My mobile phone is Sony Ericsson T610. The charger is _regulated_ 5V. May be you could find 3rd party (cheap
) replacement charger at phone shop?
BTW, most ICs are rated 5V +- 10% thus _regulated_ 4.5V would work as well. Non-regulated 4.5V typically gives 6-7V output.
Sample regulated 5V from jameco.com
http://www.jameco.com/cgi-bin/ncomme...s=503;528;779;