DEVICE OPERATION
Each die in the UT8Q1024K8 has three control inputs called
Enable (En), Write Enable (Wn), and Output Enable (G); 19
address inputs, A(18:0); and eight bidirectional data lines,
DQ(7:0). The device enable (En) controls device selection,
active, and standby modes. Asserting En enables the device,
causes IDD to rise to its active value, and decodes the 19 address
NC
NC
NC
A0
1
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
E2
2
NC
3
A18
A17
A16
A15
G
A1
4
A2
5
A3
6
A4
7
E1
8
DQ7
DQ6
VSS
DQ0
DQ1
VDD
9
inputs to each memory die . Wn controls read and write
operations. During a read cycle, G must be asserted to enable
the outputs.
10
11
12
13
14
15
16
17
18
19
20
21
22
VSS
VDD
DQ2
DQ3
W1
A5
DQ5
DQ4
A14
A13
A12
A11
A10
NC
Table 1. Device Operation Truth Table
A6
A7
A8
G
Wn
X
En
1
I/O Mode
3-state
Mode
A9
W2
NC
NC
X1
X
1
NC
Standby
0
1
0
0
Data in
3-state
Write
Read2
Read
Figure 2. 25ns SRAM Pinout (44)
0
1
0
Data out
Notes:
PIN NAMES
1. “X” is defined as a “don’t care” condition.
2. Device active; outputs disabled.
A(18:0)
DQ(7:0)
En
Address
Data Input/Output
Device Enable
WriteEnable
Output Enable
Power
READ CYCLE
A combination of Wn greater than VIH (min) withEn andG less
than VIL (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.
Wn
G
SRAM ReadCycle1, theAddressAccessisinitiatedbyachange
in address inputs while the chip is enabled with G asserted and
Wn deasserted. Valid data appears on data outputs DQ(7:0) after
the specified tAVQV is satisfied. Outputs remain active
VDD
VSS
Ground
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 (tAVAV).
Notes:
1. To avoid bus contention, on the DQ(7:0) bus, only one En can be driven low
simultaneously while G is low.
SRAM Read Cycle 2, the Chip Enable-controlled Access is
initiated by En going active while G remains asserted, Wn
remains deasserted, and the addresses remain stable for the
entire cycle. After the specified tETQV 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 is
initiated by G going active while En is asserted, Wn is
deasserted, and the addresses are stable. Read access time is
tGLQV unless tAVQV or tETQV have not been satisfied.
2