A3906SESTR-T Allegro Microsystems Inc, A3906SESTR-T Datasheet - Page 9

• Manufacturer Part Number: A3906SESTR-T
• Description: IC, MOTOR DRIVER, STEPPER, 1A, QFN-20
• Manufacturer: Allegro Microsystems Inc

Specifications of A3906SESTR-T

• No. Of Outputs: 2
• Output Current: 1A
• Output Voltage: 9V
• Driver Case Style: QFN
• No. Of Pins: 20
• Operating Temperature Range: -20°C To +85°C
• Package / Case: 20-QFN
• Applications: DC Motor Driver, Stepper Motor Driver
• Number Of Outputs: 2/1
• Current - Output: ± 1A
• Voltage - Supply: 2.5 V ~ 9 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Operating Temperature Classification: Commercial
• Motor Controller Type: DC Motor Driver
• Operating Supply Voltage (min): 2.5V
• Operating Supply Voltage (max): 9V
• Motor Type: Stepper
• Supply Voltage Range: 2.5V To 9V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Load: -
• Lead Free Status / Rohs Status: Compliant
• Other names: 620-1288-2; A3906SESTR-T

A3906
becomes an ideal location for a star ground point. A low imped-
ance ground will prevent ground bounce during high current
operation and ensure that the supply voltage remains stable at
the input terminal. The recommended PCB layout shown in the
diagram below, illustrates how to create a star ground under the
device, to serve both as low impedance ground point and thermal
path.
The two input capacitors should be placed in parallel, and as
close to the device supply pins as possible. The ceramic capaci-
tor should be closer to the pins than the bulk capacitor. This is
necessary because the ceramic capacitor will be responsible for
delivering the high frequency current components.
GND
C1
GND
U1
C2
Low Voltage Stepper and Single/Dual DC Motor Driver
R4
C3
R3
R1
R2
OUT1A
OUT2A
PCB Layout
OUT1B
OUT2B
VBB
+5V
Thermal Vias
Sense Pins The sense resistors, RSx, should have a very low
impedance path to ground, because they must carry a large cur-
rent while supporting very accurate voltage measurements by
the current sense comparators. Long ground traces will cause
additional voltage drops, adversely affecting the ability of the
comparators to accurately measure the current in the windings.
As shown in the layout below, the SENSEx pins have very short
traces to the RSx resistors and very thick, low impedance traces
directly to the star ground underneath the device. If possible,
there should be no other components on the sense circuits.
Note: When selecting a value for the sense resistors, be sure not to
exceed the maximum voltage on the SENSEx pins of ±500 mV.
PCB
A3906
C1
CP2
GND
SLEEP
IN1
IN2
C2
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
A3906
PAD
C3
SENSE1
SENSE2
OUT1B
OUT2B
R3
R4
VBB
Solder
Trace (2 oz.)
Signal (1 oz.)
Ground (1 oz.)
Thermal (2 oz.)
R1
R2
OUT2A
OUT1A
OUT1B
VBB
OUT2B
+5V
9