sla7051mlf871 Allegro MicroSystems, Inc., sla7051mlf871 Datasheet - Page 6

• Manufacturer Part Number: sla7051mlf871
• Description: Unipolar Stepper-motor Translator/pwm Driver
• Manufacturer: Allegro MicroSystems, Inc.

Layout.
plane.
driver should be soldered directly into the board.
with an electrolytic capacitor placed as close to the device
as possible.
high dv/dt switching transients, route the high-level, output
traces away from the sensitive, low-level logic traces.
Always drive the logic inputs with a low source impedance
to increase noise immunity.
Grounding. A star ground system located close to the
driver is recommended. The logic supply return and the
driver supply return should be connected together at only a
single point — the star ground.
Logic supply voltage, V
should be held to less than 0.5 V to avoid malfunctioning
operation. Both V
separately.
6
SLA7051M
UNIPOLAR STEPPER-MOTOR
TRANSLATOR/PWM DRIVER
The printed wirting board should use a heavy ground
For optimum electrical and thermal performance, the
The driver supply terminal, VBB, should be decoupled
To avoid problems due to capacitive coupling of the
BB
and V
DD
DD
. Transients at this terminal
may be turned on or off
Applications information
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
Typical application
Logic inputs. Unused logic inputs (CW/CCW, FULL/
HALF, or SYNC) must be connected to either ground or
the logic supply voltage.
Current sensing. To minimize inaccuracies caused by
ground-trace IR drops in sensing the output current level,
the current-sense resistor, R
ground return to the star ground of the device. This path
should be as short as possible. For low-value sense
resistors, the IR drops in the printed wiring board sense
resistor’s traces can be significant and should be taken into
account. The use of sockets should be avoided as they can
introduce variation in R
PWM current control. The maximum value of current
limiting (I
at the REF input with a transconductance function approxi-
mated by:
The required V
R
V
S
REF
should be increased for a proportionate increase in
.
TRIP
) is set by the selection of R
REF
should not be less than 0.1 V. If it is,
I
TRIP
S
due to their contact resistance.
= V
S
, should have an independent
REF
/R
S
S
and the voltage