m27c801 STMicroelectronics, m27c801 Datasheet - Page 11

• Manufacturer Part Number: m27c801
• Description: 8 Mbit 1mb X 8 Uv Eprom And Otp Eprom
• Manufacturer: STMicroelectronics

M27C801
2.10
the ES mode, the programming equipment must force 11.5V to 12.5V on address line A9 of
the M27C801. Two identifier bytes may then be sequenced from the device outputs by
toggling address line A0 from V
Electronic Signature mode. Byte 0 (A0 = V
(A0 = V
identifier bytes are given in
Table 3.
Erasure operation (applies to UV EPROM)
The erasure characteristics of the M27C801 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 M27C801 in about 3 years, while it would take approximately 1 week to
cause erasure when exposed to direct sunlight. If the M27C801 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 M27C801 window to prevent unintentional erasure. The recommended
erasure procedure for the M27C801 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 30 W-sec/cm
30 to 40 minutes using an ultraviolet lamp with 12000 µW/cm
should be placed within 2.5 cm (1 inch) of the lamp tubes during the erasure. Some lamps
have a filter on their tubes which should be removed before erasure.
Manufacturer code
Device code
Identifier
IH
) the device identifier code. For the STMicroelectronics M27C801, these two
Electronic signature
V
V
A0
IH
IL
Table 3
Q7
0
0
IL
to V
and can be read-out on outputs Q7 to Q0.
Q6
0
1
IH
2
. The erasure time with this dosage is approximately
. All other address lines must be held at V
IL
Q5
1
0
) represents the manufacturer code and byte 1
Q4
0
0
Q3
0
0
2
power rating. The M27C801
Q2
0
0
Q1
0
1
Device description
Q0
0
0
IL
Hex Data
during
20h
42h
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