Organization and Basis of Presentation	6 Months Ended
Jul. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Nature of Business Semtech Corporation (together with its consolidated subsidiaries, the "Company" or "Semtech") is a global supplier of high performance analog, mixed-signal semiconductors and advanced algorithms. The end-customers for the Company’s products are primarily original equipment manufacturers ("OEMs") that produce and sell electronics. The Company designs, develops and markets a wide range of products for commercial applications, the majority of which are sold into the enterprise computing, communications, high-end consumer and industrial end-markets. Enterprise Computing: datacenters, passive optical networks, desktops, notebooks, servers, monitors, printers and other computer peripherals. Communications: base stations, optical networks, carrier networks, switches and routers, cable modems, wireless LAN and other communication infrastructure equipment. High-End Consumer: handheld products, smartphones, wireless charging, set-top boxes, digital televisions, monitors and displays, tablets, digital video recorders and other consumer equipment. Industrial: analog and digital video broadcast equipment, automated meter reading, Internet of Things ("IoT"), smart grid, wireless charging, military and aerospace, medical, security systems, automotive, industrial and home automation and other industrial equipment. Fiscal Year The Company reports results on the basis of 52 and 53 week periods and ends its fiscal year on the last Sunday in January. The other quarters generally end on the last Sunday of April, July and October. All quarters consist of 13 weeks except for one 14-week period in the fourth quarter of 53-week years. The second quarter of fiscal years 2018 and 2017 each consisted of 13 weeks. Principles of Consolidation The accompanying interim unaudited consolidated financial statements have been prepared by the Company, in accordance with accounting principles generally accepted in the United States ("GAAP") and on the same basis as the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended January 29, 2017. In the opinion of the Company, these interim unaudited consolidated financial statements contain all adjustments (consisting of normal recurring adjustments) necessary to present fairly, in all material respects, the financial position of the Company for the interim periods presented. All intercompany balances have been eliminated. Certain information and footnote disclosures normally included in annual consolidated financial statements have been condensed or omitted pursuant to the rules and regulations of the U.S. Securities and Exchange Commission. Because the interim unaudited consolidated financial statements do not include all of the information and notes required by GAAP for a complete set of consolidated financial statements, they should be read in conjunction with the audited consolidated financial statements and notes included in the Company's Annual Report on Form 10-K for the year ended January 29, 2017. The results reported in these interim unaudited consolidated financial statements should not be regarded as indicative of results that may be expected for any subsequent period or for the entire year. The Company’s interim unaudited consolidated statements of income are referred to herein as the "Statements of Income." The Company’s interim unaudited consolidated balance sheets are referred to herein as the "Balance Sheets" and interim unaudited consolidated statements of cash flows as the "Statements of Cash Flows." Segment Information The Company’s Chief Executive Officer ("CEO") has been identified as the Chief Operating Decision Maker ("CODM") as defined by guidance regarding segment disclosures (see Note 14 for further discussion). In fiscal year 2016, the Company identified five operating segments in total. Four of the operating segments aggregated into one reportable segment, the Semiconductor Products Group. The remaining operating segment, the Systems Innovation Group (shown as "All others"), could not be aggregated with the other operating segments and did not meet the criteria for a separate reportable segment as defined by the guidance regarding segment disclosure. As a result, the financial activity associated with the Systems Innovation Group was reported separately from the Company’s Semiconductor Products Group. This separate reporting was included in the "All others" category. On August 5, 2016, the Company completed its divestiture of its Snowbush Intellectual Property ("Snowbush IP") business (previously part of the Company’s Systems Innovation Group) to Rambus Inc. ("Rambus") for a purchase price of $32.0 million in cash along with the opportunity to receive additional payments from Rambus through 2022 based upon a percentage of sales by Rambus of new products expected to be developed by Rambus from the disposed assets. Therefore, as of January 29, 2017, the Company no longer has a Systems Innovation Group or an "All others" category, resulting in four operating segments that aggregate into one reportable segment, the Semiconductor Products Group. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Recent Accounting Pronouncements Recently Adopted Accounting Guidance In the first quarter of fiscal year 2018, the Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Update ("ASU") No. 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718). Under the amended guidance, all excess tax benefits and tax deficiencies will be recognized in the Statements of Income as they occur. This replaced the previous guidance, which required tax benefits that exceed compensation cost ("windfalls") to be recognized in additional paid in capital. It also eliminates the need to maintain a windfall pool, and removes the requirement to delay recognizing a windfall until it reduces current taxes payable. Using the modified retrospective adoption method, in the first quarter of fiscal year 2018, the Company recognized deferred tax assets of $8.4 million for the windfall tax benefits and also recognized an increase of an equal amount in the valuation allowance against those deferred tax assets. Under the amended guidance, companies can make an accounting policy election to either continue to estimate forfeitures or account for forfeitures as they occur. Upon adoption, the Company elected to account for forfeitures when they occur, on a modified retrospective basis. In the first quarter of fiscal year 2018, a cumulative effect adjustment of $2.0 million was recorded to retained earnings. The amended guidance also changed the Statements of Cash Flow presentation of excess tax benefits, classifying them as operating activities instead of financing activities, consistent with other cash flows related to income taxes. Further, following the adoption of this updated guidance, there will be additional dilutive effects in earnings per share calculations because excess tax benefits are no longer recognized in additional paid in capital. Due to the valuation allowance maintained against the Company’s deferred tax assets, the adoption of this updated guidance did not have a material impact on the Company’s consolidated financial statements. Accounting Guidance Issued but Not Adopted as of July 30, 2017 In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815). This standard addresses narrow issues identified as a result of the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity. Part