
Chapter 16 Appendices
XVI - 4
EPROM Version
16-1-3 Erasing Data in Windowed Package
(PX-AP101C66-AC/BC)
Irradiating the chip through the window (PX-AP101C66-AC/BC) with 253.7 nm ultraviolet radiation
erases the data by changing all "0" bits to "1".
The recommended exposure is 10 W
s/cm2 -the equivalent of 15 to 20 minutes 2 cm to 3 cm below a
commercial ultraviolet lamp producing an illumination intensity of 12,000 W/cm2 at the package surface.
Remove any filters attached to the lamp. Installing a lamp reflector increases the illumination intensity by
a factor of 1.4 to 1.8, decreasing the erasure time.
If the window becomes dirty with oil, adhesive, etc., UV light permeability will decrease, causing the
erasure time to increase considerably. If this happens, clean with alcohol or another solvent that will not
harm the package. The recommended above provides sufficient leeway, with several times the amount
of time it takes to erase all the bits. However, this value will reliably erase data over all temperature and
voltage ranges, and should not be altered. The level of illumination should be regularly checked and the
lamp operation verified.
Erasure begins when the EPROM is exposed to light with a wavelength shorter than 400 nm. Since
fluorescent light and sunlight have wavelengths in this range, exposure to these light sources for ex-
tended periods of time could cause inadvertant erasure. To prevent this, cover the window with an
opaque label.
Data is not erased at wavelengths. However, because of typical semiconductor characteristics, the
circuit may malfunction if the chip is exposed to an extremely high illumination intensity. The chip will
operate normally if this exposure is stopped. However, for areas where it is continuous, take necessary
precautions.