Datasheet

AS4C16M32MD1
Confidential 40 Rev. 1.0/July 2014
7.8 Auto Precharge
Auto Precharge is a feature which performs the same individual bank pre-charge function as
described above, but without requiring an explicit command. This is accomplished by using A10
(A10 = High), to enable Auto Precharge in conjunction with a specific READ or WRITE command. A
pre-charge of the bank / row that is addressed with the READ or WRITE command is automatically
performed upon completion of the read or write burst. Auto Precharge is non-persistent in that it is
either enabled or disabled for each individual READ or WRITE command.
Auto Precharge ensures that a pre-charge is initiated at the earliest valid stage within a burst.
The user must not issue another command to the same bank until the precharging time (tRP) is
completed. This is determined as if an explicit PRECHARGE command was issued at the earliest
possible time, as described for each burst type in the Operation section of this specification.
7.9 Refresh Requirements
LPDDR SDRAM devices require a refresh of all rows in any rolling 64ms interval. Each refresh is
generated in one of two ways: by an explicit AUTO REFRESH command, or by an internally timed
event in SELF REFRESH mode. Dividing the number of device rows into the rolling 64ms interval
defines the average refresh interval (tREFI), which is a guideline to controllers for distributed
refresh timing.
7.10 Auto Refresh
AUTO REFRESH command (see Figure 33) is used during normal operation of the LPDDR
SDRAM. This command is non-persistent, so it must be issued each time a refresh is
required.