MC74ACT251 Motorola, MC74ACT251 Datasheet - Page 2

• Manufacturer Part Number: MC74ACT251
• Description: 8-Input Multiplexer
• Manufacturer: Motorola

FUNCTIONAL DESCRIPTION
8-position switch with the switch position controlled by the
state of three Select inputs, S 0 , S 1 , S 2 . Both true and
complementary outputs are provided. The Output Enable
input (OE) is active LOW. When it is activated, the logic
function provided at the output is:
Z = OE (I 0 S 0 S 1 S 2 +I 1 S 0 S 1 S 2 +
This device is a logical implementation of a single-pole,
S 2
S 1
S 0
OE
I 2 S 0 S 1 S 2 +I 3 S 0 S 1 S 2 +
I 4 S 0 S 1 S 2 +I 5 S 0 S 1 S 2 +
I 6 S 0 S 1 S 2 +I 7 S 0 S 1 S 2 )
Please note that this diagram is provided
only for the understanding of logic
operations and should not be used to
estimate propagation delays.
I 0
MC74AC251 MC74ACT251
I 1
LOGIC DIAGRAM
FACT DATA
5-2
I 2
high impedance (High Z) state. This feature allows multiplexer
expansion by tying the outputs of up to 128 devices together.
When the outputs of the 3-state devices are tied together, all
but one device must be in the high impedance state to avoid
high currents that would exceed the maximum ratings. The
Output Enable signals should be designed to ensure there is
no overlap in the active-LOW portion of the enable voltages.
When the Output Enable is HIGH, both outputs are in the
I 3
Z
I 4
Z
I 5
I 6
I 7