DRV8837C Datasheet, PDF (12/21 Pages) Texas Instruments – 1-A Low-Voltage H-Bridge Driver

DRV8837C
SLVSD61A – JULY 2016 – REVISED JULY 2016
8.2.3 Application Curves
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Figure 8. 50% Duty Cycle, Forward Direction
Figure 9. 50% Duty Cycle, Reverse Direction
Figure 10. 20% Duty Cycle, Forward Direction
Figure 11. 20% Duty Cycle, Reverse Direction
9 Power Supply Recommendations
9.1 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 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 limits the rate at which current can change
from the power supply. If the local bulk capacitance is too small, the system responds 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 size of bulk capacitor.
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