AS4C4M16S
FEBRUARY 2011
T0
T1
T2
T3
T4
T5
T6
T7
T8
CLK
Bank,
Col A
Bank
Row
Bank(s)
ADDRESS
tRP
NOP
READ
A
NOP
NOP
NOP
Precharge
NOP
Activate
NOP
COMMAND
CAS# latency=2
tCK2, DQ
DOUT A0 DOUT A1 DOUT A2 DOUT A3
CAS# latency=3
tCK3, DQ
DOUT A0 DOUT A1 DOUT A2 DOUT A3
Don’t Care
Figure 9. Read to Precharge (CAS# Latency = 2, 3)
5 Read and AutoPrecharge command
(RAS# = "H", CAS# = "L", WE# = "H", BAs = Bank, A10 = "H", A0-A7 = Column Address)
The Read and AutoPrecharge command automatically performs the precharge operation after the
read operation. Once this command is given, any subsequent command cannot occur within a time delay of
{tRP(min.) + burst length}. At full-page burst, only the read operation is performed in this command and the
auto precharge function is ignored.
6 Write command
(RAS# = "H", CAS# = "L", WE# = "L", BAs = Bank, A10 = "L", A0-A7 = Column Address)
The Write command is used to write a burst of data on consecutive clock cycles from an active row in
an active bank. The bank must be active for at least t RCD(min.) before the Write command is issued. During
write bursts, the first valid data-in element will be registered coincident with the Write command.
Subsequent data elements will be registered on each successive positive clock edge (refer to the following
figure). The DQs remain with high-impedance at the end of the burst unless another command is initiated.
The burst length and burst sequence are determined by the mode register, which is already programmed. A
full-page burst will continue until terminated (at the end of the page it will wrap to column 0 and continue).
T0
T1
T2
T3
T4
T5
T6
T7
T8
CLK
WRITE A
DIN A0
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
COMMAND
don’t care
DIN A1
DIN A2
DIN A3
DQ
The first data element and the write
are registered on the same clock edge
Figure 10. Burst Write Operation (Burst Length = 4)
9
Rev2.0 May 2014
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
