16

COMMERCIALANDINDUSTRIAL

TEMPERATURERANGES

IDT723631/723641/723651 CMOS SyncFIFO™

512 x 36, 1,024 x 36 and 2,048 x 36

NOTES:

1. tSKEW2 is the minimum time between a rising CLKA edge and a rising CLKB edge for AF to transition HIGH in the next CLKA cycle. If the time between the rising CLKB edge

and rising CLKA edge is less than tSKEW2, then AF may transition HIGH one CLKA cycle later than shown.

2. Depth is 512 for the IDT723631, 1,024 for the IDT723641, and 2,048 for the IDT723651.

3. FIFO write (CSA = LOW, W/RA = HIGH, MBA = LOW), FIFO read (CSB = LOW, W/RB = HIGH, MBB = LOW).

Figure 10. Timing for AF

AF

AF

AF

AF when FIFO is Almost-Full

Figure 12. AE

AE

AE

AE

AE Maximum Latency When Retransmit Increases the Number of Stored Words Above X.

NOTE:

1. X is the value loaded in the Almost-Empty flag Offset register.

Figure 11. Retransmit Timing Showing Minimum Retransmit Length

AF

CLKA

ENB

ENA

CLKB

3023 drw13

12

tSKEW2

tENS1

tENH1

tPAF

tENS1

tENH1

(1)

[Depth

-(Y+1)] Words in FIFO

(2)

(Depth

-Y) Words in FIFO

(2)

tPAF

CLKB

ENB

RTM

RFM

OR

B0-B35

W0

W1

W2

W0

W1

HIGH

Initiate Retransmit Mode

with W0 as First Word

Retransmit from

Selected Position

End Retransmit

Mode

3023 drw14

tENS1

tENH1

tRMS

tRMH

tRMS

tRMH

tRMS

tRMH

tA

tA

tA

tA

CLKB

RTM

RFM

AE

tPAE

X or fewer words from Empty

(X+1) or more

words from Empty

3023 drw15

tRMS

tRMH

1

2

HIGH

NOTE:

1. CSB = LOW, W/RB = HIGH, MBB = LOW. No input enables other than RTM and RFM are needed to control retransmit mode or begin a retransmit. Other enables are shown

only to relate retransmit operations to the FIFO output register.