Samsung S5PC110 Manual page 553

S5PC110_UM 1 DRAM CONTROLLER
1.2.4.1 Bank Selective Precharge Policy
Since applications include different page policy preferences, it is hard for the engineer to decide whether to use
open page policy, or close page (auto precharge) policy. Instead of applying the page policy to entire banks, the
bank selective precharge policy allows the user to choose a precharge policy for each bank (Refer to
PrechConfig.chip1_policy). You can assign certain applications to a bank that uses an open page policy, and
other applications to a bank that uses a close page (auto precharge) policy.
Open Page Policy: After a READ or WRITE, the accessed row is left open.
Close Page (Auto Precharge) Policy: Right after a READ or WRITE command, the controller issues an auto
precharge to the bank.
1.2.4.2 Timeout Precharge
If a certain bank uses an open page policy, the row is left open after a data access. If this happens and the bank
that is left open is not scheduled for a specific number of cycles (PrechConfig.tp_cnt bit-field) the controller
automatically issues a precharge command to close the bank.
Figure 1-4 Timing Diagram of Timeout Precharge
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