2708 Programming Algorithm?

From: Joe <rigdonj_at_cfl.rr.com>
Date: Mon May 6 15:29:52 2002

Steve,

   I don't have the programming instructions for the 2708 but I do have them for the intel 8708 and intels later manuals state that they're the same. Here's what I have in the sept 1975 8080 Microcomputer Systems User's manual.

At 08:21 AM 5/6/02 -0700, you wrote:
>I obtained a bunch of 2708 UVEPROM's, and I'd like to
>be able to program them. As you may know, they require
>a different algorithm than the 2716 and on, and three
>voltages, +5, +12, and -5.
>
>I'm building a little board that will program 1/2 (the
>upper or lower) of a 2716 to a 2708 (I can program
>2716's). But I can't find a description of the
>algorithm that is detailed enough. What I think I know
>is:
>
>1. The /OE line must be high

  Intel says to raise the CS*/WE line to +12 volt.


>2. select address and data (start at addr 0)

  Correct. A note here says that the logicx levels for the address, data and voltage supply lines are the same as for the read mode.

>3. bring PGM line from 0 to 27 volts for 1 mSec,

   Correct except you can use 25 (min) to 27 (max) volts according to the manual.

then
>drop back to 0 (this seems very strange)

   You have to allow for the setup time for the new address and data. The times are 10uS (min) for each but they could be different for the 2708.

>4. repeat 100 times per address (not all at once,

   NO. This isn't what's in the intel manual. It says one programming pulse per address per loop. And that a loop is one pass through all the addresses. You have to repeat the loop until N (passes) x Tpw (programming pulse width) >= 100mS.

  


>increment the address lines and loop to avoid
>"overheating" a byte.
>5. drop /OE and verify.


    "Note that programming and read loops can be alternated"


>
>
>Does anybody have an authoritative description, and a
>current requirement for the +5, +12, -5, and
>programming pulse? Thanks.

   It varies according to the temperature but the max occurs at low temp and is about 11ma for Icc _at_5.25v, 65ma for Idd @12.6v with CS*/WE high and about 35 ma with CS*/WE low, 41ma for Ibb @-5.25v with CS*/WE high and about 17ma with CS*/WE low.

  The programming pulse current is typically 10mA with 20mA max.

  Have fun!
    
   Joe


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Received on Mon May 06 2002 - 15:29:52 BST

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