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MOSFET (Si/SiC) Forum Discussions

wohehe123
Level 1
Level 1
First like given 5 sign-ins First reply posted

wohehe123_0-1672836825428.jpeg

Above is the tested waveform of my driving circuit which is like this:

wohehe123_0-1672836952369.png

You can see in the first picture the voltage between gate and source is changing slowly compared to the signal genrated from a function generator. The mosfet I am using is Infineon-BSC034N10LS5. I tried to decrease the gate resistance but it was of no use. I tried to use another MOSFET IRL520NPbF and the waveform is totally normal. But after checking the datasheets of these two MOSFETs. I notice that the total gate charge are 37nC and 20nC and the gate to source charge are 14nC and 4.6nC, the charge value of BSC034N10LS5 is only 2~3 times of that for IRL520NPbF. So why the waveform of these two devices can be so much different?

PS: when I tested the driving circuit with IRL520NPbF, I simply connected the device to the circuit. When I tested with BSC034N10LS5, I did on a PCB with the MOSFET connected with other elements, but I am pretty sure the other circuit is open circuit. I think it will not affect the result.

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1 Solution
Neo_Qin
Moderator
Moderator
Moderator
100 sign-ins 10 likes received 50 replies posted

Hi @wohehe123 ,

Obviously, you underestimated the huge impact of power MOSFET parasitic capacitance on switching performance, as well as the charge. Generally, under the same MOSFET power level, manufacturers need to make great efforts even if few pF is reduced.

You can use the simulation tool to compare the difference between these two components.

Neo_Qin_0-1672902675746.png

 

Through the analysis of the main parameters, IRL520NPbF shows that it is more suitable for use in scenarios with high switching frequency but lower power. Due to the small channel resistance, BSC034N10LS5 is more suitable for applications with lower switching frequency but higher power.

Regards,

Neo

 

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3 Replies
Neo_Qin
Moderator
Moderator
Moderator
100 sign-ins 10 likes received 50 replies posted

Hi @wohehe123 ,

Obviously, you underestimated the huge impact of power MOSFET parasitic capacitance on switching performance, as well as the charge. Generally, under the same MOSFET power level, manufacturers need to make great efforts even if few pF is reduced.

You can use the simulation tool to compare the difference between these two components.

Neo_Qin_0-1672902675746.png

 

Through the analysis of the main parameters, IRL520NPbF shows that it is more suitable for use in scenarios with high switching frequency but lower power. Due to the small channel resistance, BSC034N10LS5 is more suitable for applications with lower switching frequency but higher power.

Regards,

Neo

 

wohehe123
Level 1
Level 1
First like given 5 sign-ins First reply posted

Thanks so much, Neo!😁

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Neo_Qin
Moderator
Moderator
Moderator
100 sign-ins 10 likes received 50 replies posted

Hi @wohehe123 ,

Thank you very much for making use of Infineon community support, we will be glad to work with you in the future as well.

Regards,

Neo