On Sun, Jan 29, 2006 at 02:18:14PM -0500, John Nall wrote:
> This is kind of picking up where I left off some time ago, when I was 
> asking if the Wisp628 would program a one-time-programmable EPROM chip, 
> and Wouter responded that it would not, because it couldn't supply the 
> amount of current necessary.

That's correct. Most EPROM based chips need 50 mA of current for Vpp.

>  Someone else chimed in, Olin I believe, 
> that C chips were evil in any case and  that I should stick with flash 
> chips.

I note in your other post that it's a 14000 part. No flash equivalent for it.

> OK, I accept both of those things.  However,  there is still a nagging 
> question:  If I do, in spite of  good advice, want to play around with a 
> C chip, what is the best way to program it?  Will an ICD2 do that as a 
> matter of course?  Will Olin's EasyProg do it?  Would I have to build 
> some sort of parallel programmer?  What is the best way? 

Probably the last one. A high current switchable Vpp is pretty easy to put
together using a LM317 and a couple of transistors. Use one transistor to
ground the ADJ pin and a second to ground OUT after passing through a current
limiting resistor. When both transistors are switched on, the 1.25V output
of the LM317 is shunted via the out transistor. When both are off the ADJ
pin rises to normal voltage divider setting of 13V. If the current limiting
resistor is 100 ohms, then 130mA of current is available to drive Vpp.

This is an old Steve Ciarcia design that he used for an intelligent EPROM
programmer.

BAJ
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