UCC28711: UCC28711

robin gangopadhya18

Part Number: UCC28711
Other Parts Discussed in Thread: UCC28700, UCC28730

Hello

We have a fast design need using UCC28711 low power, input comes from an Inverter with pur sinewave. Due to low power, half wave rectification is considered suitable. We got the WebBench design giving us all we need. Some users have indicated sometime ago there might have been some typos in the equations... we are hoping Web Bench valus are updated and free of such typo related outcomes.

We are using GaN from Transform for efficiency reasons- there is no heatsinking possible other than small copper in the PCB. Our size is < 1”x.8”. Do you see any adverse effects in the control law run?

Any reviews will be highly appreciated

-r

over 4 years ago

0 Mike O' over 4 years ago

TI__Guru* 86286 points

Hello,

I regards to your question regarding power density. This device is used in sell phone battery charges in the 5 to 10 W. These design generally have a power density of 5W/in^3. Based on your power level if it is less than 10 W you can use this as an estimate to approximate your power density.

I am not aware with issues with design equations and Webench. However, you should find the following application notes useful in your design process.

https://www.ti.com/lit/pdf/slua653, UCC28700 is similar to the UCC28711 and this application note reviews the design of a 5 W auxiliary supply using the device.

Even though PSR removes the need for a opto coupler, primary sensing can have issues if the auxiliary winding is not clean. The following application notes describe the most common issues with PSR fault sensing and how to resolve them.

0844.Clean PSR Sensing App Note 10 5 20B.pdf

https://www.ti.com/lit/pdf/slua783

If this is a lower power design TI may have already have completed a reference design you can use. Have you check the reference design library that can be found at the following link. https://www.ti.com/product/UCC28711?keyMatch=UCC28711&tisearch=Search-EN-everything&usecase=GPN#design-development##reference-designs

Regards,

0 robin gangopadhya18 over 4 years ago in reply to Mike O'

Mastermind 6316 points

Hello Mike

Thnx much for the prompt reply with more solutions.

If I run Web Bench, the best solution I get even with 18v/50mA from pure sinewave Inverter input power is with UCC28730

On top of all this, due to several factors, we are seriously considering GaN from Transphorm due to their drive input being compatible with the controller.

But ours has 3 outputs ( each downstream having LDOs such as TPS7A24500) - so total power may be a bit more.

I notice there is UCC28710-17- EXcel design calculator - can we use the values obtained there for UCC28730? I do not see apparent contraindication.

Appreciate your comments again.

+1 robin gangopadhya18 over 4 years ago in reply to Mike O'

Mastermind 6316 points

Hello Mike

0 robin gangopadhya18 over 4 years ago in reply to Mike O'

Mastermind 6316 points

Hello Mike

0 robin gangopadhya18 over 4 years ago in reply to Mike O'

Mastermind 6316 points

Hello Mike

0 robin gangopadhya18 over 4 years ago in reply to Mike O'

Mastermind 6316 points

Mike : the xl calculator I mentioned gives a1= 4.41 and a2=3.19, a1=Np/Ns.

With output set at 18V, I suspect there is something strange with Na/Ns=3.19

Pl note, after the "UPGRADE", I CAN NO LONGER ATTACH A FILE.

Appreciate your review on this.

Power management

Power management forum

UCC28711: UCC28711