Independent Asynchronous Inputs and

Outputs

16 Words by 4 Bits

Data Rates up to 40 MHz

Fall-Through Time 14 ns Typical

3-State Outputs

Package Options Include Plastic

Small-Outline Package (DW), Plastic Chip

Carriers (FN), and Standard Plastic 300-mil

DIPs (N)

description

This 64-bit memory features high speed and fast

fall-through times. It is organized as 16 words by

4 bits.

A first-in, first-out (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 on the

data residing in memory. When the memory is

empty, UNCK signals have no effect.

Status of the FIFO memory is monitored by the FULL and EMPTY output flags. The FULL output is low when

the memory is full and high when it is not full. The EMPTY output is low when the memory is empty and high

when it is not empty.

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

FULL 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 FULL or EMPTY output flags. Cascading is easily accomplished in the word-width direction but

is not possible in the word-depth direction.

The SN74ALS232B is characterized for operation from 0°C to 70°C.