M27W401-80XN6TR STMicroelectronics, M27W401-80XN6TR Datasheet - Page 9

• Manufacturer Part Number: M27W401-80XN6TR
• Description: 4 Mbit 512Kb x 8 Low Voltage UV EPROM and OTP EPROM
• Manufacturer: STMicroelectronics

On-Board Programming
The M27W402 can be directly programmed in the
application circuit. See the relevant Application
Note AN620.
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
bient temperature range that is required when pro-
gramming the M27W402. To activate the ES
mode, the programming equipment must force
11.5V to 12.5V on address line A9 of the
M27W402 with V
bytes may then be sequenced from the device out-
puts by toggling address line A0 from V
other address lines must be held at V
Electronic Signature mode. Byte 0 (A0 = V
resents the manufacturer code and byte 1
(A0 = V
STMicroelectronics M27W402, these two identifier
bytes are given in Table 4 and can be read-out on
outputs Q7 to Q0.
Note that the M27W402 and M27C4002 have the
same identifier bytes.
IH
) the device identifier code. For the
PP
= V
CC
= 5V. Two identifier
IL
to V
IL
5 C am-
IL
during
IH
) rep-
. All
ERASURE OPERATION (applies to UV EPROM)
The erasure characteristics of the M27W402 are
such that erasure begins when the cells are ex-
posed to light with wavelengths shorter than ap-
proximately 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 fluo-
rescent lighting could erase a typical M27W402 in
about 3 years, while it would take approximately 1
week to cause erasure when exposed to direct
sunlight. If the M27W402 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 M27W402 window to prevent unintentional
erasure. The recommended erasure procedure for
the M27W402 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
sure time with this dosage is approximately 15 to
20 minutes using an ultraviolet lamp with 12000
placed within 2.5cm (1 inch) of the lamp tubes dur-
ing the erasure. Some lamps have a filter on their
tubes which should be removed before erasure.
W/cm
2
power rating. The M27W402 should be
M27W402
2
. The era-
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