One Ethernet input to the POE controller. Is it can handle dual-signature in the PD application? If yes, are there any reference design or sample circuit?
IEEE 802.3bt defines two PD topologies: single-signature and dual-signature. Single-signature PDs present a valid detection signature on both pairsets, while dual-signature PDs present separate detection signatures on each of the two pairsets. From the definition of dual-signature, this topology requires two separate PD controllers. You can build a dual-signature PD with 2x LT4295s, or 2x LT4293s, or 2x LT4294s, I would only use LT4275 or LT4276 if you are building a Class 4 PD.
Why are you interested in a dual-signature PD instead of a single-signature PD? Dual-signature PDs require twice the components for little benefit. What kind of circuitry are you powering with your PD?
Thank you for your help. I want to have the POE up to 90W, and I can power up the components which one need 24V/1A and other needs 12v/5.5A. And I curious that Will be the dual signature high efficiency than single-signature and more stable?
Thank you for the clarification. If I use the LTPoE++ standard, I still can use the dual-signature PD, right? But each side the maximum power will be only 45W, right? And It will cost the double of the components compare with the single-signature PD,right?
No, LTPoE++ only supports single-signature, like IEEE 802.3af and IEEE 802.3at before it. You can always use multiple DC-DC converters inside a single-signature PD, so you can split the 90W between your 12V and 24V rails.
I need dual-signature LT4295.
I need PoE pass through (power 2 devices via 1 cable, 35.6W per device).
With single-signature I need to add PSE (LTC4291-1/LTC4292) into intermediate device.
With dual-signature I do not need PSE in the middle.
Can LT4295 work like dual-signature PD?