Jan-Erik Soderholm wrote:

>> - How often does this need to be refreshed?
>=20
> The actual data sheet params was mentioned in another post in this
> thread, or maybe on Stef's page...

>> - I can't find anything on this on Microchip's website.  Is there a li=
nk
>> to a  doc discussing this?
>=20
> It's in most (all ?) data sheets. At least for devices with EEPROM...

I looked up two datasheets of PICs with EEPROM. They don't all provide th=
is
information.=20

In one (18F2431) they list D120 as "Byte Endurance at +85 =B0C" (100k) an=
d
D124 as "Number of Total Erase/Write Cycles before Refresh" (1M). This
seems to indicate that you can write to any single cell up to 100k times
(over the lifetime of the chip) and that you have to do a data refresh
after 1M total erase/write cycles on the EEPROM at a whole (other
locations). This is essentially what Bob is talking about on that page.=20

In the other (18F6680) they do not list D124 at all, only D120 as "Cell
Endurance at +85 =B0C" with 100k -- even though they refer to D124 in the
EEPROM section of the description. But that description looks a lot like
copy and paste (like some others :).

So it seems that D124 (that's the crucial piece of data here) is not
present in all datasheets of PICs with EEPROMs -- whatever that means. If
you write a lot to some cells and infrequently to others, you could go sa=
fe
and consider a typical minimum value for D124, even if it's not listed. A=
nd
I'm not sure how that applies or not to serial EEPROMs.

Does Microchip use different technology for the different EEPROMs in
different PIC and serial EEPROM models? If not, one could assume that the
D124 parameter applies, whether it's listed in the datasheet or not -- fo=
r
both PICs and serial EEPROMs.

Gerhard

--=20
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