5.08

6

IDT72V01/72V02/72V03/72V04 3.3 VOLT CMOS ASYNCHRONOUS FIFO

512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9

COMMERCIAL TEMPERATURE RANGE

low after 512/1024/2048/4096 writes to the IDT72V01/72V02/

72V03/72V04.

EMPTY FLAG (

EF

EF)

The Empty Flag (

EF) will go low, inhibiting further read

operations, when the read pointer is equal to the write pointer,

indicating that the device is empty.

EXPANSION OUT/HALF-FULL FLAG (

XO

XO/HF

HF)

This is a dual-purpose output. In the single device mode,

when Expansion In (

XI) is grounded, this output acts as an

indication of a half-full memory.

After half of the memory is filled and at the falling edge of

the next write operation, the Half-Full Flag (

HF) will be set low

and will remain set until the difference between the write

pointer and read pointer is less than or equal to one half of the

total memory of the device. The Half-Full Flag (

HF) is then

reset by using rising edge of the read operation.

In the Depth Expansion Mode, Expansion In (

XI) is con-

nected to Expansion Out (

XO) of the previous device. This

output acts as a signal to the next device in the Daisy Chain

by providing a pulse to the next device when the previous

device reaches the last location of memory.

Figure 2. Reset

NOTES:

1.

2.

Figure 3. Asynchronous Write and Read Operation

HFH

t

RS

W

R

EF

HF, FF

2679 drw 04

R

DATA OUT VALID

DATA OUT VALID

DATA IN VALID

DATA IN VALID

2679 drw 05

W