A3958SB Allegro Microsystems Inc, A3958SB Datasheet - Page 9

• Manufacturer Part Number: A3958SB
• Description: IC MOTOR DRIVER PWM FULL 24-DIP
• Manufacturer: Allegro Microsystems Inc

Specifications of A3958SB

• Applications: PWM Motor Driver
• Number Of Outputs: 1
• Current - Output: ±2A
• Voltage - Load: 20 V ~ 50 V
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 24-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

A3958
Current Sensing. To minimize inaccuracies in
sensing the I
ground trace IR drops, the sense resistor should have an
independent ground return to the ground terminal of the
device. For low-value sense resistors the IR drops in the
PCB sense resistor’s traces can be signifi cant and should be
taken into account. The use of sockets should be avoided
as they can introduce variation in R
resistance.
The maximum value of R
Braking. The braking function is implemented by
driving the device in slow-decay mode via serial port
bit D13, enabling synchronous rectifi cation via bit D12,
and chopping with the combination of D14 and the
ENABLE input terminal. Because it is possible to drive
current in either direction through the DMOS drivers, this
confi guration effectively shorts out the motor-generated
BEMF as long as the ENABLE chop mode is asserted. It
is important to note that the internal PWM current-control
circuit will not limit the current when braking, because
the current does not fl ow through the sense resistor. The
maximum brake current can be approximated by V
TRIP
current level, which may be caused by
S
is given as R
S
due to their contact
APPLICATIONS INFORMATION
S
≤ 0.5/I
TRIP
DMOS Full-Bridge PWM Motor Driver
BEMF
.
/R
L
.
Care should be taken to ensure that the maximum ratings
of the device are not exceeded in worst-case braking
situations of high speed and high inertial loads.
Thermal Protection. Circuitry turns off all drivers
when the junction temperature reaches 165°C typically. It
is intended only to protect the device from failures due to
excessive junction temperatures and should not imply that
output short circuits are permitted. Thermal shutdown has a
hysteresis of approximately 15°C.
Layout. The printed wiring board should use a heavy
ground plane. For optimum electrical and thermal perfor-
mance*, the driver should be soldered directly onto the
board. The ground side of R
path to the ground terminals of the device. This path should
be as short as is possible physically and should not have
any other components connected to it. It is recommended
that a 0.1 μF capacitor be placed between SENSE and
ground as close to the device as possible; the load supply
terminal, V
capacitor (> 47 μF is recommended) placed as close to the
device as is possible.
BB
, should be decoupled with an electrolytic
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
S
should have an individual
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