M27W201-100F6TR View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
M27W201-100F6TR Datasheet PDF : 24 Pages
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M27W201
Device Description
2.9
Electronic Signature
The Electronic Signature (ES) 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. The ES mode is functional in the 25°C ± 5°C
ambient temperature range that is required when programming the M27W201. To activate
the ES mode, the programming equipment must force 11.5V to 12.5V on address line A9 of
the M27W201 with VPP = VCC = 5V. Two identifier bytes may then be sequenced from the
device outputs by toggling address line A0 from VIL to VIH. All other address lines must be
held at VIL during Electronic Signature mode. Byte 0 (A0 = VIL) repres ents the manufacturer
code and byte 1 (A0 = VIH) the device identifier code. For the STMicroelectronics
M27W201, these two identifier bytes are given in Table 3 and can be read-out on outputs Q7
to Q0. Note that the M27W201 and M27C2001 have the same identifier byte.
Table 3. Electronic Signature
Identifier
A0 Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0 Hex Data
Manufacturer’s Code
VIL 0
0
1
0
0
0
0
0
20h
Device Code
VIH 0
1
1
0
0
0
0
1
61h
2.10
Erasure operation (applies to UV EPROM)
The erasure characteristics of the M27W201 are 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. Data shows that constant exposure to room level fluorescent lighting could erase a
typical M27W201 in about 3 years, while it would take approximately 1 week to cause
erasure when exposed to direct sunlight. If the M27W201 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 M27W201 window to prevent unintentional erasure. The recommended erasure
procedure for the M27W201 is exposure to short wave ultraviolet light which has wavelength
of 2537 Å. The integrated dose (i.e. UV intensity x exposure time) for erasure should be a
minimum of 15 W-sec/cm2. The erasure time with this dosage is approximately 15 to 20
minutes using an ultraviolet lamp with 12000 µW/cm2 power rating. The M27W201 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.
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