TS80C54 ATMEL [ATMEL Corporation], TS80C54 Datasheet - Page 40

• Manufacturer Part Number: TS80C54
• Description: 8-bit CMOS Microcontroller 16/32 Kbytes ROM/OTP
• Manufacturer: ATMEL [ATMEL Corporation]

17.4
17.4.1
18. Signature Bytes
40
EPROM Erasure (Windowed Packages Only)
AT/TS8xC54/8X2
Erasure Characteristics
D0-D7
ALE/PROG
EA/VPP
A0-A12
C o n t r o l
signals
The encryption array cannot be directly verified. Verification of the encryption array is done by
observing that the code array is well encrypted.
Figure 17-2. Programming and Verification Signal’s Waveform
Erasing the EPROM erases the code array, the encryption array and the lock bits returning the
parts to full functionality.
Erasure leaves all the EPROM cells in a 1’s state (FF).
The recommended erasure procedure is exposure to ultraviolet light (at 2537 Å) to an integrated
dose at least 15 W-sec/cm
ing for 30 minutes, at a distance of about 25 mm, should be sufficient. An exposure of 1 hour is
recommended with most of standard erasers.
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 sub-
jects the device to this type of exposure, it is suggested that an opaque label be placed over the
window.
The
bytes follow the procedure for EPROM verify but activate the control lines provided in Table 31.
for Read Signature Bytes. Table 18-1. shows the content of the signature byte for the
TS80C54/58X2.
12.75V
5V
0V
TS87C54/58X2
Programming Cycle
Data In
has four signature bytes in location 30h, 31h, 60h and 61h. To read these
1 0 0
μ
s
2
. Exposing the EPROM to an ultraviolet lamp of 12,000 μW/cm
Read/Verify Cycle
Data Out
4431E–8051–04/06
2
rat-