Texas Instruments THUNDER TNETX3270 User Manual
Page 57
TNETX3270
ThunderSWITCH
24/3 ETHERNET
SWITCH
WITH 24 10-MBIT/S PORTS AND 3 10-/100-MBIT/S PORTS
SPWS043B – NOVEMBER 1997 – REVISED APRIL 1999
57
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
SDRAM subcycle
operating characteristics over recommended operating conditions (see Figure 17)
NO.
PARAMETER
MIN
MAX
UNIT
1
tc(DCLK)
Cycle time, DCLK
12
12
ns
2
tw(DCLKL)
Pulse duration, DCLK low
5
ns
3
tw(DCLKH)
Pulse duration, DCLK high
5
ns
4
td(DCLK)
Delay time, from DA, DRAS, DCAS, and DW valid to DCLK
↑
4
ns
5
td(DA)
Delay time, from DCLK
↑
to DA, DRAS, DCAS, and DW invalid
2
ns
6
ten(DDW)
Enable time, from DCLK
↑
to before DD31–DD00 driven (write cycle)
0
ns
7
ten(DDR)
Enable time, from DCLK
↑
to before DD31–DD00 driven (read cycle)
0
ns
8
tdis(DDW)
Disable time, from DCLK
↑
to after DD31–DD00 (after final write cycle) to Z state
10
ns
9
tdis(DDR)
Disable time, from DCLK
↑
to after DD31–DD00 (after final read cycle) to Z state
11
ns
10
td(DDW)1
Delay time, from DD valid to DCLK
↑
(write cycle)
4
ns
11
td(DDW)2
Delay time, from DCLK
↑
to DD31–DD00 Z state (write cycle)
2
ns
12
td(DDR)1
Delay time, from DCLK
↑
to DD31–DD00 valid (read cycle)
10
ns
13
td(DDR)2
Delay time, from DCLK
↑
to DD31–DD00 invalid (read cycle)
0
ns
tt
Transition time, rise and fall, all signals
1
4
ns
ООООООО
ООООООО
О
О
ОО
ОО
О
О
ОООО
ОООО
ООООООООООО
ООООООООООО
ОООООООООО
ОООООООООО
DCLK
(output)
1
DA13–DA00
DRAS
DCAS
DW
(outputs)
DD31–DD00
(during writes)
(output)
ОООО
ОООО
DD31–DD00
(during reads)
(input)
Z
Z
Z
Z
2
3
4
5
6
10
8
11
12
9
13
7
Figure 17. SDRAM Subcycle