Rev. 1.01
K4B2G0446D
K4B2G0846D
datasheet
DDR3L SDRAM
8.3.3 Single-ended requirements for differential signals
Each individual component of a differential signal (CK, DQS, DQSL, DQSU, CK, DQS, DQSL, or DQSU) has also to comply with certain requirements for
single-ended signals.
CK and CK have to approximately reach VSEHmin / VSELmax [approximately equal to the ac-levels { VIH(AC) / VIL(AC)} for ADD/CMD signals] in every
half-cycle.
DQS, DQSL, DQSU, DQS, DQSL have to reach VSEHmin / VSELmax [approximately the ac-levels { VIH(AC) / VIL(AC)} for DQ signals] in every half-cycle
proceeding and following a valid transition.
Note that the applicable ac-levels for ADD/CMD and DQ’s might be different per speed-bin etc. E.g. if VIH150(AC)/VIL150(AC) is used for ADD/CMD sig-
nals, then these ac-levels apply also for the single-ended signals CK and CK .
VDD or VDDQ
VSEH min
VSEH
VDD/2 or VDDQ/2
CK or DQS
VSEL max
VSEL
VSS or VSSQ
time
Figure 3. Single-ended requirement for differential signals
Note that while ADD/CMD and DQ signal requirements are with respect to VREF, the single-ended components of differential signals have a requirement
with respect to VDD/2; this is nominally the same. The transition of single-ended signals through the ac-levels is used to measure setup time. For single-
ended components of differential signals the requirement to reach VSELmax, VSEHmin has no bearing on timing, but adds a restriction on the common
mode characteristics of these signals.
[ Table 12 ] Single-ended levels for CK, DQS, DQSL, DQSU, CK, DQS, DQSL, or DQSU
DDR3-800/1066/1333/1600
Symbol
Parameter
Unit
NOTE
Min
Max
(VDD/2)+0.175
(VDD/2)+0.175
NOTE3
Single-ended high-level for strobes
Single-ended high-level for CK, CK
Single-ended low-level for strobes
Single-ended low-level for CK, CK
NOTE3
NOTE3
(VDD/2)-0.175
(VDD/2)-0.175
V
V
V
V
1, 2
1, 2
1, 2
1, 2
VSEH
VSEL
NOTE3
NOTE :
1. For CK, CK use V /V (AC) of ADD/CMD; for strobes (DQS, DQS, DQSL, DQSL, DQSU, DQSU) use V /V (AC) of DQs.
IH IL
IH IL
2. V (AC)/V (AC) for DQs is based on V
; V (AC)/V (AC) for ADD/CMD is based on V
; if a reduced ac-high or ac-low level is used for a signal group, then the
IH
IL
REFDQ
IH
IL
REFCA
reduced level applies also here
3. These values are not defined, however the single-ended signals CK, CK, DQS, DQS, DQSL, DQSL, DQSU, DQSU need to be within the respective
limits (V (DC) max, V (DC)min) for single-ended signals as well as the limitations for overshoot and undershoot. Refer to "Overshoot and Undershoot
IH
IL
Specification"
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