LM5122: LM5122

Ralph Somma

Part Number: LM5122
Other Parts Discussed in Thread: PMP21274

Tool/software:

Hello, I am trying to create a design for a boost converter using the LM5122 with the following requirements: Vin nom = 12, 10V<Vin<50; Iout nom =2.2A, 100mA<Iout<2.5A.

Power designer creates a design with Fsw=194kHz but shows constant duty cycle, unstable output voltage, strange inductor waveforms, requires 2x 180A low side Mosfets, requires a 36A inductor and throws an error when trying to export the design for Tina

I've varied the design parameters within reason but can't create a successful design, any idea what the trouble might be?

The design doesn't have to use the LM5122 but a high efficiency design >90% using a synchronous rectifier is preferred

Thanks, Ralph

10 months ago

0 Ralph Somma 10 months ago

Prodigy 10 points

0 Ralph Somma 10 months ago

Prodigy 10 points

I've also Chrome in addition to Firefox but still cannot export a design to either Tina or Altium

0 Niklas Schwarz 10 months ago in reply to Ralph Somma

TI__Mastermind 30520 points

Hi Ralph,

Thanks for using the e2e forum.
Based on your parameters, the LM5122 device should indeed be capable of supporting this application.
For alternative calculations tools to webench, I can recommend our quickstart designer.
https://www.ti.com/tool/download/LM5122-BOOST-CALC

You may also find a suitable reference design with a bench test report for these parameters within our library

https://www.ti.com/reference-designs/index.html#search?keyword=lm5122

Please also note that due to christmas time, further answers may be delayed due to vacation leaves.

Best regards,
Niklas

0 Ralph Somma 10 months ago in reply to Niklas Schwarz

Prodigy 10 points

Hi Niklas,

Thanks for your fast reply

The reference designs are very close to meeting our requirements, with the exception of Vin min=10V

Are you able to provide PMP21274 and PMP4341 in a form that can be imported into Tina or LTspice?

I really need to be able to simulate the designs to see how they perform at Vin=10V

Thanks, Ralph

0 Ralph Somma 10 months ago in reply to Ralph Somma

Prodigy 10 points

Also, given the specifications of PMP21274 and PMP4341 are so similar, do you know why two different designs were created? Is one design superior? Presumably, the newer design PMP21274 makes up for some shortcoming with PMP4341?

Thanks, Ralph

0 Johannes Braun 9 months ago in reply to Ralph Somma

TI__Intellectual 870 points

Hi Ralph,

Thanks for using e2e. Due to the Christmas holidays, most of our team is out of office, and will return on the 7th of January. Please expect some delays in our response. Thanks for your understanding.

Kind regards,

Johannes

0 Niklas Schwarz 9 months ago in reply to Johannes Braun

TI__Mastermind 30520 points

Hi Ralph,

We have the unencrypted model files for TINA and PSpice available on the product page. Both model should come with a testbench, which can be modified to match the system requirements.
The unencrypted library file can also be transferred to LTSpice, however, once the model got transferred to another simulator, we cannot provide support on debugging anymore.

It is indeed possible that some reference designs are very similar to each other. If a new design is developed which has just some minor spec changes, an existing design might be used as basis to speed up the creation process. The individual designs should not be superior or inferior to each other. If a reference design gets outdated, it will be removed from the reference library.

Best regards,
Niklas

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LM5122: LM5122