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1 self refresh, Figure 9-4, Auto - refresh operation timing – FUJITSU MB91460 SERIES FR60 User Manual

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Chapter 31 External Bus

9.SDRAM/FCRAM Interface Operation

Figure 9-4 Single Read/Write Timing Chart

Setting TYP to 1001

B

causes a read/write command with auto - precharge to be issued. Since the cycle from

READA/WRITA issuance to ACTV issuance is fixed at CL + BL - 1, however, TYP can be set to 1001

B

only

when FCRAM is connected.

This timing is effective, for example, for recurring page misses as it eliminates the cycle for issuing the PRE
command.

Auto - refresh Operation Timing

Figure 9-5

shows auto - refresh operation timings.

Figure 9-5 Auto - refresh Timing Chart

The refresh command is issued every " refresh control register's (RCR's) RFINT5 - RFINT0 value x 32 " cycles
and access is restarted upon completion of each refresh.

Set the TRC bit in the refresh control register (RCR) according to the SDRAM/FCRAM standards.

Satisfy the maximum RAS active time as well.

9.1 Self Refresh

This section describes self - refreshing.

MCLK

A

D

Row

Col

ACTV

READA

ACTV

Row

Col

WRITA

#1

#2

Row

ACTV

WRITA

Col

#3

CL+BL-1

CL+BL-1

SRAS,SCAS,
SWE

MCLK

A

D

REF

tRC

Refresh cycle

ACTV

SRAS,SCAS,
SWE