H8SXSLASH1663R datasheet(363/1504 Pages) RENESAS

Teilenummer	H8SX/1663R

Bauteilbeschribung	Renesas 32-Bit CISC Microcomputer H8SX Family / H8SX/1600 Series

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Section 9 Bus Controller (BSC)

Rev. 2.00 Sep. 24, 2008 Page 331 of 1468

REJ09B0412-0200

(2)

Self-Refresh Mode

Some SDRAMs have a self-refresh mode (battery backup mode). The self-refresh is a kind of

standby mode and refresh timing and refresh address are controlled internally.

(a) Self-Refresh in Software Standby Mode

The self-refresh is selected by setting the RFSHE and SLFRF bits in REFCR to 1. The SELF-

command is issued as shown in figure 9.79 by executing the SLEEP instruction to enter the

software standby mode.

When an auto-refresh is requested on a transition to the software standby mode, the auto-refresh is

first performed and then the self-refresh is entered.

When making a transition to the self-refresh, set the OEE bit in SBYCR to 1 and connect the CKE

pin.

When the self-refresh is used, do not clear the OPE bit in SBYCR to 0.

Precharge-sel

RAS

CAS

CKE

PALL

SELF

NOP

Software standby

RD/

Address bus

SDRAM

High

Figure 9.79 Self-Refresh Timing in software standby mode

(TPC1 = 0, TPC0 = 0, RCW1 = 0, RCW0 = 0, RLW2 = 0, RLW1 = 0, RLW0 = 0)

H8SX/1663R Datenblatt(PDF) 363 Page - Renesas Technology Corp