Fairchild 74LCX138 service manual

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74LCX138
Low Voltage 1-of-8 Decoder/Demultiplexer

with 5V Tolerant Inputs

74LCX138 Low Voltage 1-of-8 Decoder/Demultiplexer with 5V Tolerant Inputs

March 1995
Revised February 2004

General Description

The LCX138 is a high-spee d 1-of-8 decoder /demu ltiplex er.
This device is ideally suited for high-speed memo ry chip
select address decodi ng. The multip le input ena bles allow
parallel expansion to a 1-of-24 decoder u sing just three
LCX138 devices or a 1-of-32 decoder u sing four LCX138
devices and one inverter.

The 74LCX138 is fabricated with advanced CMOS technol­ogy to achieve high speed operation while maintaining
CMOS low power dissipation.

Features

■ 5V tolerant inputs

■ 2.3V to 3.6V V

■ 6.0 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:

■ Leadless DQFN package

max (VCC = 3.3V), 10 µA ICC max

PD

Human body model
Machine model

Ordering Code:

Order Number

74LCX138M
(Note 1)

74LCX138SJ
(Note 1)

74LCX138BQX
(Note 2)

74LCX138MTC
(Note 1)

Note 1: Devices also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.
Note 2: DQFN package available in Tape and Reel only.

Package

Number

M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow

M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide

MLP016E 16-Terminal Depopulated Quad Very-Thin Flat Pack No Leads (DQFN), JEDEC MO-241,

2.5 x 3.5mm

MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide

Package Description

specifications provided

CC

= 3.0V)

CC

> 2000V

> 200V

© 2004 Fairchild Semiconductor Corporation DS012417 www.fairchildsemi.com

Connection Diagrams

Pin Descriptions

Pin Assignments for SOIC, SOP, and TSSOP

74LCX138

Pad Assignments for DQFN

(Top Through View)

Pin Names Description

A
E
E
O

0–A2
1–E2
3

0–O7

Address Inputs
Enable Inputs
Enable Input
Outputs

Functional Description

The LCX138 high-speed 1-of-8 decoder/demultiplexer
accepts three binary weighted inputs (A

when enabled, provides eight mutually exclusive active­LOW outputs (O

inputs, two active-LOW (E
All outputs will be HIGH unless E
is HIGH. The LCX138 can b e u sed as an 8-output dem ulti -

plexer by using one of the active LOW Enable inputs as the
data input and the other Enable inputs as strobes. The
Enable inputs which are not used must be permanently tied
to their appropriate active-HIGH or active-LOW state.

). The LCX138 feature s thre e Ena ble

0–O7

, E2) and one active-HIGH (E3).

1

1

, A1, A2) and,

0

and E2 are LOW and E

3

Truth Table

Inputs Outputs

E

1E2E3A0A1A2O0O1O2O3O4O5O6O7

HXXXXXHHHHHHHH
XHXXXXHHHHHHHH
XXLXXXHHHHHHHH

LLHLLLLHHHHHHH
LLHHL LHLHHHHHH
LLHLHLHHLHHHHH
LLHHHLHHHLHHHH

LLHL LHHHHHLHHH
LLHHLHHHHHHLHH
LLHLHHHHHHHHLH

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

www.fairchildsemi.com 2

LLHHHHHHHHHHHL

Logic Diagram

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

74LCX138

3 www.fairchildsemi.com

Absolute Maximum Ratings(Note 3)

Symbol Parameter Value Conditions Units

V

CC

74LCX138

V

I

V

O

I

IK

I

OK

I

O

I

CC

I

GND

T

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 State (Note 4) V
DC Input Diode Current −50 VI < GND mA
DC Output Diode Current −50 VO < GND

+50 V

> V

O

CC

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

Recommended Operating Conditions (Note 5)

Symbol Parameter Min Max Units

V

CC

V

I

V

O

I

OH/IOL

T

A

∆t/∆V Input Edge Rate, V

Note 3: 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 Operat ing Conditions” table w ill define the condition s fo r ac t ual device operation.

Note 4: I
Note 5: Unused inputs must be held HIGH or LOW. They may not float.

Supply Voltage Operating 2.0 3.6

Data Retention 1.5 3.6
Input Voltage 0.0 5.5 V
Output Voltage HIGH or LOW State 0.0 V

CC

Output Current VCC = 3.0V to 3.6V ±24.0

= 2.7V to 3.0V ±12.0

CC

= 2.3V to 2.7V ±8.0

V

CC

Free-Air Operating Temperature −40.0 85.0 °C

= 0.8V to 2.0V, VCC = 3.0V 0.0 10.0 ns/V

IN

Absolute Maximum Rating must be observed.

O

mA

V

V

mAV

DC Electrical Characteristics

Symbol Parameter Conditions

V

IH

V

IL

V

OH

V

OL

I

I

I

OFF

I

CC

∆I

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HIGH Level Input Voltage 2.3 to 2.7 1.7

LOW Level Input Voltage 2.3 to 2.7 0.7

HIGH Level Output Voltage IOH = −100 µA 2.3 to 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

LOW Level Output Voltage IOL = 100 µA 2.3 to 3.6 0.2

Input Leakage Current 0 ≤ VI ≤ 5.5V 2.3 to 3.6 ±5.0 µA
Power-Off Leakage Current VI or VO = 5.5V 0.0 10.0 µA
Quiescent Supply Current VI = VCC or GND 2.3 to 3.6 10.0

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

CC

IOH = −24 mA 3.0 2.2

IOL = 8mA 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

3.6V ≤ VI ≤ 5.5V 2.3 to 3.6 ±10.0

V

2.7 to 3.6 2.0

2.7 to 3.6 0.8

TA = −40°C to +85°C

CC

(V) Min Max

Units

V

V

V

V

µA