SN74ACT3638

512

× 32 × 2

CLOCKED BIDIRECTIONAL FIRST-IN, FIRST-OUT MEMORY

SCAS228D – JUNE 1992 – REVISED APRIL 1998

21

POST OFFICE BOX 655303

CLKB

B0 – B31

ENB

ORB

tsu(EN)

th(EN)

ta

W0

W1

High

tsu(EN)

th(EN)

RTM

RFM

ta

W2

ta

W0

ta

W1

Initiate Retransmit Mode

With W0 as First Word

Retransmit From

Selected Position

tsu(RM)

th(RM)

tsu(RM)

th(RM)

tsu(RM)

th(RM)

End Retransmit

Mode

NOTE A: CSB = L, W/RB = H, MBB = L. 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 FIFO1 output register.

Figure 17. FIFO1 Retransmit Timing Showing Minimum Retransmit Length

th(RM)

CLKB

AEB

RTM

High

RFM

tsu(RM)

12

tpd(C-AE)

X1 or Fewer Words From Empty

(X1 + 1) or More Words From Empty

NOTE A: X1 is the value loaded in the almost-full flag offset register.

Figure 18. AEB Maximum Latency When Retransmit Increases the Number of Stored Words Above X1