<PAGE>


                               FIRST AMENDMENT TO
                  SECOND AMENDED AND RESTATED CREDIT AGREEMENT


         THIS FIRST AMENDMENT TO SECOND AMENDED AND RESTATED CREDIT AGREEMENT
(this "FIRST AMENDMENT"), dated as of December 30, 1999, is entered into among
POWER-ONE, INC., a Delaware corporation (the "PARENT"), INTERNATIONAL POWER
DEVICES, INC., a Massachusetts corporation ("IPD"), MELCHER HOLDING AG, a Swiss
corporation ("MELCHER") (the Parent, IPD and Melcher are hereinafter sometimes
collectively referred to herein collectively as the "BORROWERS"), the banks
listed on the signature pages hereof (the "LENDERS"), BANK OF AMERICA, N.A., as
administrative agent for the Lenders (in said capacity, the "ADMINISTRATIVE
AGENT") and UNION BANK OF CALIFORNIA, N.A., as co-agent for the Lenders.

         A. The Borrowers, the Lenders and the Administrative Agent are parties
to that certain Second Amended and Restated Credit Agreement, dated as of August
12, 1999 (said Credit Agreement, the "CREDIT AGREEMENT"; the terms defined in
the Credit Agreement and not otherwise defined herein shall be used herein as
defined in the Credit Agreement).

         B. The Borrowers, Lenders and the Administrative Agent desire to amend
the Credit Agreement to make certain changes therein.

         NOW, THEREFORE, in consideration of the covenants, conditions and
agreements hereafter set forth, and for other good and valuable consideration,
the receipt and adequacy of which are all hereby acknowledged, the Borrowers,
Lenders and the Administrative Agent covenant and agree as follows:

         1. AMENDMENTS TO CREDIT AGREEMENT.

         (a) SECTION 7.7 of the Credit Agreement is hereby amended to read as
follows:

         " Section 7.7 CAPITAL EXPENDITURES. The Parent shall not, and shall not
         permit any of its Subsidiaries to, make or commit to make any Capital
         Expenditures (a) during Fiscal Year 1999 in excess of $28,000,000 in
         aggregate amount, (b) during Fiscal Year 2000 in excess of $25,000,000
         in aggregate amount, (c) during Fiscal Year 2001 in excess of
         $30,000,000 in aggregate amount, and (d) during Fiscal Year 2002 in
         excess of $35,000,000 in aggregate amount (in the case of clauses (a),
         (b), (c) and (d), the "Maximum Amount"); PROVIDED, HOWEVER, that the
         Maximum Amount for each Fiscal Year shall be increased by an amount
         equal to the excess, if any, of the Maximum Amount for the previous
         Fiscal Year (before making any adjustments in accordance with this
         proviso) over the actual aggregate Capital Expenditures for such
         previous Fiscal Year."


<PAGE>

         (b) Exhibit C to the Credit Agreement is hereby amended to be in the
form of Exhibit C hereto.

         2. REPRESENTATIONS AND WARRANTIES TRUE; NO EVENT OF DEFAULT. By its
execution and delivery hereof, each Borrower represents and warrants that, as of
the date hereof and after giving effect to the amendments provided in the
foregoing Section 1:

         (a) the representations and warranties contained in the Credit
Agreement are true and correct in all material respects on and as of the date
hereof as if made on and as of such date, other than as listed on SCHEDULE 1
hereto;

         (b) no event has occurred and is continuing which constitutes a Default
or an Event of Default;

         (c) each Borrower has full power and authority to execute and deliver
this First Amendment and to perform this First Amendment and the Credit
Agreement, as amended by this First Amendment, the execution and delivery of
this First Amendment and the performance of this First Amendment and the Credit
Agreement, as amended by this First Amendment, has been duly authorized by all
corporate action of each Borrower, and this First Amendment and the Credit
Agreement, as amended hereby, constitute the legal, valid and binding
obligations of each Borrower, enforceable in accordance with their respective
terms, except as enforceability may be limited by applicable debtor relief laws
and by general principles of equity (regardless of whether enforcement is sought
in a proceeding in equity or at law) and except as rights to indemnity may be
limited by federal or state securities laws;

