Summary of Significant Accounting Policies and Other Information (Policies)	12 Months Ended
Dec. 28, 2024
Accounting Policies [Abstract]
Fiscal Year	Fiscal Year References herein to “2024”, “fiscal 2024” or “fiscal year 2024” refer to the fiscal year ended December 28, 2024. References herein to “2023”, “fiscal 2023” or “fiscal year 2023” refer to the fiscal year ended December 30, 2023. References herein to “2022”, “fiscal 2022” or “fiscal year 2022” refer to the fiscal year ended December 31, 2022. The Company operates on a 52-53 week fiscal year (4-4-5 basis) ending on the Saturday closest to December 31.
Basis of Presentation	Basis of Presentation The Consolidated Financial Statements include the accounts of Littelfuse, Inc. and its subsidiaries. All significant intercompany accounts and transactions have been eliminated. The Company’s Consolidated Financial Statements were prepared in accordance with generally accepted accounting principles in the United States of America ("U.S.") and include the assets, liabilities, sales and expenses of all wholly owned subsidiaries and majority-owned subsidiaries over which the Company exercises control.
Use of Estimates	Use of Estimates The process of preparing financial statements in conformity with generally accepted accounting principles in the U.S. requires management to make estimates and assumptions that affect the amounts of assets and liabilities at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses and the accompanying notes. The Company evaluates and updates its assumptions and estimates on an ongoing basis and may employ outside experts to assist in its evaluation, as considered necessary. Actual results could differ from those estimates.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash All highly liquid investments, with an original maturity of three months or less when purchased, are considered to be cash equivalents. The Company maintains several pools including multicurrency notional pools and physical pools internationally and a zero-balance account ("ZBA") structure in the U.S. In the notional pools, actual cash balances are not physically converted and are not commingled between participating legal entities. The Company will classify any overdraft balances within accrued expenses and other current liabilities on the Consolidated Balance Sheets.
Short-Term and Long-Term Investments	Short-Term and Long-Term Investments As of December 28, 2024, the Company has an investment in Polytronics Technology Corporation Ltd. (“Polytronics”). The Company’s Polytronics shares held at the end of fiscal 2024 and 2023 represent approximately 6.7% of total Polytronics shares outstanding for both years. The Polytronics investment is carried at fair value. The fair value of the Polytronics investment was €9.8 million (approximately $10.2 million) at December 28, 2024 and €9.7 million (approximately $10.8 million) at December 30, 2023. As a result of the Company’s acquisition of IXYS Corporation ("IXYS"), the Company has equity ownerships in various investments that are accounted for under the equity method. The Company owns 45% of the outstanding equity of Powersem GmbH, a module manufacturer based in Germany, approximately 15% of the outstanding equity of EB-Tech Co., Ltd., a company with expertise in radiation technology based in South Korea, and approximately 24% of the outstanding common shares of Automated Technology (Phil), Inc., a supplier located in the Philippines that provides assembly and test services. The Company recognized a loss of $0.6 million and a gain $0.5 million from its equity method investments for both the fiscal years ended December 28, 2024 and December 30, 2023, respectively, recorded in Other (income) expense, net, in the Consolidated Statements of Net Income. The balance of these equity method investments was $13.1 million and $14.0 million as of the fiscal years ended December 28, 2024 and December 30, 2023, respectively. See Note 18, Related Party Transactions, for further discussion. The Company has investments related to its non-qualified Supplemental Retirement and Savings Plan. The Company maintains accounts for participants through which participants make investment elections. The investment securities are subject to the claims of the Company’s creditors. The investment securities are all mutual funds. The investment securities are measured at net asset value. As of December 28, 2024 and December 30, 2023, the investment securities balance was $23.3 million and $20.1 million, respectively, related to the plan and are included in Other long-term assets on the Consolidated Balance Sheets.
Trade Receivables	Trade Receivables The Company performs credit evaluations of customers’ financial condition and generally does not require collateral. A receivable is considered past due if payments have not been received within agreed upon invoice terms. Write-offs are recorded at the time a customer receivable is deemed uncollectible. The Company also maintains allowances against trade receivables for the settlement of rebates and sales discounts to customers. These allowances are based upon specific customer sales and sales discounts as well as actual historical experience.
Inventories	Inventories Inventories are stated at the lower of cost or net realizable value, which approximates current replacement cost. Cost is principally determined using the first-in, first-out method. The Company maintains excess and obsolete reserves against inventory to reduce the carrying value to the expected net realizable value. These reserves are based upon a combination of factors including historical sales volume, market conditions, and lower of cost or net realizable value of the inventory.
Property, Plant, and Equipment	Property, Plant, and Equipment Land, buildings, and equipment are carried at cost. Depreciation is calculated using the straight-line method with useful lives of up to 35 years for buildings, three to 20 years for equipment, seven years for furniture and fixtures, five years for tooling, and three years for computer equipment. Leasehold improvements are depreciated over the lesser of their useful life or the lease term. Maintenance and repair costs are charged to expense as incurred. Major overhauls that extend the useful lives of existing assets are capitalized.
Goodwill	Goodwill The Company annually tests goodwill for impairment on the first day of its fiscal fourth quarter, or more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying value. The results of the goodwill impairment test as of September 29, 2024 indicated that the estimated fair values for the Industrial controls and sensors and Automotive sensors reporting units were below their respective carrying values. Accordingly, the Company recorded non-cash impairment charges of $36.1 million and $8.6 million, respectively, to reflect the impairment of goodwill for the Industrial controls and sensors reporting unit within the Industrial segment and the Automotive sensors reporting unit within the Transportation segment. As a result of these impairment charges, the Industrial controls and sensors reporting unit had $115.2 million of goodwill as of December 28, 2024. There was no goodwill remaining within the Automotive sensors reporting unit as of December 28, 2024. For the remainder of the Company's reporting units: Electronics-Passive Products and Sensors, Electronics-Semiconductor, Passenger Car Products, Commercial Vehicle Products, and Industrial Circuit Protection, the