What impact does EPS device packaging have on high-frequency EMC?

The packaging of power devices and driver ICs in EPS has a significant impact on high-frequency EMC performance, mainly in terms of parasitic parameters:

1. Parasitic inductance: Bond wires and lead frames inside the package introduce parasitic inductance. For example, the parasitic inductance of the TO-247 package is typically higher than that of D2PAK or TOLL. High parasitic inductance leads to higher voltage overshoot (V=L*di/dt) and ringing during switching, worsening EMI.

2. Parasitic capacitance: Parasitic capacitance between device pins and between pins and the heatsink couples noise, especially the capacitance between the drain/collector and ground, which is the main path for common-mode noise current.

3. Thermal resistance and heat dissipation: The thermal resistance of the package affects the junction temperature, and high temperatures may change the switching characteristics of the device, indirectly affecting the EMI spectrum.

To improve high-frequency EMC, packages with low parasitic inductance (such as surface mount and leadless packages) should be prioritized, and loop inductance should be further reduced during layout using methods such as multilayer busbars and low-inductance traces.