TSC87C52
Programming Cycle
Data In
Read/Verify Cycle
Data Out
A0–A12
D0–D7
100us
10us
ALE/PROG
EA/VPP
1
2
3
4
5
12.75V
5V
0V
Control
signals
Figure 9 Programming and verification signal’s waveform
Signature bytes
The TSC87C52 has four signature bytes in location 30h, 31h, 60h and 61h. To read these bytes follow the procedure
for EPROM verify but activate the control lines provided in Table 6 for Read Signature Bytes. Table 7 shows the
content of the signature byte for the TSC87C52.
Table 7 Signature bytes content
Location
30h
Contents
58h
Comment
Customer selection byte: TEMIC
31h
58h
Family selection byte: C51
TSC87C52
60h
ADh
61h
XXh
Product revision number
EPROM Erasure (Windowed Packages Only)
Erasing the EPROM erases the code array and also the encryption array returning the parts to full functionality.
Erasure leaves all the EPROM cells in a 1’s state.
Erasure Characteristics
The recommended erasure procedure is exposure to ultraviolet light (at 2537 Å) to an integrated dose at least 15
2
2
W–sec/cm . Exposing the EPROM to an ultraviolet lamp of 12,000 µW/cm rating for 30 minutes, at a distance of
about 25 mm, should be sufficient.
Erasure of the EPROM begins to occur when the chip is exposed to light with wavelength shorter than approximately
4,000 Å. Since sunlight and fluorescent lighting have wavelengths in this range, exposure to these light sources over
an extended time (about 1 week in sunlight, or 3 years in room–level fluorescent lighting) could cause inadvertent
erasure. If an application subjects the device to this type of exposure, it is suggested that an opaque label be placed
over the window.
MATRA MHS
Rev. C – 10 Sept 1997
13
Preliminary
TEMIC [ TEMIC SEMICONDUCTORS ]
