Fairchild 74LCX157 service manual

查询74LCX157供应商

74LCX157
Low Voltage Quad 2-Input Multiplexer

with 5V Tolerant Inputs

74LCX157 Low Voltage Quad 2-Input Multiplexer with 5V Tolerant Inputs

May 1995
Revised February 2001

General Description

The LCX157 is a high-speed quad 2-input multiplexer. Four
bits of data from two sources can be selected using the
common Select and Enable inputs. The four outputs
present the selected da ta in the true (noninverted) form.
The LCX157 can also be used as a function generator.

The 74LCX157 is fabricated with advanced CMOS technol­ogy to achieve high speed operation while maintaining
CMOS low power dissipation.

Features

■ 5V tolerant inputs

■ 2.3V–3.6V V

■ 5.8 ns t

■ Power down high impedance inputs and outputs

■

±24 mA output drive (V

■ Implements patented noise/EMI reduction circuitry

■ Latch-up performance exce eds 500 mA

■ ESD performance:

Human body model
Machine model

specifications provided

CC

max (VCC = 3.3V), 10 µA ICC max

PD

= 3.0V)

CC

> 2000V

> 200V

Ordering Code:

Order Number Package Number Package Description

74LCX157M M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
74LCX157SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74LCX157MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide

Devices also availab l e in Tape and Reel. Specify by appending th e s uffix let t er “X” to the ordering code.

Logic Symbols

Connection Diagram

IEEE/IEC

Pin Descriptions

Pin Names Description

I

0a–I0d

I

1a–I1d

E
S Select Input

Z

a–Zd

© 2001 Fairchild Semiconductor Corporation DS012465 www.fairchildsemi.com

Source 0 Data Inputs
Source 1 Data Inputs

Enable Input

Outputs

Functional Description

The LCX157 is a quad 2-input multiplexer. It selects four
bits of data from two sources un der the control of a com­mon Select input (S). The Enable input (E

74LCX157

is HIGH, all of th e outputs (Z) are forced LOW

When E
regardless of all other inputs. The LCX157 is the logic
implementation of a 4-pole, 2-position switch where the
position of the switch is deter min ed by the log i c levels sup ­plied to the Select input. The logic equations for the outputs
are shown below:

Z

= E • (I1a • S + I0a • S)

a

= E • (I1b • S + I0b • S)

Z

b

Z

= E • (I1c • S + I0c • S)

c

= E • (I1d • S + I0d • S)

Z

d

A common use of the L CX157 is the movi ng of data from
two groups of registers to four common output busses. The
particular r eg is ter f r om w hi ch th e da t a co me s is d et e rmi n ed
by the state of the Select input. A less obvious use is as a
function generat or. The LCX157 can generate any four of
the sixteen different functions of two variables with one
variable common. This is useful for implementing gating
functions.

) is active-LOW.

Logic Diagram

Truth Table

Inputs Outputs

E

HX X X L
LH X L L
LH X H H
LL L X L
LLH X H

H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial

SI0I

1

Z

Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.

www.fairchildsemi.com 2

Absolute Maximum Ratings(Note 1)

Symbol Parameter Value Conditions Units

V
V
V
I

IK

I

OK

I

O

I

CC

I

GND

T

CC
I
O

STG

Supply Voltage −0.5 to +7.0 V
DC Input Voltage −0.5 to +7.0 V
DC Output Voltage −0.5 to VCC + 0.5 Output in HIGH or LOW St ate (Note 2) V
DC Input Diode Current −50 VI < GND mA
DC Output Diode Current −50 VO < GND

+50 V

O

> V

CC

mA

DC Output Source/Sink Current ±50 mA
DC Supply Current per Supply Pin ±100 mA
DC Ground Current per Ground Pin ±100 mA
Storage Temperature −65 to +150 °C

Recommended Operating Conditions (Note 3)

Symbol Parameter Min Max Units

V

CC

V

I

V

O

I

OH/IOL

T

A

∆t/∆V Input Edge Rate, V

Note 1: The Absolute Maximum Ratings are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated
at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the Absolute Maximum Ratings. The “Recom-
mended Operating Conditions” table will define the conditions fo r ac t ual device operation.

Note 2: I
Note 3: Unused inputs must be held HIGH or LOW. They may not flo at .

Supply Voltage Operating 2.0 3.6

Data Retention 1.5 3.6

V

Input Voltage 05.5V
Output Voltage HIGH or LOW State 0 V

CC

V

Output Current VCC = 3.0V − 3.6V ±24

= 2.7V − 3.0V ±12

CC

= 2.3V − 2.7V ±8

V

CC

mAV

Free-Air Operating T emperature −40 85 °C

= 0.8V − 2.0V, VCC = 3.0V 0 10 ns/V

IN

Absolute Maximum Rating must be observed.

O

74LCX157

DC Electrical Characteristics

Symbol Parameter Conditions

V

V

V

V

I
I
I

∆I

IH

IL

OH

OL

I
OFF
CC

CC

HIGH Level Input Voltage 2.3 − 2.7 1.7

LOW Level Input Voltage 2.3 − 2.7 0.7

HIGH Level Output Voltage IOH = −100 µA2.3 − 3.6 VCC − 0.2

IOH = −8 mA 2.3 1.8
IOH = −12 mA 2.7 2.2
IOH = −18 mA 3.0 2.4
IOH = −24 mA 3.0 2.2

LOW Level Output Voltage IOL = 100 µA2.3 − 3.6 0.2

IOH = 8 mA 2.3 0.6
IOL = 12 mA 2.7 0.4
IOL = 16 mA 3.0 0.4

IOL = 24 mA 3.0 0.55
Input Leakage Current 0 ≤ VI ≤ 5.5V 2.3 − 3.6 ±5.0 µA
Power-Off Leakage Current VI or VO = 5.5V 0 10 µA
Quiescent Supply Current VI = VCC or GND 2.3 − 3.6 10

3.6V ≤ VI ≤ 5.5V 2.3 − 3.6 ±10

Increase in ICC per Input VIH = VCC −0.6V 2.3 − 3.6 500 µA

3 www.fairchildsemi.com

V

2.7 − 3.6 2.0

2.7 − 3.6 0.8

TA = −40°C to +85°C

CC

(V) Min Max

Units

V

V

V

V

µA