the ground clamp and flyback diodes.
Figure 1 — Load-Current Paths
V
BB
DRIVE CURRENT
LOAD
CURRENT
RC
Dwg. WP-015-1
INTERNAL PWM CURRENT CONTROL
DURING BRAKE-MODE OPERATION
Brake Operation - MODE Input High. 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 dynamically brakes the motor. If the back-EMF
voltage is large, and there is no PWM current limiting, the
load current can increase to a value that approaches that
of a locked rotor condition. To limit the current, when the
ITRIP level is reached, the PWM circuit disables the
conducting sink drivers. The energy stored in the motor’s
inductance is discharged into the load supply causing the
motor current to decay.
RECIRCULATION (SLOW-DECAY MODE)
RECIRCULATION (FAST-DECAY MODE)
RS
As in the case of forward/reverse operation, the
drivers are enabled after a time given by tOFF = RT x 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 peak load current
to the desired value.
Dwg. EP-006-13A
6
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3953
FULL-BRIDGE
PWM MOTOR DRIVER
During braking, when the MODE input is high, the
peak current limit can be approximated by:
ITRIP BRAKE MH
≈
VREF
RS
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.
Brake Operation - MODE Input Low. During braking,
with the MODE input low, the internal current-control
circuitry is disabled. Therefore, care should be taken to
ensure that the motor’s current does not exceed the
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, or if the back-EMF
voltage of the motor is known, approximated by:
IPEAK BRAKE ML ≈
VBEMF – 1V
RLOAD
RC Fixed Off-Time. The internal PWM current-control
circuitry uses a one shot to control the time the driver(s)
remain(s) 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
timing terminal to ground. The fixed off-time, over a range
of values of CT = 470 pF to 1500 pF and RT = 12 kΩ to
100 kΩ, is approximated by:
tOFF ≈ RT x CT
The operation of the circuit is as follows: when the
PWM latch is reset by the current comparator, the voltage
on the RC terminal will begin to decay from approximately
0.60VCC. When the voltage on the RC terminal reaches
approximately 0.22VCC, the PWM latch is set, thereby
enabling the driver(s).
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RC Blanking. 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 tOFF
time, the comparator’s output is blanked and CT begins to
be charged from approximately 0.22VCC by an internal
current source of approximately 1 mA. The comparator
output remains blanked until the voltage on CT reaches
approximately 0.60VCC.
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 0.60VCC.
When the device is disabled, via the ENABLE input,
CT is discharged to near ground. When the device is reenabled, CT is charged by an internal current source of
approximately 1 mA. The comparator output remains
blanked until the voltage on CT reaches approximately
0.60VCC.
For 3.3 V operation, the minimum recommended
value for CT is 680 pF ± 5 %. For 5.0 V operation, the
minimum recommended value for CT is 470 pF ± 5%.
These values ensure 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 values for CT are recommended and the value of
RT can be sized to determine tOFF. For more information
regarding load current regulation, see below.
7
3953
FULL-BRIDGE
PWM MOTOR DRIVER
LOAD CURRENT REGULATION
WITH INTERNAL PWM
CURRENT-CONTROL CIRCUITRY
When the device is operating in slow current-decay
mode, there is a limit to the lowest level that the PWM
current-control circuitry can regulate load current. The
limitation is the minimum duty cycle, which is a function of
the user-selected value of tOFF and the minimum on-time
pulse tON(min) max that occurs each time the PWM latch is
reset. If the motor is not rotating (as in the case of a
stepper motor in hold/detent mode, a brush dc motor when
stalled, or at startup), the worst case value of current
regulation can be approximated by:
PWM of the PHASE and ENABLE Inputs. The PHASE
and 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 internal PWM current control is used, 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).
Enable PWM. With the MODE input low, toggling the
ENABLE input turns on and off the selected source and
sink drivers. The corresponding pair of flyback and
ground-clamp diodes conduct after the drivers are
[(VBB – VSAT(source+sink)) x tON(min)max] – (1.05(VSAT(sink) + VF) x tOFF) disabled, resulting in fast current decay. When
IAVE ≈
the device is enabled the internal current-control
1.05 x (tON(min)max + tOFF) x RLOAD
circuitry will be active and can be used to limit the
where tOFF = RT x CT, RLOAD is the series resistance of the
load current in a slow current-decay mode.
load, VBB is the motor supply voltage and t ON(min)max is
For applications that PWM the ENABLE input and
specified in the electrical characteristics table. When the
desire the internal current-limiting circuit to function in the
motor is rotating, the back EMF generated will influence
fast decay mode, the ENABLE input signal should be
the above relationship. For brush dc motor applications,
inverted and connected to the MODE input. This prevents
the current regulation is improved. For stepper motor
the device from being switched into sleep mode when the
applications, when the motor is rotating, the effect is more
ENABLE input is low.
complex. A discussion of this subject is included in the
section on stepper motors below.
