switching losses calculation
Posted by: satya_1984in@y…
on
how to calculate switching losses of TOP234G package. please specify the formula to calculate the switching losses. is there any specific considerations required to calculate switching losses integrated switch.
Comments
Dear Crusher,
we are in design stage only. still we didn't built any prototype at all. we just wants to know before building a prototype what are all the switching losses. Can u specify the Coss of TOP234G. it is not mentioned in data sheet also.
Regards
Satyanarayana.B
Dear Satya,
Open the data sheet page 33
http://www.powerint.com/sites/default/files/product-docs/top232-234.pdf
Best Regards,
PI_Crusher
Hello Satya,
In order to calculate switching losses of (an application using) TOP234G first you have to assume half of the internal power required by our chip goes into Gate losses.Now you have to measure in-circuit equivalent output capacitance you see from Drain to Source (plus transformer, etc); use a device like Smart Twizeers, from http://www.advancedevices.com/. After you know what capacitance you have there (your output capacitance Coss now), you use this formula:
Pswmax=(Tsw*Vdsmax*Ippk*fsw)+(Coss*Vdsmax^2*fsw)/2
For further information, look here: http://www.national.com/appinfo/power/files/flyback-mathcad_example.doc
Cheers,
PI_Crusher