results of the goodwill impairment test as of September 29, 2024 indicated that their estimated fair values exceeded their respective carrying values. The Company compares each reporting unit’s fair value, estimated based on comparable company market valuations and expected future discounted cash flows to be generated by the reporting unit, to its carrying value. With the exception of the Industrial controls and sensors and the Automotive sensors reporting units, the other five reporting units passed the most recent annual test conducted on September 29, 2024 with estimated fair values that exceeded the carrying values by 108%, 82%, 96%, 44%, and 409% for its reporting units: Electronics-Passive Products and Sensors, Electronics-Semiconductor, Passenger Car Products, Commercial Vehicle Products, and Industrial Circuit Protection, respectively. Relatively small changes in the Company’s key assumptions would not have resulted in any reporting units failing the goodwill impairment test. See Note 5, Goodwill and Other Intangible Assets, for additional information. There were no impairment charges recorded during the fiscal years of 2023 and 2022. The Company also performs an interim review for indicators of impairment each quarter to assess whether an interim impairment review is required for any reporting unit. As part of its interim reviews, management analyzes potential changes in the value of individual reporting units based on each reporting unit’s operating results for the period compared to expected results as of the prior year’s annual impairment test. In addition, management considers how other key assumptions, including discount rates and expected long-term growth rates, used in the last annual impairment test, could be impacted by changes in market conditions and economic events. Based on the interim assessments as of December 28, 2024, management concluded that no events or changes in circumstances indicated that it was more likely than not that the fair value for any reporting unit had declined below its carrying value.
Long-Lived Assets	Customer relationships, trademarks and tradenames are amortized using the straight-line method over estimated useful lives that have a range of 3 to 20 years. Patents, licenses, and software are amortized using the straight-line method or an accelerated method over estimated useful lives that have a range of 4 to 17 years. The distribution networks are amortized on either a straight-line or accelerated basis over estimated useful lives that have a range of 4 to 10 years. Land use rights are amortized using the straight-line method up to 50 years which is the term of the land use rights. The Company assesses potential impairments to its long-lived assets if events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An impaired asset is written down to its estimated fair value based upon the most recent information available. Estimated fair market value is generally measured by discounting estimated future cash flows. Long-lived assets, other than goodwill and other intangible assets, which are held for sale are recorded at the lower of carrying value or the fair market value less the estimated cost to sell.
Environmental Liabilities	Environmental Liabilities Environmental liabilities are accrued based on engineering studies estimating the cost of remediating sites. Expenses related to on-going maintenance of environmental sites are expensed as incurred. If actual or estimated probable future losses exceed the Company’s recorded liability for such claims, the Company would record additional charges during the period in which the actual loss or change in estimate occurred.
Pension and Other Post-retirement Benefits	Pension and Other Post-retirement Benefits The Company records annual income and expense amounts relating to its pension and post-retirement benefits plans based on calculations which include various actuarial assumptions including discount rates, expected long-term rates of return and compensation increases. The Company reviews its actuarial assumptions on an annual basis as of the fiscal year-end balance sheet date (or more frequently if a significant event requiring remeasurement occurs) and modifies the assumption based on current rates and trends when it is appropriate to do so. The effects of modifications are recognized immediately on the Consolidated Balance Sheets, but are generally amortized into operating earnings over future periods, with the deferred amount recorded in accumulated other comprehensive loss. The Company believes that the assumptions utilized in recording its obligations under its plans are reasonable based on its experience, market conditions and input from its actuaries and investment advisors.
Revenue Recognition	Revenue Recognition The Company recognizes revenue on product sales in the period in which the Company satisfies its performance obligation and control of the product is transferred to the customer. The Company’s sales arrangements with customers are predominately short term in nature and generally provide for transfer of control at the time of shipment as this is the point at which title and risk of loss of the product transfers to the customer. At the end of each period, for those shipments where title to the products and the risk of loss and rewards of ownership do not transfer until the product has been received by the customer, the Company adjusts revenues and cost of sales for the delay between the time that the products are shipped and when they are received by the customer. The amount of revenue recorded reflects the consideration to which the Company expects to be entitled in exchange for goods and may include adjustments for customer allowance, rebates, and price adjustments. The Company’s distribution channels are primarily through direct sales and independent third-party distributors. The Company has elected the practical expedient under ASC 340-40-25-4 to expense commissions when incurred as the amortization period of the commission asset the Company would have otherwise recognized is less than one year. Revenue and Billing The Company generally accepts orders from customers through receipt of purchase orders or electronic data interchange based on written sales agreements and purchasing contracts. Contract pricing and selling agreement terms are based on market factors, costs, and competition. Pricing is often negotiated as an adjustment (premium or discount) from the Company’s published price lists. The customer is invoiced when the Company’s products are shipped to them in accordance with the terms of the sales agreement. As the Company’s standard payment terms are less than one year, the Company has elected the practical expedient under ASC 606-10-32-18 to not assess whether a contract has a significant financing component. The Company also elected the practical expedient provided in ASC 606-10-25-18B to treat all product shipping and handling activities as fulfillment activities, and therefore recognize the gross revenue associated with the contract, inclusive of any shipping and handling revenue. Ship and Debit Program Some of the terms of the Company’s sales agreements and normal business conditions provide customers (distributors) the ability to receive price adjustments on products previously shipped and invoiced. This practice is common in the industry and is referred to as a “ship and debit” program. This program allows the distributors to debit the Company for the difference between the distributors’ contracted price and a lower price for specific transactions. Under certain circumstances (usually in a competitive situation or large volume opportunity), a distributor will request authorization for pricing allowances to reduce its price. When the Company approves such a reduction, the distributor is authorized to “debit” its account for the difference between the contracted price and the lower approved price. The Company establishes reserves for this program based on historic activity, distributor inventory levels and actual authorizations for the debit and recognizes these debits as a reduction of revenue. Return to Stock The Company has a return to stock policy whereby certain customers, with prior authorization from the Company's management, can return previously purchased goods for full or partial credit. The Company establishes an estimated allowance for these returns based on historic activity. Sales revenue and cost of sales are reduced to anticipate estimated returns. Volume Rebates The Company offers volume-based sales incentives to certain customers to encourage greater product sales. If customers achieve their specific quarterly or annual sales targets, they are entitled to rebates. The Company estimates the projected amount of rebates that will be achieved by the customer and recognizes this estimated cost as a reduction to revenue as products are sold.
Allowance for Credit Losses	Allowance for Credit Losses The Company currently measures the expected credit losses based on our historical credit loss experience. The Company has not experienced significant recent or historical credit losses and is not forecasting any significant credit losses which would require adjustments to our methodology. If current conditions and supportable forecasts indicate that our historical loss experience is not reasonable and no longer supportable, the Company may adjust its historical credit loss experience and to reflect these conditions and forecasts. The Company regularly analyzes its significant customer accounts and, when the Company becomes aware of a customer’s inability to meet its financial obligations, the Company records a specific reserve for bad debt to reduce the related receivable to the amount the Company reasonably believes is collectible. The Company also analyzes all other customers based on a variety of factors including the length of time the receivables are past due, the financial health of the customer, macroeconomic considerations and historical collection and loss experience. Historically, the allowance for credit losses has been adequate to cover bad debts. If circumstances related to specific customers change, the estimates of the recoverability of receivables could be further adjusted.
Advertising Costs	Advertising Costs The Company expenses advertising costs as incurred,
Shipping and Handling Fees and Costs	Shipping and Handling Fees and Costs Amounts billed to customers related to shipping and handling are classified as revenue. Costs incurred for shipping and handling of $15.3 million, $15.4 million, and $13.9 million in fiscal years 2024, 2023, and 2022, respectively, are classified in selling, general, and administrative expenses.
Foreign Currency Translation / Remeasurement	Foreign Currency Translation / Remeasurement The Company’s foreign subsidiaries use the local currency or the U.S. dollar as their functional currency, as appropriate. Assets and liabilities are translated using exchange rates at the balance sheet date, and revenues and expenses are translated at weighted average rates. Adjustments from the translation process are recognized in Shareholders’ equity as a component of Accumulated other comprehensive income (loss).
Stock-Based Compensation	Stock-Based Compensation The Company recognizes compensation expense for the cost of awards of equity compensation using a fair value method. Benefits of tax deductions in excess of recognized compensation expense are reported as operating cash flows. See Note 12, Stock-Based Compensation, for additional information on stock-based compensation.
Coal Mining Liability	Coal Mining Liability Included in accrued liabilities is an accrual related to former coal mining operations at Littelfuse GmbH (formerly known as Heinrich Industries, AG) for the amounts of €2.2 million ($2.3 million) and €2.5 million ($2.7 million) at December 28, 2024 and December 30, 2023, respectively. Management, in conjunction with an independent third-party, performs an annual evaluation of the former coal mining operations in order to develop an estimate of the probable future obligations in regard to remediating the dangers (such as a shaft collapse) of abandoned coal mine shafts in the former coal mining operations. Management accrues for costs associated with such remediation efforts based on management's best estimate when such costs are probable and reasonably able to be estimated. The ultimate determination can only be done after respective investigations because the concrete conditions are mostly unknown at this time.
Other (Income) Expense, Net	Other (Income) Expense, Net Other (income) expense, net generally consists of interest income, royalties, change in fair value of available-for-sale securities, pension non-service costs and settlements and other non-operating (income) expense.
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method. Deferred taxes are recognized for the future effects of temporary differences between financial and income tax reporting using enacted tax rates in effect for the years in which the differences are expected to reverse. The Company recognizes deferred taxes for temporary differences, operating loss carryforwards, and tax credit and other tax attribute carryforwards (excluding carryforwards where usage has been determined to be remote). Deferred tax assets are reduced by a valuation allowance if it is more likely than not that some portion, or all, of the deferred tax assets will not be realized. U.S. state and non-U.S. income taxes are provided on the portion of non-U.S. income that is expected to be remitted to the U.S. and be taxable (and non-U.S. income taxes are provided on the portion of non-U.S. income that is expected to be remitted to an upper-tier non-U.S. entity). Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment. Deferred U.S. income taxes and non-U.S. taxes are not provided on the excess of the investment value for financial reporting over the tax basis of investments in those non-U.S. subsidiaries for which such excess is considered to be permanently reinvested in those operations. Management regularly evaluates whether non-U.S. earnings are expected to be permanently reinvested. This evaluation requires judgment about the future operating and liquidity needs of the Company and its non-U.S. subsidiaries. Changes in economic and business conditions, tax laws, or the Company’s financial situation could result in changes to these judgments and the need to record additional tax liabilities. