SM2405 - Enhanced SDRAM
512Kx32 ESDRAM
Product Brief
Features
•
100% Function and Timing Compatible with JEDEC
standard SDRAM
•
Pin Compatible with JEDEC Std. SGRAM
•
Integrated 8Kbit SRAM Row Cache per Bank
•
Synchronous Operation up to 166MHz
•
22ns Row Access Latency, 10ns Column Latency
•
Two Bank Architecture
s
1K rows x 256 column x 32 bits x 2 banks
•
Early Auto-Precharge
•
Programmable Burst Length (1, 2, 4, 8, full page)
•
Programmable CAS Latency (1, 2, 3)
•
Hidden Auto-Refresh without closing Read Pages
•
Low Power Suspend, Self-Refresh, and Power Down
Modes Supported
•
Optional “No Write Transfer” Mode
•
Optional Read DQM Latency = 1 for CL=1 (EMRS)
•
Single 3.3V
±
0.3V Power Supply
•
Flexible V
DDQ
Supports LVTTL and 2.5V I/O
•
Programmable Output Impedance (EMRS)
•
2K / 32ms Refresh
•
100-pin LQFP (0.65mm pin pitch)
Description
The SM2405 Enhanced SDRAM (ESDRAM) is a single
data rate I/O device which combines raw speed with
innovative
architecture
to
optimize
system
price/performance in high performance video graphics
and embedded systems. The device is pin compatible
with industry standard SGRAM. It is also function and
timing compatible with JEDEC standard SDRAMs.
The two bank architecture combines 22ns DRAM arrays
with a 10ns SRAM row cache per bank. The SM2405 is a
superset technology of JEDEC standard SDRAM. Its two
key functional features include early auto-precharge (close
DRAM page while burst reads are performed) and an
optional No Write Transfer mode. The ESDRAM is
capable of maintaining two open read pages and two open
write pages simultaneously via the No Write Transfer
mode.
FUNCTIONAL BLOCK DIAGRAM
ADDRESS BUFFERS
ROW DECODER
BA
A(9:0)
BANK A
1K rows x
256 col x
32 bits
BANK B
1K rows x
256 col x
32 bits
DATA LATCHES
SENSE AMPLIFIERS
SENSE AMPLIFIERS
SRAM ROW CACHE
COLUMN DECODER
SRAM ROW CACHE
COLUMN DECODER
CLK
CKE
/CS
/RAS
/CAS
/WE
DQM(3:0)
COMMAND
DECODER
and
TIMING
GENERATOR
DQ(31:0)
The information contained herein is subject to change without notice.
Enhanced reserves the right to change or discontinue this product
without notice.
©
1999 Enhanced Memory Systems Inc.
1850 Ramtron Drive, Colorado Springs, CO 80921
Telephone
(800) 545-DRAM,
Fax
(719) 488-9095,
Web
http://www.edram.com
Rev. 2.0
DATA LATCHES
RAMTRON [ RAMTRON INTERNATIONAL CORPORATION ]
