UVEPROM
Austin Semiconductor, Inc.
GENERAL DESCRIPTION
The AS27C256 series is a set of 262,144 bit, ultraviolet-light
erasable, electrically programmable read-only
memories.
These devices are fabricated using power-saving CMOS tech-
nology for high speed and simple interface with MOS and bipo-
lar 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
AS27C256 is pin-compatible with 28-pin 256K ROMs and
EPROMs. It is offered in a 600mil dual-in-line ceramic package
(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
pro-
grammable by the AMD FLASHRITE Pulse programming algo-
rithm. The FLASHRITE Pulse programming algorithm uses a
V
PP
of 12.75VV and a V
CC
of 6.25V for a nominal programming
time of four seconds. For programming outside the system,
existing EPROM programmers can be used. Locations can be
programmed singly, in blocks, or at random.
AS27C256
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.
AS27C256
Rev. 2.0 7/06
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
2
AUSTIN [ AUSTIN SEMICONDUCTOR ]
