The DVD Burner Optiarc AD-5590A was released in January 2008. The Optiarc AD5593 burner adds support for LabelFlash but both drives share the same hardware and only differ in firmware. However you should not try to simply flash an Optiarc 5593 firmware on an Optiarc 5590 drive or vice versa. This will NOT work.
Click here for detailed specifications of the Optiarc AD5590A.
The following firmwares are available for download here:
Overview on the used writing strategies
Optiarc have provided a tool for changing the drive's ATA mode.