HD74LS251 Datasheet, PDF (1/6 Pages) Hitachi Semiconductor – 1 of 8 Data Selectors/Multiplexers(with strobe and three-state outputs)

HD74LS251
1 of 8 Data Selector / Multiplexer
(with strobe and three-state outputs)
REJ03D0467–0300
Rev.3.00
Jul.15.2005
This data selector / multiplexer contains full on-chip binary decoding to select one-of-eight data sources and features a
strobe-controlled 3-state output.
The strobe must be at a low logic level to enable this device. The 3-state outputs permit a number of outputs to be
connected to a common bus.
When the strobe input is high, both outputs are in a high-impedance state in which both the upper and lower transistors
of each totem-pole output are off, and the output neither drives nor loads the bus significantly. When the strobe is low,
the outputs are activated and operate as standard TTL totem-pole outputs.
To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output
control circuitry is designed so that the average output disable time is shorter than the average output enable time.
Features
• Ordering Information
Part Name
Package Type
Package Code
(Previous Code)
Package
Abbreviation
HD74LS251P
DILP-16 pin
PRDP0016AE-B
P
(DP-16FV)
HD74LS251FPEL SOP-16 pin (JEITA)
PRSP0016DH-B
(FP-16DAV)
FP
Note: Please consult the sales office for the above package availability.
Taping Abbreviation
(Quantity)
—
EL (2,000 pcs/reel)
Pin Arrangement
31
22
Data Inputs
13
04
Y5
Outputs
W6
Strobe ⁷
GND 8
D3
D2
D4
D1
D5
D0
D6
Y
D7
W
A
S
B
C
16 V_CC
15 ₄
14 ₅
13 ₆
Data Inputs
12 ₇
11 _A
10 _{B Data Select}
9C
(Top view)
Rev.3.00, Jul.15.2005, page 1 of 5