Shelf product is a high-performance CMOS static RAM
organized as 524,288 words by 8 bits. Easy memory expansion
is provided by an active LOW Chip Enable (E), an active LOW
Output Enable (G), and three-state drivers. This device has a
power-down feature that reduces power consumption by more
than 90% when deselected
.
Writing to the device is accomplished by taking Chip Enable
one (E) input LOW and Write Enable (W) inputs LOW. Data on
the eight I/O pins (DQ
0
through DQ
7
) is then written into the
location specified on the address pins (A
0
through A
18
). Reading
from the device is accomplished by taking Chip Enable one (E)
and Output Enable (G) LOW while forcing Write Enable (W)
HIGH. Under these conditions, the contents of the memory
location specified by the address pins will appear on the I/O pins.
The eight input/output pins (DQ
0
through DQ
7
) are placed in a
high impedance state when the device is deselected (E) HIGH),
the outputs are disabled (G HIGH), or during a write operation
(E LOWand W LOW).
Clk. Gen.
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
Pre-Charge Circuit
Row Select
Memory Array
1024 Rows
512x8 Columns
I/O Circuit
Column Select
Data
Control
CLK
Gen.
A10
A11
A12
A13
A14
A15
A16
A17
A18
DQ
0
- DQ
7
E
W
G
Figure 1. UT9Q512 SRAM Block Diagram
2
DEVICE OPERATION
A0
A1
A2
A3
A4
E
DQ0
DQ1
V
DD
V
SS
DQ2
DQ3
W
A5
A6
A7
A8
A9
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
NC
A18
A17
A16
A15
G
DQ7
DQ6
V
SS
V
DD
DQ5
DQ4
A14
A13
A12
A11
A10
NC
The UT9Q512 has three control inputs called Enable 1 (E), Write
Enable (W), and Output Enable (G); 19 address inputs, A(18:0);
and eight bidirectional data lines, DQ(7:0). E Device Enable
controls device selection, active, and standby modes. Asserting
E enables the device, causes I
DD
to rise to its active value, and
decodes the 19 address inputs to select one of 524,288 words in
the memory. W controls read and write operations. During a read
cycle, G must be asserted to enable the outputs.
Table 1. Device Operation Truth Table
G
X
1
X
1
0
W
X
0
1
1
E
1
0
0
0
I/O Mode
3-state
Data in
3-state
Data out
Mode
Standby
Write
Read
2
Read
Figure 2. UT9Q512 25ns SRAM Pinout (36)
(For both packages)
PIN NAMES
A(18:0)
DQ(7:0)
E
W
G
V
DD
V
SS
Address
Data Input/Output
Enable
Write Enable
Output Enable
Power
Ground
Notes:
1. “X” is defined as a “don’t care” condition.
2. Device active; outputs disabled.
READ CYCLE
A combination of W greater than V
IH
(min) and E less than V
IL
(max) defines a read cycle. Read access time is measured from
the latter of Device Enable, Output Enable, or valid address to
valid data output.
SRAM Read Cycle 1, the Address Access in figure 3a, is
initiated by a change in address inputs while the chip is enabled
with G asserted and W deasserted. Valid data appears on data
outputs DQ(7:0) after the specified t
AVQV
is satisfied. Outputs
remain active throughout the entire cycle. As long as Device
Enable and Output Enable are active, the address inputs may
change at a rate equal to the minimum read cycle time (t
AVAV
).
SRAM read Cycle 2, the Chip Enable - Controlled Access in
figure 3b, is initiated by E going active while G remains asserted,
W remains deasserted, and the addresses remain stable for the
entire cycle. After the specified t
ETQV
is satisfied, the eight-bit
word addressed by A(18:0) is accessed and appears at the data
outputs DQ(7:0).
SRAM read Cycle 3, the Output Enable - Controlled Access in
figure 3c, is initiated by G going active while E is asserted, W
is deasserted, and the addresses are stable. Read access time is
t
GLQV
unless t
AVQV
or t
ETQV
have not been satisfied.
3
WRITE CYCLE
A combination of W less than V
IL
(max) and E less than
V
IL
(max) defines a write cycle. The state of G is a “don’t care”
for a write cycle. The outputs are placed in the high-impedance
state when either G is greater than V
IH
(min), or when W is less
than V
IL
(max).
Write Cycle 1, the Write Enable - Controlled Access in figure
4a, is defined by a write terminated by W going high, with E
still active. The write pulse width is defined by t
WLWH
when the
write is initiated by W, and by t
ETWH
when the write is initiated
by E. Unless the outputs have been previously placed in the high-
impedance state by G, the user must wait t
WLQZ
before applying
data to the nine bidirectional pins DQ(7:0) to avoid bus
contention.
Write Cycle 2, the Chip Enable - Controlled Access in figure
4b, is defined by a write terminated by E going inactive. The
write pulse width is defined by t
WLEF
when the write is initiated
by W, and by t
ETEF
when the write is initiated by the E going
active. For the W initiated write, unless the outputs have been
previously placed in the high-impedance state by G, the user
must wait t
WLQZ
before applying data to the eight bidirectional
pins DQ(7:0) to avoid bus contention.
TYPICAL RADIATION HARDNESS
Table 2. Radiation Hardness
Design Specifications
1
Total Dose
Heavy Ion
Error Rate
2
50
<1E-8
krad(Si)
Errors/Bit-Day
Notes:
1. The SRAM will not latchup during radiation exposure under recommended
operating conditions.
2. 90% worst case particle environment, Geosynchronous orbit, 0.025 mils of
Aluminum.
4
ABSOLUTE MAXIMUM RATINGS
1
(Referenced to V
SS
)
SYMBOL
V
DD
V
I/O
T
STG
P
D
T
J
Θ
JC
I
I
PARAMETER
DC supply voltage
Voltage on any pin
Storage temperature
Maximum power dissipation
Maximum junction temperature
2
Thermal resistance, junction-to-case
3
DC input current
LIMITS
-0.5 to 7.0V
-0.5 to 7.0V
-65 to +150°C
1.0W
+150°C
10°C/W
±
10 mA
Notes:
1. Stresses outside the listed 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 beyond limits indicated in the operational sections of this specification is not recommended. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability and performance.
2. Maximum junction temperature may be increased to +175°C during burn-in and steady-static life.
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