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RJ45 to Fiber Converters and Fiber to RJ45 Converters

fong circle
Prodigy 70 points
Other Parts Discussed in Thread: DP83849IF, DP83849IFVS-EVK

Hi there,

We need these converters to extend the distance of RJ45 cables. Now we are using a 3-rd party product, which works in physical layer (layer-1) with a latency of 0.9us. but the reliability of this product is a big issue. So we are wondering if we could build this product ourselves with TI chips, like DP83849 series. I just had a look at the some datasheets and also the evaluation board, but i am not very sure about this, especially the type of fiber port supported, (i.e., single-mode, multi-mode).

BTW, we only need one RJ45 port and one Fiber port for each device. they are both 100mbps, full-duplex. In addition, one single fiber to connect a pair of these converters is preferred, such as 1310nm (wavelength) at one side, and 1550nm at the other side.

Since i am new with this, so more details and information are greatly appreciated:) Thanks.

Best Regards,

Circle

  • 0
    Prodigy 70 points
    One more thing, we also tested another 3-rd party product, which working in store and forward mode with a latency of 96us. and it's not working. since we are using these converters in real-time industrial environment. The main reason is layer-2 working mode and also the big latency. Since we are using the Mechatrolink protocol from YASKAWA, layer-2 and above is not standard 802.3u.
  • 0 in reply to fong circle
    TI__Mastermind 31600 points
    Circle,

    For starters, I would like to direct you to some additional information on the DP83849.

    We have an application note on flexible port switching (which includes media converter operation) on the "Technical documents" tab of the DP83849IF product folder at:
    www.ti.com/.../technicaldocuments

    We also have a Media Converter - RJ45 to Fiber Converter reference design at:
    www.ti.com/.../tida-00306

    The DP83849IFVS-EVK supports media converter operation so you can purchase the board and evaluate the functionality in your lab if you would like.

    Patrick
  • 0 in reply to Patrick OFarrell
    Prodigy 70 points

    Hi Patrick,

    Thanks for your post.

    I read about the material, and i also googled related information, but i am still confused. Here are some specific questions,

    1. Can i build Fiber-to-RJ45 converters with this chip, of which the 100mbps conversion is implemented on Layer-1 (physical layer)? Is the method similar as RJ45 to Fiber converters?

    2. what is the fiber port type on DP83849IFVS-EVK, single-mode OR multi-mode? and the wavelength? Especially, how can i get a single-mode fiber port (1310nm or 1550nm) on the media converters with this chip?

    Thanks.

  • 0 in reply to fong circle
    TI__Mastermind 31600 points

    Fong,

    When the DP83849IF is operated as a media converter, the conversion happens in the Physical layer (layer 1).  The MII or RMII data that is received on one port is transmitted on the other port. 

    The DP83849IF does not include the fiber transceiver.  The transmit and receive pins connect to an industry standard Fiber Transceiver with PECL signalling through a capacitively coupled circuit.

    Patrick

  • 0 in reply to Patrick OFarrell
    Prodigy 60 points
    Hello,
    Following the reference design I putted the DP83849IF in one of my board with the aim of use it as a Media converter R45 to fiber.
    Maybe I made a big mistake, because something is not clear on the demo board: I thought that, using it as a Media converter, the RMII part of the two interfaces were connected internally. Now I am thinking that the TXD_A has to be connected to the RXD_B and RXD_A to TXD_B, but on the demo board this is accomplished using a cable between J9 and J14 connectors, is this correct? So on my board I have to realize the connection realized with the cable, is this correct?