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. The 2017 Tax Cuts and Jobs Act (the "Tax Act"), among other things, imposed a one-time tax (the “Toll Charge”) on accumulated earnings of certain non-U.S. subsidiaries and included base broadening provisions commonly referred to as the global intangible low-taxed income provisions ("GILTI"). The Company elected to pay the 2017 Littelfuse Toll Charge over the eight-year period prescribed by the Tax Act. The anticipated 2025 annual installment payment of this Toll Charge of $8.2 million, which represents the eighth and final required installment, is included in Accrued income taxes, on the Consolidated Balance Sheets as of December 28, 2024. In accordance with guidance issued by the FASB staff, the Company has adopted an accounting policy to treat any GILTI inclusions as a period cost if and when incurred. Thus, for the fiscal years ended December 28, 2024, December 30, 2023, and December 31, 2022, deferred taxes were computed without consideration of the possible future impact of the GILTI provisions, and any current year impact was recorded as a part of the current portion of income tax expense.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are required to be recorded at fair value on a recurring basis. Fair value is determined based on the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants. The Company records the fair value of its available-for-sale securities and pension plan assets on a recurring basis. Assets measured at fair value on a nonrecurring basis include long-lived assets held and used, long-lived assets held for sale, goodwill, and other intangible assets. The fair value of cash and cash equivalents, short-term investments, accounts receivable, accounts payable, and accrued liabilities approximate their carrying values. The three-tier value hierarchy, which prioritizes valuation methodologies based on the reliability of the inputs, is: Level 1 – Valuations based on unadjusted quoted prices for identical assets and liabilities in active markets. Level 2 – Valuations based on observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data. Level 3 – Valuations based on unobservable inputs reflecting the Company’s own assumptions, consistent with reasonably available assumptions made by other market participants.
Recently Issued and Adopted Accounting Standards	Recently Adopted Accounting Standards In November 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Updates ("ASU") No. 2023-07, "Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures." The amendments in this update require additional detailed and enhanced information about reportable segments' expense, including significant segment expenses and other segment items that bridge segment revenue, significant expenses to segment profit or loss. The ASU also requires disclosure of the title and position of the Chief Operating Decision Maker (“CODM”) on an annual basis as well as an explanation of how the CODM uses the reported measures and other disclosures. The amendments in this update do not change how a public entity identifies its operating segments, aggregates those operating segments, or applies the quantitative thresholds to determine its reportable segments. The guidance is effective for fiscal years beginning after December 15, 2023 and interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The adoption of ASU 2023-07 modified the Company's disclosures in its Consolidated Financial Statements. See Note 16, Segment Information, for more details. In March 2023, the FASB issued ASU No. 2023-01, "Leases (Topic 842): Common Control Arrangements." The standard requires that leasehold improvements associated with common control leases be: 1) Amortized by the lessee over the useful life of the leasehold improvements to the common control group (regardless of the lease term) as long as the lessee controls the use of the underlying asset (the leased asset) through a lease. However, if the lessor obtained the right to control the use of the underlying asset through a lease with another entity not within the same common control group, the amortization period may not exceed the amortization period of the common control group. 2) Accounted for as a transfer between entities under common control through an adjustment to equity (or net assets for not-for-profit entities) if, and when, the lessee no longer controls the use of the underlying asset. Additionally, those leasehold improvements are subject to the impairment guidance in Topic 360, Property, Plant, and Equipment. This standard is effective for fiscal years beginning after December 15, 2023 including interim periods within those fiscal years. The adoption of ASU 2023-01 did not have a material impact on the Company's Consolidated Financial Statements. Recently Issued Accounting Standards In November 2024, the FASB issued ASU No. 2024-03, "Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40)." The amendments in this update require disclosure, in the notes to financial statements, of specified information about certain costs and expenses. The amendments require that at each interim and annual reporting period an entity (a) disclose the amounts of (i) purchases of inventory, (ii) employee compensation, (iii) depreciation, (iv) intangible asset amortization, and (v) depreciation, depletion, and amortization recognized as part of oil and gas producing activities ("DD&A") included in each relevant expense caption. A relevant expense caption is an expense caption presented on the face of the income statement within continuing operations that contains any of the expense categories listed in (i)–(v); (b) include certain amounts that are already required to be disclosed under current Generally Accepted Accounting Principles ("GAAP") in the same disclosure as the other disaggregation requirements; (c) disclose a qualitative description of the amounts remaining in relevant expense captions that are not separately disaggregated quantitatively; (d) disclose the total amount of selling expenses and, in annual reporting periods, an entity’s definition of selling expenses. The guidance is effective for fiscal years beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027, with early adoption permitted. The adoption of this guidance will increase the Company's disclosures in its Consolidated Financial Statements. The Company is currently evaluating the potential impact on the disclosures in the Company's Consolidated Financial Statements. In December 2023, the FASB issued ASU No. 2023-09, "Income Taxes (Topic 740): Improvements to Income Tax Disclosures." The amendments in this update provide more transparency about income tax information through improvements to the income tax disclosure primarily related to the income tax rate reconciliation and income taxes paid information. These requirements include: (1) consistent categories and greater disaggregation of information in the rate reconciliation and (2) income taxes paid disaggregated by jurisdiction. The other amendments in this update improve the effectiveness and comparability of disclosures by (3) adding disclosures of pretax income (or loss) and income tax expense (or benefit), and (4) removing disclosures that are no longer considered cost beneficial or relevant. The guidance is effective for fiscal years beginning after December 15, 2024 with early adoption permitted. The adoption of this guidance will modify our disclosures in the Company's Consolidated Financial Statements. In October 2023, the FASB issued ASU No. 2023-06, "Disclosure Improvements." The amendments in this update represent changes to clarify or improve the disclosure or presentation requirements of a variety of Topics in the ASC. The Company may be affected by one or more of those amendments. The amendments in this ASU should be applied prospectively and will not be effective until June 30, 2027. The Company is currently evaluating the potential effects of these amendments on its Consolidated Financial Statements.

