SLLSFV1 March 2025 MCF8329A-Q1
PRODUCTION DATA
Having an appropriate local bulk capacitance is an important factor in motor drive system design. Designs generally benefit in having 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 inductance between the power supply and the 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 PVDD voltage. When adequate bulk capacitance is used, the PVDD 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 bulk capacitor. The voltage rating for bulk capacitors needs to be higher than the operating voltage, to provide margin for cases when the motor transfers energy to the supply.
Figure 9-5 Example Setup of Motor Drive System With External Power Supply