UPD75P308 Datasheet, PDF (14/34 Pages) NEC – 4-BIT SINGLE-CHIP MICROCOMPUTER

µPD75P308
3.4 ERASURE (µPD75P308K ONLY)
The contents of the data programmed to the µPD75P308 can be erased by exposing the window of the
program memory to ultraviolet rays.
The wavelength of the ultraviolet rays used to erase the contents is about 250 nm, and the quantity of the
ultraviolet rays necessary for complete erasure is 15 W.s/cm² (= ultraviolet ray intensity x erasure time).
When a commercially available ultraviolet ray lamp (wavelength: 254 nm, intensity: 12 mW/cm²) is used,
about 15 to 20 minutes is required.
Note
1: The contents of the program memory may be erased when the µPD75P308 is exposed for a long
time to direct sunlight or the light of fluorescent lamps. To protect the contents from being
erased, mask the window of the program memory with the light-opaque film supplied as an
accessory with the UV EPROM products.
2: To erase the memory contents, the distance between the ultraviolet ray lamp and the µPD75P308
should be 2.5 cm or less.
Remarks: The time required for erasure changes depending on the degradation of the ultraviolet ray
lamp and the surface condition (dirt) of the window of the program memory.
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