We did manufacture devices with these three suffixes. A1 was the initial version. The A2 version appears due to a factory change. These two versions are the same, except being produced by a different factory. The A3 version has a change in the layout of the internal oscillator circuit. This change allows the device to use a crystal with higher ESR. The current A3 version of the device allows up to 80kΩ crystal load resistance.