Summary of Significant Accounting Policies and Other Information (Policies)

12 Months Ended

Dec. 28, 2024

References herein to “2024”, “fiscal 2024” or “fiscal year 2024” refer to the fiscal year ended December 28, 2024. References herein to “2023”, “fiscal 2023” or “fiscal year 2023” refer to the fiscal year ended December 30, 2023. References herein to “2022”, “fiscal 2022” or “fiscal year 2022” refer to the fiscal year ended December 31, 2022. The Company operates on a 52-53 week fiscal year (4-4-5 basis) ending on the Saturday closest to December 31.

Basis of Presentation

The Consolidated Financial Statements include the accounts of Littelfuse, Inc. and its subsidiaries. All significant intercompany accounts and transactions have been eliminated. The Company’s Consolidated Financial Statements were prepared in accordance with generally accepted accounting principles in the United States of America ("U.S.") and include the assets, liabilities, sales and expenses of all wholly owned subsidiaries and majority-owned subsidiaries over which the Company exercises control.

Use of Estimates

The process of preparing financial statements in conformity with generally accepted accounting principles in the U.S. requires management to make estimates and assumptions that affect the amounts of assets and liabilities at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses and the accompanying notes. The Company evaluates and updates its assumptions and estimates on an ongoing basis and may employ outside experts to assist in its evaluation, as considered necessary. Actual results could differ from those estimates.

Cash, Cash Equivalents and Restricted Cash

All highly liquid investments, with an original maturity of three months or less when purchased, are considered to be cash equivalents. The Company maintains several pools including multicurrency notional pools and physical pools internationally and a zero-balance account ("ZBA") structure in the U.S. In the notional pools, actual cash balances are not physically converted and are not commingled between participating legal entities. The Company will classify any overdraft balances within accrued expenses and other current liabilities on the Consolidated Balance Sheets.

Short-Term and Long-Term Investments

As of December 28, 2024, the Company has an investment in Polytronics Technology Corporation Ltd. (“Polytronics”). The Company’s Polytronics shares held at the end of fiscal 2024 and 2023 represent approximately 6.7% of total Polytronics shares outstanding for both years. The Polytronics investment is carried at fair value. The fair value of the Polytronics investment was €9.8 million (approximately $10.2 million) at December 28, 2024 and €9.7 million (approximately $10.8 million) at December 30, 2023.

As a result of the Company’s acquisition of IXYS Corporation ("IXYS"), the Company has equity ownerships in various investments that are accounted for under the equity method. The Company owns 45% of the outstanding equity of Powersem GmbH, a module manufacturer based in Germany, approximately 15% of the outstanding equity of EB-Tech Co., Ltd., a company with expertise in radiation technology based in South Korea, and approximately 24% of the outstanding common shares of Automated Technology (Phil), Inc., a supplier located in the Philippines that provides assembly and test services. The Company recognized a loss of $0.6 million and a gain $0.5 million from its equity method investments for both the fiscal years ended December 28, 2024 and December 30, 2023, respectively, recorded in Other (income) expense, net, in the Consolidated Statements of Net Income. The balance of these equity method investments was $13.1 million and $14.0 million as of the fiscal years ended December 28, 2024 and December 30, 2023, respectively. See Note 18, Related Party Transactions, for further discussion.

The Company has investments related to its non-qualified Supplemental Retirement and Savings Plan. The Company maintains accounts for participants through which participants make investment elections. The investment securities are subject to the claims of the Company’s creditors. The investment securities are all mutual funds. The investment securities are measured at net asset value. As of December 28, 2024 and December 30, 2023, the investment securities balance was $23.3 million and $20.1 million, respectively, related to the plan and are included in Other long-term assets on the Consolidated Balance Sheets.

Trade Receivables

The Company performs credit evaluations of customers’ financial condition and generally does not require collateral. A receivable is considered past due if payments have not been received within agreed upon invoice terms. Write-offs are recorded at the time a customer receivable is deemed uncollectible.

The Company also maintains allowances against trade receivables for the settlement of rebates and sales discounts to customers. These allowances are based upon specific customer sales and sales discounts as well as actual historical experience.

Inventories

Inventories are stated at the lower of cost or net realizable value, which approximates current replacement cost. Cost is principally determined using the first-in, first-out method. The Company maintains excess and obsolete reserves against inventory to reduce the carrying value to the expected net realizable value. These reserves are based upon a combination of factors including historical sales volume, market conditions, and lower of cost or net realizable value of the inventory.

Property, Plant, and Equipment

Land, buildings, and equipment are carried at cost. Depreciation is calculated using the straight-line method with useful lives of up to 35 years for buildings, three to 20 years for equipment, seven years for furniture and fixtures, five years for tooling, and three years for computer equipment. Leasehold improvements are depreciated over the lesser of their useful life or the lease term. Maintenance and repair costs are charged to expense as incurred. Major overhauls that extend the useful lives of existing assets are capitalized.

Goodwill

The Company annually tests goodwill for impairment on the first day of its fiscal fourth quarter, or more frequently if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying value.

The results of the goodwill impairment test as of September 29, 2024 indicated that the estimated fair values for the Industrial controls and sensors and Automotive sensors reporting units were below their respective carrying values. Accordingly, the Company recorded non-cash impairment charges of $36.1 million and $8.6 million, respectively, to reflect the impairment of goodwill for the Industrial controls and sensors reporting unit within the Industrial segment and the Automotive sensors reporting unit within the Transportation segment. As a result of these impairment charges, the Industrial controls and sensors reporting unit had $115.2 million of goodwill as of December 28, 2024. There was no goodwill remaining within the Automotive sensors reporting unit as of December 28, 2024. For the remainder of the Company's reporting units: Electronics-Passive Products and Sensors, Electronics-Semiconductor, Passenger Car Products, Commercial Vehicle Products, and Industrial Circuit Protection, the results of the goodwill impairment test as of September 29, 2024 indicated that their estimated fair values exceeded their respective carrying values.

