DRV8832-Q1 Datasheet, PDF (16/20 Pages) Texas Instruments – Low-Voltage Motor Driver IC

DRV8832-Q1
SLVSBW9C – APRIL 2013 – REVISED DECEMBER 2015
9 Power Supply Recommendations
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9.1 Power Supervisor
The DRV8832-Q1 is capable of entering a low-power sleep mode by bringing both of the INx control inputs logic
low. The outputs will be disabled Hi-Z.
To exit the sleep mode, bring either or both of the INx inputs logic high. This will enable the H-bridges. When
exiting the sleep mode, the FAULTn pin will pulse low.
9.2 Bulk Capacitance
Having appropriate local bulk capacitance is an important factor in motor drive system design. It is generally
beneficial to have more bulk capacitance, while the disadvantages are increased cost and physical size.
The amount of local capacitance needed depends on a variety of factors, including:
• The highest current required by the motor system.
• The power supply’s capacitance and ability to source current.
• The amount of parasitic inductance between the power supply and motor system.
• The acceptable voltage ripple.
• The type of motor used (Brushed DC, Brushless DC, Stepper).
• The motor braking method.
The inductance between the power supply and motor drive system will limit the rate current can change from the
power supply. If the local bulk capacitance is too small, the system will respond to excessive current demands or
dumps from the motor with a change in voltage. When adequate bulk capacitance is used, the motor voltage
remains stable and high current can be quickly supplied.
The data sheet generally provides a recommended value, but system-level testing is required to determine the
appropriate sized bulk capacitor.
Power Supply
Parasitic Wire
Inductance
Motor Drive System
VCC
++
+
Motor Driver
±±
GND
Local
Bulk Capacitor
IC Bypass
Capacitor
Figure 15. Example Setup of Motor Drive System with External Power Supply
The voltage rating for bulk capacitors should be higher than the operating voltage, to provide margin for cases
when the motor transfers energy to the supply.
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