IDT7280L15PAGI8(2012) Просмотр технического описания (PDF) - Integrated Device Technology

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IDT7280L15PAGI8
(Rev.:2012)

CMOS DUAL ASYNCHRONOUS FIFO DUAL 256 x 9, DUAL 512 x 9, DUAL 1,024 x 9, DUAL 2,048 x 9, DUAL 4,096 x 9, DUAL 8,192 x 9

Integrated Device Technology 

IDT7280/7281/7282/7283/7284/7285 5V ASYNCHRONOUS FIFO

DUAL 256 x 9, 512 x 9, 1,024 x 9, 2,048 x 9, 4,096 x 9 and 8,192 x 9

COMMERCIAL TEMPERATURE RANGE

W

tRHF

R

tWHF

HF

HALF-FULL OR LESS

MORE THAN HALF-FULL

Figure 9. Half-Full Flag Timing

HALF-FULL OR LESS

3208 drw 11

WRITE TO

LAST PHYSICAL

LOCATION

W

R

tXOL

tXOH

READ FROM

LAST PHYSICAL

LOCATION

tXOL

tXOH

XO

Figure 10. Expansion Out

3208 drw 12

tXI

tXIR

XI

tXIS

WRITE TO

FIRST PHYSICAL

W

LOCATION

R

tXIS

READ FROM

FIRST PHYSICAL

LOCATION

Figure 11. Expansion In

3208 drw 13

OPERATING MODES:

Care must be taken to assure that the appropriate flag is monitored by

each system (i.e. FFis monitored on the device where Wis used; EFis monitored

on the device where R is used).

SINGLE DEVICE MODE

A single IDT7280/7281/7282/7283/7284/7285 may be used when the

application requirements are for 256/512/1,024/2,048/4,096/8,192 words or

less. These FIFOs are in a Single Device Configuration when the Expansion

In (XI) control input is grounded (see Figure 12).

DEPTH EXPANSION

These devices can easily be adapted to applications when the require-

ments are for greater than 256/512/1,024/2,048/4,096/8,192 words. Figure

14 demonstrates a four-FIFO Depth Expansion using two IDT7280/7281/

7282/7283/7284/7285s. Any depth can be attained by adding additional

IDT7280/7281/7282/7283/7284/7285s. These FIFOs operate in the Depth

Expansion mode when the following conditions are met:

1. ThefirstFIFOmustbedesignatedbygroundingtheFirstLoad(FL)control

input.

2. All other FIFOs must have FL in the HIGH state.

3. TheExpansionOut(XO)pinofeachdevicemustbetiedtotheExpansion

In (XI) pin of the next device. See Figure 14.

4. ExternallogicisneededtogenerateacompositeFullFlag(FF)andEmpty

Flag (EF). This requires the ORing of all EFs and ORing of all FFs (i.e. all

must be set to generate the correct composite FF or EF). See Figure 14.

5. The Retransmit (RT) function and Half-Full Flag (HF) are not available in

the Depth Expansion Mode.

7

JUNE 29, 2012

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