See accompanying notes.

The following description of the Littelfuse, Inc. 401(k) Retirement and Savings Plan (the Plan) provides general information about the Plan’s provisions. Littelfuse, Inc. (the Company) is the Plan’s sponsor. Participants should refer to the plan document and summary plan description for a more complete description of the Plan’s provisions, copies of which may be obtained from the plan sponsor.

The Plan is a defined-contribution plan, which is optional to all eligible U.S. employees of the Company. Eligible participants are automatically enrolled in the Plan unless they affirmatively decline to participate. The entry date into the Plan is the first day of the month following or coincident with the date of hire.

The Plan is administered by the T. Rowe Price Trust Company (the Trustee) under the direction of the plan administrator. The Plan is subject to the provisions of the Employee Retirement Income Security Act of 1974 (ERISA).

Effective September 30, 2011, the Cole Hersee Company 401(k) Savings Plan (Cole Hersee Plan) merged with the Plan. Former Cole Hersee Plan participants are now eligible to participate in the Plan going forward. All Cole Hersee Plan employees who were active on September 30, 2011, became 100% vested. At the date of transfer, Cole Hersee Plan assets of $6,760,944 were transferred into the Plan.

Each year, participants may make elective deferral contributions to the Plan in any pay period up to a maximum of 90% of their eligible compensation for that pay period, as defined in the Plan. Participants may also contribute amounts representing distributions from other qualified plans. If a participant is automatically enrolled, the participant’s deferral is set at 2% of eligible compensation until changed by the participant. Effective January 1, 2011, for Littelfuse employees, and January 1 2012, for Cole Hersee Plan employees, all eligible participants contributing less than 10% will have their deferral rate increased by 1% annually until they reach 10% or opt out of the automatic increase. Participants who have attained age 50 before the end of the year are eligible to make catch-up contributions. Highly compensated participants, as defined by the Internal Revenue Service (IRS), are subject to more restrictive maximum limits. The Company matches participant contributions dollar for dollar up to the first 4% of the participant’s eligible compensation, as defined in the Plan. All contributions are subject to certain limitations of the Internal Revenue Code (the Code).

Certain plan participants, who meet certain eligibility requirements, will receive an annual non-elective company contribution equal to 5% of their eligible compensation for the plan year. These plan participants are defined as the 60 Point Group. The 60 Point Group is a grandfathered benefit and is not open to future participants. The annual contribution for this group is made regardless of a participant’s deferrals and invested in the same manner as his or her elective deferrals.

Effective January 1, 2012, the Company will make an annual non-safe harbor, non-elective company contribution equal to 2% of eligible compensation for the plan year. The contribution is made to eligible participants employed at the end of the plan year.

Participants direct their elective contributions into various investment options offered by the Plan and can change their investment options on a daily basis. If a participant is automatically enrolled, his or her contributions are invested in the applicable lifestyle fund based on the participant’s age until the participant changes his or her election. The Company’s contributions are allocated in the same manner as that of the participant’s elective contributions.

Each participant’s account is credited with the participant’s contributions, the Company’s matching contributions, and allocations of plan earnings and is charged with an allocation of administrative expenses. Plan earnings are allocated based on the participant’s share of net earnings or losses of the participant’s respective elected investment options. Allocations of administrative expenses are based on the participant’s account balance as defined. The benefit to which a participant is entitled is the participant’s vested account balance.

Vesting

Participants are immediately vested in their contributions plus actual earnings thereon, as well as the Company’s matching and non-elective contributions.

Forfeitures

Forfeited balances of terminated participant accounts are utilized on a prioritized basis in the plan year in which the forfeiture occurs and may be used to reduce future company contributions and administrative expenses. Unallocated forfeiture balances as of December 31, 2012 and 2011, were $14,952 and $15,170, respectively. Forfeitures used to reduce Company contributions and administrative expenses were $28,685 and $22,824 for the years ended December 31, 2012 and 2011, respectively.

Participant Loans

Participants may borrow from their accounts up to a maximum equal to the lesser of $50,000 or 50% of their vested account balance. Loan terms range from 1 to 5 years or up to 25 years for the purchase of a primary residence. The $50,000 limit is reduced by the participant’s highest outstanding loan balance during the preceding 12-month period. A participant may not have more than two loans outstanding at any point in time.

The loans bear interest at a rate commensurate with local prevailing rates at the date of issuance as determined quarterly by the plan administrator. Principal and interest are paid ratably through monthly payroll deductions. If a participant terminates employment with the Company, the entire unpaid principal sum plus accrued interest (plus any other amounts due under the loan) will become immediately due and payable. If the loan is not repaid, it will automatically be treated as a distribution to the participant after three months.

Participants are entitled to receive a distribution of the vested balances in their accounts upon reaching age 59 1/2, termination of employment, disability, death, or in the event of a financial hardship. Distributions may be made in a lump sum or in periodic installments and are taxable to the participant when received. Distributions prior to age 59 1/2 may subject the participant to a 10% federal income tax penalty.

Upon separation from service with the Company due to death, disability, retirement, or termination, a participant whose vested account balance exceeds $1,000 may elect to receive either a lump sum or may elect installment payments on a quarterly or annual basis. A participant whose vested account balance is $1,000 or less and has not commenced receiving installment payments will automatically receive a lump-sum distribution equal to his or her vested account balance after three months.

