SN74ALS666, SN74ALS667

8-BIT D-TYPE TRANSPARENT READ-BACK LATCHES

WITH 3-STATE OUTPUTS

SDAS227A – JUNE 1984 – REVISED JANUARY 1995

Copyright

1

POST OFFICE BOX 655303

– SN74ALS666...True Outputs

– SN74ALS667... Inverted Outputs

Small-Outline (DW) Packages and Standard

Plastic (NT) 300-mil DIPs

description

These 8-bit D-type transparent latches are

designed specifically for storing the contents of

the input data bus, plus reading back the stored

data onto the input data bus. In addition, they

provide a 3-state buffer-type output and are easily

utilized in bus-structured applications.

While the latch enable (LE) is high, the Q outputs

of the SN74ALS666 follow the data (D) inputs. The

Q outputs of the SN74ALS667 provide the inverse

of the data applied to its D inputs. The Q or

Q output of both devices is in the high-impedance

state if either output-enable (OE1 or OE2) input is

at a high logic level.

Read back is provided through the read-back

control (OERB) input. When OERB is taken low,

the data present at the output of the data latches

passes back onto the input data bus. When OERB

is taken high, the output of the data latches is

isolated from the D inputs. OERB does not affect

the internal operation of the latches; however,

caution should be exercised to avoid a bus

conflict.

The

SN74ALS666

and

SN74ALS667

are

characterized for operation from 0

°C to 70°C.

SN74ALS666 ...DW OR NT PACKAGE

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OERB

OE1

1D

2D

3D

4D

5D

6D

7D

8D

CLR

GND

OE2

1Q

2Q

3Q

4Q

5Q

6Q

7Q

8Q

PRE

LE

SN74ALS667 . . . DW OR NT PACKAGE

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OERB

OE1

1D

2D

3D

4D

5D

6D

7D

8D

CLR

GND

OE2

1Q

2Q

3Q

4Q

5Q

6Q

7Q

8Q

PRE

LE

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.