M27C512

Erasure operation (applies for UV EPROM)

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Erasure operation (applies for UV EPROM)

The erasure characteristics of the M27C512 is 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.

Research shows that constant exposure to room level fluorescent lighting could erase a

typical M27C512 in about 3 years, while it would take approximately 1 week to cause

erasure when exposed to direct sunlight. If the M27C512 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 M27C512 window to prevent unintentional erasure. The recommended erasure

procedure for the M27C512 is exposure to short wave ultraviolet light which has wavelength

2537 Å. The integrated dose (i.e. UV intensity x exposure time) for erasure should be a

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.