ZHCSK26E March 2017 – July 2022 LMH1297
PRODUCTION DATA
OUT0 is a 100-? driver output. In EQ mode, OUT0 serves as a host-side output from the SDI_IO cable equalizer. In CD mode, OUT0 serves as a host-side loop-back output. OUT0 also supports polarity inversion.
In EQ mode, OUT0 is enabled by default, regardless of the logic applied to the OUT0_SEL pin.
The driver offers users the capability to select higher output amplitude and de-emphasis levels for longer board trace that connects the drivers to their downstream receivers. Driver de-emphasis provides transmitter equalization to reduce the ISI caused by the board trace.
In EQ mode, the HOST_EQ0 pin determines the output amplitude (VOD) and de-emphasis levels applied to the OUT0 PCB driver. In CD mode, the VOD and de-emphasis levels for OUT0 are set by default to 570 mVp-p and –0.4 dB. These settings can be changed through register control if desired.
Table 8-10 details the OUT0 VOD and de-emphasis settings that can be applied. The HOST_EQ0 pin settings can be overridden by register control. When these parameters are controlled by registers, the VOD and de-emphasis levels can be programmed independently. For more information, refer to the LMH1297 Programming Guide.
| EQ/CD_SEL (MODE) | HOST_EQ(1) | OUT0± VOD (mVp-p) | OUT0± DEM (dB) | RECOMMENDED BOARD TRACE AT OUT0±(2) |
|---|---|---|---|---|
| L (EQ mode) | H | 400 | 0 | < 1 inch |
| F | 570 | –0.4 | 1-2 inches | |
| R | 660 | –2.1 | 4-5 inches | |
| L | 830 | –4.4 | 8-10 inches | |
| H (CD mode) | X | 570 | –0.4 | 1-2 inches |