K4B4G0446B Datasheet, PDF(16/59 Page) Samsung semiconductor – DDP 4Gb B-die DDR3 SDRAM Specification

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K4B4G0446B Datasheet, PDF (16/59 Pages) Samsung semiconductor – DDP 4Gb B-die DDR3 SDRAM Specification

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K4B4G0446B

K4B4G0846B

DDP 4Gb DDR3 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

preceeding and following a valid transition.

Note that the applicable ac-levels for ADD/CMD and DQâs 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

VSEL max

CK or DQS

VSS or VSSQ

VSEL

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 charateristics of these signals.

[ Table 11 ] Single ended levels for CK, DQS, DQSL, DQSU, CK, DQS, DQSL or DQSU

Symbol

VSEH

VSEL

Parameter

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

DDR3-800/1066/1333/1600

Min

Max

(VDD/2)+0.175

Note3

(VDD/2)+0.175

Note3

(VDD/2)-0.175

Note3

(VDD/2)-0.175

Unit Notes

1, 2

Notes:

1. For CK, CK use VIH/VIL(AC) of ADD/CMD; for strobes (DQS, DQS, DQSL, DQSL, DQSU, DQSU) use VIH/VIL(AC) of DQs.

2. VIH(AC)/VIL(AC) for DQs is based on VREFDQ; VIH(AC)/VIL(AC) for ADD/CMD is based on VREFCA; if a reduced ac-high or ac-low level is used for a

signal group, then the reduced level applies also here

3. These values are not defined, however they single-ended signals CK, CK, DQS, DQS, DQSL, DQSL, DQSU, DQSU need to be within the respective

limits (VIH(DC) max, VIL(DC)min) for single-ended signals as well as the limitations for overshoot and undershoot. Refer to "Overshoot and Undershoot

Specification"

Page 16 of 59

Rev. 1.0 March 2009

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