         (d) neither the execution and delivery of this First Amendment, or the
performance of this First Amendment or the Credit Agreement, as amended by this
First Amendment, nor the consummation of any transactions herein or therein,
will contravene or conflict with any Applicable Law to which any Borrower or any
of their respective Subsidiaries is subject or any indenture, agreement or other
instrument to which any Borrower or any of their respective Subsidiaries or any
of their respective property is subject, except to the extent that any such
contravention or conflict could not reasonably be expected to have a Material
Adverse Effect; and

         (e) no authorization, approval, consent or other action by, notice to,
or filing with, any governmental authority or other Person, is required for the
(i) execution and delivery of this First Amendment or performance by the
Borrowers of this First Amendment and the Credit Agreement, as amended by this
First Amendment, or (ii) acknowledgment of this First Amendment by each of the
Subordinated Creditors (as defined in the Subordination Agreement).

         3. CONDITIONS OF EFFECTIVENESS. This First Amendment shall be effective
as of December 30, 1999, subject to the following:


                                      -2-
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         (a) the Administrative Agent shall have received counterparts of this
First Amendment executed by the Determining Lenders;

         (b) the Administrative Agent shall have received counterparts of this
First Amendment executed by each Borrower and acknowledged by each of the
Subordinated Creditors;

         (c) the representations and warranties set forth in Section 3 shall be
true and correct in all material respects; and

         (d) the Administrative Agent and the Determining Lenders shall have
received in form and substance satisfactory to the Administrative Agent and the
Determining Lenders, such other documents, certificates and instruments as the
Determining Lenders shall reasonably require.

         4. ACKNOWLEDGMENT. By signing below, each of the Subordinated Creditors
(i) acknowledges and consents to the execution, delivery and performance by the
Borrowers of this First Amendment and (ii) acknowledges and agrees that its
obligations in respect of its Subordination Agreement are not released,
diminished, waived, modified, impaired or affected in any manner by this First
Amendment or any of the provisions contemplated herein except as expressly
provided herein.

         5. REFERENCE TO THE CREDIT AGREEMENT.

         (a) Upon the effectiveness of this First Amendment, each reference in
the Credit Agreement to "this Agreement", "hereunder", or words of like import
shall mean and be a reference to the Credit Agreement, as amended by this First
Amendment.

         (b) The Credit Agreement, as amended by this First Amendment, and all
other Loan Documents shall remain in full force and effect and are hereby
ratified and confirmed.

         6. COSTS, EXPENSES AND TAXES. The Borrower agrees to promptly pay all
reasonable costs and expenses of the Administrative Agent in connection with the
preparation, reproduction, execution and delivery of this First Amendment and
the other instruments and documents to be delivered hereunder (including the
reasonable fees and out-of-pocket expenses of counsel for the Administrative
Agent).

         7. EXECUTION IN COUNTERPARTS. This First Amendment may be executed in
any number of counterparts and by different parties hereto in separate
counterparts, each of which when so executed and delivered shall be deemed to be
an original and all of which when taken together shall constitute but one and
the same instrument.

         8. GOVERNING LAW; BINDING EFFECT. This First Amendment shall be
governed by and construed in accordance with the laws of the State of Texas and
shall be binding upon the Borrower and each Lender and their respective
successors and assigns.


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<PAGE>

         9. HEADINGS. Section headings in this First Amendment are included
herein for convenience of reference only and shall not constitute a part of this
First Amendment for any other purpose.

         10. ENTIRE AGREEMENT. THE CREDIT AGREEMENT, AS AMENDED BY THIS FIRST
AMENDMENT, AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN
THE PARTIES AS TO THE SUBJECT MATTER THEREIN AND HEREIN AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL
AGREEMENTS BETWEEN THE PARTIES.

================================================================================

                   REMAINDER OF PAGE LEFT INTENTIONALLY BLANK

================================================================================



                                      -4-
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this First
Amendment as of the date first above written.

                                        POWER-ONE, INC.



                                        By:   __________________________________
                                              Name:  Ed. K. Schnopp
                                              Title:  Vice President


                                        INTERNATIONAL POWER DEVICES, INC.



                                        By:   __________________________________
                                              Name:  Ed K. Schnopp
                                              Title:____________________________


                                        MELCHER HOLDING AG



                                        By:   __________________________________
                                              Name:  Dr. Hans Gruter
                                              Title:  Director



                                        By:   __________________________________
                                              Name:  Marcel V. Galli
                                              Title:  Secretary to the Board of
                                                      Directors


                                      -5-
<PAGE>

                                        BANK OF AMERICA,  N.A., as a Lender, as
                                        Administrative  Agent, and as Issuing
                                        Bank



                                        By:   __________________________________
                                              Name:  Douglas T. Meckelnburg
                                              Title:  Vice President


                                      -6-
<PAGE>

                                        UNION BANK OF CALIFORNIA, N.A.




