CSD18510Q5B: How to more accurately predict the Reverse Recovery losses in FETs/Diodes

Oisin Anderson

Part Number: CSD18510Q5B

Hi,

I'm trying to predict the losses in DC-DC converters using only datasheet information where possible. One of the parameters that I haven't had much luck with is the Qrr/Trr related losses.

In most datasheets, the Qrr losses are only specified for one operating condition, but from some of your training material (https://training.ti.com/understanding-mosfet-datasheets-switching-parameters https://training.ti.com/reverse-recovery ) and other research papers, these losses can vary a lot with changes to di/dt, forward current before reverse recovery and temperature.

My question is: Is there any equation that you can apply to datasheet Qrr/Trr parameters to correct for different operating conditions? For example, if my application the di/dt is closer to 1000A/us, rather than the 300A/us specified in the CSD18510Q5B datasheet (a random FET I chose), is there a scaling factor I can apply? How to scale for different di/dt and I_F would be what I'm looking for mainly.

Kind regards,

Oisin Anderson

over 3 years ago

0 John Wallace1 over 3 years ago

TI__Mastermind 34005 points

Hello Oisin,

Thanks for your interest in TI FETs, I am not aware of a scaling factor for Qrr based on di/dt and IF. I have some inquires into my colleagues to see if they have any input on your request. I will update you as soon as I have additional information.

Thanks,

John Wallace

TI FET Applications

+1 John Wallace1 over 3 years ago in reply to John Wallace1

TI__Mastermind 34005 points

Hello Oisin,

I checked with my colleagues and there are no analytical equations that can calculate Qrr with a different di/dt and IF accurately, because it is very different from technology to technology. As a first approximation, you can probably assume that Qrr is proportional to both di/dt and IF. However, we have no data and would not be able to recommend the proportionality factor.

Best Regards,

John

0 Oisin Anderson over 3 years ago in reply to John Wallace1

Prodigy 10 points

Hi John,

Thanks for your help, hopefully I can find something eventually.

Kind regards,

Oisin

0 John Wallace1 over 3 years ago in reply to Oisin Anderson

TI__Mastermind 34005 points

Hi Oisin,

I did a google search on "mosfet reverse recovery" and found some interesting articles and app notes. You can also search for "hard commutation". Hope this helps.

Thanks,

John

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CSD18510Q5B: How to more accurately predict the Reverse Recovery losses in FETs/Diodes