HYB25D256[400/800/160]B[T/C](L)
256-Mbit Double Data Rate SDRAM
Pin Configuration
Table 4
Symbol
CK, CK
Input/Output Functional Description
Type
Function
Input
Clock: CK and CK are differential clock inputs. All address and control input
signals are sampled on the crossing of the positive edge of CK and negative
edge of CK. Output (read) data is referenced to the crossings of CK and CK
(both directions of crossing).
CKE
Input
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. CKE must be maintained high throughout 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.
CS
Chip Select: 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. The standard pinout includes one CS
pin.
RAS, CAS, WE Input
Command Inputs: RAS, CAS and WE (along with CS) define the command
being entered.
DM
Input
Input
Input
Input Data Mask: DM is an input mask signal for write data. Input data is
masked when DM is sampled HIGH coincident 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.
BA0, BA1
A0 – A12
Bank Address Inputs: BA0 and BA1 define to which bank an Active, Read,
Write or Precharge command is being applied. BA0 and BA1 also determines
if the mode register or extended mode register is to be accessed during a
MRS or EMRS cycle.
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 memory array in the respective bank. A10 is sampled
during a Precharge command to determine 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.
DQ
Input/Output
Input/Output
Data Input/Output: Data bus.
DQS
Data Strobe: Output with read data, input with write data. Edge-aligned with
read data, centered in write data. Used to capture write data.
NC
–
No Connect: No internal electrical connection is present.
DQ Power Supply: 2.5 V ± 0.2 V/ 2.6V ± 0.1V.
DQ Ground
VDDQ
VSSQ
VDD
Supply
Supply
Supply
Supply
Supply
Power Supply: 2.5 V ± 0.2 V / 2.6V ± 0.1V
Ground
VSS
VREF
SSTL_2 reference voltage: (VDDQ / 2)
Data Sheet
11
Rev. 1.21, 2004-07
02102004-TSR1-4ZWW
QIMONDA [ QIMONDA AG ]
