参数资料
型号: W949D2CBJX6E
厂商: WINBOND ELECTRONICS CORP
元件分类: DRAM
英文描述: 16M X 32 DDR DRAM, 5 ns, PBGA90
封装: 8 X 13 MM, 0.80 MM PITCH, HALOGEN FREE AND LEAD FREE, VFBGA-90
文件页数: 50/60页
文件大小: 1160K
代理商: W949D2CBJX6E
W949D6CB / W949D2CB
512Mb Mobile LPDDR
Publication Release Date: Jun, 14, 2011
- 54 -
Revision A01-006
19. tHZ and tLZ transitions occur in the same access time windows as valid data transitions. These parameters
are not referred to a specific voltage level, but specify when the device is no longer driving (HZ), or begins
driving (LZ).
20. tDQSQ consists of data pin skew and output pattern effects, and p-channel to n-channel variation of the
output drivers for any given cycle.
21. The specific requirement is that DQS be valid (HIGH, LOW, or some point on a valid transition) on or before
the corresponding CK edge. A valid transition is defined as monotonic and meeting the input slew rate
specifications of the device. When no writes were previously in progress on the bus, DQS will be transitioning
from Hi-Z to logic LOW. If a previous write was in progress, DQS could be HIGH, LOW, or transitioning from
HIGH to LOW at this time, depending on tDQSS.
22. The maximum limit for this parameter is not a device limit. The device operates with a greater value for this
parameter, but system performance (bus turnaround) will degrade accordingly.
23. A low level on DQS may be maintained during High-Z states (DQS drivers disabled) by adding a weak pull-
down element in the system. It is recommended to turn off the weak pull-down element during read and write
bursts (DQS drivers enabled).
24. At least one clock cycle is required during tWR time when in auto precharge mode.
25. tDAL = (tWR/tCK) + (tRP/tCK): for each of the terms, if not already an integer, round to the next higher
integer.
26. There must be at least two clock pulses during the tXSR period.
27. There must be at least one clock pulse during the tXP period.
28. tREFI values are dependent on density and bus width.
29. A maximum of 8 Refresh commands can be posted to any given LPDDR SDRAM, meaning that the maximum
absolute interval between any Refresh command and the next Refresh command is 8*tREFI.
8.5.1 CAS Latency Definition (With CL=3)
CL=3
tLZmin
tRPRE
tDQSCKmin
tRPST
T5n
T5
T4n
T3n
T2n
T4
T3
T2
READ
NOP
Command
CK
DQS
All DQ,
collectively
1)DQ transitioning after DQS transition define tDQSQ window.
2)ALL DQ must transition by tDQSQ after DQS transitions, regardless of tAC
3)tAC is the DQ output window relative to CK,and is the long term component of DQ skew.
T0
T1
T2
T2n
T3
T3n
T4
T4n
T5
T5n
T6
tLZmin
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