I addresses the complexity of accounting for certain financial instruments with down round features. Part II addresses the difficulty of navigating Topic 480, Distinguishing Liabilities from Equity, because of the existence of pending content in the Accounting Standards Codification ("ASC") that results from the indefinite deferral of accounting requirements concerning mandatorily redeemable financial instruments of certain non-public entities and certain mandatorily redeemable non-controlling interests. The Company does not expect the adoption of this pronouncement to have a material impact on the Company’s consolidated financial statements. In March 2017, the FASB issued ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715). This standard amends the Statements of Income presentation of the components of net periodic benefit cost for defined benefit pension and other post retirement plans. This standard requires companies to: (1) disaggregate the current service cost component from the other components of net periodic benefit cost (the "other components") and present it in the same line items on the Statements of Income as other current compensation costs for related employees and (2) present the other components outside of operating profit. This standard is required to be applied retrospectively and is effective for annual and interim periods beginning after December 15, 2017. The Company does not expect the adoption of this pronouncement to have a material impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350). The pronouncement was issued to simplify the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. This pronouncement stipulates that an entity should perform a goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and will recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, with the loss recognized not exceeding the total amount of goodwill allocated to that reporting unit. The amendments in this pronouncement are to be applied on a prospective basis. This guidance will be effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019, with early adoption permitted for interim or annual goodwill impairment tests performed on testing dates after January 31, 2017. The adoption of this pronouncement is not expected to have a material impact on the Company’s consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805). This standard clarifies the definition of a business to assist entities with evaluating when a set of assets acquired or disposed of should be considered a business. The new standard requires an entity to evaluate if substantially all the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets; if so, the set would not be considered a business. The new standard also requires a business to include at least one substantive process and narrows the definition of outputs. The new standard is effective for interim and annual periods beginning after December 15, 2017, and may be adopted earlier. The standard would be applied prospectively to any transaction occurring on or after the adoption date. The impact of this standard will be dependent upon the specific facts and circumstances of any applicable future acquisitions or dispositions. In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Asset Transfers Other Than Inventory (Topic 740). This accounting standard update is aimed at recognizing the income tax consequences of intra-entity transfers of assets other than inventory when they occur. This removes the exception to postpone recognition until the asset has been sold to an outside party. This ASU will be effective in the first quarter of fiscal year 2020. The standard update is required to be applied on a modified retrospective basis through a cumulative-effect adjustment to the Balance Sheet as of the beginning of the fiscal year of adoption. The Company is currently assessing the impact this pronouncement will have on its consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments (Topic 230). The primary purpose of this ASU is to reduce the diversity in practice that has resulted from the lack of consistent principles on this topic. This ASU is effective for fiscal years beginning after December 15, 2017. This ASU will be effective for the Company as of the beginning of fiscal year 2019. Early adoption is permitted in any interim or annual period. The Company is continuing to assess the overall impacts of the new standard. The Company does not expect the adoption of this pronouncement to have a material impact on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will require that substantially all leases be recognized by lessees on their Balance Sheets as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. The new standard also will result in enhanced quantitative and qualitative disclosures, including descriptions of significant judgments made by management, to provide greater insight into the extent of expense recognized and expected to be recognized from existing leases. The standard requires modified retrospective adoption and will be effective for the Company as of the beginning of fiscal year 2020. The Company expects the valuation of right of use assets and lease liabilities, previously described as operating leases, to be the present value of the Company's forecasted future lease commitments. The Company is continuing to assess the overall impacts of the new standard, including the discount rate to be applied in these valuations. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which will require an entity to recognize revenue from the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance addresses, in particular, contracts with more than one performance obligation, as well as the accounting for some costs to obtain or fulfill a contract with a customer, and provides for additional disclosures with respect to revenues and cash flows arising from contracts with customers. Public entities are required to apply the amendments on either a full- or modified-retrospective basis for annual periods beginning after December 15, 2017 and for interim periods within those annual periods. This update will be effective for the Company beginning in the first quarter of fiscal year 2019. The Company plans to adopt the standard retrospectively with the cumulative effect of initially applying it recognized at the date of initial application ("modified retrospective" approach). The Company’s assessment has identified a change in revenue recognition timing on the Company's component sales made to certain distributors where revenues are currently deferred and not recognized until the distributor sells the components to the distributor’s customers. The Company expects to recognize revenue when the Company delivers or "sells into" the distributor rather than deferring recognition until the distributor sells the components or "sells through" to the end customer. On the date of initial application, the Company will remove the deferred net revenue on component sales made to certain distributors through a cumulative adjustment to retained earnings. The Company expects the revenue deferral to be offset by the acceleration of revenue recognition as control of the product transfers to its customer. As the Company continues its assessment, it is also identifying and preparing to implement changes to accounting policies, business processes and internal controls to support the new accounting and disclosure requirements.

