ST 74LCX157 User Manual

Low voltage CMOS Quad 2 channel multiplexer

Features

■ 5V tolerant inputs

■ High speed:

–t

= 6.0ns (Max) at V

PD

■ Power down protection on inputs and outputs

■ Symmetrical output impedance:

–|I

■ PCI bus levels guaranteed at 24mA

■ Balanced propagation delays:

–t

■

Operating voltage range:
–V

■ Pin and function compatible with

| = IOL = 24mA (Min) at VCC = 3V

OH

≅ t

PLH

PHL

(Opr) = 2.0V to 3.6V

CC

74 series 157

■ Latch-up performance exceeds

500mA (JESD 17)

■ ESD performance:

– HBM > 2000V

(MIL STD 883 method 3015); MM > 200V

CC

= 3V

74LCX157

with 5V tolerant inputs

SO-16 TSSOP16

Description

The 74LCX157 is a low voltage CMOS Quad 2
channel multiplexer fabricated with sub-micron
silicon gate and double-layer metal wiring C
technology. It is ideal for low power and high
speed 3.3V applications; it can be interfaced to
5V signal environment for inputs.

It consists of four 2-input digital multiplexer with
common select and strobe inputs. It is a non­inverting multiplexer. When the STROBE
held high selection of data is inhibited and all the
outputs become low. The SELECT decoding
determines whether the A or B inputs get routed
to their corresponding Y outputs.

2

MOS

input is

It has same speed performance at 3.3V than 5V
AC/ACT family, combined with a lower power
consumption.

All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.

Order codes

Part number Package Packaging

74LCX157MTR SO-16 Tape and reel

74LCX157TTR TSSOP16 Tape and reel

February 2007 Rev 6 1/17

www.st.com

17

Contents 74LCX157

Contents

1 Logic symbols and I/O equivalent circuit . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.3 Truth table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.4 Logic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.1 Recommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5 Test circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6 Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2/17

74LCX157 Logic symbols and I/O equivalent circuit

1 Logic symbols and I/O equivalent circuit

Figure 1. IEC logic symbols

Figure 2. Input and output equivalent circuit

3/17

Pin settings 74LCX157

2 Pin settings

2.1 Pin connection

Figure 3. Pin connection (top through view)

2.2 Pin description

Table 1. Pin description

Pin N° Symbol Name and function

1 SELECT Common data select inputs

2, 5, 11, 14 1A to 4A Data inputs from source A

3, 6, 10, 13 1B to 4B Data inputs from source B

4, 7, 9, 12 1Y to 4Y Multiplexer outputs

15 STROBE

8 GND Ground (0V)

16 V

CC

Strobe input

Positive supply voltage

4/17

74LCX157 Pin settings

2.3 Truth table

Table 2. Truth table

Inputs Output

STROBE SELECT A B Y

HXXXL

LLLXL

LLHXH

LHXLL

LHXHH

Note: X : Do not care

2.4 Logic diagram

Figure 4. Logic diagram

Note: This logic diagram has not to be used to estimate propagation delays

5/17

Maximum rating 74LCX157

3 Maximum rating

stressing the device above the rating listed in the “absolute maximum ratings” table may
cause permanent damage to the device. these are stress ratings only and operation of the
device at these or any other conditions above those indicated in the operating sections of
this specification is not implied. exposure to absolute maximum rating conditions for
extended periods may affect device reliability. refer also to the STMicroelectronics sure
program and other relevant quality documents.

Table 3. Absolute maximum ratings

Symbol Parameter Value Unit

V

V

V

I

I

I

GND

T

T

1. IO absolute maximum rating must be observed

2. VO < GND

Supply voltage -0.5 to +7.0 V

CC

V

DC input voltage -0.5 to +7.0 V

I

DC output voltage (VCC = 0V)

O

DC output voltage (high or low state)

O

I

DC input diode current -50 mA

IK

DC output diode current

OK

I

DC output current ± 50 mA

O

DC supply current per supply pin ± 100 mA

CC

(2)

(1)

-0.5 to +7.0 V

-0.5 to VCC + 0.5

-50 mA

DC ground current per supply pin ± 100 mA

Storage temperature -65 to +150 °C

stg

Lead temperature (10 sec) 300 °C

L

V

3.1 Recommended operating conditions

Table 4. Recommended operating conditions

Symbol Parameter Value Unit

V

V

V

V

Supply voltage

CC

Input voltage 0 to 5.5 V

I

Output voltage (VCC = 0V)

O

Output voltage (high or low state)

O

IOH, IOLHigh or low level output current (VCC = 3.0 to 3.6V)

I

, IOLHigh or low level output current (VCC = 2.7V)

OH

T

dt/dv

1. Truth table guaranteed: 1.5V to 3.6V

2. VIN from 0.8V to 2V at VCC = 3.0V

Operating temperature -40 to 85 °C

op

Input rise and fall time

6/17

(1)

(2)

2.0 to 3.6 V

0 to 5.5 V

0 to V

CC

± 24 mA

± 12 mA

0 to 10 ns/V

V