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66AK2H14: MDIO level translator

Madhu Sharma
Expert 2915 points

Part Number: 66AK2H14
Other Parts Discussed in Thread: PCA9306, TXS0102

Hi,

In the EVB of K2H SOC, PCA9306DCUT is used for level translating MDC and MDIO signals. 

Please clarify below mentioned related to this:

1) In the EVB, I noticed that signals are given 220E pull up to 2.5V supply ( VCC_2V5), but the VREF2 pin of the IC connected to 3.3V. As per my understanding, VREF2 must be connected to 2.5V. Is there any specific reason for connecting it to 3.3V?

2) Using PCA9306DCUT, Is it possible to work with maximum speed that is supported by MDC/ MDIO interface ?

Thanks & Regards,

Madhu

  • 0
    TI__Guru**** 161600 points
    Hi,

    As per my understanding, VREF2 must be connected to 2.5V. Is there any specific reason for connecting it to 3.3V?

    Have a look at PCA9306 datasheet (www.ti.com/.../pca9306.pdf), section 6.3 Recommended Operating Conditions. Both VREF1 and VREF2 operate between 0 V and 5.5 V, with the following note:
    "(1) To support translation, VREF1 supports 1.2 V to VREF2 - 0.6 V. VREF2 must be between VREF1 + 0.6 V to 5.5 V. See Typical Application for more information."

    2) Using PCA9306DCUT, Is it possible to work with maximum speed that is supported by MDC/ MDIO interface ?

    It should be possible to support the max speed of the interface.

    Best Regards,
    Yordan
  • 0
    TI__Mastermind 42545 points
    Hi Madhu,
    While the PCA9306 device will operate as an MDIO voltage translator at full speed, we found that the routing could cause some glitching on the clock signal. This was solved on the K2H EVM but we moved to a better solution on the K2E EVM. That part is the TXS0102DCUR. I would recommend that you use that in place of the PCA9306. You can download the K2E EVM schematics to show how it is connected.
    Regards,
    Bill
  • 0 in reply to Bill Taboada
    Expert 2915 points

    Hi Bill,

    Thanks for the valuable information.

    I am interfacing four ethernet interfaces to single SOC. So can I route management clock and data outputs from TXS0102 to all the four PHYs in parallel? 

    Please suggest if there is any better way to connect common management signals to four ethernet PHYs.

    Thanks & Regards,

    Madhu.

  • 0 in reply to Madhu Sharma
    Expert 2915 points

    Hi Bill,

    Adding to above query, in K2E EVM, TXS0102 is used only for MDIO signal. For MDC, SN74LVC8T245RHLR is used. Can I use the same for my case?

    Regards,

    Madhu