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Which MOSFET for lowest switching loss?

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eem2am

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switching loss

I am doing 40W boost converter LED driver.

V(in) = 9V
V(out) = ~30V
I(out) = 1.3A

Here is the FET current

2v96qec.jpg

(https://i25.tinypic.com/2v96qec.jpg)
** ** **

Here is the schematic:

sbn213.jpg

(https://i31.tinypic.com/sbn213.jpg)
** ** **

I have a choice between N MOSFET’s for the switch:-
…….either IRLR3110 from irf.com
………..or IPD079N06L3 from Infineon

…..which one of these will give the lowest switching losses?






Infineon IPD079 N MOSFET datasheet:

https://www.infineon.com/dgdl/IPD07...e0e77&fileId=db3a30431ddc9372011e2b5528634dc0




IRLR33110 Datasheet:

https://www.irf.com/product-info/datasheets/data/irlr3110zpbf.pdf
 

KMoffett

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switching loss of mosfet

Out of curiosity...when I see a power supply of "9V", I assume that the circuit is intended to run off of a small, rectangular PP3 9V battery. Is this the case for your converter?

Ken
 

eem2am

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mosfet switching loss

Hi Ken,

Thanks for your reply.

Actually , the supply is a 13.5V battery but it will go down to 9V during transient conditions.

-Regulations state we have to design for this voltage (9V) too which is a nuisance but we have to have the capability to give full output power at 9V input.
 

KMoffett

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mosfet switch loss

My concern was trying to pull 4.3A out of a 9V battery. 8(

Never mind. :)

Ken
 

Kral

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switching loss mosfet

eem2am,
The switching losses and I squared R losses of the IPD079N should be lower since the rise and fall times and Rds(on) are all lower. In addition, the dissipation in the driver chip should also be lower, since the Total gate charge of the IPD079N is lower.
Regards,
Kral
 

eem2am

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calculating mosfet switching loss

Thankyou Kral, and Ken.

Kral......so is it 'tr' and 'tf' that are the main parameters for determining switching losses?

-If you see the equation at top right of page 16 of LTC1871 datasheet .....


https://cds.linear.com/docs/Datasheet/1871fe.pdf

......the lower part of the expression concerns switching loss........and the only parameter it uses is the 'Crss' parameter.

.......so from this, is it really the 'Crss' parameter alone which determines the switching loss ?
 

ark5230

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mosfet loss

Is this switching loss higher than the output load current? If no then the relative proportion becomes the point of concern to decide what issue to address first.
Raoof
 

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