Et r on Tech
EM658160
4Mx16 DDR SDRAM
Pin Descriptions
Table 1. Pin Details of EM658160
Description
Symbol
Type
CK, /CK
Input
Differential Clock: CK, /CK are driven by the system clock. All SDRAM input signals
are sampled on the positive edge of CK. Both CK and /CK increment the internal burst
counter and controls the output registers.
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.
BS0, BS1
A0-A11
Input
Input
Bank Select: BS0 and BS1 defines to which bank the BankActivate, Read, Write, or
BankPrecharge command is being applied.
Address Inputs: A0-A11 are sampled during the BankActivate command (row
address A0-A11) and Read/Write command (column address A0-A7with A10 defining
Auto Precharge).
/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 positive edges 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 BS is turned on to the active state. When the /WE is asserted
"LOW," the Precharge command is selected and the bank designated by BS 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 positive edges 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 positive edges of CK. The /WE input
is used to select the BankActivate or Precharge command and Read or Write
command.
LDQS,
UDQS
Input /
Output
Bidirectional Data Strobe: Specifies timing for Input and Output data. Read Data
Strobe is edge triggered. Write Data Strobe provides a setup and hold time for data
and DQM. LDQS is for DQ0~7, UDQS is for DQ8~15.
LDM,
UDM
Input
Data Input Mask: Input data is masked when DM is sampled HIGH during a write
cycle. LDM masks DQ0-DQ7, UDM masks DQ8-DQ15.
DQ0 - DQ15 Input /
Output
Data I/O: The DQ0-DQ15 input and output data are synchronized with the positive
edges of CK and /CK. The I/Os are byte-maskable during Writes.
Etron Confidential
3
Rev. 1.1
Jan. 2002
ETRON [ ETRON TECHNOLOGY, INC. ]
