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M27V201

On-Board Programming

The M27V201 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 ± 5°C am-

bient temperature range that is required when pro-

gramming the M27V201. To activate the ES mode,

the programming equipment must force 11.5V to

12.5V on address line A9 of the M27V201 with

sequenced from the device outputs by toggling ad-

identifier

code.

For

the

STMicroelectronics

M27V201, these two identifier bytes are given in

Table 4 and can be read-out on outputs Q0 to Q7.

Note that the M27V201 and M27C2001 have the

same identifier bytes.

ERASURE OPERATION (applies to UV EPROM)

The erasure characteristics of the M27V201 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. Data

shows that constant exposure to room level fluo-

rescent lighting could erase a typical M27V201 in

about 3 years, while it would take approximately 1

week to cause erasure when exposed to direct

sunlight. If the M27V201 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 M27V201 window to prevent unintentional era-

sure. The recommended erasure procedure for

the M27V201 is exposure to short wave ultraviolet

light which has wavelength of 2537 Å. The inte-

grated dose (i.e. UV intensity x exposure time) for

erasure should be a minimum of 15 W-sec/cm

The erasure time with this dosage is approximate-

ly 15 to 20 minutes using an ultraviolet lamp with

12000

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.