The Company compares each reporting unit’s fair value, estimated based on comparable company market valuations and expected future discounted cash flows to be generated by the reporting unit, to its carrying value. With the exception of the Industrial controls and sensors and the Automotive sensors reporting units, the other five reporting units passed the most recent annual test conducted on September 29, 2024 with estimated fair values that exceeded the carrying values by 108%, 82%, 96%, 44%, and 409% for its reporting units: Electronics-Passive Products and Sensors, Electronics-Semiconductor, Passenger Car Products, Commercial Vehicle Products, and Industrial Circuit Protection, respectively. Relatively small changes in the Company’s key assumptions would not have resulted in any reporting units failing the goodwill impairment test. See Note 5, Goodwill and Other Intangible Assets, for additional information.

There were no impairment charges recorded during the fiscal years of 2023 and 2022.

The Company also performs an interim review for indicators of impairment each quarter to assess whether an interim impairment review is required for any reporting unit. As part of its interim reviews, management analyzes potential changes in the value of individual reporting units based on each reporting unit’s operating results for the period compared to expected results as of the prior year’s annual impairment test. In addition, management considers how other key assumptions, including discount rates and expected long-term growth rates, used in the last annual impairment test, could be impacted by changes in market conditions and economic events. Based on the interim assessments as of December 28, 2024, management concluded that no events or changes in circumstances indicated that it was more likely than not that the fair value for any reporting unit had declined below its carrying value.

Long-Lived Assets

Customer relationships, trademarks and tradenames are amortized using the straight-line method over estimated useful lives that have a range of 3 to 20 years. Patents, licenses, and software are amortized using the straight-line method or an accelerated method over estimated useful lives that have a range of 4 to 17 years. The distribution networks are amortized on either a straight-line or accelerated basis over estimated useful lives that have a range of 4 to 10 years. Land use rights are amortized using the straight-line method up to 50 years which is the term of the land use rights.

The Company assesses potential impairments to its long-lived assets if events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An impaired asset is written down to its estimated fair value based upon the most recent information available. Estimated fair market value is generally measured by discounting estimated future cash flows. Long-lived assets, other than goodwill and other intangible assets, which are held for sale are recorded at the lower of carrying value or the fair market value less the estimated cost to sell.

Environmental Liabilities

Environmental liabilities are accrued based on engineering studies estimating the cost of remediating sites. Expenses related to on-going maintenance of environmental sites are expensed as incurred. If actual or estimated probable future losses exceed the Company’s recorded liability for such claims, the Company would record additional charges during the period in which the actual loss or change in estimate occurred.

Pension and Other Post-retirement Benefits

The Company records annual income and expense amounts relating to its pension and post-retirement benefits plans based on calculations which include various actuarial assumptions including discount rates, expected long-term rates of return and compensation increases. The Company reviews its actuarial assumptions on an annual basis as of the fiscal year-end balance sheet date (or more frequently if a significant event requiring remeasurement occurs) and modifies the assumption based on current rates and trends when it is appropriate to do so. The effects of modifications are recognized immediately on the Consolidated Balance Sheets, but are generally amortized into operating earnings over future periods, with the deferred amount recorded in accumulated other comprehensive loss. The Company believes that the assumptions utilized in recording its obligations under its plans are reasonable based on its experience, market conditions and input from its actuaries and investment advisors.

Revenue Recognition

The Company recognizes revenue on product sales in the period in which the Company satisfies its performance obligation and control of the product is transferred to the customer. The Company’s sales arrangements with customers are predominately short term in nature and generally provide for transfer of control at the time of shipment as this is the point at which title and risk of loss of the product transfers to the customer. At the end of each period, for those shipments where title to the products and the risk of loss and rewards of ownership do not transfer until the product has been received by the customer, the Company adjusts revenues and cost of sales for the delay between the time that the products are shipped and when they are received by the customer. The amount of revenue recorded reflects the consideration to which the Company expects to be entitled in exchange for goods and may include adjustments for customer allowance, rebates, and price adjustments. The Company’s distribution channels are primarily through direct sales and independent third-party distributors.

The Company has elected the practical expedient under ASC 340-40-25-4 to expense commissions when incurred as the amortization period of the commission asset the Company would have otherwise recognized is less than one year.

Revenue and Billing

The Company generally accepts orders from customers through receipt of purchase orders or electronic data interchange based on written sales agreements and purchasing contracts. Contract pricing and selling agreement terms are based on market factors, costs, and competition. Pricing is often negotiated as an adjustment (premium or discount) from the Company’s published price lists. The customer is invoiced when the Company’s products are shipped to them in accordance with the terms of the sales agreement. As the Company’s standard payment terms are less than one year, the Company has elected the practical expedient under ASC 606-10-32-18 to not assess whether a contract has a significant financing component. The Company also elected the practical expedient provided in ASC 606-10-25-18B to treat all product shipping and handling activities as fulfillment activities, and therefore recognize the gross revenue associated with the contract, inclusive of any shipping and handling revenue.

