a4983 Allegro MicroSystems, Inc., a4983 Datasheet - Page 10

• Manufacturer Part Number: a4983
• Description: Dmos Microstepping Driver With Translator
• Manufacturer: Allegro MicroSystems, Inc.

A4983
Layout The printed circuit board should use a heavy ground-
plane. For optimum electrical and thermal performance, the
A4983 must be soldered directly onto the board. On the under-
side of the A4983 package is an exposed pad, which provides a
path for enhanced thermal dissipation. The thermal pad should be
soldered directly to an exposed surface on the PCB. Thermal vias
are used to transfer heat to other layers of the PCB. Thermal vias
should not have any thermal relief and should be connected to
internal layers, if available, to maximize the dissipation area.
Grounding In order to minimize the effects of ground bounce
and offset issues, it is important to have a low impedance single-
point ground, known as a star ground, located very close to the
device. By making the connection between the exposed thermal
pad and the groundplane directly under the A4983, that area
becomes an ideal location for a star ground point.
DMOS Microstepping Driver with Translator
Application Layout
A low impedance 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.
Thermal Vias
C4
PCB
C3
1
C7
OUT2B
ENABLE
GND
CP1
CP2
VCP
NC
C6
RS1
A4983
A4983
PAD
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
R6
RS2
OUT1B
R1
STEP
GND
VDD
REF
DIR
NC
C9
C1
Solder
Trace (2 oz.)
Signal (1 oz.)
Ground (1 oz.)
Thermal (2 oz.)
C8
R2
C2
R3
V
V
BB
DD
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