
Table 3: FBGA 78-Ball Descriptions (Continued)
Symbol Type Description
CKE Input Clock enable: CKE HIGH activates, and CKE LOW deactivates, the internal clock
signals, device input buffers, and output drivers. Taking CKE LOW provides PRE-
CHARGE POWER-DOWN and SELF REFRESH operations (all banks idle), or active
power-down (row active in any bank). CKE is asynchronous for self refresh exit.
After V
REFCA
has become stable during the power-on and initialization sequence,
it must be maintained during all operations (including SELF REFRESH). CKE must
be maintained HIGH throughout read and write accesses. Input buffers (exclud-
ing CK_t, CK_c, ODT, RESET_n, and CKE are disabled during power-down. Input
buffers (excluding CKE and RESET#) are disabled during self refresh.
CS_n Input Chip select: All commands are masked when CS_n is registered HIGH. CS_n pro-
vides for external rank selection on systems with multiple ranks. CS_n is consid-
ered part of the command code.
DM_nS Input Input data mask: DM_n is an input mask signal for write data. Input data is
masked when DM is sampled LOW coincident with that input data during a write
access. DM is sampled on both edges of DQS. DM is not supported on x4 configu-
rations. LDM_n is associated with DQ[7:0]. The DM, DBI, and TDQS functions are
enabled by mode register settings. See the Data Mask (DM) section.
ODT Input On-die termination: ODT (registered HIGH) enables termination resistance in-
ternal to the DDR4 SDRAM. When enabled, ODT (R
TT
) is applied only to each DQ,
DQS_t, DQS_c, DM_n/DBI_n/TDQS_t, and TDQS_c signal for the x4 and x8 configu-
rations (when the TDQS function is enabled via mode register). The ODT pin will
be ignored if the mode registers are programmed to disable R
TT
.
PAR Input Parity for command and address: This function can be enabled or disabled via
the mode register. When enabled, the parity signal covers all command and ad-
dress inputs, including RAS_n/A16, CAS_n/A15, WE_n/A14, A[17:0], A10/AP, A12/
BC_n, BA[1:0], BG[1:0], C0/A18, C1/A19, C2/A20. Control pins NOT covered by the
parity signal are CS_n, CKE, and ODT. Unused address pins that are density- and
configuration-specific should be treated internally as 0s by the DRAM parity log-
ic.
RAS_n/A16,
CAS_n/A15,
WE_n/A14
Input Command inputs: RAS_n/A16 , CAS_n/A15, and WE_n/A14 (along with CS_n and
ACT_n) define the command and/or address being entered. See the ACT_n de-
scription in this table.
RESET_n Input Active LOW asynchronous reset: Reset is active when RESET_n is LOW, and in-
active when RESET_n is HIGH. RESET_n must be HIGH during normal operation.
RESET_n is a CMOS rail-to-rail signal with DC HIGH and LOW at 80% and 20% of
V
DD
; that is, 960 mV for DC HIGH and 240 mV for DC LOW.
TEN Input Connectivity test mode: TEN is active when HIGH and inactive when LOW. TEN
must be LOW during normal operation. TEN is a CMOS rail-to-rail signal with DC
HIGH and LOW at 80% and 20% of V
DD
(960mV for DC HIGH and 240mV for DC
LOW).
16Gb: x4, x8 TwinDie DDR4 SDRAM
Ball Assignments and Descriptions
PDF: 09005aef85fd40a1
DDR4_16Gb_x4_x8_2CS_TwinDie.pdf - Rev. D 12/16 EN
5
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