DS80PCI402 Datasheet, PDF (14/39 Pages) Texas Instruments – 2.5 Gbps / 5.0 Gbps / 8.0 Gbps 4 Lane PCI Express Repeater with Equalization and De-Emphasis

Table 3: Output Voltage and De-emphasis Settings
Level
DEMA1 DEMA0
DEMB1 DEMB0
VOD Vp-p
DEM dB
Inner Amplitude
(see note below)
Vp-p
Suggested Use
1
0
0
0.8
0
0.8
FR4 <5 inch 4–mil trace
2
0
R
0.9
0
0.9
FR4 <5 inch 4–mil trace
3
0
Float
0.9
- 3.5
0.6
FR4 10 inch 4–mil trace
4
0
1
1.0
0
1.0
FR4 <5 inch 4–mil trace
5
R
0
1.0
- 3.5
0.7
FR4 10 inch 4–mil trace
6
R
R
1.0
-6
0.5
FR4 15 inch 4–mil trace
7
R
Float
1.1
0
1.1
FR4 <5 inch 4–mil trace
8
R
1
1.1
- 3.5
0.7
FR4 10 inch 4–mil trace
9
Float
0
1.1
-6
0.6
FR4 15 inch 4–mil trace
10
Float
R
1.2
0
1.2
FR4 <5 inch 4–mil trace
11
Float
Float
1.2
- 3.5
0.8
FR4 10 inch 4–mil trace
12
Float
1
1.2
-6
0.6
FR4 15 inch 4–mil trace
13
1
0
1.3
0
1.3
FR4 <5 inch 4–mil trace
14
1
R
1.3
- 3.5
0.9
FR4 10 inch 4–mil trace
15
1
Float
1.3
-6
0.7
FR4 15 inch 4–mil trace
16
1
1
1.3
-9
0.5
FR4 20 inch 4–mil trace
Note: The VOD output amplitude and DEM de-emphasis levels are set with the DEMA/B[1:0] pins.
The de-emphasis levels are also available in GEN 3 mode when RATE = 1 (tied to VDD).
Table 4: RX-Detect Settings
PRSNT#
0
0
0
0
1
RXDET
0
Tie 20kΩ
to GND
Float
(Default)
1
X
SMBus REG
bit[3:2]
00
01
10
11
Input Termination Termination sensed Comments
on output pins
High Impedance
X
Manual RX-Detect, input is high
impedance mode
High Impedance High Z until receiver Auto RX-Detect, outputs test every 12
50 Ω
is detected
msec for 600 msec then stops; termination
is high-z until detection; once detected
input termination is 50 Ω
Reset function by pulsing PRSNT# high for
5 usec then low again
High Impedance High Z until recevier Auto RX-Detect, outputs test every 12
50 Ω
is detected msec until detection occurs; termination is
high-z until detection; once detected input
termination is 50 Ω
50 Ω
X
Manual RX-Detect, input is 50 Ω
High Impedance
X
Power down mode, input is high
impedance, output drivers are disabled
Used to reset RX-Detect State Machine
when held high for 5 usec
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