64Mb: x4, x8, x16
SDRAM
PIN DESCRIPTIONS
PIN NUMBERS
38
SYMBOL
CLK
TYPE
Input
DESCRIPTION
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. Deactivating the clock provides PRECHARGE POWER-DOWN and
SELF REFRESH operation (all banks idle), ACTIVE POWER-DOWN (row
active in any bank) or CLOCK SUSPEND operation (burst/access in
progress). CKE is synchronous except after the device enters power-
down and self refresh modes, where CKE becomes asynchronous until
after exiting the same mode. The input buffers, including CLK, are
disabled during power-down and self refresh modes, providing low
standby power. CKE may be tied HIGH.
Chip Select: CS# enables (registered LOW) and disables (registered
HIGH) the command decoder. All commands are masked when CS# is
registered HIGH. CS# provides for external bank selection on systems
with multiple banks. CS# is considered part of the command code.
Command Inputs: WE#, CAS# and RAS# (along with CS#) define the
command being entered.
Input/Output Mask: DQM is an input mask signal for write accesses and
an output enable signal for read accesses. Input data is masked when
DQM is sampled HIGH during a WRITE cycle. The output buffers are
placed in a High-Z state (two-clock latency) when DQM is sampled
HIGH during a READ cycle. On the x4 and x8, DQML (Pin 15) is a NC and
DQMH is DQM. On the x16, DQML corresponds to DQ0-DQ7 and
DQMH corresponds to DQ8-DQ15. DQML and DQMH are considered
same state when referenced as DQM.
Bank Address Inputs: BA0 and BA1 define to which bank the ACTIVE,
READ, WRITE or PRECHARGE command is being applied.
Address Inputs: A0-A11 are sampled during the ACTIVE command (row-
address A0-A11) and READ/WRITE command (column-address A0-A9
[x4]; A0-A8 [x8]; A0-A7 [x16]; with A10 defining auto precharge) to
select one location out of the memory array in the respective bank. A10
is sampled during a PRECHARGE command to determine if all banks are
to be precharged (A10 HIGH) or bank selected by BA0, BA1 (LOW). The
address inputs also provide the op-code during a LOAD MODE
REGISTER command.
37
CKE
Input
19
CS#
Input
16, 17, 18
39
15, 39
WE#, CAS#,
RAS#
x4, x8: DQM
x16: DQML,
DQMH
Input
Input
20, 21
23-26, 29-34, 22, 35
BA0, BA1
A0-A11
Input
Input
2, 4, 5, 7, 8, 10, 11, 13, 42, DQ0-DQ15
44, 45, 47, 48, 50, 51, 53
2, 5, 8, 11, 44, 47, 50, 53
DQ0-DQ7
5, 11, 44, 50
DQ0-DQ3
36, 40
NC
3, 9, 43, 49
6, 12, 46, 52
1, 14, 27
28, 41, 54
V
DD
Q
V
SS
Q
V
DD
V
SS
x16: I/O Data Input/Output: Data bus for x16 (4, 7, 10, 13, 42, 45, 48, 51 are
NCs for x8; and 2, 4, 7, 8, 10, 13, 42, 45, 47, 48, 51, 53 are NCs for x4).
x8: I/O Data Input/Output: Data bus for x8 (2, 8, 47, 53 are NCs for x4).
x4: I/O Data Input/Output: Data bus for x4.
–
No Connect: These pins should be left unconnected.
Supply DQ Power: Isolated DQ power on the die for improved noise immunity.
Supply DQ Ground: Isolated DQ ground on the die for improved noise
immunity.
Supply Power Supply: +3.3V ±0.3V.
Supply Ground.
64Mb: x4, x8, x16 SDRAM
64MSDRAM.p65 – Rev. 11/99
7
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©1999, Micron Technology, Inc.
MICRON [ MICRON TECHNOLOGY ]
