without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to
obtain the latest version of this device specification before relying on any published information and before placing orders for products.
Integrated Silicon Solution, Inc. — 1-800-379-4774
Rev. C
02/01/05
1
IS41LV8205A
FUNCTIONAL BLOCK DIAGRAM
ISSI
®
OE
WE
CAS
CONTROL
LOGIC
WE
CONTROL
LOGIC
OE
CONTROL
LOGIC
OE
RAS
DATA I/O BUS
CAS
CAS
WE
RAS
RAS
CLOCK
GENERATOR
COLUMN DECODER
SENSE AMPLIFIERS
REFRESH
COUNTER
DATA I/O BUFFERS
I/O0-I/O7
ROW DECODER
ADDRESS
BUFFERS
A0-A10
MEMORY ARRAY
2,097,152 x 8
TRUTH TABLE
Function
Standby
Read
Write: Word (Early Write)
Read-Write
Hidden Refresh
Read
Write
(1)
RAS
H
L
L
L
L→H→L
L→H→L
L
H→L
CAS
H
L
L
L
L
L
H
L
WE
X
H
L
H→L
H
L
X
X
OE
X
L
X
L→H
L
X
X
X
Address t
R
/t
C
X
ROW/COL
ROW/COL
ROW/COL
ROW/COL
ROW/COL
ROW/NA
X
I/O
High-Z
D
OUT
D
IN
D
OUT
, D
IN
D
OUT
D
OUT
High-Z
High-Z
RAS-Only
Refresh
CBR Refresh
Note:
1. EARLY WRITE only.
2
Integrated Silicon Solution, Inc. — 1-800-379-4774
Rev. C
02/01/05
IS41LV8205A
Functional Description
The IS41LV8205A is CMOS DRAMs optimized for high-
speed bandwidth, low power applications. During READ or
WRITE cycles, each bit is uniquely addressed through the
11 address bits. These are entered 11 bits (A0-A10) at a
time. The row address is latched by the Row Address
Strobe (RAS). The column address is latched by the
Column Address Strobe (CAS).
RAS
is used to latch the
first nine bits and
CAS
is used the latter ten bits.
ISSI
Auto Refresh Cycle
®
To retain data, 2,048 refresh cycles are required in each
32 ms period. There are two ways to refresh the memory:
1. By clocking each of the 2,048 row addresses (A0
through A10) with RAS at least once every 32 ms. Any
read, write, read-modify-write or RAS-only cycle refreshes
the addressed row.
2. Using a
CAS-before-RAS
refresh cycle.
CAS-before-RAS
refresh is activated by the falling edge of
RAS,
while
holding
CAS
LOW. In
CAS-before-RAS
refresh cycle,
an internal 9-bit counter provides the row addresses
and the external address inputs are ignored.
CAS-before-RAS
is a refresh-only mode and no data
access or device selection is allowed. Thus, the output
remains in the High-Z state during the cycle.
Memory Cycle
A memory cycle is initiated by bring
RAS
LOW and it is
terminated by returning both
RAS
and
CAS
HIGH. To
ensures proper device operation and data integrity any
memory cycle, once initiated, must not be ended or
aborted before the minimum t
RAS
time has expired. A new
cycle must not be initiated until the minimum precharge
time t
RP
, t
CP
has elapsed.
Power-On
After application of the V
DD
supply, an initial pause of
200 µs is required followed by a minimum of eight
initialization cycles (any combination of cycles contain-
ing a
RAS
signal).
During power-on, it is recommended that
RAS
track with
V
DD
or be held at a valid V
IH
to avoid current surges.
Read Cycle
A read cycle is initiated by the falling edge of
CAS
or
OE,
whichever occurs last, while holding
WE
HIGH. The
column address must be held for a minimum time specified
by t
AR
. Data Out becomes valid only when t
RAC
, t
AA
, t
CAC
and t
OEA
are all satisfied. As a result, the access time is
dependent on the timing relationships between these
parameters.
Write Cycle
A write cycle is initiated by the falling edge of
CAS
and
WE,
whichever occurs last. The input data must be valid
at or before the falling edge of
CAS
or
WE,
whichever
occurs last.
Integrated Silicon Solution, Inc. — 1-800-379-4774
Rev. C
02/01/05
3
IS41LV8205A
ABSOLUTE MAXIMUM RATINGS
(1)
Symbol
V
T
V
DD
I
OUT
P
D
T
STG
Parameters
Voltage on Any Pin Relative to GND
Supply Voltage
Output Current
Power Dissipation
Storage Temperature
3.3V
3.3V
Rating
–0.5 to +4.6
–0.5 to +4.6
50
1
–55 to +125
Unit
V
V
mA
W
°C
ISSI
®
Note:
1. Stress greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device.
This is a stress rating only and functional operation of the device at these or any other conditions above those indicated
in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended
periods may affect reliability.
RECOMMENDED OPERATING CONDITIONS
(Voltages are referenced to GND.)
Symbol
V
DD
V
IH
V
IL
Parameter
Supply Voltage
Input High Voltage
Input Low Voltage
3.3V
3.3V
3.3V
Min.
3.0
2.0
–0.3
Typ.
3.3
—
—
Max.
3.6
V
DD
+ 0.3
0.8
Unit
V
V
V
CAPACITANCE
(1,2)
Symbol
C
IN
1
C
IN
2
C
IO
Parameter
Input Capacitance: A0-A10(A11)
Input Capacitance:
RAS, CAS, WE, OE
Data Input/Output Capacitance: I/O0-I/O3
Max.
5
7
7
Unit
pF
pF
pF
Notes:
1. Tested initially and after any design or process changes that may affect these parameters.
2. Test conditions: T
A
= 25°C, f = 1 MHz.
4
Integrated Silicon Solution, Inc. — 1-800-379-4774
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
