SIXTH AMENDMENT TO LOAN AND SECURITY AGREEMENT

Exhibit 10.15

SIXTH AMENDMENT TO

LOAN AND SECURITY AGREEMENT

THIS SIXTH AMENDMENT TO LOAN AND SECURITY AGREEMENT (this “Amendment”) is entered into this 23rd day of November 2011 (“Closing Date”), by and between SILICON VALLEY BANK (“Bank”) and IWATT INC., a Delaware corporation (“Borrower”).

RECITALS

A. Bank and Borrower have entered into that certain Loan and Security Agreement dated as of November 25, 2008 (as the same may from time to time be amended, modified, supplemented or restated, the “Loan Agreement”).

B. Bank has extended credit to Borrower for the purposes permitted in the Loan Agreement.

C. Borrower has requested that Bank amend the Loan Agreement to (i) extend the Revolving Line Maturity Date and (ii) make certain other revisions to the Loan Agreement as more fully set forth herein.

D. Although Bank is under no obligation to do so, Bank is willing to (i) extend the Revolving Line Maturity Date and (ii) make certain other revisions to the Loan Agreement, all on the terms and conditions set forth in this Amendment, so long as Borrower complies with the terms, covenants and conditions set forth in this Amendment in a timely manner.

AGREEMENT

NOW, THEREFORE, in consideration of the foregoing recitals and other good and valuable consideration, the receipt and adequacy of which is hereby acknowledged, and intending to be legally bound, the parties hereto agree as follows:

1. Definitions. Capitalized terms used but not defined in this Amendment, including its preamble and recitals, shall have the meanings given to them in the Loan Agreement.

2. Amendments to Loan Agreement.

2.1 Section 2.1.2 (Letters of Credit). Section 2.1.2 of the Loan Agreement is hereby amended by deleting it in its entirety and replacing it with the following:

2.1.2 [Intentionally Omitted].

2.2 Section 2.1.3 (Foreign Exchange Sublimit). Section 2.1.3 of the Loan Agreement is hereby amended by deleting it in its entirety and replacing it with the following:

2.1.3 [Intentionally Omitted].

2.3 Section 2.1.4 (Cash Management Services Sublimit). Section 2.1.4 of the Loan Agreement is hereby amended by deleting it in its entirety and replacing it with the following:

2.1.4 [Intentionally Omitted].

2.4 Section 2.1.5 (Overall Aggregate Sublimit for Letter of Credit and Foreign Exchange). Section 2.1.5 of the Loan Agreement is hereby amended by deleting it in its entirety and replacing it with the following:

2.1.5 [Intentionally Omitted].

2.5 Section 2.2 (Overadvance). Section 2.2 of the Loan Agreement is hereby amended by deleting it in its entirety and replacing it with the following:

If, at any time, the outstanding principal amount of any Advances exceeds the lesser of either the Revolving Line or the Borrowing Base (the amount of such excess amount being an “Overadvance”), Borrower shall immediately pay to Bank in cash such excess. Without limiting Borrower’s obligation to repay Bank any amount of the Overadvance, Borrower agrees to pay Bank interest on the outstanding amount of any Overadvance, on demand, at the Default Rate.

2.6 Section 2.4 (Fees). Section 2.4(b) of the Loan Agreement is hereby amended by deleting it in its entirety and replacing it with the following:

(b) [Intentionally Omitted].

2.7 Section 4.1 (Grant of Security Interest). Section 4.1 of the Loan Agreement is hereby amended by adding the following new paragraphs immediately after the first paragraph as follows:

Borrower acknowledges that it previously has entered, and/or may in the future enter, into Bank Services Agreements with Bank. Regardless of the terms of any Bank Services Agreement, Borrower agrees that any amounts Borrower owes Bank thereunder shall be deemed to be Obligations hereunder and that it is the intent of Borrower and Bank to have all such Obligations secured by the first priority perfected security interest in the Collateral granted herein (subject only to Permitted Liens that may have superior priority to Bank’s Lien in this Agreement).

