The TUSB521-Q1 used in a device
application enables the system to pass USB 3.1 Gen 1 transmitter and receiver
compliance. The TUSB521-Q1 recovers incoming data by applying equalization that
compensates for channel loss, typical FR4 channel loss is provided in
Table 3-3. The amount of equalization the TUSB521-Q1 is configured to provide to the signal
needs to be set according to the amount of loss before the signal enters the device,
also known as the pre-channel. The EQ settings for the TX and RX lanes of the USB3.1
signal can be set independently either through pin-strap or through I2C. For pin-strap,
The equalization selection is configured through the EQ and SSEQ pins. The USB
equalization values available for the TUSB521-Q1 are listed in
Table 2-2.
Table 2-1 Example FR4 Trace Loss At
5GBps
| FR4 PCB Trace Length
(Inches) |
Loss at 2.5GHz
(dB) |
| 1 |
0.5 |
| 2 |
1 |
| 3 |
1.5 |
| 4 |
2 |
| 5 |
2.5 |
| 6 |
2.9 |
| 7 |
3.4 |
| 8 |
3.9 |
| 9 |
4.4 |
| 10 |
4.9 |
| 11 |
5.4 |
| 12 |
5.9 |
| 13 |
6.4 |
| 14 |
6.9 |
Table 2-2 TUSB521-Q1 Receiver
Equalization GPIO Control
EQUALIZATION
SETTING # |
RX1 and RX2 PORTS |
SSTX PORT |
| EQ1 PIN LEVEL |
EQ0 PIN LEVEL |
EQ GAIN AT 2.5GHz (dB) |
SSEQ1 PIN LEVEL |
SSEQ0 PIN LEVEL |
EQ GAIN AT 2.5GHz (dB) |
| 0 |
0 |
0 |
–0.7 |
0 |
0 |
–0.9 |
| 1 |
0 |
R |
1.8 |
0 |
R |
0.2 |
| 2 |
0 |
F |
2.7 |
0 |
F |
1.1 |
| 3 |
0 |
1 |
3.7 |
0 |
1 |
2.2 |
| 4 |
R |
0 |
4.6 |
R |
0 |
3.0 |
| 5 |
R |
R |
5.5 |
R |
R |
4.0 |
| 6 |
R |
F |
6.3 |
R |
F |
4.8 |
| 7 |
R |
1 |
7.0 |
R |
1 |
5.6 |
| 8 |
F |
0 |
7.8 |
F |
0 |
6.4 |
| 9 |
F |
R |
8.5 |
F |
R |
7.0 |
| 10 |
F |
F |
9.1 |
F |
F |
7.6 |
| 11 |
F |
1 |
9.7 |
F |
1 |
8.2 |
| 12 |
1 |
0 |
10.1 |
1 |
0 |
8.7 |
| 13 |
1 |
R |
10.7 |
1 |
R |
9.2 |
| 14 |
1 |
F |
11.1 |
1 |
F |
9.7 |
| 15 |
1 |
1 |
11.6 |
1 |
1 |
10.2 |