I have a 950, not a 650, but I've seen 650 owners here say that they use their Blackberry charger with their eReader, so it should be okay. Thankfully Sony is using the micro-USB standard in these readers, and that cable would work perfectly fine with my 950. I use my Motorola Droid 2 charger cable with my reader.
I'd wait for a 650 owner to confirm if you want to make absolutely sure though.