HD74HC257
Quad. 2-to-1-line Data Selectors/Multiplexers
(with noninverted 3-state outputs)
Description
The large output drive capability coupled with the 3-state feature make this device ideal for interfacing with
bus lines in a bus organized system. When the output control input line is taken high, the outputs of all four
multiplexers are sent into a high impedance state. When the output control line is low, the select input
chooses whether the A or B input is used.
Features
High Speed Operation: t
pd
(Data to Y) = 10.5 ns typ (C
L
= 50 pF)
High Output Current: Fanout of 15 LSTTL Loads
Wide Operating Voltage: V
CC
= 2 to 6 V
Low Input Current: 1 A max
Low Quiescent Supply Current: I
CC
(static) = 4 A max (Ta = 25C)
Function Table
Inputs
Outputs
Output Control
Select
A
B
Y
L
L
L
X
L
L
L
H
X
H
L
H
X
L
L
L
H
X
H
H
H
X
X
X
High impedance
Notes H: high level, L: low level, X: irrelevant
Cautions
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copyright, trademark, or other intellectual property rights for information contained in this document.
Hitachi bears no responsibility for problems that may arise with third party's rights, including
intellectual property rights, in connection with use of the information contained in this document.
2. Products and product specifications may be subject to change without notice. Confirm that you have
received the latest product standards or specifications before final design, purchase or use.
3. Hitachi makes every attempt to ensure that its products are of high quality and reliability. However,
contact Hitachi's sales office before using the product in an application that demands especially high
quality and reliability or where its failure or malfunction may directly threaten human life or cause risk
of bodily injury, such as aerospace, aeronautics, nuclear power, combustion control, transportation,
traffic, safety equipment or medical equipment for life support.
4. Design your application so that the product is used within the ranges guaranteed by Hitachi particularly
for maximum rating, operating supply voltage range, heat radiation characteristics, installation
conditions and other characteristics. Hitachi bears no responsibility for failure or damage when used
beyond the guaranteed ranges. Even within the guaranteed ranges, consider normally foreseeable
failure rates or failure modes in semiconductor devices and employ systemic measures such as fail-
safes, so that the equipment incorporating Hitachi product does not cause bodily injury, fire or other
consequential damage due to operation of the Hitachi product.
5. This product is not designed to be radiation resistant.
6. No one is permitted to reproduce or duplicate, in any form, the whole or part of this document without
written approval from Hitachi.
7. Contact Hitachi's sales office for any questions regarding this document or Hitachi semiconductor
products.
Hitachi, Ltd.
Semiconductor & Integrated Circuits.
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Tel: Tokyo (03) 3270-2111 Fax: (03) 3270-5109
Copyright ' Hitachi, Ltd., 1999. All rights reserved. Printed in Japan.
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