ZHCSN67N July 1997 – April 2021 SN55LVDS31 , SN65LVDS31 , SN65LVDS3487 , SN65LVDS9638
PRODUCTION DATA
Following the choice of dielectrics and design specifications, you should decide how many levels to use in the stack. To reduce the TTL/CMOS to LVDS crosstalk, it is a good practice to have at least two separate signal planes as shown in #SLLS3739393.
The separation between layers 2 and 3 should be 127 μm (0.005 in). By keeping the power and ground planes tightly coupled, the increased capacitance acts as a bypass for transients.
One of the most common stack configurations is the six-layer board, as shown in #SLLS3735292.
In this particular configuration, it is possible to isolate each signal layer from the power plane by at least one ground plane. The result is improved signal integrity; however, fabrication is more expensive. Using the 6-layer board is preferable, because it offers the layout designer more flexibility in varying the distance between signal layers and referenced planes, in addition to ensuring reference to a ground plane for signal layers 1 and 6.