LM5180-Q1: POE DC-DC Flyback

Rama Prasad

Part Number: LM5180-Q1
Other Parts Discussed in Thread: LM5180, LM5185-Q1, LM5185

Tool/software:

Hi TI Team,

I am currently facing Radiated Emission (RE) issues (EN 55032, CLASS B target) with a flyback design using the LT3758. I am looking for a low-EMI flyback controller from TI for the following requirements:

Input Voltage: PoE, 60V
Output Voltage/Current: 5V, 1A
Key Requirements: Small form factor and low EMI

I considered the LM5180, but its absolute maximum input voltage 965V) is very close to the POE operating voltage (57V). Could you please suggest a suitable alternative for this application?

Thank you for your support.

8 months ago

0 Youhao Xi 8 months ago

TI__Guru* 78060 points

TI has many PoE devices but they are supported by a different group. Let me forward this to them.

Best Regards,

Youhao

0 Richard Herring 8 months ago

TI__Mastermind 22995 points

Hello Rama,

I just reviewed this post that was reassigned, and I am not the expert on this device. I am confirming the correct team to assign this to.

Regards,

0 Ray DiCecco 8 months ago in reply to Richard Herring

TI__Genius 11350 points

Hi Rama, the Vin abs max for the LM5180 is 70V. 65V is the maximum operating Vin. Is this enough margin for your application?

Regards,

Ray

0 Rama Prasad 8 months ago in reply to Ray DiCecco

Prodigy 125 points

Hi Ray

I feel it's insufficient, as the PoE cable lengths in our end application are several hundred meters. Therefore, I prefer to use parts with at least an 85V minimum and a 100V rating for better reliability. Please suggest if you have a suitable option that can help mitigate the RE issue

0 Manuel Alva Hernandez 8 months ago in reply to Rama Prasad

TI__Genius 15336 points

Hi Rama,

The highest input voltage range in our family that can fit your requirements is LM5185-Q1 that have a VIN_max of 100V.

Thank you

0 Rama Prasad 8 months ago in reply to Manuel Alva Hernandez

Prodigy 125 points

I have gone through LM5185, Its a perfect match. But for 5V output i couldn't find any readily available transformer. So its to be customized. this will increase my project delivery plan. pls suggest if there is any transformer available for 9V-60Vin, 5Vout/1A

0 Manuel Alva Hernandez 8 months ago in reply to Rama Prasad

TI__Genius 15336 points

Hi Rama,

Do not know of any transformer available to step down to that voltage.

Thank you

0 Youhao Xi 8 months ago in reply to Manuel Alva Hernandez

TI__Guru* 78060 points

Hi Rama,

If you can consider the LM5185, please confirm your min input voltage. I am afraid 9Vin is a typo for PoE application. Is your operating Vin range really 9V to 60V?

Thanks,

Youhao

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LM5180-Q1: POE DC-DC Flyback