DDR SDRAM 512Mb C-die (x4, x8, x16)
DDR SDRAM
7.0 Input/Output Function Description
SYMBOL
TYPE
DESCRIPTION
Clock : CK and CK are differential clock inputs. All address and control input signals are sam-
pled on the positive edge of CK and negative edge of CK. Output (read) data is referenced to
both edges of CK. Internal clock signals are derived from CK/CK.
CK, CK
Input
Clock Enable : CKE HIGH activates, and CKE LOW deactivates internal clock signals, and
device input buffers and output drivers. Taking CKE Low provides PRECHARGE POWER-
DOWN and SELF REFRESH operation (all banks idle), or ACTIVE POWER-DOWN (row
ACTIVE in any bank). CKE is synchronous for POWER-DOWN entry and exit, and for SELF
REFRESH entry. CKE is asynchronous for SELF REFRESH exit, and for output disable. CKE
must be maintained high throughput READ and WRITE accesses. Input buffers, excluding CK,
CK and CKE are disabled during POWER-DOWN. Input buffers, excluding CKE are disabled
during SELF REFRESH. CKE is an SSTL_2 input, but will detect an LVCMOS Low level after
Vdd is applied upon 1st power up, After VREF has become stable during the power on and ini-
CKE
Input
tialization sequence, it must be maintained for proper operation of the CKE receiver. For
proper SELF-REFRESH entry and exit, VREF must be maintained to this input.
Chip Select : CS enables(registered LOW) and disables(registered HIGH) the command
decoder. All commands are masked when CS is registered HIGH. CS provides for external
bank selection on systems with multiple banks. CS is considered part of the command code.
CS
Input
Input
RAS, CAS, WE
Command Inputs : RAS, CAS and WE (along with CS) define the command being entered.
Input Data Mask : DM is an input mask signal for write data. Input data is masked when DM is
sampled HIGH along with that input data during a WRITE access. DM is sampled on both
edges of DQS. Although DM pins are input only, the DM loading matches the DQ and DQS
loading. For the x16, LDM corresponds to the data on DQ0~D7 ; UDM corresponds to the data
on DQ8~DQ15. DM may be driven high, low, or floating during READs.
LDM,(UDM)
BA0, BA1
Input
Input
Bank Addres Inputs : BA0 and BA1 define to which bank an ACTIVE, READ, WRITE or PRE-
CHARGE command is being applied.
Address Inputs : Provide the row address for ACTIVE commands, and the column address and
AUTO PRECHARGE bit for READ/WRITE commands, to select one location out of the mem-
ory array in the respective bank. A10 is sampled during a PRECHARGE command to deter-
mine whether the PRECHARGE applies to one bank (A10 LOW) or all banks (A10 HIGH). If
only one bank is to be precharged, the bank is selected by BA0, BA1. The address inputs also
provide the op-code during a MODE REGISTER SET command. BA0 and BA1 define which
mode register is loaded during the MODE REGISTER SET command (MRS or EMRS).
A [0 : 12]
Input
DQ
I/O
I/O
Data Input/Output : Data bus
Data Strobe : Output with read data, input with write data. Edge-aligned with read data, cen-
tered in write data. Used to capture write data. For the x16, LDQS corresponds to the data on
DQ0~D7 ; UDQS corresponds to the data on DQ8~DQ15
LDQS,(U)DQS
NC
-
No Connect : No internal electrical connection is present.
DQ Power Supply : +2.5V ± 0.2V. (+2.6V ±0.1V for DDR400)
DQ Ground.
VDDQ
VSSQ
VDD
Supply
Supply
Supply
Supply
Input
Power Supply : +2.5V ± 0.2V. (+2.6V ±0.1V for DDR400)
Ground.
VSS
VREF
SSTL_2 reference voltage.
Rev. 1.1 June. 2005
SAMSUNG [ SAMSUNG ]
