May 2007

Rev 2

1/23

AN2523

Application note

Migrating from STR91xF to STR91xFA

Introduction

STR9 microcontrollers have two major salestype groups, as follows:

●

The initial group consist of devices STR91xFxxxxx, for example STR912FW44X6, with

silicon revisions B, and D. Revision D is in production. Detailed technical information for

these devices may be found in the STR91xF datasheet, STR91xF reference manual,

and STR91xF errata documents.

●

The second group consists of devices STR91xFAxxxxx, for example

STR912FAW44X6, with revisions E and G. Revision G is in production. Detailed

technical information for these devices may be found in the STR91xFA datasheet and

STR91xFA reference manual documents.

This document describes at the system level the feature enhancements and silicon fixes

incorporated in the new STR91xFA devices, compared to the original STR91xF devices.

It also describes what are the impacts when the STR91xF is replaced with the STR91xFA in

your design.

The changes in the STR91xFA can be grouped into two categories:

●

changes that are needed to fix the functional issues in the STR91xF

●

changes that are feature enhancements to the STR91xF

The enhancements are new features and will have no impact in your existing STR91xF

design. You have the option to add these new features to your design or not using it at all.

The functional or silicon fixes in the STR91xFA are targeted at solving the problems that are

documented in the STR91xF Errata Sheet. If you have implemented software workaround

on some of the issues, the workarounds will work fine with the STR91xFA and no software

change is required. Below is a summary of the changes, followed by detail descriptions.

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