SN54HC166, SN74HC166

8-BIT PARALLEL-LOAD SHIFT REGISTERS

SCLS117B – DECEMBER 1982 – REVISED MAY 1997

1

POST OFFICE BOX 655303

Small-Outline (D) and Ceramic Flat (W)

Packages, Ceramic Chip Carriers (FK), and

Standard Plastic (N) and Ceramic (J)

300-mil DIPs

description

The ’HC166 parallel-in or serial-in, serial-out

registers feature gated clock (CLK, CLK INH)

inputs and an overriding clear (CLR) input. The

parallel-in or serial-in modes are established by

the shift / load (SH/LD) input. When high, SH/LD

enables the serial (SER) data input and couples

the eight flip-flops for serial shifting with each

clock (CLK) pulse. When low, the parallel

(broadside)

data

inputs

are

enabled,

and

synchronous loading occurs on the next clock

pulse. During parallel loading, serial data flow is

inhibited. Clocking is accomplished on the

low-to-high-level edge of CLK through a 2-input

positive-NOR gate permitting one input to be used

as a clock-enable or clock-inhibit function. Holding

either CLK or CLK INH high inhibits clocking;

holding either low enables the other clock input.

This allows the system clock to be free running,

and the register can be stopped on command with

the other clock input. CLK INH should be changed

to the high level only when CLK is high. CLR

overrides all other inputs, including CLK, and

resets all flip-flops to zero.

The SN54HC166 is characterized for operation over the full military temperature range of –55

°C to 125°C. The

SN74HC166 is characterized for operation from –40

°C to 85°C.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

32 1 20 19

910 11 1213

4

5

6

7

8

18

17

16

15

14

H

NC

G

F

B

C

NC

D

CLK INH

SN54HC166 ...FK PACKAGE

(TOP VIEW)

NC – No internal connection

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

SER

A

B

C

D

CLK INH

CLK

GND

SH/LD

H

G

F

E

CLR

SN54HC166 ...J OR W PACKAGE

SN74HC166 . . . D OR N PACKAGE

(TOP VIEW)

Copyright

© 1997, Texas Instruments Incorporated

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.