Phase PWM. Toggling the PHASE terminal selects which
sink/source pair is enabled, producing a load current that
The following procedure can be used to evaluate the
varies with the duty cycle and remains continuous at all
worst-case slow current-decay internal PWM load current
times. This can have added benefits in bidirectional brush
regulation in the system:
dc servo motor applications as the transfer function
Set VREF to 0 volts. With the load connected and the
between the duty cycle on the PHASE input and the
PWM current control operating in slow current-decay
average voltage applied to the motor is more linear than in
mode, use an oscilloscope to measure the time the output
the case of ENABLE PWM control (which produces a
is low (sink on) for the output that is chopping. This is the
discontinuous current at low current levels). For more
typical minimum on time (tON(min) typ) for the device. The
information see “DC Motor Applications” below.
CT then should be increased until the measured value of
Synchronous Fixed-Frequency PWM. The internal
tON(min) is equal to tON(min) max as specified in the electrical
PWM current-control circuitry of multiple A3953S—
characteristics table. When the new value of CT has been
devices can be synchronized by using the simple circuit
set, the value of RT should be decreased so the value for
shown in figure 3. A 555 IC can be used to generate the
tOFF = RT x CT (with the artificially increased value of CT) is
reset pulse/blanking signal (t1) for the device and the
equal to the nominal design value. The worst-case loadperiod of the PWM cycle (t2). The value of t1 should be a
current regulation then can be measured in the system
minimum of 1.5 ms. When used in this configuration, the
under operating conditions.
RT and CT components should be omitted. The PHASE
and ENABLE inputs should not be PWM with this circuit
configuration due to the absence of a blanking function
synchronous with their transitions.
8
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3953
FULL-BRIDGE
PWM MOTOR DRIVER
Figure 3
Synchronous Fixed-Frequency Control Circuit
To minimize current-sensing inaccuracies caused by
ground trace I x 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 x R drops
in the printed wiring board can be significant and should
be taken into account. The use of sockets should be
avoided as their contact resistance can cause variations in
the effective value of RS.
20 kΩ
t
100 kΩ
V CC
2
RC 1
1N4001
2N2222
t
RC N
1
Dwg. EP-060
Miscellaneous Information. A logic high applied to both
the ENABLE and MODE terminals puts the device into a
sleep mode to minimize current consumption when not in
use.
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.
APPLICATION NOTES
Current Sensing. The actual peak load current (IPEAK)
will be above the calculated value of ITRIP due to delays in
the turn off of the drivers. The amount of overshoot can
be approximated by:
IOS ≈
(VBB – [(ITRIP x RLOAD) + VBEMF]) x tPWM(OFF)
LLOAD
where VBB is the motor supply voltage, VBEMF is the backEMF voltage of the load, RLOAD and LLOAD are the resistance and inductance of the load respectively, and
tPWM(OFF) is specified in the electrical characteristics table.
The reference terminal has a maximum input bias
current of ±5 µA. This current should be taken into
account when determining the impedance of the external
circuit that sets the reference voltage value.
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Generally, 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
should not cause the absolute maximum voltage rating of
1.0 V (0.4 V for VCC = 3.3 V operation), for the SENSE
terminal, to be exceeded.
The current-sensing comparator functions down to
ground allowing the device to be used in microstepping,
sinusoidal, and other varying current-profile applications.
Thermal Considerations. For reliable operation it is
recommended that the maximum junction temperature be
kept below 110°C to 125°C. The junction temperature can
be measured best by attaching a thermocouple to the
power tab/batwing of the device and measuring the tab
temperature, TTAB. The junction temperature can then be
approximated by using the formula:
TJ ≈ TTAB + (ILOAD x 2 x VF x RθJT)
where VF may be chosen from the electrical specification
table for the given level of ILOAD. The value for RθJT is
given in the package thermal resistance table for the
appropriate package.
