SN74ALS233B

16

× 5 ASYNCHRONOUS FIRST-IN, FIRST-OUT MEMORY

SCAS253B – MARCH 1990 – REVISED APRIL 1998

1

POST OFFICE BOX 655303

Outputs

Small-Outline Package (DW), Plastic Chip

Carriers (FN), and Standard Plastic 300-mil

DIPs (N)

description

This 80-bit memory uses advanced low-power

Schottky technology and features high speed and

a fast fall-through time. It is organized as 16 words

by 5 bits.

A FIFO memory is a storage device that allows

data to be written into and read from its array at

independent data rates. This FIFO is designed to

process data at rates up to 40 MHz in a bit-parallel

format, word by word.

Data is written into memory on a low-to-high

transition at the load clock (LDCK) input and is

read out on a low-to-high transition at the unload

clock (UNCK) input. The memory is full when the

number of words clocked in exceeds by 16 the

number of words clocked out. When the memory

is full, LDCK signals have no effect. When the

memory is empty, UNCK signals have no effect.

Status of the FIFO memory is monitored by the FULL, EMPTY, FULL–1, and EMPTY+1 output flags. The FULL

output is low when the memory is full and high when it is not full. The FULL–1 output is low when the memory

contains 15 data words. The EMPTY output is low when the memory is empty and high when it is not empty.

The EMPTY+1 output is low when one word remains in memory.

A low level on the reset (RST) input resets the internal stack control pointers and also sets EMPTY low and sets

FULL, FULL–1, and EMPTY+1 high. The Q outputs are not reset to any specific logic level. The first low-to-high

transition on LDCK, after either a RST pulse or from an empty condition, causes EMPTY to go high and the data

to appear on the Q outputs. It is important to note that the first word does not have to be unloaded. Data outputs

are noninverting with respect to the data inputs and are at high impedance when the output-enable (OE) input

is low. OE does not affect the output flags. Cascading is easily accomplished in the word-width direction but is

not possible in the word-depth direction.

The SN74ALS233B is characterized for operation from 0

°C to 70°C.

Copyright

© 1998, 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.

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3

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OE

FULL–1

FULL

LDCK

D0

D1

D2

D3

D4

GND

EMPTY+1

UNCK

EMPTY

Q0

Q1

Q2

Q3

Q4

RST

DW OR N PACKAGE

(TOP VIEW)

32 1 20 19

910 11 12 13

4

5

6

7

8

UNCK

EMPTY

Q0

Q1

Q2

LDCK

D0

D1

D2

D3

FN PACKAGE

(TOP VIEW)

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19

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15

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11

18

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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.