- on computers and microprocessors
- Published in issue 4/1984 on page 36
intelligent EPROM eraser
intelligent EPROM eraser elektor april 1984 intelligent EPROM eraser The circuit described checks that during the erasure process, that is, when the EPROM is subject to ultraviolet (UV) ra- diation, even the last bit has been erased. As soon as this is so, the circuit arranges for the UV radiation to be continued for an ap- propriate period to ensure that the long-term stability of the new data is guaranteed. In other words, erasing is only carried out for as long as it is really necessary: no longer, no shorter. Furthermore, the circuit indicates whether the EPROM (new or used) is in good working order. An intensity of radiation of 12 000 1.1W/cm2 gives an energy of 0.012 J/cm2 every second, as 1 Jloule) = 1 WlattIslecond). The requi- red dose (energy) is 15 J/cm2 and this will there- fore take 15/0.012 seconds = 1250 seconds = 20 min. 50 sec. Si Erasure of EPROMs can be a confusing matter: one manufacturer states an erasure period of ten minutes, the next one of a couple of hour...