TS87C54X2 Temic Semiconductors, TS87C54X2 Datasheet - Page 39

• Manufacturer Part Number: TS87C54X2
• Description: 8-bit CMOS Microcontroller 0-60 MHz
• Manufacturer: Temic Semiconductors

8.4 EPROM Erasure (Windowed Packages Only)
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).
8.4.1 Erasure Characteristics
The recommended erasure procedure is exposure to ultraviolet light (at 2537 Å) to an integrated dose at least 15
W-sec/cm
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 subjects the device to this type of exposure, it is suggested that an opaque
label be placed over the window.
Rev. B - Aug. 31, 1999
2
ALE/PROG
. Exposing the EPROM to an ultraviolet lamp of 12,000 W/cm
EA/VPP
A0-A12
Control sig-
nals
D0-D7
12.75V
5V
0V
Figure 12. Programming and Verification Signal’s Waveform
Programming Cycle
Data In
100 s
Read/Verify Cycle
Data Out
2
rating for 30 minutes, at a distance
TS80C54X2/C58X2
TS87C54X2/C58X2
39