29 Jul
2004
29 Jul
'04
1:13 p.m.
>I have a couple of "ultraviolet" LEDs
with me, but I doubt they are the
>right frequency to erase EPROMs.
If they're the high power UV LEDs then they should
work. A friend of
mine uses those to erase his EPROMs and the erase time is about the same
as for a UV light.
There are not yet available UV LEDs that radiate at short enough wavelength
to erase EPROMs in a reasonable time. Most EPROMs will start to erase at
<400nm but take hours of exposure, to erase an EPROM in 20 mins or so needs
12mW/cm^2 of 257nm light on the die face. The longer wavelengths just warm
the chip up a bit.
This is why UV tubes for photo resist and similar won't erase EPROMs either,
they output nearer 400nm which is where state of the art UV LEDs are at.
Lee.
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29 Jul
29 Jul
1:51 p.m.
On Fri, Jul 30, 2004 at 02:13:47AM +0100, Davison, Lee wrote:
I will have to check, but IIRC, my LEDs are 450nm.
-ethan
--
Ethan Dicks, A-130-S Current South Pole Weather at 30-Jul-2004 01:50 Z
South Pole Station
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Ethan.Dicks(a)amanda.spole.gov http://penguincentral.com/penguincentral.html
>I have a couple of "ultraviolet"
LEDs with me, but I doubt they are the
>right frequency to erase EPROMs.
If they're the high power UV LEDs then they
should work. A friend of
mine uses those to erase his EPROMs and the erase time is about the same
as for a UV light.
There are not yet available UV LEDs that radiate at short enough wavelength
to erase EPROMs in a reasonable time. Most EPROMs will start to erase at
<400nm but take hours of exposure, to erase an EPROM in 20 mins or so needs
12mW/cm^2 of 257nm light on the die face. The longer wavelengths just warm
the chip up a bit. 
30 Jul
30 Jul
3:01 a.m.
At 01:51 AM 7/30/04 +0000, Ethan wrote:
On Fri, Jul 30, 2004 at 02:13:47AM +0100, Davison, Lee
wrote:
I will have to check, but IIRC, my LEDs are 450nm.
I just called and talked to my friend about this. He has some >>
prototype << high power UV LEDs that are about 375nm. He also some that are
deeper UV but the phone connection was lousy and I couldn't get any more
details. I'm not even sure which ones he used to erase the EPROMs with or
how long it took. Your 450nm LEDs probably won't work.
Joe
>I have a couple of "ultraviolet"
LEDs with me, but I doubt they are the
>right frequency to erase EPROMs.
If they're the high power UV LEDs then they
should work. A friend of
mine uses those to erase his EPROMs and the erase time is about the same
as for a UV light.
There are not yet available UV LEDs that radiate at short enough wavelength
to erase EPROMs in a reasonable time. Most EPROMs will start to erase at
<400nm but take hours of exposure, to erase an EPROM in 20 mins or so needs
12mW/cm^2 of 257nm light on the die face. The longer wavelengths just warm
the chip up a bit.
7449
days inactive
7450
days old
2 comments
3 participants
participants (3)
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dickset＠amanda.spole.gov -
Lee.Davison＠merlincommunications.com -
rigdonj＠cfl.rr.com