M27C4001 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
M27C4001 Datasheet PDF : 24 Pages
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M27C4001
Device operation
2.10
Erasure operation (applies to UV EPROM)
The erasure characteristics of the M27C4001 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 M27C4001 in about 3 years, while it would take approximately 1 week to cause
erasure when exposed to direct sunlight. If the M27C4001 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 M27C4001 window to prevent unintentional erasure. The recommended erasure
procedure for the M27C4001 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 M27C4001
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.
Table 2. Operating Modes(1)
Mode
E
G
Read
VIL
VIL
Output Disable
VIL
VIH
Program
VIL Pulse
VIH
Verify
VIH
VIL
Program Inhibit
VIH
VIH
Standby
VIH
X
Electronic Signature
VIL
VIL
1. X = VIH or VIL, VID = 12V ± 0.5V.
Table 3. Electronic Signature
A9
Vpp
Q7 - Q0
X
VCC or VSS
Data Out
X
VCC or VSS
Hi-Z
X
VPP
Data In
X
VPP
Data Out
X
VPP
Hi-Z
X
VCC or VSS
Hi-Z
VID
VCC
Codes
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
Electronic
Signature
VIH
0
1
0
0
0
0
0
1
41h
11/25
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