262,144-bit Static Random-Access Memory (SRAM) device organized as
32,768 words × 8 bits. It is designed for memory applications requiring fast data access at low voltage, including Pentium
TM
,
PowerPC
TM
, and portable computing. Alliance’s advanced circuit design and process techniques permit 5.0V operation
without sacrificing performance or operating margins.
The device enters
standby mode
when CE is high. Equal address access and cycle times (t
AA
, t
RC
, t
WC
) of 12 ns with output
enable access times (t
OE
) of 6 ns are ideal for high-performance applications. The chip enable (CE) input permits easy memory
expansion with multiple-bank memory organizations.
A write cycle is accomplished by asserting chip enable (CE) and write enable (WE) LOW. Data on the input pins I/O0-I/O7 is
written on the rising edge of WE (write cycle 1) or CE (write cycle 2). To avoid bus contention, external devices should drive
I/O pins only after outputs have been disabled with output enable (OE) or write enable (WE).
A read cycle is accomplished by asserting chip enable (CE) and output enable (OE) LOW, with write enable (WE) high. The
chip drives I/O pins with the data word referenced by the input address. When chip enable or output enable is high, or write
enable is low, output drivers stay in high-impedance mode.
All chip inputs and outputs are TTL-compatible. Operation is from a single 5.0±0.5V supply. The AS7C256B is packaged in
high volume industry standard packages.
Absolute maximum ratings
Parameter
Voltage on V
CC
relative to GND
Voltage on any pin relative to GND
Power dissipation
Storage temperature (plastic)
Ambient temperature with V
CC
applied
DC current into outputs (low)
Note:
Stresses 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 outside those indicated in the operational sections of this specification is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect reliability.
Symbol
V
t1
V
t2
P
D
T
stg
T
bias
I
OUT
Min
–0.5
–0.5
–
–55
–55
–
Max
+7.0
V
CC
+ 0.5
1.25
+125
+125
50
Unit
V
V
W
o
C
o
C
mA
Truth table
CE
WE
OE
Data
High Z
High Z
D
OUT
D
IN
Mode
Standby (I
SB
, I
SB1
)
Output disable (I
CC
)
Read (I
CC
)
Write (I
CC
)
H
L
L
L
Notes:
H = V
IH
, L = V
IL
, x = Don’t care.
V
LC
= 0.2V, V
HC
= V
CC
- 0.2V.
Other inputs
≥
V
HC
or V
LC
.
X
H
H
L
X
H
L
X
12/5/06; V.1.0
Alliance Memory
P. 2 of 8
AS7C256B
®
Recommended operating conditions
Parameter
Supply voltage
Input voltage
Ambient operating temperature (Industrial)
Note:
1 V
IL
min = –1.5V for pulse width less than 10ns, once per cycle.
Symbol
V
CC
V
IH
V
IL
(1)
Min
4.5
2.2
-0.5
(1)
–40
Typical
5.0
–
–
–
Max
5.5
V
CC
+0.5
0.8
85
Unit
V
V
V
o
T
A
C
DC operating characteristics (over the operating range)
1
AS7C256B-12
Parameter
Input leakage current
Output leakage current
Operating power supply current
Symbol
|I
LI
|
|I
LO
|
I
CC
I
SB
Standby power supply current
I
SB1
V
OL
V
OH
Test conditions
V
CC
= Max,
V
in
= GND to V
CC
V
CC
= Max,
CS
= V
IH
,
V
OUT
= GND to V
CC
V
CC
= Max, CE
≤
V
IL
f = f
Max
, I
OUT
= 0mA
V
CC
= Max, CE
>
V
IH
f = f
Max
, I
OUT
= 0mA
V
CC
= Max, CE
>
V
CC
–0.2V
V
IN
< GND + 0.2V or
V
IN
> V
CC
–0.2V, f = 0
(2)
I
OL
= 8 mA, V
CC
= Min
I
OH
= –4 mA, V
CC
= Min
Min
–
–
–
–
Max
5
5
160
50
Unit
µA
µA
mA
mA
–
–
2.4
15
0.4
–
mA
V
V
Output voltage
Notes:
All values are maximum guaranteed values.
f
Max
= 1/t
RC
, only address inputs cycling at f
Max
, f = 0 means that no inputs are cycling.
Capacitance (f = 1MHz, T
a
= room temperature, V
CC
= NOMINAL)
2
Parameter
Input capacitance
I/O capacitance
Note:
This parameter is guaranteed by device characterization, but is not production tested.
从全球来看，智能电视在设备互联接口、内容服务接口、应用程序开发接口、系统安全可信技术等方面的标准尚未统一，厂商采用不同的操作系统和内容接口，各自的应用互不兼容，对产业整体发展造成障碍，在应用丰富度上也很欠缺。近日国内一些家电厂商主办智能电视开发论坛，力图吸引更多的开发者参与进来，从这一点来看，目前还是家电厂商较为主动地在推动智能电视标准化以及各类应用的开发。 TV OS成产业角逐焦点 ...[详细]
嵌入式系统
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
