Programming instructions

Misc. Digital Components
Multisim Component Reference Guide 9-6 ni.com
9.1.8 Tristate Buffer
This component is a non-inverting buffer with a three-state output. It has a greater fan-out and
offers a high-current source and sink capability for driving high-current loads. The buffer has
an active-high enable input.
If the device is not “enabled”, then the buffer output goes into a high-impedance (Z) state. In
this state, the output pin is effectively disconnected from the rest of the circuit. Thus, the
buffer is useful for circuits where outputs from different digital devices meet at the same
node.
Truth table:
where Z is a high-impedance state
Note When using a tristate buffer use the Models tab of the Circuit/Component Properties
dialog box. Select the LS-BUF or LS-OC-BUF (OC = Open-collector) model if the
buffer is being used as a TTL device. Select HC-BUF or HC-OD-BUF if the tristate
buffer is being used as a CMOS device. Otherwise, by default, the tristate buffer will
behave as a regular digital device without any high-current capabilities.
9.1.9 Buffer
This component is a non-inverting buffer. It has a greater fan-out and offers a high-current
source and sink capability for driving high-current loads.
input
enable
input
output
11 1
01 0
X0 Z
ComponentRef.book Page 6 Thursday, December 7, 2006 10:12 AM