Input/Output Functional Descriptions
Symbol
Type
Function
CK0_t, CK0_c,
CK1_t, CK1_c
Clock: CK_t and CK_c are differential clock inputs. All address and control input signals
are sampled on the crossing of the positive edge of CK_t and negative edge of CK_c.
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 Self-Refresh exit. After VREFCA and Internal DQ Vref
CKE0, CKE1
Input have become stable during the power on and initialization sequence, they must be
maintained during all operations (including Self-Refresh). CKE must be maintained high
throughout read and write accesses. Input buffers, excluding CK_t, CK_c, ODT and CKE,
are disabled during power-down. Input buffers, excluding CKE, are disabled during Self-
Refresh.
Chip Select: All commands are masked when CS_n is registered HIGH. CS_n provides for
external Rank selection. CS_n is considered part of the command code.
CS0_n, CS1_n,
CS2_n, CS3_n
Input
Chip ID: Chip ID is only used for 3DS for 2,4,8 high stack via TSV to select each slice of
stacked component. Chip ID is considered part of the command code.
C0, C1, C2
Input
On-Die Termination: ODT (registered HIGH) enables RTT_NOM termination resistance
internal to the DDR4 SDRAM. When enabled, ODT is only applied to each DQ, DQS_t,
DQS_c, TDQS_t, and TDQS_c signal. The ODT pin will be ignored if MR1 is programmed
ODT0, ODT1
Input
to disable RTT_NOM.
Activation Command Input: ACT_n defines the Activation command being entered along
Input with CS_n. The input into RAS_n/A16, CAS_n/A15, and WE_n/A14 will be considered as
Row Address A16, A15, and A14.
ACT_n
Command Inputs: RAS_n/A16, CAS_n/A15, and WE_n/A14 (along with CS_n) define the
command being entered. Those pins are multi-function. For example, for activation with
Input ACT_n Low, these are Addresses like A16, A15, and A14, but for non-activation
command with ACT_n High, these are Command pins for Read, Write, and other
commands defined in command truth table.
RAS_n/A16,
CAS_n/A15,
WE_n/A14
Bank Group Inputs: BG0 - BG1 define to which bank group an Active, Read, Write, or
Input Precharge command is being applied. BG0 also determines which mode register is to be
accessed during a MRS cycle.
BG0 - BG1
BA0 - BA1
Bank Address Inputs: BA0 - BA1 define to which bank an Active, Read, Write, or
Input Precharge command is being applied. Bank address also determines which mode
register is to be accessed during a MRS cycle.
Address Inputs: Provide the row address for ACTIVATE Commands and the column
address for Read/Write commands to select one location out of the memory array in the
Input respective bank. A10/AP, A12/BC_n, RAS_n/A16, CAS_n/A15 and WE_n/A14 have
additional functions. See other rows. The address inputs also provide the op-code during
Mode Register Set commands. A17 is only defined for 16Gb x4 SDRAM configurations.
A0 - A17
Rev. 1.2 / Jul.2019
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