DP83867CS datasheet(36/114 Pages) TI1

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Rhi

Rlo

±25%

VDDIO

STRAP

DP83867

DP83867CS, DP83867IS, DP83867E

SNLS504 – OCTOBER 2015

www.ti.com

9.5 Programming

9.5.1 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

Since strap pins may have alternate functions after reset is deasserted, they should not be

connected directly to VDD or GND.

Configuration of the device may be done via the 4-level strap pins or via the management register interface. A

pullup resistor and a pulldown resistor of suggested values may 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 3.3 V, 2.5 V, and 1.8 V. As the strap inputs will be

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

The device should feature 4-level strap pins, each supporting at least 4 selectable options.

Figure 17. Strap Circuit

Table 6. 4-level Strap Resistor Ratios

MODE

Target Voltage

IDEAL Rhi (k

Ω)

IDEAL Rlo (k

Ω)

Vmin (V)

Vtyp (V)

Vmax (V)

0.065*VDDIO

OPEN

0.139*VDDIO

0.15*VDDIO

0.16*VDDIO

2.49

0.228*VDDIO

0.244*VDDIO

0.256*VDDIO

6.04

2.49

0.728*VDDIO

0.783*VDDIO

0.82*VDDIO

2.49

OPEN

For SGMII Mode 4 strap, it is recommended to use Rhi=4k

Ω and Rlo=10kΩ on RX_D0 & RX_D1 , RX_D2 &

RX_D3.

All straps have a 9k

Ω ±25% internal pull down resistor. The voltage at strap pins should be between the Vmin

and Vmax mentioned in the 'Target Voltage' column in the table above. Strap resistors with 1% tolerance are

recommended.

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