Controller for multi output flyback

Satyajit C

Prodigy 30 points

Other Parts Discussed in Thread: UCC28781, UCC28782, UCC28C43, LM5155

Hi,

I want to design a multioutput flyback converter with following specifications:

Input : 16 V - 48 V, 28 V Typ

Outputs: 5 V 8 A ; 5 V 5 A ; 15 V 1.5 A ; 15 V 1.5 A ; 28 V 1.5 A

Frequency: 250 KHz

All outputs are isolated

My plan is to control 5 V, 8 A output using input-side switch and some flyback controller IC and for rest outputs use switching regulators. Does that sound good?

I planned to use TL491 as flyback controller but I understand it may not suit at 250 KHz. Please correct me if needed.

My main question is : Can someone please suggest best flyback controller IC for these output and frequency specifications? If Ltspice model and design procedure of this IC is available it is best.

over 2 years ago

0 JCHK over 2 years ago

TI__Guru 50090 points

Hi Satyajit,

Most of our dedicated flyback controllers run with maximum switching frequencies around 100kHz. We do have our latest Active-Clamp Flyback or Zero-Voltage Switching controllers the UCC28782 or UCC28781. This can run at 250 Khz and might be better options.

If you want to try to run a general purpose PWM as a flyback, the UCC28C53 might be a good option. However, it will have higher switching losses than the dedicated flyback controllers.

All of this can be made to support multiple ouput voltages, but keep in mind, only one fo the rails is regulated well. If accuracy is needed for the other isolated railed you will need to post regulate with a DC/DC converter.

I hope this helps.

0 Satyajit C over 2 years ago in reply to JCHK

Prodigy 30 points

Thanks JCHK

Is there any design sheet for the UCC28782 or UCC28781

Also how can I possibly get the Ltspice model of these

Please suggest

0 JCHK over 2 years ago in reply to Satyajit C

TI__Guru 50090 points

Hi Satyajit,

Unfortunately, the UCC28781 and UCC28782 controllers do not have a spice model. We do have a simplis model and design calculator that can be used to help select parameters.

You can import the UCC28C43 pspice model into LTspice. The key differences between the UCC28C4x series and UCC28C5x series are as follows:

I hope this helps get you started.

0 Satyajit C over 2 years ago in reply to JCHK

Prodigy 30 points

Thanks JCHK

I learnt that LM5155 is one option. Also some reference designs are available for that.

Is it a good option. If yes, where can I find its Ltspice model?

+1 JCHK over 2 years ago in reply to Satyajit C

TI__Guru 50090 points

Hi Satyajit,

The LM5155 might be another option. Here is the unencrypted model. You should be able to import this into LTSpice.

I hope this helps.

+1 Satyajit C over 2 years ago in reply to JCHK

Prodigy 30 points

Hi JCHK,

Thanks for your reply. I am not able to import it in Ltspice. Can you suggest the steps or any link guide for steps

0 JCHK over 2 years ago in reply to Satyajit C

TI__Guru 50090 points

Hi Satyajit,

We do not support LTspice as we have Pspice for TI. If you want to import an unencrypted model into LTSpice there are several online articles as to how to import 3rd party models.

I hope this answers your question.

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Controller for multi output flyback