Datasheet

CURRENT STATE
CS RAS CAS
WE
COMMAND ACTION NOTES
Any
H X X X DESELECT NOP or Continue previous operation
L H H H No Operation NOP or Continue previous operation
Idle
L L H H ACTIVE Select and activate row
L L L H AUTO REFRESH Auto refresh 10
L L L L MRS Mode register set 10
Row Active
L H L H READ Select column & start read burst
L H L L WRITE Select column & start write burst
L L H L PRECHARGE Deactivate row in bank (or banks) 4
Read (Auto precharge
Disabled)
L H L H READ Select column & start new read burst 5, 6
L H L L WRITE Select column & start write burst 5, 6, 13
L L H L PRECHARGE Truncate read burst, start precharge
L H H L BURST TERMINATE Burst terminate 11
Write (Auto precharge
Disabled)
L H L H READ Select column & start read burst 5, 6, 12
L H L L WRITE Select column & start new write burst 5, 6
L L H L PRECHARGE Truncate write burst & start precharge 12
Table 10 – Current State BANK n- Command to BANK n
Notes:
1. The table applies when both CKEn-1 and CKEn are HIGH, and after tXSR or tXP has been met if the previous state was Se
lf
Refresh or Power Down.
2. DESELECT and NOP are functionally interchangeable.
3. All states and sequences not shown are illegal or reserved.
4. This command may or may not be bank specific. If all banks are being precharged, they must be in a valid state for
precharging.
5. A command other than NOP should not be issued to the same bank while a READ or WRITE burst with Auto Precharge is
enabled.
6. The new Read or Write command could be Auto Prechrge enabled or Auto Precharge disabled.
7. Current State Definitions:
Idle: The bank has been precharged, and tRP has been met.
Row Active: A row in the bank has been activated, and tRCD has been met. No data bursts/accesses and no register
accesses are in prog
ress.
Read: A READ burst has been initiated, with Auto Precharge disabled, and has not yet terminated or been terminated.
W
rite: A WRITE burst has been initiated, with Auto Precharge disabled, and has not yet terminated or been terminated
.
8. The following states must not be interrupted by a command issued to the same bank. DESEDECT or NOP commands or
allowable commands to the other bank should be issued on any clock edge occurring during these states. Allowable
commands to the other bank are determined by its current state and this table, and according to next table.
Precharging: Starts with the registration of a PRECHARGE command and ends when tRP is met. Once tRP is met, the ban
k
will be in the idle state.
Row Activating: Starts with registration of an ACTIVE command and ends when tRCD is met. Once tRCD is met, the bank w
ill
be in the ‘row active’ state.
Read with AP Enabled: Starts with the registration of the READ command with Auto Precharge enabled and ends when tRP
has been met. Once tRP has been met, the bank will be in the idle state.
Write with AP Enabled: Starts with registration of a WRITE command with Auto Precharge enabled and ends when tRP has
been met. Once tRP is met, the bank will be in the idle state.
9. The following states must not be interrupted by any executable command; DESEDECT or NOP commands must be applied to
each positive clock edge during these states.
Refreshing: Starts with registration of an AUTO REFRESH command and ends when tRFC is met. Once tRFC is met, the
Mobile DDR SDRAM will be in an ‘all banks idle’ state.
Accessing Mode Register: Starts with registration of a MODE REGISTER SET command and ends when tMRD has been met.
Once tMRD is met, the Mobile DDR SDRAM will be in an ‘all banks idle’ state.
AS4C32M16MD1A-5BCN
Confidential
- 17/56 -
Rev.1.2 July 2016