Power Requirements?

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This topic contains 1 reply, has 2 voices, and was last updated by  Daniel Shwartzberg 1 year, 6 months ago.

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    Are power requirements part of the HDBaseT certified?

    From my google research, there appears to be a lot of confusion around the power distribution features regarding HDBaseT.  At the wire level, HDBaseT conforms to the new IEEE 802.at‐2009 Power over Ethernet Plus (PoE+) standard.  The PoE+ devices can deliver up to about 25 watts of power over a single pair of wires which is DC power.

    First off –

    1. Seeing if there is a requirement from the manufacturers to send power over the HDBaseT connection to the receiving device from the power source on the transmitter end.  Understand, this eliminates the need to have yet another wall wart behind a display.  It is not clear if all vendors will support this configuration.

    2. Secondly, are there certain power requirements/standards set in place for baluns to receive particular voltages? Can manufacturer A determine their baluns only require 5v at each Balun where manufacturer B determines 12 or 24 volts at either endpoint?

    3. Any other document when it comes to power?

    Thank you

    Daniel Shwartzberg
    HDBaseT Alliance

    Hello – and thanks for the great question.

    Power is one of the five elements that HDBaseT can support (the others being AV, Ethernet, Controls and USB). And apart from AV, the HDBaseT Alliance does not demand equipment vendors implement any or all of the others. We do this for a couple of key reasons:

    • to allow for vendors to offer product differentiation at different price points (a high-end product may support all of the elements, while a low-end product can support a subset of them)
    • not all products require all five elements (for example, while a KVM extender needs to support USB, an AV matrix probably does not)

    This gives system designers and installers the option to chose the right products at the right price to meet their customers needs. So, as you correctly state, not all vendors implement power delivery over the link.

    The HDBaseT spec defines PoH (Power over HDBaseT), which is an “extension” of the IEEE POE/POE+ specs and is compatible with them. PoH can work over all 4 pairs in the cable – 2 for power delivery and 2 for return – and can operate with DC voltages of 44-57 V (48V is the standard voltage used by PoH modules in the equipment). Maximum current per wire pair is 1A. PoH defines five “Types” of power scheme:

    • Type 1 (based on IEEE 802.3af / 802.3at-type1)
    • Type 2 (based on IEEE 802.3at-type2)
    • Type 2-Twin (based on IEEE 802.3at-type2 [two power interfaces] but only defined in the HDBaseT spec)
    • Type3 (defined in HDBaseT spec)
    • Type3-Twin (defined in HDBaseT spec)

    Given a 1A max per wire pair, this means that Type3-Twin yields 48V*1A*2pairs = 96W of DC power theoretically on a very short cable. Since power is dissipated in the cable, we can guarantee maximum of 72W will be available over a 100m cable. Depending upon the power needs of the product, the vendor will choose which Type of PoH to implement. This means that when choosing products you must ensure that the Power Sourcing Equipment (PSE) is compatible with the Powered Device (PD) in terms of the amount of power being delivered over the cable.

    The HDBaseT Alliance website has a listing of all certified products. You can find it here: https://hdbaset.org/advanced-search/ . You can search for products that are PSE or PD according to your needs. Unfortunately, restrictions prevent us from stating the PoH Type, and for that you should refer to the vendor documentation. Note that PoH is the only power delivery scheme that the HDBaseT Alliance will certify, since it is extremely safe. I should mention that the certified product listing details all the elements of HDBaseT that the product supports (not only the power), so you can be sure to choose equipment for both sides of the link that meets your needs. Only spec/buy certified products, as this guarantees that the products have passed testing at the Alliance Certification Lab and so will interoperate.

    Hope this (long) answer has helped clarify things for you.

    Take care.


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