AS4C256K16FO
®
5V 256K X 16 CMOS DRAM (Fast Page Mode)
Features
• Organization: 262,144 words × 16 bits
• Refresh
• High speed
- 512 refresh cycles, 8 ms refresh interval
- RAS-only or CAS-before-RAS refresh or self-refresh
- Self-refresh option is available for new generation
device only. Contact Alliance for more information.
• Read-modify-write
- 25/30/35/50 ns RAS access time
- 12/16/18/25 ns column address access time
- 7/10/10/10 ns CAS access time
• Low power consumption
- Active: 770 mW max (ASAS4C256K16FO-50)
- Standby: 5.5 mW max, CMOS I/O
• Fast page mode
• TTL-compatible, three-state I/O
• JEDEC standard packages
- 400 mil, 40-pin SOJ
• AS4C256K16FO-50 timings are also valid for
AS4C256K16FO-60.
- 400 mil, 40/44-pin TSOP II
• Single 5V power supply/built-in V generator
bb
• Latch-up current > 200 mA
Pin arrangement
Pin designation
Pin(s)
A0 to A8
RAS
Description
Address inputs
TSOP II
SOJ
V
V
SS
1
44
43
42
41
40
39
38
37
36
35
CC
V
1
2
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
GND
I/O15
I/O14
I/O13
I/O12
GND
I/O11
I/O10
I/O9
I/O8
NC
CC
I/O0
I/O15
2
I/O0
I/O1
I/O2
I/O3
I/O1
I/O2
I/O3
I/O14
I/O13
I/O12
3
Row address strobe
Input/output
3
4
4
5
I/O0 to I/O15
OE
5
V
V
6
V
6
CC
SS
CC
I/O4
I/O11
I/O10
I/O9
7
Output enable
I/O4
I/O5
I/O6
I/O7
NC
7
I/O5
8
8
I/O6
9
UCAS
Column address strobe, upper byte
Column address strobe, lower byte
Read/write control
Power (+5V ± 10%)
Ground
9
I/O7
I/O8
10
10
11
12
13
14
15
16
17
18
19
20
LCAS
NC
LCAS
UCAS
OE
NC
NC
WE
RAS
NC
A0
NC
LCAS
UCAS
OE
13
14
15
16
17
18
19
20
21
22
32
31
30
29
28
27
26
25
24
23
WE
WE
RAS
NC
A8
VCC
A0
A7
A1
A6
A8
GND
A2
A5
A7
A1
A3
A4
A6
V
GND
A2
A5
CC
A3
A4
V
V
CC
SS
Selection guide
Symbol
tRAC
–25
25
–30
–35
35
–50
50
Unit
ns
Maximum RAS access time
30
16
10
10
Maximum column address
access time
tCAA
tCAC
tOEA
12
7
18
10
10
25
10
10
ns
ns
ns
Maximum CAS access time
Maximum output enable (OE)
access time
7
Minimum read or write cycle
time
tRC
40
65
70
85
ns
Minimum EDO page mode
cycle time
tPC
12
200
2.0
12
180
2.0
14
160
2.0
25
140
2.0
ns
Maximum operating current
ICC1
ICC2
mA
mA
Maximum CMOS standby
current
4/11/01; V.0.9.1
Alliance Semiconductor
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