SN74ACT3631

512

× 36

CLOCKED FIRST-IN, FIRST-OUT MEMORY

SCAS246G – AUGUST 1993 – REVISED APRIL 1998

17

POST OFFICE BOX 655303

CLKB

B0 – B35

ENB

OR

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(EN)

th(EN)

tsu(EN)

th(EN)

tsu(EN)

th(EN)

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 FIFO output register.

Figure 10. Retransmit Timing Showing Minimum Retransmit Length

th(RM)

CLKB

AE

RTM

High

RFM

tsu(RM)

12

tpd(C-AE)

X or Fewer Words From Empty

(X + 1) or More Words From Empty

NOTE A: X is the value loaded in the AE flag offset register.

Figure 11. AE Maximum Latency When Retransmit Increases the Number of Stored Words Above X