Hi, if i want to calculate Poss accurately, need the expression of Coss(v). The curve is plotted at every datasheet, but where to get the equation of the curve. Thanks!
Hello,
you would need to digitize the waveform and then use this formula:
and for a buck converter the capacitive losses in each switching cycle that are dissipated in the HS device are:
Do you already have the digitalized data, that would save me a lot of time.
Thanks!
We don’t have it but it is relatively easy to generate, which device are you looking for?
EPC8009/EPC8010/EPC8002
Thanks!
Hi Shengnan,
here is the EPC8010 Coss you are using:
| Vds (V) | Coss (pF) |
|---|---|
| 5.83E-01 | 6.38E+01 |
| 3.83E+00 | 5.99E+01 |
| 7.24E+00 | 5.70E+01 |
| 1.06E+01 | 5.44E+01 |
| 1.43E+01 | 5.16E+01 |
| 1.79E+01 | 4.91E+01 |
| 2.13E+01 | 4.67E+01 |
| 2.47E+01 | 4.49E+01 |
| 3.03E+01 | 3.87E+01 |
| 3.12E+01 | 3.82E+01 |
| 3.38E+01 | 3.60E+01 |
| 3.45E+01 | 3.54E+01 |
| 3.74E+01 | 3.29E+01 |
| 3.79E+01 | 3.25E+01 |
| 4.07E+01 | 3.01E+01 |
| 4.12E+01 | 2.97E+01 |
| 4.42E+01 | 2.76E+01 |
| 4.46E+01 | 2.74E+01 |
| 4.76E+01 | 2.56E+01 |
| 4.79E+01 | 2.55E+01 |
| 5.10E+01 | 2.40E+01 |
| 5.14E+01 | 2.39E+01 |
| 5.45E+01 | 2.26E+01 |
| 5.47E+01 | 2.26E+01 |
| 5.80E+01 | 2.16E+01 |
| 5.83E+01 | 2.16E+01 |
| 6.15E+01 | 2.08E+01 |
| 6.18E+01 | 2.07E+01 |
| 6.51E+01 | 2.01E+01 |
| 6.52E+01 | 2.02E+01 |
| 6.85E+01 | 1.97E+01 |
| 6.87E+01 | 1.97E+01 |
| 7.19E+01 | 1.93E+01 |
| 7.21E+01 | 1.93E+01 |
| 7.55E+01 | 1.89E+01 |
| 7.57E+01 | 1.89E+01 |
| 7.89E+01 | 1.86E+01 |
| 7.91E+01 | 1.86E+01 |
| 8.23E+01 | 1.83E+01 |
| 8.25E+01 | 1.83E+01 |
| 8.57E+01 | 1.81E+01 |
| 8.59E+01 | 1.81E+01 |
| 8.91E+01 | 1.78E+01 |
| 8.93E+01 | 1.78E+01 |
| 9.25E+01 | 1.78E+01 |
| 9.27E+01 | 1.77E+01 |
| 9.61E+01 | 1.75E+01 |
| 9.62E+01 | 1.75E+01 |
| 9.95E+01 | 1.75E+01 |
| 9.96E+01 | 1.74E+01 |
@Shengnan, I use the following webpage to extract the Coss curves, which has worked well for me.
great tool…thanks for sharing!
Thank you both! 