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Table 3: 78-Ball FBGA – x4, x8 Ball Descriptions (Continued)
Symbol
Type
Description
DQ[3:0]
I/O
Data input/output: Bidirectional data bus for the x4 configuration. DQ[3:0] are
referenced to VREFDQ.
DQ[7:0]
I/O
Data input/output: Bidirectional data bus for the x8 configuration. DQ[7:0] are
referenced to VREFDQ.
DQS, DQS#
I/O
Data strobe: Output with read data. Edge-aligned with read data. Input with write
data. Center-aligned to write data.
TDQS, TDQS#
Output
Termination data strobe: Applies to the x8 configuration only. When TDQS is
enabled, DM is disabled, and the TDQS and TDQS# balls provide termination
resistance.
VDD
Supply
Power supply: 1.5V ±0.075V.
VDDQ
Supply
DQ power supply: 1.5V ±0.075V. Isolated on the device for improved noise immunity.
VREFCA
Supply
Reference voltage for control, command, and address: VREFCA must be
maintained at all times (including self refresh) for proper device operation.
VREFDQ
Supply
Reference voltage for data: VREFDQ must be
maintained at all times (excluding self refresh) for proper device operation.
VSS
Supply
Ground.
VSSQ
Supply
DQ ground: Isolated on the device for improved noise immunity.
ZQ
Reference
External reference ball for output drive calibration: This ball is tied to an
external
240Ω resistor (RZQ), which is tied to VSSQ.
NC
–
No connect: These balls should be left unconnected (the ball has no connection to
the DRAM or to other balls).
NF
–
No function: When configured as a x4 device, these balls are NF. When configured
as a x8 device, these balls are defined as TDQS#, DQ[7:4].
2Gb: x4, x8, x16 DDR3 SDRAM
Ball Assignments and Descriptions
PDF: 09005aef826aaadc
2Gb_DDR3_SDRAM.pdf – Rev. K 04/10 EN
20
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