2

COMMERCIAL TEMPERATURE RANGE

IDT72125PARALLEL-TO-SERIALCMOSFIFO

1,024 x 16

PIN CONFIGURATION

PIN DESCRIPTIONS

PLASTIC THIN DIP (P28, order code: TP)

SOIC (SO28, order code: SO)

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

FF

EF

RSIX

RS

2665 drw 02

Symbol

Name

I/O

Description

D0–D15

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

SerialOutputClock

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

FirstLoad/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

directionafterResetandtellsthedevicewhethertoreadouttheLeastSignificantorMostSignificantbitfirst.

RSIX

Read Serial In

I

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

Expansion

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

SO

SerialOutput

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,

thedeviceisnotfull.

EF

EmptyFlag

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-FullFlag

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

O

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

OutExpansion

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

Almost-Empty,

is 1/8-full up to 7/8-full. In the Expansion configuration (RSOX connected to RSIX of the next device) a

Almost-FullFlag

pulse is sent from RSOX to RSIX to coordinate the width, depth or daisy chain expansion.

VCC

Power Supply

Single power supply of 5V.

GND

Ground

Single ground of 0V.