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DP83848K: LED_SPEED

zhang ping
Genius 3865 points

Part Number: DP83848K

We found the following problems when using DP83848K:

When set to 10M/100M adaptive, LED_SPEED can be expected to be OFF at 10M and ON at 100M.

But when the cable is not plugged in, it is also ON, is this normal? What should I do if I want to be OFF when the network cable is not connected?

  • 0
    TI__Guru**** 217450 points

    Hello Zhang ping, 

    Thank you for the query.

    Can you please share the schematics. 

    Regards,

    Sreenivasa

  • 0 in reply to Kallikuppa Sreenivasa
    TI__Guru**** 217450 points

    Hello Zhang ping, 

    Did you resolve the issue ?

    Regards,

    Sreenivasa

  • 0 in reply to Kallikuppa Sreenivasa
    Genius 3865 points

    I want to know what state will be recognized when the network cable is not inserted again, ON or off?

  • 0 in reply to zhang ping
    TI__Guru**** 217450 points

    Hello Zhang ping, 

    Please see if the below helps.

    Since i do not have the schematics, i would request you to look at the configuration on the board and make the required changes.

    LED Direct Control Register (LEDCR)

    6.3.3.1 LED Because the Auto-Negotiation strap options share the LED output pins, the external components required for strapping and LED usage must be considered in order to avoid contention. Specifically, when the LED output is used to drive the LED directly, the active state of the output driver is dependent on the logic level sampled by the AN input upon power up/reset. For example, if the AN input is resistively pulled low then the corresponding output will be configured as an active high driver. Conversely, if the AN input is resistively pulled high, then the corresponding output will be configured as an active low driver. Refer to Figure 6-1 for an example of AN connection to external components. In this example, the AN strapping results in Auto-Negotiation with 10BASE-T Half-Duplex , 100BASE-TX, Half-Duplex advertised. The adaptive nature of the LED output helps to simplify potential implementation issues of this dual purpose pin.

    Regards,

    Sreenivasa