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3953 Schematic ( PDF Datasheet ) - Allegro MicroSystems

Teilenummer 3953
Beschreibung FULL-BRIDGE PWM MOTOR DRIVER
Hersteller Allegro MicroSystems
Logo Allegro MicroSystems Logo 




Gesamt 14 Seiten
3953 Datasheet, Funktion
3953
FULL-BRIDGE PWM MOTOR DRIVER
BRAKE 1
REF 2
VBB
RC 3
GROUND 4
GROUND 5
LOGIC
SUPPLY
6
VCC
PHASE 7
ENABLE 8
LOGIC
VBB
16
LOAD
SUPPLY
15 OUTB
14 MODE
13 GROUND
12 GROUND
11 SENSE
10 OUTA
LOAD
9 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 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 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-lead plastic
SOIC with copper heat-sink tabs. For both package styles, the power tab is at
ground potential and needs no electrical isolation.
FEATURES
I ±1.3 A Continuous Output Current I Sleep (Low Current
I 50 V Output Voltage Rating
Consumption) Mode
I 3 V to 5.5 V Logic Supply Voltage I Internal Transient-
I Internal PWM Current Control
Suppression Diodes
I Saturated Sink Drivers (Below 1 A) I Internal Thermal-
I Fast and Slow Current-Decay Modes Shutdown Circuitry
I Automotive Capable
I Crossover-Current
and UVLO Protection
Always order by complete part number:
Part Number
Package
A3953SB
16-Pin DIP
A3953SLB
16-Lead SOIC
RθJA
43°C/W
67°C/W
RθJT
6°C/W
6°C/W






3953 Datasheet, Funktion
3953
FULL-BRIDGE
PWM MOTOR DRIVER
FUNCTIONAL DESCRIPTION
Internal PWM Current Control During Forward and
Reverse Operation. The A3953Scontains 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 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 approxi-
mated by:
ITRIP
VREF
RS
ISO
where ISO is the offset due to base drive current.
In forward or reverse mode the current-control cir-
cuitry 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, respec-
tively.
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
RECIRCULATION (SLOW-DECAY MODE)
RECIRCULATION (FAST-DECAY MODE)
RS
Dwg. EP-006-13A
The user selects an external resistor (RT) and capaci-
tor (CT) to determine the time period (tOFF = RT x CT)
during which the drivers remain disabled (see RC Fixed
Off-Timebelow). 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
I TRIP
LOAD
CURRENT
RC
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 motors 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 motors
inductance is discharged into the load supply causing the
motor current to decay.
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-Timebelow). Depending on the
back-EMF voltage (proportional to the motors 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.
115 Northeast Cutoff, Box 15036
6 Worcester, Massachusetts 01615-0036 (508) 853-5000

6 Page









3953 pdf, datenblatt
3953
FULL-BRIDGE
PWM MOTOR DRIVER
A3953SLB
Dimensions in Inches
(for reference only)
16 9
0.0125
0.0091
0.2992
0.2914
0.020 1 2 3
0.013
0.4133
0.3977
0.050
BSC
0.419
0.394
0.050
0.016
0° TO 8°
0.0926
0.1043
0.0040 MIN.
Dimensions in Millimeters
(controlling dimensions)
16 9
Dwg. MA-008-17A in
0.32
0.23
7.60
7.40
0.51 1 2 3
0.33 10.50
10.10
1.27
BSC
10.65
10.00
1.27
0.40
0° TO 8°
2.65
2.35
0.10 MIN.
Dwg. MA-008-17A mm
NOTES: 1. Exact body and lead configuration at vendors option within limits shown.
2. Lead spacing tolerance is non-cumulative.
3. Webbed lead frame. Leads 4, 5, 12, and 13 are internally one piece.
4. Supplied in standard sticks/tubes of 47 devices or add TRto part number for tape and reel.
115 Northeast Cutoff, Box 15036
12 Worcester, Massachusetts 01615-0036 (508) 853-5000

12 Page





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