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TO-247-4L Half-Bridge Evaluation Board
User’s Guide
©
2019 ROHM Co., Ltd.
No. 61UG047E Rev.001
August.2019
■
Waveform comparison by using different Cgs capacitances
（
Without protection circuit
）
Figure 34 shows the measurement result and the effect of using Cgs on the self-turn on and surge voltage.
From the waveforms, we can see that the self-turn on can be prevented by adding the Cgs. However, we also understand that the
Cgs does not give a significant effect on the negative surge at turn off. Furthermore, switching loss increases when Cgs is added,
thus it is necessary to measure the heat dissipation on the device at actual application board when selecting the Cgs value.
Figure 34. Cgs comparison
（
SCT3040KR, without protection circuit
）
2.2nF
3.3nF
No Cgs
4.7nF
No Cgs
2.2nF
3.3nF
4.7nF
No Cgs
Rg=10
Ω
