MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

1

REV 0

4/99

Octal Bus Buffer

Inverting

The MC74VHCT540A is an advanced high speed CMOS inverting octal

bus buffer fabricated with silicon gate CMOS technology. It achieves high

speed operation similar to equivalent Bipolar Schottky TTL while maintaining

CMOS low power dissipation.

The MC74VHCT540A features inputs and outputs on opposite sides of the

package and two AND–ed active–low output enables. When either OE1 or

OE2 are high, the terminal outputs are in the high impedance state.

The VHCT inputs are compatible with TTL levels. This device can be used

as a level converter for interfacing 3.3V to 5.0V, because it has full 5V CMOS

level output swings.

The VHCT540A input and output (when disabled) structures provide

protection when voltages between 0V and 5.5V are applied, regardless of

the supply voltage. These input and output structures help prevent device

destruction caused by supply voltage – input/output voltage mismatch,

battery backup, hot insertion, etc.

The internal circuit is composed of three stages, including a buffer output

which provides high noise immunity and stable output. The inputs tolerate

voltages up to 7V, allowing the interface of 5V systems to 3V systems.

• High Speed: tPD = 3.7ns (Typ) at VCC = 5V

• Low Power Dissipation: ICC = 4µA (Max) at TA = 25°C

• TTL–Compatible Inputs: VIL = 0.8V; VIH = 2.0V

• Power Down Protection Provided on Inputs

• Balanced Propagation Delays

• Designed for 2V to 5.5V Operating Range

• Low Noise: VOLP = 1.2V (Max)

• Pin and Function Compatible with Other Standard Logic Families

• Latchup Performance Exceeds 300mA

• ESD Performance: HBM > 2000V; Machine Model > 200V

• Chip Complexity: 124 FETs or 31 Equivalent Gates

18

Y1

2

A1

17

Y2

3

A2

16

Y3

4

A3

15

Y4

5

A4

14

Y5

6

A5

13

Y6

7

A6

12

Y7

8

A7

11

Y8

9

A8

OE1

OE2

1

19

OUTPUT

ENABLES

DATA

INPUTS

INVERTING

OUTPUTS

LOGIC DIAGRAM

MC74VHCT540A

PIN ASSIGNMENT

A5

A3

A2

A1

OE1

GND

A8

A7

A6

A4

5

4

3

2

1

10

9

8

7

6

14

15

16

17

18

19

20

11

12

13

Y3

Y2

Y1

OE2

VCC

Y8

Y7

Y6

Y5

Y4

L

L

H

X

L

L

X

H

L

H

X

X

FUNCTION TABLE

Inputs

Output Y

OE1

OE2

A

H

L

Z

Z

DW SUFFIX

20–LEAD SOIC WIDE PACKAGE

CASE 751D–05

ORDERING INFORMATION

MC74VHCTXXXADW

MC74VHCTXXXADT

MC74VHCTXXXAM

SOIC WIDE

TSSOP

SOIC EIAJ

DT SUFFIX

20–LEAD TSSOP PACKAGE

CASE 948E–02

M SUFFIX

20–LEAD SOIC EIAJ PACKAGE

CASE 967–01