PRELIMINARY
4Mb : 256K x 18, 128K x 32/36
3.3V I/O PIPELINED, DCD SYNCBURST SRAM
GENERAL DESCRIPTION (co n t in u e d )
Asynchronous inputs include the output enable
(OE#), clock (CLK) and snooze enable (ZZ). There is also
a burst mode input (MODE) that selects between inter-
leaved and linear burst modes. The data-out (Q), en-
abled by OE#, is also asynchronous. WRITE cycles can
be from one to two bytes wide (x18) or from one to four
bytes wide (x32/x36), as controlled by the write control
inputs.
devices, BWa# controls DQa’s and DQPa; BWb# con-
trols DQb’s and DQPb; BWc# controls DQc’s and DQPc;
BWd# controls DQd’s and DQPd. GW# LOW causes all
bytes to be written. Parity bits are only available on the
x18 and x36 versions.
This device incorporates an additional pipelined
enable register which delays turning off the output
buffer an additional cycle when a deselect is executed.
This feature allows depth expansion without penaliz-
ing system performance.
Micron’s 4Mb SyncBurst SRAMs operate from a
+3.3V VDD power supply, and all inputs and outputs are
TTL-compatible. The device is ideally suited for
Pentium® and PowerPC pipelined systems and systems
that benefit from a very wide, high-speed data bus. The
device is also ideal in generic 16-, 18-, 32-, 36-, 64- and
72-bit-wide applications.
Burst operation can be initiated with either address
status processor (ADSP#) or address status controller
(ADSC#) inputs. Subsequent burst addresses can be
internally generated as controlled by the burst advance
input (ADV#).
Address and write control are registered on-chip to
simplify WRITE cycles. This allows self-timed WRITE
cycles. Individual byte enables allow individual bytes
to be written. During WRITE cycles on the x18 device,
BWa# controls DQa’s and DQPa; BWb# controls DQb’s
and DQPb. During WRITE cycles on the x32 and x36
PleaserefertoMicron’sWebsite(www.micron.com/
mti/msp/html/sramprod.html)forthelatestdatasheet.
TQFP PIN ASSIGNMENT TABLE
PIN #
1
2
3
4
5
6
7
8
x18
NC
NC
NC
x32/x36
NC/DQPc*
DQc
PIN #
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
x18
x32/x36
VSS
VDDQ
DQd
DQd
NC/DQPd*
MODE
PIN #
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
x18
NC
NC
NC
x32/x36
NC/DQPa*
DQa
PIN #
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
x18
x32/x36
VSS
VDDQ
DQb
DQb
NC/DQPb*
SA
SA
ADV#
ADSP#
ADSC#
OE#
BWE#
GW#
CLK
DQc
NC
NC
NC
DQa
NC
NC
SA
VDDQ
VSS
VDDQ
VSS
NC
NC
DQb
DQb
DQc
DQc
DQc
DQc
NC
NC
DQa
DQa
SA
SA
SA
DQa
DQa
VSS
VDDQ
DQa
DQa
ZZ
VDD
NC
VSS
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
VSS
VDDQ
SA
SA1
SA0
DNU
DNU
VSS
VDD
NF**
NF**
SA
DQb
DQb
DQc
DQc
VDD
VDD
NC
VSS
VDD
VSS
CE2#
BWa#
BWb#
DQb
DQb
DQd
DQd
DQa
DQa
DQb
DQb
VDDQ
VSS
SA
SA
SA
SA
SA
SA
VDDQ
VSS
NC
NC
BWc#
BWd#
DQb
DQb
DQPb
NC
DQd
DQd
DQd
DQd
DQa
DQa
DQPa
NC
DQb
DQb
DQb
DQb
CE2
CE#
SA
SA
*No Connect (NC) is used on the x32 version. Parity (DQPx) is used on the x36 version.
**Pins 43 and 42 are reserved for address expansion, 8Mb and 16Mb respectively.
4Mb: 256K x 18, 128K x 32/36 3.3V I/O Pipelined, DCD SyncBurst SRAM
MT58L256L18D1.p65 – Rev 12/99
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©1999, Micron Technology, Inc.
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