5.36

2

IDT72132, IDT72142

CMOS SERIAL-TO-PARALLEL FIFO 2048 x 9 AND 4096 x 9

COMMERCIAL TEMPERATURE RANGES

PIN DESCRIPTIONS

Symbol

Name

I/O

Description

SI

Serial Input

I

Serial data is shifted in least significant bit first. In the serial cascade mode, the Serial Input

RS

Reset

I

When

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

RAM array.

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

WRITE after power-up.

R must be HIGH during an RS cycle.

NW

Next Write

I

To program the Serial In word width , connect

SICP

Serial Input Clock

I

Serial data is read into the serial input register on the rising edge of SICP. In both Depth and

Serial Word Width Expansion modes, all of the SICP pins are tied together.

R

Read

I

When READ is LOW, data can be read from the RAM array sequentially, independent of SICP.

In order for READ to be active,

EF must be HIGH. When the FIFO is empty (EF-LOW), the

FL/RT

First Load/

I

This is a dual-purpose input. In the single device configuration (

XI grounded), activating

retransmit (

FL/RT-LOW) will set the internal READ pointer to the first location. There is no

effect on the WRITE pointer.

R must be HIGH and SICP must be LOW before setting FL/RT

LOW. Retransmit is not possible in depth expansion. In the depth expansion configuration,

FL/RT grounded indicates the first activated device.

XI

Expansion In

I

In the single device configuration,

XI is grounded. In depth expansion or daisy chain

expansion,

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

SIX

Serial Input

I

In the Expansion mode, the SIX pin of the least significant device is tied HIGH. The SIX pin

operation, SIX is tied HIGH.

OE

Output Enable

I

When

OE is set LOW, the parallel output buffers receive data from the RAM array. When OE

is set HIGH, parallel three state buffers inhibit data flow.

Output Data

O

Data outputs for 9-bit wide data.

FF

Full Flag

O

When

FF goes LOW, the device is full and data must not be clocked by SICP. When FF is

HIGH, the device is not full. See the diagram on page 7 for more details.

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.

AEF

Almost-Empty/

O

When

AEF is LOW, the device is empty to 1/8 full or 7/8 to completely full. When AEF is HIGH,

the device is greater than 1/8 full, but less than 7/8 full.

XO/HF

Expansion Out/

O

This is a dual-purpose output. In the single device configuration (

XI grounded), the device is

more than half full when

HF is LOW. In the depth expansion configuration (XO connected to

XI of the next device), a pulse is sent from XO to XI when the last location in the RAM array

is filled.

Data Set

O

NW to program the Serial In data word

width, etc.

Power Supply

Single Power Supply of 5V.

GND

Ground

Three grounds at 0V.

2752 tbl 01

Retransmit

Expansion

Half-Full Flag

Almost-Full Flag

STATUS FLAGS

Number of Words in FIFO

IDT72132

IDT72142

FF

AEF

HF

EF

00

H

L

H

L

1-255

1-511

H

L

H

H

256-1024

512-2048

H

H

H

H

1025-1792

2049-3584

H

H

L

H

1793-2047

3585-4095

H

L

L

H

2048

4096

L

L

L

H

2752 tbl 02