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 33915 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 33915 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 33915 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

Power management

Power management forum

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