• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 33 subscribers
  • Views 529 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DP83TC811R-Q1: Strapping Questions

Steve Patterson
Intellectual 570 points

Part Number: DP83TC811R-Q1

I'm trying to design the 100BaseT1 PHY into our system and ran into the following strapping questions (and a few other questions):

  • Is there an internal Power On Reset function? The datasheet seems to imply that there is, but it’s not explicitly stated. In other words, does it need a reset signal input, or will it POR on its own if the reset pin is left floating?
  • One cannot use the default strapping of RX_D0 - RX_D2 because that would be MAC[2:0] = 0, which is Reserved per Table 20. Correct? This seems odd that the default configuration is not a valid one.
  • On strapping the LED_0/1, Figure 28 shows the connection, but Rp is not specified. What resistor value should be used?
  • On strapping the LED_0/1, what’s the default if no strap is applied (i.e. only the LED and current limit R)? Figure 28 shows no default, yet Table 18 lists a default.
  • Is there an errata for this PHY?

Thanks for any info on these items.

  • 0
    TI__Mastermind 18425 points
    Hello Steve,

    The device does have POR. It does not need a Reset signal and can operate if the reset signal is left floating.
    Yes, the default for MAC[2:0] mode is reserved. This is due to the order in which MAC modes are tied to strap pins.
    For Rp, 2.49kohm resistor can be used. Mode 4 resistor value is recorded in the strap table but I can see that mode 1 value is not clearly mentioned. We will loop that in the next revision of the datasheet.
    The default when no other component is connected on LED pins is Mode 1. When LEDs are used, it is required to use strap resistors to put it in Mode 1 or Mode 4.
    We typically do not create Errata for our parts. Any significant update to the product that will affect customer application is recorded in the datasheet in form of datasheet revision. The datasheet also has a Revision History section which contains details of all the changes.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    Intellectual 570 points
    Thanks for the timely and complete answers, Aniruddha. One quick suggestion on datasheet clarity - Figure 28 lists the implementation for the LED Pull Up and Pull Down, but does not directly tie this into which mode each selects. I believe a pull-down selects Mode 0, but an explicit statement or just changing Pull Up/Down to Mode 1/4 would make it explicit. Thanks again!