UCC15240-Q1: Input Current increases with switching frequency

Vivek Gandham

Part Number: UCC15240-Q1

Tool/software:

Hi Team,

I am using UCC15240-Q1 in one of my program, I am using this as a Gate driver power supply, while testing this gate driver we observed the IC draws more current with increase in frequency.

May i know why this is drawing more current?

Regards

Vivek

1 month ago

0 Steven Mappus1 1 month ago

TI__Mastermind 33115 points

The bias power required by your gate driver is P=Qg*VDD-VEE*Fsw. VDD-VEE is regulated by UCC15240-Q1 and Qg is fixed according to the SiC/IGBT data sheet, for a fixed VDD-VEE. Fsw is also fixed in most switching converter/inverter applications but if you vary Fsw, you can see that the required power (and therefore the bias supply input current) will vary as a result. You move the same amount of charge at a higher frequency, you require more power and if you require more power, you must provide more current for a given input voltage. This is the behavior of all gate driver/bias supply circuits.

Steve

0 kalana de silva 1 month ago in reply to Steven Mappus1

Prodigy 140 points

If I am using a 15V VDD rail and a -4V VEE rail can you explain how to size the capacitors properly ?
Datasheet is not very clear on this calculation.

If you can provide an example that would be great.
Thank you

0 Steven Mappus1 1 month ago in reply to kalana de silva

TI__Mastermind 33115 points

The UCC15240-Q1 Excel Design Tool will calculate the cap values for you.

Steve

0 kalana de silva 1 month ago in reply to Steven Mappus1

Prodigy 140 points

Thank you! That helps.
Is there a model to simulate UCC15240 ?

0 Steven Mappus1 1 month ago in reply to kalana de silva

TI__Mastermind 33115 points

Only have SIMPLIS here (UCC14241 sim is same as UCC15241)

Steve

0 kalana de silva 1 month ago in reply to Steven Mappus1

Prodigy 140 points

Hi, Steve,
The online tool suggest to place a capacitor between VDD and VEE. Screen shot is below is this additionally to the 2.2uF capacitor already placed at the device ? C15 in the screenshot

0 Steven Mappus1 1 month ago in reply to kalana de silva

TI__Mastermind 33115 points

Yes, the 2.2μF capacitor is placed at the UCC15240-Q1 and the additional VDD-VEE capacitor (COUT1b) is placed at the gate driver/load.

Steve

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UCC15240-Q1: Input Current increases with switching frequency