Organization and Basis of Presentation

Nature of Business

Semtech Corporation (together with its consolidated subsidiaries, the "Company" or "Semtech") is a global supplier of high performance analog, mixed-signal semiconductors and advanced algorithms. The end-customers for the Company’s products are primarily original equipment manufacturers ("OEMs") that produce and sell electronics.

The Company designs, develops and markets a wide range of products for commercial applications, the majority of which are sold into the enterprise computing, communications, high-end consumer and industrial end-markets.

Enterprise Computing: datacenters, passive optical networks, desktops, notebooks, servers, monitors, printers and other computer peripherals.

Communications: base stations, optical networks, carrier networks, switches and routers, cable modems, wireless LAN and other communication infrastructure equipment.

High-End Consumer: handheld products, smartphones, wireless charging, set-top boxes, digital televisions, monitors and displays, tablets, digital video recorders and other consumer equipment.

Industrial: analog and digital video broadcast equipment, automated meter reading, Internet of Things ("IoT"), smart grid, wireless charging, military and aerospace, medical, security systems, automotive, industrial and home automation and other industrial equipment.

Fiscal Year

The Company reports results on the basis of 52 and 53 week periods and ends its fiscal year on the last Sunday in January. The other quarters generally end on the last Sunday of April, July and October. All quarters consist of 13 weeks except for one 14-week period in the fourth quarter of 53-week years. The second quarter of fiscal years 2018 and 2017 each consisted of 13 weeks.

Principles of Consolidation

The accompanying interim unaudited consolidated financial statements have been prepared by the Company, in accordance with accounting principles generally accepted in the United States ("GAAP") and on the same basis as the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended January 29, 2017. In the opinion of the Company, these interim unaudited consolidated financial statements contain all adjustments (consisting of normal recurring adjustments) necessary to present fairly, in all material respects, the financial position of the Company for the interim periods presented. All intercompany balances have been eliminated. Certain information and footnote disclosures normally included in annual consolidated financial statements have been condensed or omitted pursuant to the rules and regulations of the U.S. Securities and Exchange Commission. Because the interim unaudited consolidated financial statements do not include all of the information and notes required by GAAP for a complete set of consolidated financial statements, they should be read in conjunction with the audited consolidated financial statements and notes included in the Company's Annual Report on Form 10-K for the year ended January 29, 2017. The results reported in these interim unaudited consolidated financial statements should not be regarded as indicative of results that may be expected for any subsequent period or for the entire year.

