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Negative voltage supply

Category: Datasheet/Specs
Product Number: LTC4279 PSE PoE, LTC4279

Hi, i'm looking about Poe PSE controller and i find your LTC4279 LTPOE++. I can't understand why  is used a negative voltage to supply the LTC4279. The positive is the AGND and the reference is VEE at -55V. I have never seen the same connections on PSEs of other productors. I think easy to resolve connecting the +55V on AGND and the ground on VEE but i'm perplexed, Is it only for convention or there are specific reason?

Bye

  • IEEE calls out a requirement where the PSE shall switch the more negative rail.

    Negative voltage is a typical convention used by other PSE products.

    The PoE supply is floating since isolation is required.  The convention of the PSE input supply does not matter to the PSE as long as the high side is connected to the LTC4279 AGND and the low side is connected to the LTC4279 VEE.