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APPLICATION INFORMATION

Multipoint Configuration

Multidrop Configuration

D

D

Unused Channel

Live Insertion/Glitch Free Power Up/Down

SN65MLVD047

SLLS606A – MARCH 2004 – REVISED JULY 2005

The SN65MLVD047 is designed to allow multipoint communication on a shared bus.

Multipoint is a bus configuration with multiple drivers and receivers present. An example is shown in Figure 17.

The figure shows transceivers interfacing to the bus, but a combination of drivers, receivers, and transceivers is

also possible. Termination resistors need to be placed on each end of the bus, with the termination resistor value

matched to the loaded bus impedance.

Figure 17. Multipoint Architecture

Multidrop configuration is similar to multipoint configuration, but only one driver is present on the bus. A multidrop

system can be configured with the driver at one end of the bus, or in the middle of the bus. When a driver is

located at one end, a single termination resistor is located at the far end, close to the last receiver on the bus.

Alternatively, the driver can be located in the middle of the bus, to reduce the maximum flight time. With a

centrally located driver, termination resistors are located at each end of the bus. In both cases the termination

resistor value should be matched to the loaded bus impedance. Figure 18 shows examples of both cases.

Figure 18. Multidrop Architectures With Different Driver Locations

The SN65MLVD047 is designed to allow multipoint communication on a standard bus. A 360-k

Ω pull-down

resistor is built in every LVTTL input. The unused driver inputs and outputs may be left floating.

During a live insertion event or a power cycle the outputs of the SN65MLVD047 leave the high impedance state

output state (high or low) of the device reflects the input level at the corresponding A pin.

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