EtronTech
EM68B08CWAH
Ball Descriptions
Table 3. Ball Descriptions
Symbol
Type
Description
CK, CK#
Input
Differential Clock:
CK, CK# are driven by the system clock. All SDRAM input signals are sampled on the
crossing of positive edge of CK and negative edge of CK#. Output (Read) data is
referenced to the crossings of CK and CK# (both directions of crossing).
CKE
Input
Clock Enable:
CKE activates (HIGH) and deactivates (LOW) the CK signal. If CKE goes LOW
synchronously with clock, the internal clock is suspended from the next clock cycle
and the state of output and burst address is frozen as long as the CKE remains LOW.
When all banks are in the idle state, deactivating the clock controls the entry to the
Power Down and Self Refresh modes.
BA0-BA1
A0-A13
Input
Input
Bank Address:
BA0-BA1 defines to which bank the BankActivate, Read, Write, or BankPrecharge
command is being applied.
Address Inputs:
A0-A13 are sampled during the BankActivate command (row address A0-A13) and
Read/Write command (column address A0-A9 with A10 defining Auto Precharge).
A13 row address use on x8 components only.
CS#
Input
Input
Chip Select:
CS# enables (sampled LOW) and disables (sampled HIGH) the command decoder.
All commands are masked when CS# is sampled HIGH. CS# provides for external
bank selection on systems with multiple banks. It is considered part of the command
code.
RAS#
Row Address Strobe:
The RAS# signal defines the operation commands in conjunction with the CAS# and
WE# signals and is latched at the crossing of positive edges of CK and negative edge
of CK#. When RAS# and CS# are asserted "LOW" and CAS# is asserted "HIGH,"
either the BankActivate command or the Precharge command is selected by the WE#
signal. When the WE# is asserted "HIGH," the BankActivate command is selected
and the bank designated by BA is turned on to the active state. When the WE# is
asserted "LOW," the Precharge command is selected and the bank designated by BA
is switched to the idle state after the precharge operation.
CAS#
WE#
Input
Input
Column Address Strobe:
The CAS# signal defines the operation commands in conjunction with the RAS# and
WE# signals and is latched at the crossing of positive edges of CK and negative edge
of CK#. When RAS# is held "HIGH" and CS# is asserted "LOW," the column access
is started by asserting CAS# "LOW." Then, the Read or Write command is selected
by asserting WE# “HIGH " or “LOW".
Write Enable:
The WE# signal defines the operation commands in conjunction with the RAS# and
CAS# signals and is latched at the crossing of positive edges of CK and negative
edge of CK#. The WE# input is used to select the BankActivate or Precharge
command and Read or Write command.
Bidirectional Data Strobe:
DQS,
Input /
Output
Output with read data, input with write data for source synchronous operation. Edge-
aligned with read data, center-aligned with write data. DQS# is only used when
differential data strobe mode is enabled via the LOAD MODE command.
DQS#
Etron Confidential
5
Rev. 1.2
Nov. /2013
ETRON [ ETRON TECHNOLOGY, INC. ]
