CY74FCT257T Datasheet, PDF (1/12 Pages) Texas Instruments – QUAD 2-INPUT MULTIPLEXER WITH 3-STATE OUTPUTS

D Function, Pinout, and Drive Compatible
With FCT and F Logic
D Reduced V_OH (Typically = 3.3 V) Version of
Equivalent FCT Functions
D Edge-Rate Control Circuitry for
Significantly Improved Noise
Characteristics
D I_off Supports Partial-Power-Down Mode
Operation
D Matched Rise and Fall Times
D Fully Compatible With TTL Input and
Output Logic Levels
D ESD Protection Exceeds JESD 22
– 2000-V Human-Body Model (A114-A)
– 200-V Machine Model (A115-A)
– 1000-V Charged-Device Model (C101)
D 64-mA Output Sink Current
32-mA Output Source Current
D 3-State Outputs
CY74FCT257T
QUAD 2-INPUT MULTIPLEXER
WITH 3-STATE OUTPUTS
SCCS019D – MAY 1994 – REVISED NOVEMBER 2001
Q OR SO PACKAGE
(TOP VIEW)
S₁
I_0a 2
I_1a 3
Y_a 4
I_0b 5
I_1b 6
Y_b 7
GND 8
16 ^V_CC
15 OE
14 I_0c
13 I_1c
12 Y_c
11 I_0d
10 I_1d
9 Y_d
description
The CY74FCT257T has four identical two-input multiplexers that select four bits of data from two sources under
the control of a common data-select (S) input. The I₀ inputs are selected when S is low, and the I₁ inputs are
selected when S is high. Data at the output is noninverted.
The CY74FCT257T is a logic implementation of a four-pole, two-position switch, where the position of the switch
is determined by the logic levels at S. Outputs are in the high-impedance state when the output-enable (OE)
input is high.
All but one device must be in the high-impedance state to avoid currents exceeding the maximum ratings if
outputs are tied together. OE inputs must ensure that there is no overlap when outputs of 3-state devices are
tied together.
This device is fully specified for partial-power-down applications using I_off. The I_off circuitry disables the outputs,
preventing damaging current backflow through the device when it is powered down.
NAME
I
S
OE
Y
PIN DESCRIPTION
DESCRIPTION
Data inputs
Common data-select input
Output-enable input (active low)
Data outputs
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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Copyright  2001, Texas Instruments Incorporated
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