DP83867CSRGZR.B datasheet(38/129 Pages) TI2

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7.5 Programming

7.5.1 Strap Configuration

The DP83867 uses many of the functional pins as strap options to place the device into specific modes

of operation. The values of these pins are sampled at power up or hard reset. During software resets, the

strap options are internally reloaded from the values sampled at power up or hard reset. The strap option pin

assignments are defined below. The functional pin name is indicated in parentheses.

The strap pins supported are 4-level straps, which are described in greater detail below.

Note

Because strap pins can have alternate functions after reset is deasserted, the pins can not be

connected directly to VDD or GND.

Configuration of the device can be done through the 4-level strap pins or through the management register

interface. A pullup resistor and a pulldown resistor of suggested values can be used to set the voltage ratio of

the 4-level strap pin input and the supply to select one of the possible selected modes.

The MAC interface pins must support I/O voltages of 3.3V, 2.5V, and 1.8V. As the strap inputs are implemented

on these pins, the straps must also support operation at 3.3V, 2.5V, and 1.8V supplies.

For more information about configuring 4-level straps, see the Configuring Ethernet Devices with 4-Level Straps

application report (SNLA258).

Rhi

Rlo

±25%

VDDIO

STRAP

DP83867

Figure 7-10. Strap Circuit

Table 7-5. 4-Level Strap Resistor Ratios

MODE

TARGET VOLTAGE

Recommended Rhi (kΩ)

Recommended Rlo (kΩ)

Vmin (V)

Vtyp (V)

Vmax (V)

0.098 × VDDIO

OPEN

0.140 × VDDIO

0.165 × VDDIO

0.191 × VDDIO

2.49

0.225 × VDDIO

0.255 × VDDIO

0.284 × VDDIO

5.76

2.49

0.694 × VDDIO

0.783 × VDDIO

0.888 × VDDIO

2.49

OPEN

For SGMII Mode 4 strap, TI recommends using Rhi = 4kΩ and Rlo = 10kΩ on RX_D0 and RX_D1 , RX_D2 and

RX_D3.

All straps have a 9kΩ ±25% internal pulldown resistor. The voltage at strap pins can be between the Vmin and

Vmax mentioned in the Target Voltage column in Table 7-5. Strap resistors with 1% tolerance are recommended.

DP83867CS, DP83867IS, DP83867E

SNLS504F – OCTOBER 2015 – REVISED JANUARY 2025

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