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M74HCT257 Schematic ( PDF Datasheet ) - ST Microelectronics

Teilenummer M74HCT257
Beschreibung HCT257 QUAD 2 CHANNEL MULTIPLEXER 3-STATE HCT258 QUAD 2 CHANNEL MULTIPLEXER 3-STATE / INVERTING
Hersteller ST Microelectronics
Logo ST Microelectronics Logo 




Gesamt 12 Seiten
M74HCT257 Datasheet, Funktion
M54/M74HCT257
M54/M74HCT258
HCT257 QUAD 2 CHANNEL MULTIPLEXER (3-STATE)
HCT258 QUAD 2 CHANNEL MULTIPLEXER (3-STATE, INVERTING)
. HIGH SPEED
tPD = 16 ns (TYP.) at VCC = 5 V
. LOW POWER DISSIPATION
ICC = 4 µA (MAX.) at TA = 25 °C
. COMPATIBLE WITH TTL OUTPUTS
VIH = 2V (MIN.) VIL = 0.8V (MAX)
. OUTPUT DRIVE CAPABILITY
15 LSTTL LOADS
. SYMMETRICAL OUTPUT IMPEDANCE
IOH= IOL = 6 mA (MIN.)
. BALANCED PROPAGATION DELAYS
tPLH = tPHL
. PIN AND FUNCTION COMPATIBLE
WITH 54/74LS257/258
B1R
(Plastic Package)
F1R
(Ceramic Package)
M 1R
(Micro Package)
C1R
(Chip Carrier)
ORDER CODES :
M54HCTXXXF1R M74HCTXXXM1R
M74HCTXXXB1R M74HCTXXXC1R
DESCRIPTION
The M54/74HCT257 and the M54/74HCT258 are
high speed CMOS MULTIPLEXERs fabricated with
silicon gate C2MOS technology.
They have the same high speed performance of
LSTTL combined with true CMOS low power con-
sumption.
These IC’s are composed of an independent 2-
channel multiplexer with common SELECT and EN-
ABLE INPUT.
The M54/74HCT258 is an inverting multiplexer
while the M54/74HCT257 is a non-inverting multi-
plexer. When the ENABLE INPUT is held ”High”,
outputs of both IC’s become high-impedance state.
If SELECT INPUT is held ”Low”, ”A” data is selected,
when SELECT INPUT is high ”H”, ”B” data is
chosen.
All inputs are equipped with protection circuits
against static discharge and transient excess volt-
age.
This integrated circuit has input and output charac-
teristics that are fully compatible with 54/74 LSTTL
logic families. M54/74HCT devices are designed to
directly interface HSC2MOS systems with TTL and
NMOS components. They are also plug in replace-
PIN CONNECTIONS (top view)
H CT 2 57
HCT258
February 1993
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M74HCT257 Datasheet, Funktion
M54/M74HCT257/258
AC ELECTRICAL CHARACTERISTICS (CL = 50 pF, Input tr = tf = 6 ns)
Symbol
Parameter
Test Conditions
VCC
(V)
tTLH Output Transition 4.5
tTHL Time
tPLH Propagation
tPHL Delay Time
(A, B - Y)
4.5
HCT257
HCT258
TA = 25 oC
54HC and 74HC
Min. Typ. Max.
7 12
Value
-40 to 85 oC
74HC
Min. Max.
15
-55 to 125 oC
54HC
Min. Max.
18
Unit
ns
19 30 38 45 ns
17 27 34 41
tPLH Propagation
tPHL Delay Time
(SELECT - Y)
4.5
20 30 38 45 ns
tPZL Output Enable
tPZH Time
4.5 RL = 1 K
18 30 38 45 ns
tPLZ Output Disable 4.5 RL = 1 K
tPHZ Time
16 30 38 45 ns
CIN Input Capacitance
5 10 10 10 pF
COUT Output
Capacitance
10
pF
CPD (*) Power Dissipation
Capacitance
HCT257
HCT258
34
33
pF
(*) CPD is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without load.
(Refer to Test Circuit). Average operting current can be obtained by the following equation. ICC(opr) = CPD VCC fIN + ICC/4 (per Channel)
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M74HCT257 pdf, datenblatt
M54/M74HCT257/258
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsability for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may results from its use. No
license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentioned
in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied.
SGS-THOMSON Microelectronics products are not authorized for use ascritical components in life support devices or systems without express
written approval of SGS-THOMSON Microelectonics.
© 1994 SGS-THOMSON Microelectronics - All Rights Reserved
SGS-THOMSON Microelectronics GROUP OF COMPANIES
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