Ship and Debit Program

Some of the terms of the Company’s sales agreements and normal business conditions provide customers (distributors) the ability to receive price adjustments on products previously shipped and invoiced. This practice is common in the industry and is referred to as a “ship and debit” program. This program allows the distributors to debit the Company for the difference between the distributors’ contracted price and a lower price for specific transactions. Under certain circumstances (usually in a competitive situation or large volume opportunity), a distributor will request authorization for pricing allowances to reduce its price. When the Company approves such a reduction, the distributor is authorized to “debit” its account for the difference between the contracted price and the lower approved price. The Company establishes reserves for this program based on historic activity, distributor inventory levels and actual authorizations for the debit and recognizes these debits as a reduction of revenue.

Return to Stock

The Company has a return to stock policy whereby certain customers, with prior authorization from the Company's management, can return previously purchased goods for full or partial credit. The Company establishes an estimated allowance for these returns based on historic activity. Sales revenue and cost of sales are reduced to anticipate estimated returns.

Volume Rebates

The Company offers volume-based sales incentives to certain customers to encourage greater product sales. If customers achieve their specific quarterly or annual sales targets, they are entitled to rebates. The Company estimates the projected amount of rebates that will be achieved by the customer and recognizes this estimated cost as a reduction to revenue as products are sold.

Allowance for Credit Losses

The Company currently measures the expected credit losses based on our historical credit loss experience. The Company has not experienced significant recent or historical credit losses and is not forecasting any significant credit losses which would require adjustments to our methodology. If current conditions and supportable forecasts indicate that our historical loss experience is not reasonable and no longer supportable, the Company may adjust its historical credit loss experience and to reflect these conditions and forecasts. The Company regularly analyzes its significant customer accounts and, when the Company becomes aware of a customer’s inability to meet its financial obligations, the Company records a specific reserve for bad debt to reduce the related receivable to the amount the Company reasonably believes is collectible. The Company also analyzes all other customers based on a variety of factors including the length of time the receivables are past due, the financial health of the customer, macroeconomic considerations and historical collection and loss experience. Historically, the allowance for credit losses has been adequate to cover bad debts. If circumstances related to specific customers change, the estimates of the recoverability of receivables could be further adjusted.

Advertising Costs

The Company expenses advertising costs as incurred,

Shipping and Handling Fees and Costs

Amounts billed to customers related to shipping and handling are classified as revenue. Costs incurred for shipping and handling of $15.3 million, $15.4 million, and $13.9 million in fiscal years 2024, 2023, and 2022, respectively, are classified in selling, general, and administrative expenses.

Foreign Currency Translation / Remeasurement

The Company’s foreign subsidiaries use the local currency or the U.S. dollar as their functional currency, as appropriate. Assets and liabilities are translated using exchange rates at the balance sheet date, and revenues and expenses are translated at weighted average rates. Adjustments from the translation process are recognized in Shareholders’ equity as a component of Accumulated other comprehensive income (loss).

Stock-Based Compensation

The Company recognizes compensation expense for the cost of awards of equity compensation using a fair value method. Benefits of tax deductions in excess of recognized compensation expense are reported as operating cash flows. See Note 12, Stock-Based Compensation, for additional information on stock-based compensation.

Coal Mining Liability

Included in accrued liabilities is an accrual related to former coal mining operations at Littelfuse GmbH (formerly known as Heinrich Industries, AG) for the amounts of €2.2 million ($2.3 million) and €2.5 million ($2.7 million) at December 28, 2024 and December 30, 2023, respectively. Management, in conjunction with an independent third-party, performs an annual evaluation of the former coal mining operations in order to develop an estimate of the probable future obligations in regard to remediating the dangers (such as a shaft collapse) of abandoned coal mine shafts in the former coal mining operations. Management accrues for costs associated with such remediation efforts based on management's best estimate when such costs

are probable and reasonably able to be estimated. The ultimate determination can only be done after respective investigations because the concrete conditions are mostly unknown at this time.

Other (Income) Expense, Net

Other (income) expense, net generally consists of interest income, royalties, change in fair value of available-for-sale securities, pension non-service costs and settlements and other non-operating (income) expense.

Income Taxes

The Company accounts for income taxes using the asset and liability method. Deferred taxes are recognized for the future effects of temporary differences between financial and income tax reporting using enacted tax rates in effect for the years in which the differences are expected to reverse. The Company recognizes deferred taxes for temporary differences, operating loss carryforwards, and tax credit and other tax attribute carryforwards (excluding carryforwards where usage has been determined to be remote). Deferred tax assets are reduced by a valuation allowance if it is more likely than not that some portion, or all, of the deferred tax assets will not be realized. U.S. state and non-U.S. income taxes are provided on the portion of non-U.S. income that is expected to be remitted to the U.S. and be taxable (and non-U.S. income taxes are provided on the portion of non-U.S. income that is expected to be remitted to an upper-tier non-U.S. entity). Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment.

Deferred U.S. income taxes and non-U.S. taxes are not provided on the excess of the investment value for financial reporting over the tax basis of investments in those non-U.S. subsidiaries for which such excess is considered to be permanently reinvested in those operations. Management regularly evaluates whether non-U.S. earnings are expected to be permanently reinvested. This evaluation requires judgment about the future operating and liquidity needs of the Company and its non-U.S. subsidiaries. Changes in economic and business conditions, tax laws, or the Company’s financial situation could result in changes to these judgments and the need to record additional tax liabilities.

The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement.

The 2017 Tax Cuts and Jobs Act (the "Tax Act"), among other things, imposed a one-time tax (the “Toll Charge”) on accumulated earnings of certain non-U.S. subsidiaries and included base broadening provisions commonly referred to as the global intangible low-taxed income provisions ("GILTI").

