MICROCIRCUIT CORPORATION
DESCRIPTION
The Accutek AK49256 high density memory modules is a random
access memory organized in 256K x 9 bit words. The assembly
consists of nine standard 256K x 1 DRAMs in plastic leaded chip
carriers (PLCC) mounted on the front side of a printed circuit board.
The module can be configured as a leadless 30 pad SIM or a leaded
30 pin SIP. This packaging approach provides a 6 to 1 density in-
crease over standard DIP packaging.
The operation of the AK49256 is identical to nine 256K x 1 DRAMs.
For the lower eight bits data input is tied to the data output and
brought out separately for each device, with common RAS and CAS
control. This common I/O feature dictates the use of early-write cy-
cles to prevent contention of D and Q. Since the Write-Enable (WE)
signal must always go low before CAS in a write cycle, Read-Write
and Read-Modify-Write operation is not possible. For the ninth bit,
the data input (D
9
) and the data output (Q
9
) pins are brought out
separately and controlled by a separate PCAS for that bit. Bit nine is
generally used for parity.
ACCUTEK
AK49256S / AK49256G
262,144 Word by 9 Bit MOS
Dynamic Random Access Memory
Front View
30-Pin SIM
1
30
30-Pin SIP
1
FEATURES
·
262,144 by 9 bit organization
·
Optional 30 Pad leadless SIM (Single In-Line Module) or 30
Pin leaded SIP (Single In-Line Package)
·
JEDEC standard pinout
·
Common CAS and RAS control for the lower eight bits
·
Separate PCAS control for D
9
and Q
9
·
3.15 Watt active and 205 mW standby (max)
·
Operating free air temperature 0
0
C to 70
0
C
·
Upward compatible with AK491024, AK591024, AK594096 and
AK5916384
·
Functionally and Pin compatible with AK59256A
PIN NOMENCLATURE
A
0
- A
8
DQ
1
- DQ
8
D
9
Q
9
CAS, PCAS
RAS
WE
Vcc
Vss
NC
Address Inputs
Data In / Data Out
Data In 9
Data Out 9
Column Address Strobe
Row Address Strobe
Write Enable
5v Supply
Ground
No Connect
PIN ASSIGNMENT
PIN #
SYMBOL
PIN #
SYMBOL
FUNCTIONAL DIAGRAM
DQ5
A8
NC
NC
DQ6
WE
Vss
DQ7
NC
DQ8
Q9
RAS
PCAS
D9
Vcc
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Vcc
CAS
DQ!
A0
A1
DQ2
A2
A3
Vss
DQ3
A4
A5
DQ4
A6
A7
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
MODULE OPTIONS
Leadless SIM: AK49256S
Leaded SIP: AK49256G
15
ACCUTEK [ ACCUTEK MICROCIRCUIT CORPORATION ]
