DP83867CS datasheet(39/114 Pages) TI1

39 / 114 page

VDD

470Q

GND

Mode 4

Mode 1

DP83867CS, DP83867IS, DP83867E

www.ti.com

SNLS504 – OCTOBER 2015

Table 10. RGMII Receive Clock Skew Details

RGMII CLOCK SKEW

MODE

RGMII RX CLOCK SKEW

RX[2]

RX[1]

RX[0]

2.0 ns

1.5 ns

1.0 ns

0.5 ns

4.0 ns

3.5 ns

3.0 ns

2.5 ns

9.5.2 LED Configuration

The DP83867 supports four configurable Light Emitting Diode (LED) pins: LED_0, LED_1, and LED_2. A GPIO

can also be configured to operate as an LED. Several functions can be multiplexed onto the LEDs for different

modes of operation. The LED operation mode can be selected using the LEDCR1 register (address 0x0018).

Since the LED output pins are also used as straps, 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.

If a given strap input is resistively pulled low then the corresponding output will be configured as an active high

driver. In the context of the 4-level straps, this will occur for modes 1, 2, and 3. Conversely, if a given strap input

is resistively pulled high, then the corresponding output will be configured as an active low driver. In the context

of the 4-level straps, this will occur only for mode 4.

Refer to Figure 18 for an example of strap connections to external components. In this example, the strapping

results in Mode 1 for LED_0 and Mode 4 for LED_1.

The adaptive nature of the LED outputs helps to simplify potential implementation issues of these dual purpose

pins.

Figure 18. Example Strap Connections

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DP83867CS Datasheet(PDF) 39 Page - Texas Instruments