A3989SEVTR-T Allegro Microsystems Inc, A3989SEVTR-T Datasheet - Page 6

• Manufacturer Part Number: A3989SEVTR-T
• Description: IC, MOTOR DRIVER, STEPPER, 1.2A, QFN-36
• Manufacturer: Allegro Microsystems Inc

Specifications of A3989SEVTR-T

• Motor Type: Stepper
• No. Of Outputs: 3
• Output Current: 1.2A
• Output Voltage: 36V
• Supply Voltage Range: 3V To 5.5V
• Driver Case Style: QFN
• No. Of Pins: 36
• Applications: DC Motor Driver, Stepper Motor Driver
• Number Of Outputs: 2
• Voltage - Load: 8 V ~ 36 V
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 36-VFQFN Exposed Pad
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 620-1183-2

A3989
is detected, synchronous rectification is turned off to prevent
reversal of the load current.
Mixed Decay Operation
mixed decay mode. Referring to figure 2, as the trip point is
reached, the device goes into fast decay mode for 30.1% of
the fixed off-time period. After this fast decay portion, t
device switches to slow decay mode for the remainder of the
off-time. The dc driver decay mode is determined by the MODE
pin. During transitions from fast decay to slow decay, the drivers
are forced off for approximately 600 ns. This feature is added to
prevent shoot-through in the bridge. As shown in figure 2, during
this “dead time” portion, synchronous rectification is not active,
and the device operates in fast decay and slow decay only.
The stepper driver operates in
Bipolar Stepper and High Current DC Motor Driver
V
PHASE
I
OUT
I
Trip
–
FD
+
0
DT
Figure 2. Mixed Decay Mode Operation
9 μs
FD
FD
SR
, the
Fixed Off-Time 30 μs
Enlargement A
SD
DT
MODE
decay mode and slow decay mode for the dc driver. A logic high
puts the device in slow decay mode. Synchronous rectification is
always enabled when ENABLE is low.
Braking
pin and applying an ENABLE chop command implements
the Braking function. Because it is possible to drive current in
both directions through the DMOS switches, this configura-
tion effectively shorts the motor-generated BEMF as long as the
ENABLE chop mode is asserted. The maximum current can be
approximated by V
the maximum ratings of the device are not exceeded in worst case
braking situations: high speed and high inertia loads.
I
OUT
21 μs
SD
SR
Control input MODE is used to toggle between fast
Driving the device in slow decay mode via the MODE
See Enlargement A
SD
DT
BEMF
/R
L
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
. Care should be taken to ensure that
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