The power dissipation of the batwing packages can be
improved by 20% to 30% 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 that run at
high load currents and/or high duty cycles can be improved by adding external diodes in parallel with the
internal diodes. In internal PWM slow-decay applications,
only the two ground clamp diodes need be added. For
internal fast-decay PWM, or external PHASE or ENABLE
input PWM applications, all four external diodes should be
added for maximum junction temperature reduction.
PCB Layout. The load supply terminal, VBB, should be
decoupled with an electrolytic capacitor (>47 µF is recom-
9
3953
FULL-BRIDGE
PWM MOTOR DRIVER
mended) placed as close to the device as is physically
practical. To minimize the effect of system ground I x R
drops on the logic and reference input signals, the system
ground should have a low-resistance return to the motor
supply voltage.
See also “Current Sensing” and “Thermal Considerations” above.
Fixed Off-Time Selection. With increasing values of tOFF,
switching losses will decrease, low-level load-current
regulation will improve, EMI will be 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 µs to 35 µs.
Stepper Motor Applications. The MODE terminal can
be used to optimize the performance of the device in
microstepping/sinusoidal stepper-motor drive applications.
When the load current is increasing, slow decay mode is
used to limit the switching losses in the device and iron
losses in the motor. This also improves the maximum rate
at which the load current can increase (as compared to
fast decay) due to the slow rate of decay during tOFF.
When the load current is decreasing, fast-decay mode is
used to regulate the load current to the desired level. This
prevents tailing of the current profile caused by the backEMF voltage of the stepper motor.
In stepper-motor applications applying a constant
current to the load, slow-decay mode PWM is typically
used to limit the switching losses in the device and iron
losses in the motor.
the motor is more linear than in the case of ENABLE
PWM control (which produces a discontinuous current at
low current 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 produces a
current generated by the back-EMF. The current generated will depend on the mode of operation. If the internal
current control circuitry is not being used, then the maximum load current generated can be approximated by
ILOAD = (VBEMF + VBB)/RLOAD where VBEMF is proportional to
the motor’s speed. If the internal slow current-decay
control circuitry is used, then the maximum load current
generated can be approximated by ILOAD = VBEMF/RLOAD.
For both cases care must be taken to ensure that the
maximum ratings of the device are not exceeded. If the
internal fast current-decay control circuitry is used, then
the load current will regulate to a value given by:
ILOAD = VREF/RS.
CAUTION: In fast current-decay mode, 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 that the capacitance is sufficient to absorb
the energy without exceeding the voltage rating of any
devices connected to the motor supply.
See also “Brake Operation” above.
Figure 4 — Typical Application
In dc servo applications, which 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
10
VBB
+5 V
REF
2
15
3
14
VBB
4
6
ENABLE
47 µF
MODE
13
LOGIC
12
5
PHASE
16
11
VCC
10
7
8
0.5 Ω
30 kΩ
1
470 pF
BRAKE
+
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 reference
input voltage (REF). 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.
VBB
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
9
Dwg. EP-047-2A
3953
FULL-BRIDGE
PWM MOTOR DRIVER
Soldering Considerations. The lead (Pb) free (100%
matte tin) plating on lead terminations is 100% backwardcompatible for use with traditional tin-lead solders of any
composition, at any temperature of soldering that has
been traditionally used for that tin-lead solder alloy.
Further, 100% matte tin finishes solder well with tin-lead
solders even at temperatures below 232°C. This is because the matte tin dissolves easily in the tin-lead. Additional information on soldering is available on the Allegro
Web site, www.allegromicro.com.
www.allegromicro.com
11
3953
FULL-BRIDGE
PWM MOTOR DRIVER
A3953SB
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
BSC
8
0.13
MIN
5.33
MAX
0.39
3.81
2.93
MIN
0.558
0.356
NOTES: 1.
2.
3.
4.
5
Dwg. MA-001-17A mm
Exact body and lead configuration at vendor’s option within limits shown.
Lead spacing tolerance is non-cumulative.
Lead thickness is measured at seating plane or below.
Webbed lead frame. Leads 4, 5, 12, and 13 are internally one piece.
