LM51561H-Q1：LM51561H-Q1 for QR-FLYBACK or 6V-60V input isolated DC/DC Converter with soft-switching

Andy Chen

Prodigy 100 points

Part Number: LM51561H-Q1
Other Parts Discussed in Thread: LM51561, LM5156, UCC28600, LM25180

I would like to design a QR-Flyback with LM51561H-Q1 SYNC-PIN.

The pri-Aux power will be the SYNC-single clock.

Will it work?

Could you offer the TI-Tina file for LM51561H-Q1 and suitable design?

Thank you

7 months ago

0 Andy Chen 7 months ago

Prodigy 100 points

20W-30W

0 Niklas Schwarz 7 months ago in reply to Andy Chen

TI__Mastermind 21110 points

Hi Andy,

Thanks for using the e2e forum.
LM51561 is a peak current control controller fit for Flyback applications, so this device should be a good fit for your specs.
A good reference should be our flyback EVM:
https://www.ti.com/tool/LM5156HEVM-FLY

We also have a quickstart calculation tool for this device, which is very useful for initial calculations:
https://www.ti.com/tool/download/SNVC240

Simulation files can be found for PSpice on the product page.
https://www.ti.com/product/LM5156#design-tools-simulation

Best regards,
Niklas

0 Andy Chen 7 months ago in reply to Niklas Schwarz

Prodigy 100 points

My question is could the pri-Aux voltage be the sync singal.

I don't have the Pspice software, I just downloaded TI-Tina.

Thanks

0 Niklas Schwarz 7 months ago in reply to Andy Chen

TI__Mastermind 21110 points

Hi Andy,

Thanks for the update and sorry for the misunderstanding from my side.
So the questions is about a quasi-resonant Flyback implementation.

I have rather limited experience on QR-Flyback designs, so I will get in touch with a colleague who is an expert in this field.
I will get back to you with more feedback by tomorrow.

Regarding simulation models, we do not have a TINA model for LM5156. The available model we have runs on PSpice for TI, which can be downloaded for free here:
https://www.ti.com/tool/PSPICE-FOR-TI
I am sorry if this comes with additional inconveniences.

Best regards,
Niklas

+1 Niklas Schwarz 7 months ago in reply to Niklas Schwarz

TI__Mastermind 21110 points

Hi Andy,

Thanks for your patience.
I got some feedback on the QR-Flyback design.

The LM5156 is not fit for a quasi-resonant implementation.
This device is designed to run with a fixed frequency and the implementation idea with feeding into the sync pin has never been tested.

We have other devices from a different product line that are specialized on QR-Design, e.g. the UCC28600.
https://www.ti.com/product/UCC28600
In comparison to our controllers, these are more on the higher power side, so I am not fully sure if this still fits with your input voltage range.

Another part from the low power side would be from the LM25180 series.
https://www.ti.com/product/de-de/LM25180-Q1
This flyback device is not quasi resonant either, but has a regulation design that is closer to your requirements than the LM5156 device.

I would suggest to look into these device and open new e2e threads if there are additional questions.

Best regards,
Niklas

Power management

Power management forum

LM51561H-Q1：LM51561H-Q1 for QR-FLYBACK or 6V-60V input isolated DC/DC Converter with soft-switching