In-service withdrawals are available in certain limited circumstances, as defined by the Plan. Hardship withdrawals are allowed for participants incurring an immediate and heavy financial need, as defined by the Plan. Hardship withdrawals are strictly regulated by the IRS, and a participant must exhaust all available loan options and available distributions prior to requesting a hardship withdrawal.

Plan Termination

Although it has not expressed any intent to do so, the Company has the right under the Plan to discontinue its contributions at any time and to terminate the Plan subject to the provisions of ERISA. If the Plan terminates, participants will become 100% vested in their accounts.

2. Summary of Significant Accounting Policies

Basis of Accounting

The accompanying financial statements have been prepared on the accrual basis of accounting.

Payment of Benefits

Benefits are recorded when paid.

In May 2011, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2011-04, Amendments to Achieve Common Fair Value Measurements and Disclosure Requirements in U.S. GAAP and IFRSs. The new guidance amends previous guidance to converge the fair value measurement guidance in GAAP and International Financial Reporting Standards (IFRSs). Some of the amendments clarify the application of existing fair value measurement requirements, while other amendments change a particular principle in the previous guidance. In addition, the new guidance requires additional fair value disclosures (although certain of these new disclosures will not be required for nonpublic entities as defined by Accounting Standards Codification (ASC) Topic 820, Fair Value Measurement). The amendments are to be applied prospectively and are effective for annual periods beginning after December 15, 2011. Adoption of ASU 2011-04 did not have an effect on the Plan’s net assets available for benefits or its changes in net assets available for benefits.

For the years ended December 31, 2012 and 2011, the Plan’s investments (including investments purchased, sold, as well as held during the year) appreciated (depreciated) in fair value as follows:

In accordance with the FASB ASC Topic 820, Fair Value Measurements, assets and liabilities measured at fair value are categorized into the following fair value hierarchy:

Level 1 – Fair value is based on unadjusted quoted prices for identical assets or liabilities in an active market that the Plan has the ability to access at the measurement date.

Level 2 – Fair value is based on quoted prices in markets that are not active, quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability.

Level 3 – Fair value is based on prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable. These inputs reflect management’s judgment about the assumptions that a market participant would use in pricing the investment and are based on the best available information, some of which may be internally developed.

A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

Following is a description of the valuation technique and inputs used for each major class of assets measured at fair value by the Plan.

Registered investment companies – Valued at quoted market prices, which represent the net asset values (NAV) of shares held by the Plan at year-end.

Common stock – Valued at the last reported prices on an active national securities exchange on the last business day of the plan year.

Common/collective trust fund – Valued at the NAV provided by the administrator of the fund. The NAV is based on underlying assets owned by the fund, minus its liabilities, and then divided by the number of shares outstanding.

The following tables set forth, by level within the fair value hierarchy, the Plan’s investment assets at fair value. There were no liabilities subject to fair value measurements.

The Plan has received a determination letter from the IRS dated July 18, 2011, stating that the Plan is qualified under Section 401(a) of the Code, and therefore, the related trust is exempt from taxation. Subsequent to this determination by the IRS, the Plan was amended. Once qualified, the Plan is required to operate in conformity with the Code to maintain its qualified status. The plan administrator believes the Plan is being operated in compliance with the applicable requirements of the Code and, therefore, believes that the Plan, as amended, is qualified and the related trust is tax-exempt.

Accounting principles generally accepted in the United States require plan management to evaluate uncertain tax positions taken by the Plan. The financial statement effects of a tax position are recognized when the position is more likely than not, based on the technical merits, to be sustained upon examination by the IRS. The plan administrator has analyzed the tax positions taken by the Plan and has concluded that as of December 31, 2012, there are no uncertain positions taken or expected to be taken. The Plan has recognized no interest or penalties related to uncertain tax positions. The Plan is subject to routine audits by taxing jurisdictions; however, there are currently no audits for any tax periods in progress. The plan administrator believes the Plan is no longer subject to income tax examinations for years prior to 2009.

6. Related-Party Transactions

Littelfuse Inc. Common Stock

Transactions in shares of Littelfuse Inc. common stock qualify as party-in-interest transactions. At December 31, 2012 and 2011, the Plan held 43,056 and 45,833 shares of Littelfuse, Inc. common stock, respectively, representing 5.3% and 4.4%, respectively, of the total net assets of the Plan.

Registered Investment Companies Managed by T. Rowe Price Trust Company

Certain plan investments are shares of registered investment companies managed by the Trustee of the Plan. These transactions qualify as party-in-interest transactions; however, they are exempt from the prohibited transactions rules under ERISA. Fees paid by the Plan to the Trustee for investment management services were deducted from the net asset values of shares of registered investment companies held by the Plan.

The Plan invests in various investment securities. Investment securities are exposed to various risks such as interest rate, market volatility, and credit risks. Due to the level of risk associated with certain investment securities, it is at least reasonably possible that changes in the values of investment securities will occur in the near term and that such changes could materially affect participants’ account balances and the amounts reported in the statements of net assets available for benefits.

December 31, 2012