CY74FCT2257T Datasheet, PDF (1/6 Pages) Texas Instruments – Quad 2-Input Multiplexer

1CY74FCT2257T
Data sheet acquired from Cypress Semiconductor Corporation.
Data sheet modified to remove devices not offered.
CY74FCT2257T
SCCS038 - September 1994 - Revised March 2000
Features
• Function and pinout compatible with FCT and F logic
• 25Ω output series resistors to reduce transmission line
reflection noise
• FCT-C speed at 4.3 ns max.,
FCT-A speed at 5.0 ns max.
• TTL output level versions of equivalent FCT functions
• Edge-rate control circuitry for significantly improved
noise characteristics
• Power-off disable feature
• Fully compatible with TTL input and output logic levels
• ESD > 2000V
• Sink current 12 mA
Source current15 mA
• Extended commercial temp. range of –40˚C to +85˚C
• Three-state outputs
Quad 2-Input Multiplexer
Functional Description
The FCT2257T has four identical two-input multiplexers that
select four bits of data from two sources under the control of a
common data Select input (S). The I0 inputs are selected
when the Select input is LOW and the I1 inputs are selected
when the Select input is HIGH. Data appears at the output in
true non-inverted form for the FCT2257T. On-chip termination
resistors have been added to the outputs to reduce system
noise caused by reflections. The FCT2257T can be used to
replace the FCT257T to reduce noise in an existing design.
The FCT2257T is a logic implementation of a four-pole,
two-position switch where the position of the switch is
determined by the logic levels supplied to the select input. Out-
puts are forced to a high-impedance “OFF” state when the
Output Enable input (OE) 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. Design of the output enable signals must ensure
that there is no overlap when outputs of three-state devices
are tied together.
The outputs are designed with a power-off disable feature to
allow for live insertion of boards.
Logic Block Diagram
I_0a
I_1a
I_0b
I_1b
I_0c
I_1c
I_0d
I_1d
S
OE
Y_a
Y_b
Y_c
Y_d
FCT2257T–1
Pin Configurations
SOIC/QSOP
Top View
S1
I_0a
2
I_1a
3
Y_a
4
I_0b
5
I_1b
6
Y_b
7
GND ₈
16 VCC
15 OE
14 ^I0c
13 ^I1c
12 ^Yc
11
I_0d
10 ^I1d
9 Yd
FCT2257T–3
Pin Description
Name
I
S
OE
Y
Description
Data Inputs
Common Select Input
Enable Inputs (Active LOW)
Data Outputs
Function Table^[1]
Inputs
Output
OE
S
I₀
I₁
Y
H
X
X
X
Z
L
H
X
L
L
L
H
X
H
H
L
L
L
X
L
L
L
H
X
H
Note:
1. H = HIGH Voltage Level, L = LOW Voltage Level, X = Don’t Care,
Z = High impedance (OFF) state.
Copyright © 2000, Texas Instruments Incorporated