Unused Input

Input

Output

Input

Unused Input

Output

SN74LVC1G86

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SCES222P – APRIL 1999 – REVISED SEPTEMBER 2015

11 Layout

11.1 Layout Guidelines

When using multiple bit logic devices, inputs should not float. In many cases, functions or parts of functions of

digital logic devices are unused. Some examples are when only two inputs of a triple-input AND gate are used,

or when only 3 of the 4-buffer gates are used. Such input pins should not be left unconnected because the

undefined voltages at the outside connections result in undefined operational states.

Specified in Figure 5 are rules that must be observed under all circumstances. All unused inputs of digital logic

devices must be connected to a high or low bias to prevent them from floating. The logic level that should be

applied to any particular unused input depends on the function of the device. Generally they will be tied to GND

transceiver. If the transceiver has an output enable pin, it will disable the outputs section of the part when

asserted. This will not disable the input section of the I/Os so they also cannot float when disabled.

11.2 Layout Example

Figure 5. Layout Diagram

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