A43P26161 AMIC Technology, Corp., A43P26161 Datasheet - Page 14

• Manufacturer Part Number: A43P26161
• Description: 1M x 16-Bit x 4 Banks Low Power Synchronous DRAM
• Manufacturer: AMIC Technology, Corp.

All Banks Precharge
All banks can be precharged at the same time by using
Precharge all command. Asserting low on
t
the end of tRP after performing precharge all, all banks are
in idle state.
Auto Refresh
The storage cells of SDRAM need to be refreshed every
64ms to maintain data. An auto refresh cycle accomplishes
refresh of a single row of storage cells. The internal counter
increments automatically on every auto refresh cycle to
refresh all the rows. An auto refresh command is issued by
asserting low on
and
with all banks being in idle state and the device is not in
power down mode (CKE is high in the previous cycle). The
time required to complete the auto refresh operation is
specified by “t
required can be calculated by dividing “t
time and then rounding up to the next higher integer. The
auto refresh command must be followed by NOP’s until the
auto refresh operation is completed. All banks will be in the
idle state at the end of auto refresh operation. The auto
refresh is the preferred refresh mode when the SDRAM is
being used for normal data transactions. The auto refresh
cycle can be performed once in 15.6us or a burst of 4096
auto refresh cycles once in 64ms.
PRELIMINARY
WE
RAS
(min) requirement, performs precharge on all banks. At
WE
with high on A10/AP after both banks have satisfied
. The auto refresh command can only be asserted
RC
(min)”. The minimum number of clock cycles
CS
(July, 2005, Version 1.1)
,
RAS
and
CAS
RC
with high on CKE
” with clock cycle
CS
,
RAS
and
13
Self Refresh
The self refresh is another refresh mode available in the
SDRAM. The self refresh is the preferred refresh mode for
data retention and low power operation of SDRAM. In self
refresh mode, the SDRAM disables the internal clock and all
the input buffers except CKE. The refresh addressing and
timing is internally generated to reduce power consumption.
The self refresh mode is entered from all banks idle state by
asserting low on
being low matters, all the other inputs including clock are
ignored to remain in the self refresh.
The self refresh is exited by restarting the external clock and
then asserting high on CKE. This must be followed by NOP’s
for a minimum time of “t
state to begin normal operation. If the system uses burst
auto refresh during normal operation, it is recommended to
used burst 4096 auto refresh cycles immediately after exiting
self refresh.
Deep Power Down Mode
The Deep Power Down Mode is an unique function on Low
Power SDRAMs with very low standby currents. All internal
voltage generators inside the Low Power SDRAMs are
stopped and all memory data will be lost in this mode. To
enter the Deep Power Down Mode all banks must be
precharged and the necessary Precharged Delay t
occur.
WE . Once the self refresh mode is entered, only CKE state
CS
,
RAS
AMIC Technology, Corp.
RC
” before the SDRAM reaches idle
,
CAS
and CKE with high on
A43P26161
RP
must