16 Sep
2007
16 Sep
'07
9:37 p.m.
How long should you erase EPROMs for? "Until
they're done", I suppose,
IIRC most data sheets give times of around 20 minutes.
There was a circuit in one of the maganzines (probably Elektor) a few
years back for an intellegent EPROM eraser. It kept on reading out all
the locations of the chip and left the lamp on until all bits read out as
1'sm then gave <n> times more exposure to be sure. Now whether the rest
of the chip (address decoerd sense amplifier, etc) was known to work
correctly when exposed to UV light, so how reliable this test is, is another
matter
-tony