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DP83822IF: LED_1 straps and MDI termination

Bernhard Boehmer
Expert 1200 points
Part Number: DP83822IF


Hello TI,

snls505g Fig. 9.2 on p.104 shows the 49R9 resistors connected to "3.3V supply" and the transformer centre taps to AVD Supply. Since AVD could be 1.8V, this connection is unfortunate. Better would probably be to follow TIDA-00928E2(001)_CU and connect the 49R9 resistors to AVD and leave the transformer centre taps only connected to decoupling caps.

Table 8-10 on p. 49 describes possible straps for LED_1 as either Mode 1 or Mode 4. What is the difference between these two, please?

Other strap values seem to be readable in register 0x0467, however, LED_1 is not represented there. Is this correct?

  • +1
    TI__Mastermind 20696 points

    Hi Bernhard, 

    Bernhard Boehmer said:
    snls505g Fig. 9.2 on p.104 shows the 49R9 resistors connected to "3.3V supply" and the transformer centre taps to AVD Supply. Since AVD could be 1.8V, this connection is unfortunate. Better would probably be to follow TIDA-00928E2(001)_CU and connect the 49R9 resistors to AVD and leave the transformer centre taps only connected to decoupling caps.

    The figure is wrong and we are in the process of updating this figure. The 49.9 resistors MUST be connected to AVD, not 3.3V supply at all times. 

    The center taps also must be connected to the AVD. 



    Bernhard Boehmer said:
    Table 8-10 on p. 49 describes possible straps for LED_1 as either Mode 1 or Mode 4. What is the difference between these two, please?

    There is no difference. 


    Bernhard Boehmer said:
    Other strap values seem to be readable in register 0x0467, however, LED_1 is not represented there. Is this correct?

    Your understanding is correct. 

    Best,
    J