Comparing TO-247 vs TO-247-4 Power Semiconductor Packages: Double Pulse Test Results

TO-247-4 is a four-lead version of the common TO-247 power semiconductor package, featuring an additional Kelvin terminal that separates the gate drive path from the main current path. I compare the switching performance of a three-lead TO-247 and a four-lead TO-247-4 using a double pulse test board.

■ Package Basics and Theory
- Differences between the 3-lead TO-247 and the 4-lead TO-247-4
- Role of the Kelvin terminal (driver source) in isolating gate drive from main current
- How parasitic capacitance and inductance affect MOSFET switching speed
- Internal package structure: lead frame, bonding wires, and parasitic elements

■ Double Pulse Test Experiment
- Test board design with gate driver circuit, current probe points, and air-core inductor
- Switching loss measurement using both three-terminal and four-terminal configurations
- Comparison of switching waveforms and loss values between the two packages
- Effect of switching speed increase on voltage overshoot and ringing

■ Practical Considerations
- Why Kelvin terminal packages are commonly used with SiC MOSFETs
- Impact of faster switching on main circuit parameter design
- Recommendations for gate driver and main circuit design when using four-terminal packages

電力電子機器の設計に携わる方や、パッケージ構成がスイッチング特性に与える影響を理解したい方に向けて、パッケージの基本構造から実験結果までを段階的に解説しています。理論と実測の両面から、四端子パッケージを設計に取り入れる際の考慮点が把握できます。