0

50

100

150

200

250

0

10k 20k 30k 40k 50k 60k 70k 80k

SD_TH RESISTOR VALUE (:)

DS50PCI401

www.ti.com

SNLS292J – JUNE 2009 – REVISED APRIL 2013

Table 3. De-Emphasis Input Select Pins for A and B ports (3–Level Input) (continued)

RATE

DEM1

Typical De-

Typical DE Pulse

Typical VOD

Suggested Use

(1)

)

Emphasis Level

Width

1/F

1

0

-6dB

200ps

1000mV

1/F

1

1

-6dB

200ps enhanced

1000mV

10 inches FR4 (6-mil trace)

1/F

0

F

-9dB

200ps enhanced

1000mV

1/F

1

F

-12dB

200ps enhanced

1000mV

1/F

F

0

-9dB

200ps enhanced

1200mV

20 inches FR4 (6-mil trace)

1/F

F

1

-12dB

200ps enhanced

1400mV

30 inches FR4 (6-mil trace)

1/F

F

F

Reserved, don't

use

Table 4. Idle Control (3–Level Input)

TXIDLEA/B

Function

0

This state is for lossy media, dedicated Idle threshold detect circuit disabled,

output follows input based on EQ settings. Idle state not guaranteed.

Float

Float enables automatic idle detection. Idle on the input is passed to the

output. This is the recommended default state. Output driven to Idle if diff input

signal less than value set by SD_TH pin.

1

Manual override, output forced to Idle. Diff inputs are ignored.

Table 5. Receiver Electrical Idle Detect Threshold Adjust (Analog input - connect Resistor to GND or

Float)

SD_TH resistor value (

Typical Receiver Electrical Idle Detect Threshold (DIFF p-p)

Float (no resistor required)

130mV (default condition)

0

225mV

80K

20mV

(1)

SD_TH resistor value can be set from 0 through 80K Ohms to achieve desired idle detect threshold, see Figure 1. 8K Ohm is approx

130mV.

Figure 1. Typical Idle threshold vs SD_TH resistor value

Table 6. Receiver Detect Pins for A and B ports (LVCMOS inputs)

PRSNT#

ENRXDET

RXDETA/B

Function

0

1

0

Disable RXDETA termination mode: Rx detection state machine disabled. Input

termination >50K

Ω. Associated output channels in low power idle mode.

0

1

1

Force RXDETA termination mode: Rx detection state machine disabled. Input termination

50

Ω. Associated output channels set to active.

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