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TLK2501EVM: TLK2501 - optical interface problem

Marco Signoretti
Prodigy 20 points
Part Number: TLK2501EVM
Other Parts Discussed in Thread: TLK2501

Hi,

I have two boards TLK2501 EVM that i want connect with optical fiber. In each board I have mounted a clock generator with frequency = 125MHz and i have two power supply VDD =2.5 V e VCC=3.3V,

Connector J7 in each board are in this state:

TESTEN = GND

PRBSEN = GND

LOCKREFN = '1' or "high"

ENABLE =  '1' or "high"

TX_ERR = GND

LOOPEN = GND

TX_EN = '1' or "high"

I have mounted in each board the optical transceiver (pn HFBR 5961ALZ).

In this configuration, if i connect the two boards with SMA cable, i see the same signal on the oscilloscope the signals TD0 (Connector J1 of board #1) and RD0 (Connector J3 of board #2). 

If i connect the optical interface with loopback with TXP and LTXP etc etc, i see with the oscilloscope the signal RD0 (Connector J3 of board #2), with a lot of noise.

which is the correct configuration to transmit in optical fiber between two evaluation board? some advice?

I have the screenshot of the setup and the wave form if necessary.

Best regards

Marco

  • 0
    TI__Genius 16150 points

    Hi Marco,

    It seems an interfacing issue due your system is working with SMA cable but not when you connect the optical cable through an optical transceiver. I took a look into the HFBR-5961ALZ and it seems this interface handles LVPCEL signals while the TLK2501 accepts CML signals, hence you should adapt the signals to link up the devices.

    Please take a look into this application note where you can find how to interface between different signals.

    www.ti.com/.../slla120.pdf

    I hope this helps.

    Best Regards,

    Luis Omar Moran

    High Speed Interface

    SWAT Team

  • 0 in reply to Luis Omar Moran
    Prodigy 20 points

    thank you Luis,

    if i want use a cots high speed transceiver with CML compatible signals ( different from Netlight 1417K4A that it is impossible to find at the "market" ), which is the part number that Texas Instruments reccomends?

    Best regards,

    Marco