IDT72V85 查看數據表（PDF） - Integrated Device Technology
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IDT72V85 Datasheet PDF : 11 Pages
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IDT72V81/72V82/72V83/72V84/72V85
W
R
tWHF
HF
HALF-FULL OR LESS
Commercial Temperature Range
tRHF
MORE THAN HALF-FULL
Figure 9. Half-Full Flag Timing
HALF-FULL OR LESS
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WRITE TO
LAST PHYSICAL
LOCATION
W
R
tXOL
tXOH
READ FROM
LAST PHYSICAL
LOCATION
tXOL
tXOH
XO
Figure 10. Expansion Out
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tXI
tXIR
XI
tXIS
WRITE TO
FIRST PHYSICAL
W
LOCATION
tXIS
READ FROM
FIRST PHYSICAL
R
LOCATION
Figure 11. Expansion In
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OPERATING MODES:
Care must be taken to assure that the appropriate flag is monitored by each
system (i.e. FFis monitored on the device whereWis used; EFis monitored on
the device where R is used).
Single Device Mode
A single IDT72V81/72V82/72V83/72V84/72V85 may be used when the
application requirements are for 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 requirements
are for greater than 512/1,024/2,048/4,096/8,192 words. Figure 14 demon-
strates a four-FIFO Depth Expansion using two IDT72V81/72V82/72V83/
72V84/72V85s. Any depth can be attained by adding additional IDT72V81/
72V82/72V83/72V84/72V85s. 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 FLin 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.
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