The Company elected to pay the 2017 Littelfuse Toll Charge over the eight-year period prescribed by the Tax Act. The anticipated 2025 annual installment payment of this Toll Charge of $8.2 million, which represents the eighth and final required installment, is included in Accrued income taxes, on the Consolidated Balance Sheets as of December 28, 2024.

In accordance with guidance issued by the FASB staff, the Company has adopted an accounting policy to treat any GILTI inclusions as a period cost if and when incurred. Thus, for the fiscal years ended December 28, 2024, December 30, 2023, and December 31, 2022, deferred taxes were computed without consideration of the possible future impact of the GILTI provisions, and any current year impact was recorded as a part of the current portion of income tax expense.

Fair Value Measurements

Certain assets and liabilities are required to be recorded at fair value on a recurring basis. Fair value is determined based on the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants. The Company records the fair value of its available-for-sale securities and pension plan assets on a recurring basis. Assets measured at fair value on a nonrecurring basis include long-lived assets held and used, long-lived assets held for sale, goodwill, and other intangible assets. The fair value of cash and cash equivalents, short-term investments, accounts receivable, accounts payable, and accrued liabilities approximate their carrying values. The three-tier value hierarchy, which prioritizes valuation methodologies based on the reliability of the inputs, is:

Level 1 – Valuations based on unadjusted quoted prices for identical assets and liabilities in active markets.

Level 2 – Valuations based on observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data.

Level 3 – Valuations based on unobservable inputs reflecting the Company’s own assumptions, consistent with reasonably available assumptions made by other market participants.

Recently Issued and Adopted Accounting Standards

Recently Adopted Accounting Standards

In November 2023, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Updates ("ASU") No. 2023-07, "Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures." The amendments in this update require additional detailed and enhanced information about reportable segments' expense, including significant segment expenses and other segment items that bridge segment revenue, significant expenses to segment profit or loss. The ASU also requires disclosure of the title and position of the Chief Operating Decision Maker (“CODM”) on an annual basis as well as an explanation of how the CODM uses the reported measures and other disclosures. The amendments in this update do not change how a public entity identifies its operating segments, aggregates those operating segments, or applies the quantitative thresholds to determine its reportable segments. The guidance is effective for fiscal years beginning after December 15, 2023 and interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The adoption of ASU 2023-07 modified the Company's disclosures in its Consolidated Financial Statements. See Note 16, Segment Information, for more details.

In March 2023, the FASB issued ASU No. 2023-01, "Leases (Topic 842): Common Control Arrangements." The standard requires that leasehold improvements associated with common control leases be: 1) Amortized by the lessee over the useful life of the leasehold improvements to the common control group (regardless of the lease term) as long as the lessee controls the use of the underlying asset (the leased asset) through a lease. However, if the lessor obtained the right to control the use of the underlying asset through a lease with another entity not within the same common control group, the amortization period may not exceed the amortization period of the common control group. 2) Accounted for as a transfer between entities under common control through an adjustment to equity (or net assets for not-for-profit entities) if, and when, the lessee no longer controls the use of the underlying asset. Additionally, those leasehold improvements are subject to the impairment guidance in Topic 360, Property, Plant, and Equipment. This standard is effective for fiscal years beginning after December 15, 2023 including interim periods within those fiscal years. The adoption of ASU 2023-01 did not have a material impact on the Company's Consolidated Financial Statements.

Recently Issued Accounting Standards

In November 2024, the FASB issued ASU No. 2024-03, "Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40)." The amendments in this update require disclosure, in the notes to financial statements, of specified information about certain costs and expenses. The amendments require that at each interim and annual reporting period an entity (a) disclose the amounts of (i) purchases of inventory, (ii) employee compensation, (iii) depreciation, (iv) intangible asset amortization, and (v) depreciation, depletion, and amortization recognized as part of oil and gas producing activities ("DD&A") included in each relevant expense caption. A relevant expense caption is an expense caption presented on the face of the income statement within continuing operations that contains any of the expense categories listed in (i)–(v); (b) include certain amounts that are already required to be disclosed under current Generally Accepted Accounting Principles ("GAAP") in the same disclosure as the other disaggregation requirements; (c) disclose a qualitative description of the amounts remaining in relevant expense captions that are not separately disaggregated quantitatively; (d) disclose the total amount of selling expenses and, in annual reporting periods, an entity’s definition of selling expenses. The guidance is effective for fiscal years beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027, with early adoption permitted. The adoption of this guidance will increase the Company's disclosures in its Consolidated Financial Statements. The Company is currently evaluating the potential impact on the disclosures in the Company's Consolidated Financial Statements.

In December 2023, the FASB issued ASU No. 2023-09, "Income Taxes (Topic 740): Improvements to Income Tax Disclosures." The amendments in this update provide more transparency about income tax information through improvements to the income tax disclosure primarily related to the income tax rate reconciliation and income taxes paid information. These requirements include: (1) consistent categories and greater disaggregation of information in the rate reconciliation and (2) income taxes paid disaggregated by jurisdiction. The other amendments in this update improve the effectiveness and comparability of disclosures by (3) adding disclosures of pretax income (or loss) and income tax expense (or benefit), and (4) removing disclosures that are no longer considered cost beneficial or relevant. The guidance is effective for fiscal years beginning after December 15, 2024 with early adoption permitted. The adoption of this guidance will modify our disclosures in the Company's Consolidated Financial Statements.

In October 2023, the FASB issued ASU No. 2023-06, "Disclosure Improvements." The amendments in this update represent changes to clarify or improve the disclosure or presentation requirements of a variety of Topics in the ASC. The Company may be affected by one or more of those amendments. The amendments in this ASU should be applied prospectively and will not be effective until June 30, 2027. The Company is currently evaluating the potential effects of these amendments on its Consolidated Financial Statements.