DSP56364 datasheet(40/148 Pages) FREESCALE

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External Memory Expansion Port (Port A)

DSP56364 Technical Data, Rev. 4.1

3-24

Freescale Semiconductor

140

Column address valid to CAS assertion

tASC

TC − 4.0

6.0

—

141

CAS assertion to column address not valid

tCAH

3.5

× T

C − 4.0

31.0

—

142

Last column address valid to RAS deassertion

tRAL

× T

C − 4.0

46.0

—

143

WR deassertion to CAS assertion

tRCS

1.25

× T

C − 4.0

8.5

—

144

CAS deassertion to WR assertion

tRCH

1.25

× T

C − 4.0

8.5

—

145

CAS assertion to WR deassertion

tWCH

3.25

× T

C − 4.2

28.3

—

146

WR assertion pulse width

tWP

4.5

× T

C − 4.5

40.5

—

147

Last WR assertion to RAS deassertion

tRWL

4.75

× T

C − 4.3

43.2

—

148

WR assertion to CAS deassertion

tCWL

3.75

× T

C − 4.3

33.2

—

149

Data valid to CAS assertion (write)

tDS

0.5

× T

C − 4.0

1.0

—

150

CAS assertion to data not valid (write)

tDH

3.5

× T

C − 4.0

31.0

—

151

WR assertion to CAS assertion

tWCS

1.25

× T

C − 4.3

8.2

—

152

Last RD assertion to RAS deassertion

tROH

4.5

× T

C − 4.0

41.0

—

153

RD assertion to data valid

tGA

3.25

× T

C − 7.0

—

25.5

154

RD deassertion to data not valid6

tGZ

0.0

—

155

WR assertion to data active

0.75

× T

C − 0.3

7.2

—

156

WR deassertion to data high impedance

0.25

× T

—2.5

1 The number of wait states for Page mode access is specified in the DCR.

2 The refresh period is specified in the DCR.

3 The asynchronous delays specified in the expressions are valid for DSP56364.

4 All the timings are calculated for the worst case. Some of the timings are better for specific cases (e.g., t

PC equals 3 × TC for

read-after-read or write-after-write sequences).

5 BRW[1:0] (DRAM control register bits) defines the number of wait states that should be inserted in each DRAM out-of-page

access.

6 RD deassertion will always occur after CAS deassertion; therefore, the restricted timing is t

OFF and not tGZ.

Table 3-12 DRAM Page Mode Timings, Four Wait States1, 2, 3 (continued)

No.

Characteristics

Symbol

Expression4

Min

Max

Unit

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