m27128a STMicroelectronics, m27128a Datasheet - Page 8

• Manufacturer Part Number: m27128a
• Description: Nmos 128k 16k X 8 Uv Eprom
• Manufacturer: STMicroelectronics

M27128A
Program Verify
A verify should be performed on the programmed
bits to determine that they were correctly pro-
grammed. The verify is accomplished with G = V
E = V
Electronic Signature
The Electronic Signature mode allows the reading
out of a binary code from an EPROM that will
identify its manufacturer and type. This mode is
intended for use by programming equipment to
automatically match the device to be programmed
with its corresponding programming algorithm.
This mode is functional in the25 C
temperature range that is required when program-
ming the M27128A.
To activate this mode, the programming equipment
must force 11.5V to 12.5V on address line A9 of the
M27128A. Two identifier bytes may then be se-
quenced from the device outputs by toggling ad-
dress line A0 from V
must be held at V
mode. Byte 0 (A0 = V
turer code and byte 1 (A0 = V
code. For the SGS-THOMSON M27128A, these
two identifier bytes are given below.
ORDERING INFORMATION SCHEME
For a list of available options (Speed, V
catalogue.
For further information on any aspect of this device, please contact SGS-THOMSON Sales Office nearest
to you.
8/10
IL
, P = V
IH
blank
-20
-25
-30
and V
Example:
-2
-3
-4
Speed and V
IL
IL
to V
during Electronic Signature
PP
IL
) represents the manufac-
250 ns, 5V
300 ns, 5V
450 ns, 5V
200 ns, 5V
300 ns, 5V
250 ns, 5V
200 ns, 5V 5%
at 12.5V.
IH
. All other address lines
IH
CC
) the device identifier
Tolerance
10%
5%
5%
5%
10%
10%
5 C ambient
CC
M27128A
Tolerance, Package, etc...) refer to the current Memory Shortform
IL
,
F
-2
ERASURE OPERATION (applies to UV EPROM)
The erasure characteristic of the M27128A is such
that erasure begins when the cells are exposed to
light with wavelengths shorter than approximately
4000 Å. It should be noted that sunlight and some
type of fluorescent lamps have wavelengths in the
3000-4000 Å range. Research shows that constant
exposure to room level fluorescent lighting could
erase a typical M27128A in about 3 years, while it
would take approximately 1 week to cause erasure
when exposed to direct sunlight. If the M27128A is
to be exposed to these types of lighting conditions
for extended periods of time, it is suggested that
opaque labels be put over the M27128A window to
prevent unintentional erasure. The recommended
erasure procedure for the M27128A is exposure to
short wave ultraviolet light which has wavelength
2537 Å. The integrated dose (i.e. UV intensity x
exposure time) for erasure should be a minimum
of 15 W-sec/cm
is approximately 15 to 20 minutes using an ultra-
violet lamp with 12000 W/cm
M27128A should be placed within 2.5cm (1 inch)
of the lamp tubes during the erasure. Some lamps
have a filter on their tubes which should be re-
moved before erasure.
Package
FDIP28W
F
1
2
. The erasure time with this dosage
Temperature Range
1
6
–40 to 85 C
0 to 70 C
2
power rating. The