UVEPROM
Austin Semiconductor, Inc.
GENERAL DESCRIPTION
The AS27C256A series is a set of 262,144 bit, ultraviolet-
light erasable, electrically programmable read-only
memo-
ries. These devices are fabricated using power-saving CMOS
technology for high speed and simple interface with MOS and
bipolar circuits. All inputs (including program data inputs)
can be driven by Series 54 TTL circuits without the use of
external pullup resistors. Each output can drive one Series 54
TTL circuit without external resistors. The data outputs are 3-
state for connecting multiple devices to a common bus. The
AS27C256A is pin-compatible with 28-pin 256K ROMs and
EPROMs. It is offered in a 600mil dual-in-line ceramic pack-
age (J suffix) and a 450 x 550 mil ceramic LCC (ECA suffix)
rated for operation from -55°C to 125°C.
Because this EPROM operates from a single 5V supply (in
the read mode), it is ideal for use in microprocessor-based sys-
tems. One other supply (12.75V) is needed for programming.
All programming signals are TTL level. This device is
programmable by the AMD FLASHRITE Pulse programming
algorithm. The FLASHRITE Pulse programming algorithm
uses a V
PP
of 12.75VV and a V
CC
of 6.25V for a nominal pro-
gramming time of four seconds. For programming outside the
system, existing EPROM programmers can be used. Loca-
tions can be
programmed singly, in blocks, or at random.
AS27C256A
FUNCTIONAL BLOCK DIAGRAM*
EPROM 32,768 x 8
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
E\
G\
10
9
8
7
6
5
4
3
25
24
21
23
2
26
27
20
22
0
A
0
32,767
A
A
A
A
A
A
A
A
11
12
13
15
16
17
18
19
DQ0
DQ1
DQ2
DQ3
DQ4
DQ5
DQ6
DQ7
14
[PWR DWN]
&
EN
* This symbol is in accordance with ANSI/IEEE std 91-1984 and IEC Publication 617-12.
AS27C256A
Rev. 1.1 6/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
2
MICROSS [ MICROSS COMPONENTS ]
