Yes, the d22a is a rebadged Liteon 1633S. BYS3 is the latest firmware and you'll find this on dhc014's brilliant firmware collection site here.
It can also be crossflashed to much newer and better firmware that you will find on my site. I would recommend the Sony 710A firmware BYX3, which is basically 1653S firmware for the 710A/1633S. There's also a LED fix version that changes the led operation to green for reading and red for writing.
Please note that flashing to the 710A firmware voids the warranty.