K4C561638C-TCD4000 Datasheet, PDF (39/42 Pages) Samsung semiconductor – 256Mb Network-DRAM

K4C5608/1638C
256Mb Network-DRAM
Power Down Mode( PD="L" )
When all banks are in the idle state and all outputs are in Hi-Z states, the K4C560838/1638C-TC become Power Down Mode by
asserting PD is "Low". When the device enters the Power Down Mode, all input and output buffers except for PD are disabled after
specified time. Therefore, the power dissipation lowers. To exit the Power Down Mode, PD has to be brought to "High" and the DESL
command has to be issued at next CK rising edge after PD goes high. The Power Down exit function is asynchronous operation.
Mode Register Set (1st command + 2nd command = RDA + MRS)
When all banks are in the idle state, issuing the MRS command following to the RDA command can program the Mode Register. In a
point to notice, the read mode started with the RDA command is canceled by the MRS command having gone into the next clock of the
RDA command instead of the LAL command. The data to be set in the Mode Register is transferred using A0 to A14, BA0 and BA1
address inputs. The K4C560838/1638C-TC have two mode registers. These are Regule and Extended Mode Register. The Regular or
Extended Mode Register is chosen by BA0 in the MRS command.The Regular Mode Register designates the operation mode for a
read or write cycle. The Regular Mode Register has four function fields.
The four fields are as follows :
(R-1) Burst Length field to set the length of burst data
(R-2) Burst Type field to designate the lower address access sequence in a burst cycle
(R-3) CAS Latency field to set the access time in clock cycle
(R-4) Test Mode field to use for supplier only.
The Extended Mode Register has two function fields.
The two fields are as follows:
(E-1) DLL Switch field to choose either DLL enable or DLL disable
(E-2) Output Driver Impedance Control field.
Once these fields in the Mode Register are set up, the register contents are maintained until the Mode Register is set up again by
another MRS command or power supply is lost. The initial value of the Regular or Extended Mode Register after power-up is unde-
fined, therefore the Mode Register Set command must be issued before proper operation.
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REV. 0.7 Aug. 2003