ZHCS823H March 2012 – March 2019 SN65HVD72 , SN65HVD75 , SN65HVD78
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
When connecting a node to the bus, the distance between the transceiver inputs and the cable trunk, known as the stub, should be as short as possible. Stubs present a non-terminated piece of bus line which can introduce reflections as the length of the stub increases. As a general guideline, the electrical length, or round-trip delay, of a stub should be less than one-tenth of the rise time of the driver, thus giving a maximum physical stub length as shown in Equation 1.
where
Per Equation 1, Table 3 shows the maximum cable-stub lengths for the minimum driver output rise times of the SN65HVD7x half-duplex family of transceivers for a signal velocity of 78%.
| DEVICE | MINIMUM DRIVER OUTPUT RISE TIME (ns) | MAXIMUM STUB LENGTH | |
|---|---|---|---|
| (m) | (ft) | ||
| SN65HVD72 | 300 | 7 | 23 |
| SN65HVD75 | 2 | 0.05 | 0.16 |
| SN65HVD78 | 1 | 0.025 | 0.08 |