Supplied in standard sticks/tubes of 25 devices.
www.allegromicro.com
12
3953
FULL-BRIDGE
PWM MOTOR DRIVER
A3953SLB
Dimensions in Inches
(for reference only)
16
9
0.0125
0.0091
0.419
0.394
0.2992
0.2914
0.050
0.016
0.020
0.013
1
2
0.050
3
0° TO 8°
BSC
0.4133
0.3977
0.0926
0.1043
0.0040 MIN.
Dwg. MA-008-17A in
Dimensions in Millimeters
(controlling dimensions)
16
9
0.32
0.23
10.65
10.00
7.60
7.40
1.27
0.40
0.51
0.33
1
2
1.27
3
10.50
10.10
BSC
0° TO 8°
2.65
2.35
0.10 MIN.
NOTES: 1.
2.
3.
4.
13
Dwg. MA-008-17A mm
Exact body and lead configuration at vendor’s option within limits shown.
Lead spacing tolerance is non-cumulative.
Webbed lead frame. Leads 4, 5, 12, and 13 are internally one piece.
Supplied in standard sticks/tubes of 47 devices or add “TR” to part number for tape and reel.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3953
FULL-BRIDGE
PWM MOTOR DRIVER
The products described here are manufactured under one or more
U.S. patents, including U. S. Patent No. 5,684,427, 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.
14
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3953
FULL-BRIDGE
PWM MOTOR DRIVER
MOTOR DRIVERS
Output Ratings*
Part Number†
INTEGRATED CIRCUITS FOR BRUSHLESS DC MOTORS
3-Phase Power MOSFET Controller
—
28 V
3933
3-Phase Power MOSFET Controller
—
50 V
3932
3-Phase Power MOSFET Controller
—
50 V
7600
2-Phase Hall-Effect Sensor/Driver
400 mA
26 V
3626
Bidirectional 3-Phase Back-EMF Controller/Driver
±600 mA
14 V
8906
2-Phase Hall-Effect Sensor/Driver
900 mA
14 V
3625
3-Phase Back-EMF Controller/Driver
±900 mA
14 V
8902–A
3-Phase Controller/Drivers
±2.0 A
45 V
2936 & 2936-120
INTEGRATED BRIDGE DRIVERS FOR DC AND BIPOLAR STEPPER MOTORS
Dual Full Bridge with Protection & Diagnostics
±500 mA
30 V
3976
PWM Current-Controlled Dual Full Bridge
±650 mA
30 V
3966
PWM Current-Controlled Dual Full Bridge
±650 mA
30 V
3968
PWM Current-Controlled Dual Full Bridge
±750 mA
45 V
2916
PWM Current-Controlled Dual Full Bridge
±750 mA
45 V
2919
PWM Current-Controlled Dual Full Bridge
±750 mA
45 V
6219
PWM Current-Controlled Dual Full Bridge
±800 mA
33 V
3964
PWM Current-Controlled Full Bridge
±1.3 A
50 V
3953
PWM Current-Controlled Dual Full Bridge
±1.5 A
45 V
2917
PWM Current-Controlled Microstepping Full Bridge
±1.5 A
50 V
3955
PWM Current-Controlled Microstepping Full Bridge
±1.5 A
50 V
3957
PWM Current-Controlled Dual DMOS Full Bridge
±1.5 A
50 V
3972
Dual Full-Bridge Driver
±2.0 A
50 V
2998
PWM Current-Controlled Full Bridge
±2.0 A
50 V
3952
DMOS Full Bridge PWM Driver
±2.0 A
50 V
3958
Dual DMOS Full Bridge
±2.5 A
50 V
3971
UNIPOLAR STEPPER MOTOR & OTHER DRIVERS
Voice-Coil Motor Driver
±500 mA
6V
8932–A
Voice-Coil Motor Driver
±800 mA
16 V
8958
Unipolar Stepper-Motor Quad Drivers
1A
46 V
7024 & 7029
Unipolar Microstepper-Motor Quad Driver
1.2 A
46 V
7042
Unipolar Stepper-Motor Translator/Driver
1.25 A
50 V
5804
Unipolar Stepper-Motor Quad Driver
1.8 A
50 V
2540
Unipolar Stepper-Motor Quad Driver
1.8 A
50 V
2544
Unipolar Stepper-Motor Quad Driver
3A
46 V
7026
Unipolar Microstepper-Motor Quad Driver
3A
46 V
7044
Function
* Current is maximum specified test condition, voltage is maximum rating. See specification for sustaining voltage limits or
over-current protection voltage limits. Negative current is defined as coming out of (sourcing) the output.
† Complete part number includes additional characters to indicate operating temperature range and package style.
Also, see 3175, 3177, 3235, and 3275 Hall-effect sensors for use with brushless dc motors.
14
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000