r8a77850anbg Renesas Electronics Corporation., r8a77850anbg Datasheet - Page 568

Manufacturer Part Number

r8a77850anbg

Renesas 32-bit Risc Microcomputer Superh? Risc Engine Family

Manufacturer

Renesas Electronics Corporation.

Manufacturer

BOSTOCK HK LIMITED

Part Number:

r8a77850anbgV

Manufacturer:

Renesas Electronics America

12. DDR2-SDRAM Interface (DBSC2)

Figure 12.15 shows a case in which the pages for both of banks A and B are closed, the page for

bank C is open, and a page hit has occurred. When the tRRD time constraint has been satisfied

starting from issue of the ACT command for bank A, the ACT command for bank B is issued.

Because time tRCD has elapsed from the issue of the ACT command for bank A, a READ

command can be used. The READ command has a burst length of 4, so after two cycles a READ

command for bank B can be issued. A further two cycles later, a READ command for bank C can

be issued. However, the next request is access for which bank C must be closed, and so after the

elapse of time tRTP a PRE command is issued.

Rev.1.00 Jan. 10, 2008 Page 538 of 1658

REJ09B0261-0100

Example of CL = 3

Figure 12.15 tRRD and tRTP