ZHCSAB9E September 2012 – June 2019 DP83848-EP
PRODUCTION DATA.
Since the auto-negotiation (AN) 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 outputs are used to drive LEDs directly, the active state of each output driver is dependent on the logic level sampled by the corresponding AN input upon power-up/reset. For example, if a given AN input is resistively pulled low then the corresponding output will be configured as an active high driver. Conversely, if a given AN input is resistively pulled high, then the corresponding output will be configured as an active low driver.
Refer to Figure 5-1 for an example of AN connections to external components. In this example, the AN strapping results in auto-negotiation with 10/100 half or full duplex advertised.
The adaptive nature of the LED outputs helps to simplify potential implementation issues of these dual purpose pins.