7721 datasheet(410/577 Pages) RENESAS

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APPLICATION

7721 Group User’s Manual

16–7

16.1 Memory connection

Table 16.1.3 Calculation formula and Value for each

parameter in Figure 16.1.3 (unit : ns)

Calculation formula and Value

tw(EL)

td(E-RASL)

td(E-CASL)

td(E-CA)

tpzx(E-DLZ)

tpzx(E-DHZ)

tsu(DL-E)

tsu(DH-E)

1 ! 109

f(XIN)

4 ! 109

f(XIN)

– 25

+ 37.5

1 ! 109

f(XIN)

+ 25

1 ! 109

f(XIN)

– 20

Note: When accessing DRAM, Wait is always inserted

regardless of the contents of the Wait bit,

source’s Wait bit, and destination’s Wait bit.

Fig. 16.1.4 Relationship between tCAC, tRAC, tAA and f(XIN)

137.5

100

150

200

250

300

350

400

450

500

451

380

324

280

243

213

187

165

146

130

115

102

486

415

359

315

278

248

222

181

165

150

137

125

115

105

335.5

282.5

240.5

207.5

179.5

157.5

94.5

83.5 73.5

64.5 57.5

49.5

43.5 37.5 32.5

27.5

Column address access time :

tAA

RAS access time

tRAC

CAS access time

tCAC

[ns]

External clock input frequency f(XIN)

[MHz]

107.5

121.5

200

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