unconnected because the undefined voltages at the outside connections result in undefined operational states.

All unused inputs of digital logic devices must be connected to a logic high or logic low voltage, as defined by the

input voltage specifications, to prevent them from floating. The logic level that must be applied to any particular

makes more sense for the logic function or is more convenient.

11.2 Layout Example

1

2

3

4

5

6

7

16

15

14

13

12

11

10

D3

D2

D0

W

GND

V

CC

D5

D7

A

GND

V

CC

D6

D1

0.1

F

Bypass capacitor

placed close to the

device

Recommend GND flood fill for

improved signal isolation, noise

reduction, and thermal dissipation

Unused output

left floating

G

C

8

9

B

D4

Y

Unused input

tied to GND

Unused input

Avoid 90°

corners for

signal lines

Figure 11-1. Example layout for the SN74HCS151-Q1.

SN74HCS151-Q1

SCLS819B – AUGUST 2020 – REVISED DECEMBER 2021

www.ti.com

16

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