SLA7062 Ver la hoja de datos (PDF) - Allegro MicroSystems
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Fabricante
SLA7062 Datasheet PDF : 16 Pages
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SLA7060M THRU SLA7062M
UNIPOLAR STEPPER-MOTOR
TRANSLATOR/DRIVERS
Applications information
Layout.
The printed wirting board should use a heavy ground
plane.
For optimum electrical and thermal performance, the
driver should be soldered directly into the board.
The driver supply terminal, VBB, should be decoupled
with an electrolytic capacitor (>47 µF is recommended)
placed as close to the device as possible.
To avoid problems due to capacitive coupling of the
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, VDD. Transients at this terminal
should be held to less than 0.5 V to avoid malfunctioning
operation. Both VBB and VDD may be turned on or off
separately.
Logic inputs. Unused logic inputs (CW/CCW, M1, M2,
RESET, 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 resistors, RS, should have an independent
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 RS due to their contact resistance.
PWM current control. The maximum value of current
limiting (ITRIP) is set by the selection of RS and the voltage
at the REF input with a transconductance function ap-
proximated by:
ITRIP = VREF/RS
The required VREF should not be less than 0.1 V. If it is,
RS should be increased for a proportionate increase in
VREF.
RS = 0.1 Ω to 2 Ω
R1 = 10 kΩ
R2 = 5.1 kΩ
R3 = 10 kΩ
CA = 100 µF, 50 V
CB = 10 µF, 10 V
C1 = 0.1 µF
Typical application
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