5.35

2

COMMERCIAL TEMPERATURE RANGES

IDT72105, IDT72115, IDT72125,

256 x 16, 512 x 16, 1024 x 16 PARALLEL-TO-SERIAL CMOS FIFO

PIN CONFIGURATION

Symbol

Name

I/O

Description

Inputs

I

Data inputs for 16-bit wide data.

RS

Reset

I

When

RS is set low, internal READ and WRITE pointers are set to the first location of the RAM

array.

FF and HF go HIGH. EF and AEF go LOW. A reset is required before an initial WRITE

after power-up.

W must be high during the RS cycle. Also the First Load pin (FL) is programmed

only during Reset.

W

Write

I

A write cycle is initiated on the falling edge of WRITE if the Full Flag (

FF) is not set. Data set-up

and hold times must be adhered to with respect to the rising edge of WRITE. Data is stored in the

RAM array sequentially and independently of any ongoing read operation.

SOCP

Serial Output

Clock

I

A serial bit read cycle is initiated on the rising edge of SOCP if the Empty Flag (

EF) is not set. In

both Depth and Serial Word Width Expansion modes, all of the SOCP pins are tied together.

FL/DIR

First Load/

Direction

I

This is a dual purpose input used in the width and depth expansion configurations. The First

Load (

FL) function is programmed only during Reset (RS) and a LOW on FL indicates the first

device to be loaded with a byte of data. All other devices should be programmed HIGH. The

Direction (DIR) pin controls shift direction after Reset and tells the device whether to read out the

Least Significant or Most Significant bit first.

RSIX

Read Serial In

Expansion

I

In the single device configuration, RSIX is set HIGH. In depth expansion or daisy chain

expansion, RSIX is connected to RSOX (expansion out) of the previous device.

SO

Serial Output

O

Serial data is output on the Serial Output (SO) pin. Data is clocked out LSB or MSB depending

on the Direction pin programming. During Expansion the SO pins are tied together.

FF

Full Flag

O

When

FF goes LOW, the device is full and further WRITE operations are inhibited. When FF is

HIGH, the device is not full.

EF

Empty Flag

O

When

EF goes LOW, the device is empty and further READ operations are inhibited. When EF is

HIGH, the device is not empty.

HF

Half-Full Flag

O

When

HF is LOW, the device is more than half-full. When HF is HIGH, the device is empty to

half-full.

RSOX/

AEF Read Serial

Out Expansion

Almost-Empty,

Almost-Full

Flag

O

This is a dual purpose output. In the single device configuration (RSIX HIGH), this is an

AEF

output pin. When

AEF is LOW, the device is empty-to-(1/8 full -1) or (7/8 full +1)-to-full. When

AEF is HIGH, the device is 1/8-full up to 7/8-full. In the Expansion configuration (RSOX

connected to RSIX of the next device) a pulse is sent from RSOX to RSIX to coordinate the

width, depth or daisy chain expansion.

Power Supply

Single power supply of 5V.

GND

Ground

Single ground of 0V.

2665 tbl 01

PIN DESCRIPTIONS

DIP/SOIC

TOP VIEW

5

6

7

8

9

10

11

12

13

HF

GND

1

2

3

4

14

28

27

26

25

24

23

22

21

RSOX/

AEF

FL/DIR

Vcc

SO

SOCP

20

19

18

17

16

15

W

P28-2

SO28-3

FF

EF

RSIX

RS

2665 drw 02a