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TUSB9260 SATA_TXP/TXM Swap

Scott McElroy1
Intellectual 2155 points
Other Parts Discussed in Thread: TUSB9260, TPS2560

Team,

I know I have seen posts on this before but I haven't really been able to get a definitive answer to the questions that I have below.

1-     On Page 19 of the TUSB9260 Demo Board Guide, there is a note saying that the Tx differential pair  between TUSB9260 and SATA connector were swapped to simplify board layout and the firmware has taken this swap into account.  I’m assuming that the firmware the customer gets with this device doesn’t have this Tx swapping. Is that true? If not, is there a way to get a hold of it. Or should the pins be swapped.

2- Also on page 19, why power pins 38, 49, and 63 for the TUSB9260 device are not lumped in with the other Vdd power pins. One is terminated to USB2_1p1V.  Is there a reason for treating these Vdd pins differently?

3- I had to deviate a bit from the reference design because the SATA drive 
 that we will be powering will require more current and is also powered by +3.3V and not 5V which is what the reference design is doing. So I’m using another TI switcher to produce 3.3V.  My question is in regards to the usage of TPS2560 which limits the inrush current. The demo guide recommends using the TPS2560 device. Is it still recommended that I use a TPS2560 with the scenario that I described since now we have the SATA drive being powered by 3.3V and with VBUS being 5V there should be no direct path between the two rails?

Help on this would be greatly appreciated, Thank you in advance.

  • 0
    TI__Guru* 76130 points

    Hello Scott, see my answers below:

    1) The default firmware available at ti.com implements the TX_swap, so if you are using the default firmware you must swap the TX pair, there is a firmware version which do not implement this swapping, I can send it to you upon request.

    2) Those pins are for the analog 1.1V rail, for some reason the datasheet and the Imp guide does not match, the recommendation is to implement these pins independent from the other VDD11.

    3) You can "replace" the TPS2560 with your power switch, just make sure you provide the functionality of the TPS2560, this is the inrush protection for the 5V and 3.3V rails.

      Regards.

  • 0 in reply to Elias Villegas M.
    TI__Intellectual 2155 points

    Elias,

    I appreciate the answers to these questions. The first two question make perfect sense to me, but could you please clarify what you mean by the last question. I'm not quite sure if I understand your answer very well. Thanks.

  • 0 in reply to Scott McElroy1
    TI__Guru* 76130 points

    Probably I didn't understand the question,

    What I'm trying to say is that you can replace the power switch with another one that meets your requirements, but you still need to use a power management device like the EVM implementation.

    Regards.