T i m i n g D i a g r a m s

SDRAM burst read

SDRAM read, CAS latency = 2

BCLK

TA* (Note-5)

TEA*/LAST* (Note-5) PortA2/AMUX Non-muxed address Muxed address BE*[3:0]* (DQM)

read D[31:0] CS[4:0]* CAS3* (RAS) CAS2* (CAS) CAS1* (WE) CAS0* (A10/AP) RW*

T1

active

read

nop

T2

T2

T2

T2

inhibit

T1

prechg

nop

nop

nop

bterm

inhibit

 

 

 

 

30

 

 

 

30

 

 

 

 

 

 

 

 

31

31

 

 

 

37

37

 

 

 

 

 

 

6

 

 

 

 

 

 

 

 

 

35

 

35

 

 

 

 

 

 

 

36

 

 

 

 

 

 

 

36

 

 

 

 

 

10

11

 

 

 

 

 

 

 

 

 

 

 

 

 

27

 

 

 

 

 

 

 

27

 

34

 

34

 

 

 

 

 

 

 

 

 

34

34

 

 

 

 

 

 

34

34

 

 

 

 

 

34

34

 

 

34

34

34

 

 

 

 

 

 

 

A10

 

 

 

 

 

 

 

 

12

 

 

 

 

 

 

 

 

 

Notes:

1Port size determines which byte enable signals are active:

8-bit port = BE3*

16-bit port = BE[3:2]

32-bit port = BE[3:0]

2The precharge and/or active commands are not always present. These commands depend on the address of the previous SDRAM access.

3If CAS latency = 3, 5 NOPs occur between the read and burst terminate commands.

4If CAS latency = 3, 3 inhibits occur after burst terminate.

5The TA* and TEA*/LAST signals are for reference only.

2 8 4

N S 7 5 2 0 H a r d w a r e R e f e r e n c e , R e v . D 0 3 / 2 0 0 6

Page 298
Image 298
Digi NS7520 manual Sdram burst read