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AN2061

4.3 Field Reprogramming with ST10F2xx

Flash programming/reprogramming in the field, requires to be able to deal safely with all the

possible events that may occur in the application.

This analysis is application dependent and has to be carefully conducted by the user. This sec-

tion assumes that users have experience with all the generic aspects of field reprogramming

and will focus only on ST10F2xx specific events.

4.3.1 Field events and Flash reliability

User’s applications must meet ST’s recommendations for Flash programming and erasing.

Failure to do so, could result in lower data retention and/or altered Flash reliability. The condi-

tions leading to an altered data retention or to an altered reliability depend on the command

issued to the Flash and the event that occurred during this command (supply out of range, re-

set).

From FMEA’s perspective, customers should consider that when ST advice are not imple-

mented, Flash reliability can be altered. When ST advice are implemented and provided all

field specific events are within ST recommendations (see hereafter), the Flash will meet ST

published specification.

4.3.2 List of Events and Suggested Handling Methods

4.3.2.1 Reset

Reset is one of the events possible during field reprogramming, whatever the possible causes

of reset (spurious reset, external hardware reset, reset due to power-shut down).

Detection Method:

Reset can occur at any time and there is no possibility to prevent this.

Suggested Handling Method:

Restart the Flash command that was interrupted (i.e.: erasing or programming); use status bits

and Flash information to recognize this event.

4.3.2.2 Supply variations

ST10 supply must be kept within the limits published in the Data Sheet during any erase or

programming command.

Detection method:

A specific hardware should be added to monitor the supply and reset the ST10F2xx device

when the supply is going out of the functional specification.

Suggested Handling Method:

Restart the whole Flash command (i.e.: erasing or programming).

Note: As for any other parameter, the ST10 supply should stay within the maximum absolute

ratings defined in the published Data Sheet.

4.3.2.3 Temperature out of specification

Temperature during erasing, programming and read / fetch operations is influencing the reli-

ability of the embedded-Flash.

The embedded-Flash must be programmed and erased only while the junction temperature is