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UCC28C43：Why does the MOSFET heat up when using the UCC28C43 in high-frequency push-pull converters?

VBsemi MOSFET
Prodigy 150 points
Part Number: UCC28C43

Tool/software:

Hi engineers,

I’m working on a high-frequency push-pull converter using the UCC28C43 PWM controller, targeting around 100kHz operation for a compact power supply. I noticed that the MOSFETs are getting unusually hot, even though the load is within the expected range, and the gate drive waveforms seem clean on the oscilloscope.

Here are some additional details:

  • Topology: Push-pull with center-tap transformer

  • 输入电压：~48V

  • 开关频率：~100kHz

  • 栅极驱动电阻器：10Ω

  • 使用额定值为 100V Vds 的低 Rds（on） MOSFET

  • 变压器设计具有适合目标电压的匝数比

  • 尚未实现缓冲电路

问题：
1️推挽式转换器中 MOSFET 发热的常见原因是什么，UCC28C43处于高频状态？
2️⃣ 在某些条件下，此控制器是否存在变压器芯饱和或击穿？
3️⃣ 是否有关于栅极驱动电阻值、变压器设计考虑或使用 UCC28C43 进行定时死区时间调整以最大限度地减少发热的建议？
4️⃣ 在此设置中实施缓冲器会显着减少 MOSFET 发热吗？

任何见解、波形参考或实际调试技巧将不胜感激！

提前感谢您的支持。

  • 0
    TI__Guru 73795 points

    Hi,

    1., Conduction power losses from drain current flow through channel with Rdson, and switching power losses from Coss and gate charge.

    2., IC has nothing to do transformer saturation which needs transformer designer to make proper design to avoid.

    3., UCC28C43 is a single PWM drive IC, so no dead time control parameter to adjust. Not sure what you are asking or how you use the UCC28C43 in your circuit. You need to provide details. Gate resistor for UCC28C43 is usually in a range of 2 to 50-ohm, usually with 50kHz to 200kHz frequency, it is usually from trial-and-error. Transformer design has nothing to do with gate resistor value so not sure what really you are asking.

    4., Snubber can help reduce high volage spikes caused power losses so should help to some extent.

    MOSFET temperature is basically reduced through reducing its conduction power losses and switching power losses, lower Rdson, lower gate charge, lower switching frequency and adequate heatsink and with adequate airflow are main factors.