16 Sep
2007
16 Sep
'07
10:38 p.m.
Tony Duell wrote:
Cute idea.
Reading a M2732A data sheet you need a minimum of 15 W-sec/cm^2
to erase with light at 2537 A. With a lamp of 12000 uW/cm^2 that
is about 15 to 20 min. The recommend the chip be about 2.5 cm from the lamp.
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
Ben alias woodelf.
I wonder how much UV the big sparks you see in the lab on old horror
movies are. :)