If this Agreement is terminated, Bank’s Lien in the Collateral shall continue until the Obligations (other than inchoate indemnity obligations) are satisfied in full, and at such time, Bank shall, at Borrower’s sole cost and expense, terminate its security interest in the Collateral and all rights therein shall revert to Borrower. In the event (x) all Obligations (other than inchoate indemnity obligations), except for Bank Services, are satisfied in full, and (y) this Agreement is terminated, Bank shall terminate the security interest granted herein upon Borrower providing cash collateral acceptable to Bank in its good faith business judgment for Bank Services, if any. In the event such Bank Services

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consist of outstanding Letters of Credit, Borrower shall provide to Bank cash collateral in an amount equal to 105% of the Dollar Equivalent (or 110% if the Dollar Equivalent is denominated in Foreign Currency) of the face amount of all such Letters of Credit plus all interest, fees, and costs due or to become due in connection therewith (as estimated by Bank in its good faith business judgment), to secure all of the Obligations relating to such Letters of Credit.

2.8 Section 9.1 (Rights and Remedies). Section 9.1(c) of the Loan Agreement is hereby amended by deleting it in its entirety and replacing it with the following:

(c) for any Letters of Credit, demand that Borrower (i) deposit cash with Bank in an amount equal to 105% of the Dollar Equivalent (or 110% if the Dollar Equivalent is denominated in Foreign Currency) of the aggregate face amount of all Letters of Credit remaining undrawn (plus all interest, fees, and costs due or to become due in connection therewith (as estimated by Bank in its good faith business judgment)), to secure all of the Obligations relating to such Letters of Credit, as collateral security for the repayment of any future drawings under such Letters of Credit, and Borrower shall forthwith deposit and pay such amounts, and (ii) pay in advance all letter of credit fees scheduled to be paid or payable over the remaining term of any Letters of Credit;

2.9 Section 12.9 (Survival). Section 12.9 of the Loan Agreement is hereby amended by deleting it in its entirety and replacing it with the following:

12.9 Survival. All covenants, representations and warranties made in this Agreement continue in full force until this Agreement has terminated pursuant to its terms and ail Obligations (other than inchoate indemnity obligations and any other obligations which, by their terms, are to survive the termination of this Agreement) have been paid in full and satisfied. Without limiting the foregoing, except as otherwise provided in Section 4.1, the grant of security interest by Borrower in Section 4.1 shall survive until the termination of all Bank Services Agreements. The obligation of Borrower in Section 12.3 to indemnify Bank shall survive until the statute of limitations with respect to such claim or cause of action shall have run.

2.10 Section 13 (Definitions).

(a) The following terms and their respective definitions set forth in Section 13.1 of the Loan Agreement are hereby amended by deleting each in its entirety and replacing each with the following:

“Availability Amount” is (a) the lesser of (i) the Revolving Line or (ii) the amount available under the Borrowing Base minus (b) the outstanding principal balance of any Advances.

“Credit Extension” is any Advance or any other extension of credit by Bank for Borrower’s benefit under this Agreement,

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“FX Forward Contract” is any foreign exchange contract by and between Borrower and Bank under which Borrower commits to purchase from or sell to Bank a specific amount of Foreign Currency on a specified date.

“Letter of Credit” is a standby or commercial letter of credit issued by Bank upon request of Borrower based upon an application, guarantee, indemnity, or similar agreement.

“Loan Documents” are, collectively, this Agreement, the Perfection Certificate, the IP Agreement, the Warrant, any Bank Services Agreement, any subordination agreement, any note, or notes or guaranties executed by Borrower, and any other present or future agreement between Borrower and/or for the benefit of Bank in connection with this Agreement, all as amended, restated, or otherwise modified.

“Obligations” are Borrower’s obligation to pay when due any debts, principal, interest, Bank Expenses, and other amounts Borrower owes Bank now or later, whether under this Agreement, the other Loan Documents, or otherwise, including, without limitation, any interest accruing after Insolvency Proceedings begin and debts, liabilities, or obligations of Borrower assigned to Bank, and the performance of Borrower’s duties under the Loan Documents,

“Revolving Line Maturity Date” is December 24, 2011.

(b) The following term and its respective definition is hereby added in alphabetical order to Section 13.1 of the Loan Agreement as follows:

“Bank Services” are any products, credit services, and/or financial accommodations previously, now, or hereafter provided to Borrower or any of its Subsidiaries by Bank or any Bank Affiliate, including, without limitation, any letters of credit, cash management services (including, without limitation, merchant services, direct deposit of payroll, business credit cards, and check cashing services), interest rate swap arrangements, and foreign exchange services as any such products or services may be identified in Bank’s various agreements related thereto (each, a “Bank Services Agreement”).

