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TPS23861: Power injector with 4-pairs(2x2 pair 45W) using TPS23861 Single-port.

BJ Han
Expert 2035 points
Part Number: TPS23861
Other Parts Discussed in Thread: , MSP430G2553

Dear TI,

I'm developing power injector with 4-pairs(2x2 pair 45W) using TPS23861 Single-port.

-Spec (10/100/1000 Data Rates)

Class

Type

#Pairs

Power Sourced at PSE

5

3

4

45W

I intend to develop using 2-Ports. Is it possible?

Also, do you need an additional MCU to be compatible with Endspan and Midspan?

If there is no MCU in the 2(PSE) x 1(PD) solution, the 2 PSE will perform detection and classification at same time.

Thus, the detection and classification not conflict?

Do I need an external 3.3V power to drive the TPS23861?

  • 0
    TI__Genius 9230 points
    Hi BJ,

    I have notified our PSE expert, Penny. She can provide assistance, shortly.

    Thanks,
    Thomas A.
  • 0
    TI__Genius 15655 points

    Hi BJ,

    Are you doing to design IEEE802.3BT PSE injector?  TPS23861 is compliant to IEEE802.3at standard. It can only support to Type 2, class 4. If you need high power, you can control TPS23861 through an external MCU(we use MSP430G2553 on our EVM). You need to disable on channel's detection and classification, turn on one channel first and then force to turn on the second channel in manual mode. TPS23861 needs external 3.3V power supply.  you can refer to TPS23861EVM-612 schematic to do your design. Please follow the power on sequence described in http://www.ti.com/lit/an/slva723/slva723.pdf.  Thanks.

    Best regards,

    Penny

  • 0 in reply to Penny Xu
    Expert 2035 points

    Hi Penny,

    Thank you for your reply.

    In the TPS23861 2x1 solution(2 PSE ports and 1 PD interface = UPoE or PoE ++), Do you need a MCU?
    In the TPS23861 2x2 solution(2 PSE ports and 2 PD interface = at + at), Do you need a MCU?

    If you design in this way, is it compatible with existing IEEE802.3af and at? (PD application : IP Telephone, IP Camera.. etc..) 

    What is the MAX output per channel for the TPS23861?

    Thank you.

  • 0 in reply to BJ Han
    TI__Genius 15655 points
    Hi BJ,

    In the TPS23861 2x1 solution(2 PSE ports and 1 PD interface = UPoE or PoE ++), you do need an MCU to set one channel in manual mode and disable that channel's detection/classification and once the first channel is fully turned, the MCU needs to force turn on the second channel.
    In the TPS23861 2x2 solution(2 PSE ports and 2 PD interface = at + at), if you need the power up to 60W in total 2 channels, you don't need an MCU since two channels can operate separately like 2 .at channels.

    As for today, any high power solutions(>30W, like UPoE, PoE++, HDBaseT) are non compliant. The upcoming IEEE802.3bt standard will be ratified next year which can support up to 90W from the PSE side. We are developing a new PSE device which will be compliant to .bt standard.

    The highest current limit of TPS23861 is 920mA per channel. For example, you DC voltage is 52V, the max power per channel is 48w.

    Best regards,
    Penny
  • 0 in reply to Penny Xu
    Expert 2035 points
    HI Penny,
    Thanks for your detailed explanation.
    Does this mean that you can not be compatible with existing PD devices(.af and .at) in the circuit configuration?
    So, how do you design if you do not know whether a PD device is 1chip(2x1) or 2chip(2x2)?

    I am sorry to interrupt you because I am defining the development concept.
  • 0 in reply to BJ Han
    TI__Genius 15655 points
    Hi BJ,

    No. The non compliant doesn't mean it can't detect or classify standard PD. It is just because the high power is not defined in the current standard. For the UPoE system, there are usually two kinds of structures: LLDP(1 PD) and Forced UPoE(2 PDs). The LLDP approach usually doesn't need hardware classification. The PD is turned on at 15W first and the power negotiation is done by data line. The forced UPoE is to have 2 channels to do detection and classification at the same time and they don't impact each other. So in your system, do you have LLDP? Or you will reply on hardware classification to do power negotiation?

    Best regards,
    Penny
  • 0 in reply to Penny Xu
    Expert 2035 points
    Hi Penny,

    Thanks for your detailed explanation.

    Do I mean using LLPD to recognize PD?
    If so, this will not be implemented in this model.