GS6081 Datasheet, PDF (13/19 Pages) Semtech Corporation – Input signal trace equalizationnull

Rset = 8*(75/0.8) = 750Ω
This formula is not valid for long, unterminated, or improperly terminated cables.
This formula should be considered as a starting point, and actual swing values may vary
based on layout.
Table 4-5: Typical R_SET Values
Output Swing (mV_pp)
1040
800
500
R_SET (Ω)
576
750
1210
4.7 Output Return Loss Measurement
The GS6081 has a feature designed to facilitate reliable output return loss (ORL)
measurement while the device is still powered. The device can be put into a BALANCE
mode which prevents the outputs from toggling while the device is powered on,
allowing the ORL to be measured while the device is still powered.
When EQ_EN is LOW while SD_EN is HIGH, the device goes into BALANCE mode. This
mode is used during ORL measurement, disabling the AC signal path of the device
without powering it down. When in BALANCE mode, the device produces equal
pull-down currents in both differential shoulders of both serial data differential outputs,
effectively stopping all outputs at the output common mode voltage level. Semtech
recommends using BALANCE mode when measuring ORL with +2.5V termination
voltage.
GS6081
Final Data Sheet
PDS-060046
Rev.4
July 2014
www.semtech.com
13 of 19
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