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DP83822IF: DP83822 use for FX

user6019263
Prodigy 220 points
Part Number: DP83822IF
Other Parts Discussed in Thread: DP83822HF, TIDA-00928

Hi:

     I have several question regarding for DP83822 .

      i> the latest Dp83822hf  datasheet 2019 verdion, both of VDDIO and AVD can use 1.8V , whle old version for AVD can only use 3.3V , how can I choise the AVD . 

      ii>I use TIDA-00928  reference to desing the 83822,I want to use 100base-FX mode with AFBR5803z model  , regarding for COL signal  bootstrap, from the bootstrap table , should config with mode 2, or 3, but in TIDA-00928 which connect to GND with 2.2K parellar with 470 ohm and LED , if this config ok ? what is the meaning for LED ?

     iii>when config RX-ER with 13K and 1.96K , the LED_1 will as signal detection and is active LOW ,it is digical signal , but AFBR 5803 SD output is PECL , if it is can direct drive 83822 LED_1.

regard

Jonathan

  • 0
    TI__Mastermind 18425 points

    Hi Jonathan,

    i> Yes, DP83822 can support 3.3V and 1.8V for AVD. You can use either of the voltage levels. Please note that Analog supply (AVD) and magnetic center tap must be at the same potential.

    ii> COL pin can be used as GPIO2 and can also work as LED. If you don't want to use it as LED, then do not follow the schematic of TIDA-00928. You can just strap it to mode 2 or mode 3 to enable fiber mode.

    iii> LED_1 pin is CMOS. In order to transition from PECL to CMOS, you would need a buffer. You can opt for a different Fiber transceiver that can support CMOS Signal Detect output. DP83822 can work with SFF and SFP tranceivers rated for 100Base-FX ethernet.

    -Regards

    Aniruddha

  • 0 in reply to Aniruddha Khadye
    Prodigy 220 points

    Hi:

         got , thank you,

              one more question regarding bootstrap. I design as FX mode  with RGMII,so I config as COL mdoe 3 with RH=6.2K, RL=1.96K, RX_ER as mode 2  with RH=13.3K, RL=1.96K, RX_DV as mode 1,thank means no RH and no RL .

        if it is ok for my set ? but see some E2E question , you advice set RX_ER as mode 4, from 83822 datasheet , that means the the SD_DIS are  disable , so which is right .

    Regards

  • 0 in reply to user6019263
    TI__Mastermind 18425 points

    Hi,

    If you want FX with RGMII then RX_ER should be mode 3 to enable RGMII and SD_EN. Please refer to the latest datasheet from ti.com. The strap table on page 48 has been updated since there was a error. RX_ER strap is "SD_EN"

    COL as mode 3 and RX_DV as mode 1 is ok.

    -Regards

    Aniruddha