POWER OF ATTORNEY
(Robert Charles Mahoney)


I hereby appoint Keith D. Jackson, George H. Cave and Judith A. Boyle, and each
of them,
attorney-in-fact for me, each with full power of substitution, to prepare,
execute and deliver on
my behalf reports required to be filed by me pursuant to Section 16 of the
Securities Exchange
Act of 1934, as amended ("Section 16"), and Rule 144 and Rule 145 under the
Securities Act of
1933 (singly or collectively ("Rule 144")), and any and all related documents
and instruments.
Among other things, each attorney-in-fact is authorized to file original reports
  (either
electronically or otherwise), signed by me or on my behalf, on Forms 3, 4 and 5,
  Form 144 with
the Securities and Exchange Commission, any and all related documents and
instruments, and
to provide any necessary copies of such signed forms, documents and instruments
to The
NASDAQ Stock Market and ON Semiconductor Corporation as required by the rules
under
Section 16 and Rule 144 as in effect from time to time.

This power of attorney is effective from the date hereof until April 15, 2009,
unless earlier
revoked or terminated.



/s/ ROBERT MAHONEY
Robert Charles Mahoney


Dated:	March 3, 2008

H:\SECURITIES\Section 16\POA\2008 POA\2008 POA TXT FILING FOLDER\Mahoney 2008
POA.doc