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TXB0104: TXB0104

stephen malchi
Intellectual 385 points
Part Number: TXB0104
Other Parts Discussed in Thread: SN65LVDS100

Hi,

Can we use TXB0104RGY for differential signals or is there are level translator for differential signal with the same footprint?

We are already using this translator on our board, but now the customer wants to use the signals as differential and we were wondering if we could use the same or a different part without a PCB change.

Rgds,

Stephen

  • 0
    TI__Intellectual 2100 points
    Hey Stephen,

    This chip can't be used for LVDS differential signals, it can only be used for CMOS single ended signals. I have a couple questions to aid in finding you a suitable part and are as follows:

    - What type of signals are you trying to use (I ask in case maybe there is an application specific chip that should be used)?
    - What speed of signals do you plan on using?

    Best Regards,
    Nick
  • 0 in reply to Nicholas Mariani9
    Intellectual 385 points
    Hi Nick,

    We want to translate LVPECL to LVDS.
    Speeds from 10MHz to 150 MHz

    RGds,
    Stephen
  • 0
    TI__Intellectual 2100 points

    Hi Stephen,

    Unfortunately, I'm  not seeing a part that is pin/pad compatible with this one that can do what you want. I have come across the part SN65LVDS100 which is classfied as a "repeater/buffer/translator" and should be able to convert your signal from LVPECL to LVDS up to 2Gbps (Yes, this is high but the chip is designed to be highly flexible). The major downside is that it is only one channel so you will have to use one for every diff pair. Take a look at it and let me know if it matches what you're looking for.

    You can find more differential components and solutions here.

    If you have any more questions or additional parameters let me know and I'll swing back and help you out.

    Best Regards, 

    Nick

    If this answered your question please hit the green "Verify Answer" button below near the red "Reply" button!

  • 0 in reply to Nicholas Mariani9
    Intellectual 385 points

    Hi Nick,

    Thanks for the quick response. I was looking at SN65LVDS100 part it looks good but we have lot of differential pairs and I was wondering if we can use pull up /down resistors as described in this application note by TI please see page 4 figure 4

    http://www.ti.com.cn/cn/lit/an/scaa062/scaa062.pdf

    The LVPECL signals on our board are coming from outside world and the LVDS signals are going to Xilinx 7-series FPGA.

    Rgds,

    Stephen

  • 0 in reply to stephen malchi
    TI__Intellectual 2100 points

    Is your LVPECL going to exceed the 3.6 volt input threshold on the SN65LVDS100? If it does that's fine, but you will have to use the figure 4 termination setup from that document where you have the 33 ohm series termination resistor for input current limiting. If not, then you should use the figure 5 50 ohm (technically 50.56) termination with the 130 ohm to the supply rail and 83 ohm to GND.

    I looked a little more and I actually found this part (DS90LV804) that should work in your application too. I bet you'd prefer this since it allows 4 channels per chip! It is in a WQFN package so it can be a pain to hand solder if prototyping but can be done with a hot air rework station. It also goes to 4.3 volts on the inputs so you get a bit more headroom. The trade off is in speed, it only goes 800Mbps, not a problem for your application.

    Let me know what you think.

    Best,

    Nick

    If this answers your question, please hit the green "Verify Answer" button near the red "Reply" button!