(c) The defined terms “Cash Management Services”, “FX Business Day”, “FX Reduction Amount”, “FX Reserve”, “Letter of Credit Application”, “Letter of Credit Reserve”, “Settlement Date” set forth in Section 13.1 of the Loan Agreement and all references thereto in the Loan Agreement are hereby deleted in their entirety.

3. Limitation of Amendments.

3.1 The amendments set forth in Sections 2 above, are effective for the purposes set forth herein and shall be limited precisely as written and shall not be deemed to (a) be a consent to any amendment, waiver or modification of any other term or condition of any Loan Document, or (b) otherwise prejudice any right or remedy which Bank may now have or may have in the future under or in connection with any Loan Document.

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3.2 This Amendment shall be construed in connection with and as part of the Loan Documents and all terms, conditions, representations, warranties, covenants and agreements set forth in the Loan Documents, except as herein amended, are hereby ratified and confirmed and shall remain in full force and effect.

3.3 In addition to those Events of Default specifically enumerated in the Loan Documents, the failure to comply with the terms of any covenant or agreement contained herein shall constitute an Event of Default and shall entitle the Bank to exercise all rights and remedies provided to the Bank under the terms of any of the other Loan Documents as a result of the occurrence of the same.

4. Representations and Warranties. To induce Bank to enter into this Amendment, Borrower hereby represents and warrants to Bank as follows:

4.1 Immediately after giving effect to this Amendment (a) the representations and warranties contained in the Loan Documents are true, accurate and complete in all material respects as of the date hereof (except to the extent such representations and warranties relate to an earlier date, in which case they are true and correct in all material respects as of such date), and (b) no Event of Default, has occurred and is continuing;

4.2 Borrower has the power and authority to execute and deliver this Amendment and to perform its obligations under the Loan Agreement, as amended by this Amendment;

4.3 The organizational documents of Borrower delivered to Bank on the Effective Date are true, accurate and complete and have not been amended, supplemented or restated and are and continue to be in full force and effect;

4.4 The execution and delivery by Borrower of this Amendment and the performance by Borrower of its obligations under the Loan Agreement, as amended by this Amendment, have been duly authorized;

4.5 The execution and delivery by Borrower of this Amendment and the performance by Borrower of its obligations under the Loan Agreement, as amended by this Amendment, do not and will not contravene (a) any law or regulation binding on or affecting Borrower, (b) any contractual restriction with a Person binding on Borrower, (c) any order, judgment or decree of any court or other governmental or public body or authority, or subdivision thereof, binding on Borrower, or (d) the organizational documents of Borrower;

4.6 The execution and delivery by Borrower of this Amendment and the performance by Borrower of its obligations under the Loan Agreement, as amended by this Amendment, do not require any order, consent, approval, license, authorization or validation of, or filing, recording or registration with, or exemption by any governmental or public body or authority, or subdivision thereof, binding on Borrower, except as already has been obtained or made; and

4.7 This Amendment has been duly executed and delivered by Borrower and is the binding obligation of Borrower, enforceable against Borrower in accordance with its terms,

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except as such enforceability may be limited by bankruptcy, insolvency, reorganization, liquidation, moratorium or other similar laws of general application and equitable principles relating to or affecting creditors’ rights.

5. Prior Agreement. The Loan Documents are hereby ratified and reaffirmed and shall remain in full force and effect. This Amendment is not a novation and the terms and conditions of this Amendment shall be in addition to and supplemental to all terms and conditions set forth in the Loan Documents. In the event of any conflict or inconsistency between this Amendment and the terms of such documents, the terms of this Amendment shall be controlling, but such document shall not otherwise be affected or the rights therein impaired.

6. Counterparts. This Amendment may be executed in any number of counterparts and all of such counterparts taken together shall be deemed to constitute one and the same instrument.

7. Effectiveness. This Amendment shall be deemed effective upon (a) the due execution and delivery to Bank of this Amendment by each party hereto and (b) payment of all Bank’s legal fees and expenses in connection with the preparation and negotiation of this Amendment and the other Loan Documents,

[Signature Page Follows.]

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IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed and delivered as of the date first written above.