On Wed, 18 Feb 1998 09:16:13 +0100 Caisson writes: >> Van: Allan Grant >> Aan: PICLIST@MITVMA.MIT.EDU >> Onderwerp: How to use Datarase II for PIC16c74a ? >> Datum: dinsdag 17 februari 1998 0:54 >> >> What is the best time to erase PIC16c74A with Datarase II (Walling >Co)? [...] >Too short will cause a Memory-effect (so I am being told) like with >NiCad's, wich >will disable your (on-board) EPROM in time. Under-erased bits can appear "programmed" again (especially at low voltage and high temperature) and cause the program to malfunction. Experiment with your chip and your eraser to find the minimum effective time. Then add a generous margin (twice the time for quick prototype tests, four times the time for chips that will be used at low voltage, high temperature, or near customers) A method that has worked well for me is to set the timer to somewhat more than the minimum time, then cycle chips through the eraser so each one is exposed to 2 erase cycles before being reused. > >> Can I spoil the chip if I will erase longer time then necessary? >No. You can bake it for as long as you wish. you _could_ forget it >till >next day. >It won't get more empty than empty, and it won't distroy or damage it. Intel used to say that a UV exposure equivalent to about 150 hours in an eraser was the absolute maximum rating for their EPROM chips. I don't know what the mechanism of failure was or if newer chips are still subject to this. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]