ADSP-21020

External Memory Three-State Control

 

 

 

 

 

 

 

K/B/T Grade

K/B/T Grade

B/T Grade

K Grade

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

20 MHz

25 MHz

30 MHz

33.3 MHz

Frequency Dependency*

 

Parameter

Min

Max

Min

Max

Min

Max

Min

Max

Min

Max

Unit

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Timing Requirement:

 

 

 

 

 

 

 

 

 

 

 

tSTS

 

, Setup before CLKIN High

14

50

12

40

10

33

9

30

14 + DT/4

tCK

ns

xTS

tDADTS

xTS

Delay after Address, Select

 

28

 

19

 

13

 

10

 

28 + 7DT/8

ns

tDSTS

xTS

Delay after

XRD

,

XWR

Low

 

16

 

11

 

7

 

6

 

16 + DT/2

ns

Switching Characteristic:

 

 

 

 

 

 

 

 

 

 

 

tDTSD

Memory Interface Disable before

 

 

 

 

 

 

 

 

 

 

 

 

CLKIN High

0

 

–2

 

–4

 

–5

 

DT/4

 

ns

tDTSAE

 

High to Address, Select Enable

0

 

0

 

0

 

0

 

 

 

ns

xTS

 

 

 

 

 

 

NOTES

*DT = tCK – 50 ns.

xTS should only be asserted (low) during an active memory access cycle.

Memory Interface = PMA23-0, PMD47-0, PMS1-0, PMRD, PMWR, PMPAGE, DMA31-0, DMD39-0, DMS3-0, DMRD, DMWR, DMPAGE. Address = PMA23-0, DMA31-0. Select = PMS1-0, DMS3-0.

x = PM or DM.

CLKIN

tSTS

tSTS

PMTS, DMTS

tDADTS

t DSTS

tDTSD

xRD, xWR

t DTSAE

ADDRESS,

SELECTS

DATA

Figure 9. External Memory Three-State Control

REV. C

–17–

Page 17
Image 17
Analog Devices ADSP-21020 manual Setup before Clkin High 14 + DT/4, Xts, XTS Delay after Address, Select 28 + 7DT/8