EtronTech
Pin Descriptions
Table 1. Pin Details of EM639165
Symbol
CLK
Type
Input
Description
EM639165
Clock:
CLK is driven by the system clock. All SDRAM input signals are sampled
on the positive edge of CLK. CLK also increments the internal burst counter and
controls the output registers.
Clock Enable:
CKE activates(HIGH) and deactivates(LOW) the CLK signal. If
CKE goes low synchronously with clock(set-up and hold time same as other
inputs), 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. CKE is synchronous except after the device
enters Power Down and Self Refresh modes, where CKE becomes
asynchronous until exiting the same mode. The input buffers, including CLK, are
disabled during Power Down and Self Refresh modes, providing low standby
power.
Bank Select:
BA0,BA1 input select the bank for operation.
BA1
0
0
1
1
BA0
0
1
0
1
Select Bank
BANK #A
BANK #B
BANK #C
BANK #D
CKE
Input
BA0,BA1
Input
A0-A11
Input
Address Inputs:
A0-A11 are sampled during the BankActivate command (row
address A0-A11) and Read/Write command (column address A0-A8 with A10
defining Auto Precharge) to select one location out of the 2M available in the
respective bank. During a Precharge command, A10 is sampled to determine if
all banks are to be precharged (A10 = HIGH). The address inputs also provide
the op-code during a Mode Register Set command.
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.
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 CLK. 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.
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 CLK. 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# "LOW" or "HIGH."
CS#
Input
RAS#
Input
CAS#
Input
3
Rev 1.6 Feb. 2007
ETRON [ ETRON TECHNOLOGY, INC. ]