                                        By:   __________________________________
                                              Name:_____________________________
                                              Title:____________________________


                                      -7-
<PAGE>



                                        CITY NATIONAL BANK



                                        By:   __________________________________
                                              Name:_____________________________
                                              Title:____________________________


                                      -8-
<PAGE>

                                        CALIFORNIA BANK & TRUST



                                        By:   __________________________________
                                              Name:_____________________________
                                              Title:____________________________


                                      -9-
<PAGE>

ACKNOWLEDGED AND AGREED:


POWER-ONE, INC. (as a Subordinated Creditor for loans to International Power
Devices, Inc. and Melcher Holding AG)


By:   ______________________________
      Name:  Ed K. Schnopp
      Title:  Vice President


INTERNATIONAL POWER DEVICES, INC. (as a Subordinated Creditor for loans to
Power-One, Inc. and Melcher Holdings AG)


By:   ______________________________
      Name:  Ed K. Schnopp
      Title:


POWER-ELECTRONICS, INC.


By:   ______________________________
      Name:_________________________
      Title:________________________


PODER UNO DE MEXICO, S.A. DE C.V.


By:   ______________________________
      Name:_________________________
      Title:________________________


                                      -10-
<PAGE>

MELCHER HOLDING AG (as a Subordinated Creditor for loans to Power-One, Inc. and
International Power Devices, Inc.)


By:   ______________________________
      Name:  Dr. Hans Gruter
      Title:  Director


By:   ______________________________
      Name:  Marcel V. Galli
      Title:  Secretary to the Board of Directors


                                      -11-
<PAGE>

MELCHER AG


By:   ______________________________
      Name:  Dr. Hans Gruter
      Title:  Director


By:   ______________________________
      Name:  Marcel V. Galli
      Title: Secretary to the Board of Directors


DOMENIC MELCHER AG


By:   ______________________________
      Name:  Dr. Hans Gruter
      Title:  Director


By:   ______________________________
      Name:  Marcel V. Galli
      Title: Secretary to the Board of Directors


MELCHER S.A.


By:   ______________________________
      Name:  Dr. Hans Gruter
      Title:  President Directeur General


MELCHER LTD.


By:   ______________________________
      Name:  Dr. Hans Gruter
      Title:  Director


                                      -12-
<PAGE>

MELCHER S.R.L.


By:   ______________________________
      Name:  Dr. Hans Gruter
      Title:  Director


MELCHER GMBH


By:   ______________________________
      Name:  Dr. Hans Gruter
      Title:


MELCHER B.V.


By:   ______________________________
      Name:  Dr. Claus Maier
      Title:  Director


MELCHER SIMP LTD.


By:   ______________________________
      Name:  Dr. Martin Schnider
      Title:  Director


MELCHER PRODUKTION AG


By:   ______________________________
      Name:  Dr. Hans Gruter
      Title:  Director


By:   ______________________________
      Name:  Marcel V. Galli
      Title: Secretary to the Board of Directors


                                      -13-
<PAGE>

MELCHER S.R.O.


By:   ______________________________
      Name:  Dr. Martin Schnider
      Title:  Director


LR CRYSTAL IMMO A.S.


By:   ______________________________
      Name:  Dr. Martin Schnider
      Title:  Member of Supervisory Board


                                      -14-
<PAGE>


                                  SCHEDULE 1

     Lucent Technologies and its wholly owned subsidiaries have contacted
     the Parent about Lucent's Patent Nos. 5,303,138; 5,528,482; and
     5,872,705 (collectively, the "Lucent Patents") and have solicited the
     Parent to take a license under the Lucent Patents. In a latter to the
     Parent, dated October 19, 1999, Lucent asserted that the Parent's
     products (such as the Parent's HES, OES and IES Series DC/DC
     converters) "infringe" the Lucent Patents. Because the Parent is in the
     process of obtaining and analyzing relevant information, and because of
     the preliminary nature of the communications between the Parent and
     Lucent, the Parent is currently unable to estimate the outcome of any
     claim related to the Lucent Patents.


                                      -15-
<PAGE>


                                    EXHIBIT C




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