power mosfet question

[wei9321]

I have a question
I use the same type mosfet,but the d/c is different
we use it on the same DC-DC converter,but their difference in efficiency is about
6~7%
as the picture,i measure their VGS wave have big difference

I can't point out their question
why?

 

[zuisti]

I have a question
I use the same type mosfet,but the d/c is different
we use it on the same DC-DC converter,but their difference in efficiency is about 6~7%

Too little info to help ...
However, usually the smaller input voltage the lower efficiency ...

 

[wei9321]

Too little info to help ...
However, usually the smaller input voltage the lower efficiency ...

d/c ,I mean date code(the same type mosfet,but date code is different)
the picture vgs wave at vin=24V,
OUTPUT:24V/500mA
"their difference in efficiency is about 6~7%"
the better mosfet efficiency about 81%
the better mosfet efficiency about 75%

 

[Orson Cart]

You'll probably find the difference in On resistance is within the range specified (on the data sheet) but the poorer devices are at one end of the spectrum and the good devices wereat the other - this is why engineers have to design with "worst case" data... Orson Cart.