Eprom programming voltages...

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Eprom programming voltages...

Post by danielj » Sun May 22, 2011 8:05 pm


Quick Q - the AMD2764/128/256 etc EPROMs, the datasheets I've been throwing up on the interweb are correct, they are 12.5V Vpp? Just checking before I randomly decide to stick 50V through them...


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Re: Eprom programming voltages...

Post by flynnjs » Sun May 22, 2011 8:55 pm

Typically, non-CMOS units require 21V and CMOS units 12.5V.

27128 c.f 27C128

However, best bet is to check the datasheet first. If unsure
start with 12.5v first.

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Re: Eprom programming voltages...

Post by 1024MAK » Sun May 22, 2011 9:50 pm

Also a lot of EPROM's have the programming voltage marked on them (but not all).
If unsure, try the lower voltage first.

Mark K.

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Re: Eprom programming voltages...

Post by george.h » Mon May 23, 2011 1:25 pm

I'd give the same advice.

If it's not marked and your not sure, try 12.5v first. If it fails to program using the standard "intelligent" programming methods, or programs but fails the verify, check which byte(s) it is trying to program against what it is reading back. If you find that the value(s) read back have "1" bits where it has been trying to program "0"s, the device needs the higher voltage (usually 21v).

If you're lucky (like me with my Technomatic Eprommer II =P~ ) you can get away with just changing the programminig voltage and re-programming immediately. If you're not, your programmer with insist on doing a blank check first which means you'll probably need to bung it in the eraser before programming it at the higher voltage.

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