The Company’s interim unaudited consolidated statements of income are referred to herein as the "Statements of Income." The Company’s interim unaudited consolidated balance sheets are referred to herein as the "Balance Sheets" and interim unaudited consolidated statements of cash flows as the "Statements of Cash Flows."

Segment Information

The Company’s Chief Executive Officer ("CEO") has been identified as the Chief Operating Decision Maker ("CODM") as defined by guidance regarding segment disclosures (see Note 14 for further discussion). In fiscal year 2016, the Company identified five operating segments in total. Four of the operating segments aggregated into one reportable segment, the Semiconductor Products Group. The remaining operating segment, the Systems Innovation Group (shown as "All others"), could not be aggregated with the other operating segments and did not meet the criteria for a separate reportable segment as defined by the guidance regarding segment disclosure. As a result, the financial activity associated with the Systems Innovation Group was reported separately from the Company’s Semiconductor Products Group. This separate reporting was included in the "All others" category. On August 5, 2016, the Company completed its divestiture of its Snowbush Intellectual Property ("Snowbush IP") business (previously part of the Company’s Systems Innovation Group) to Rambus Inc. ("Rambus") for a purchase price of $32.0 million in cash along with the opportunity to receive additional payments from Rambus through 2022 based upon a percentage of sales by Rambus of new products expected to be developed by Rambus from the disposed assets. Therefore, as of January 29, 2017, the Company no longer has a Systems Innovation Group or an "All others" category, resulting in four operating segments that aggregate into one reportable segment, the Semiconductor Products Group.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Recent Accounting Pronouncements

Recently Adopted Accounting Guidance

In the first quarter of fiscal year 2018, the Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Update ("ASU") No. 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718). Under the amended guidance, all excess tax benefits and tax deficiencies will be recognized in the Statements of Income as they occur. This replaced the previous guidance, which required tax benefits that exceed compensation cost ("windfalls") to be recognized in additional paid in capital. It also eliminates the need to maintain a windfall pool, and removes the requirement to delay recognizing a windfall until it reduces current taxes payable. Using the modified retrospective adoption method, in the first quarter of fiscal year 2018, the Company recognized deferred tax assets of $8.4 million for the windfall tax benefits and also recognized an increase of an equal amount in the valuation allowance against those deferred tax assets. Under the amended guidance, companies can make an accounting policy election to either continue to estimate forfeitures or account for forfeitures as they occur. Upon adoption, the Company elected to account for forfeitures when they occur, on a modified retrospective basis. In the first quarter of fiscal year 2018, a cumulative effect adjustment of $2.0 million was recorded to retained earnings. The amended guidance also changed the Statements of Cash Flow presentation of excess tax benefits, classifying them as operating activities instead of financing activities, consistent with other cash flows related to income taxes. Further, following the adoption of this updated guidance, there will be additional dilutive effects in earnings per share calculations because excess tax benefits are no longer recognized in additional paid in capital. Due to the valuation allowance maintained against the Company’s deferred tax assets, the adoption of this updated guidance did not have a material impact on the Company’s consolidated financial statements.

Accounting Guidance Issued but Not Adopted as of July 30, 2017

In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815). This standard addresses narrow issues identified as a result of the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity. Part I addresses the complexity of accounting for certain financial instruments with down round features. Part II addresses the difficulty of navigating Topic 480, Distinguishing Liabilities from Equity, because of the existence of pending content in the Accounting Standards Codification ("ASC") that results from the indefinite deferral of accounting requirements concerning mandatorily redeemable financial instruments of certain non-public entities and certain mandatorily redeemable non-controlling interests. The Company does not expect the adoption of this pronouncement to have a material impact on the Company’s consolidated financial statements.

In March 2017, the FASB issued ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715). This standard amends the Statements of Income presentation of the components of net periodic benefit cost for defined benefit pension and other post retirement plans. This standard requires companies to: (1) disaggregate the current service cost component from the other components of net periodic benefit cost (the "other components") and present it in the same line items on the Statements of Income as other current compensation costs for related employees and (2) present the other components outside of operating profit. This standard is required to be applied retrospectively and is effective for annual and interim periods beginning after December 15, 2017. The Company does not expect the adoption of this pronouncement to have a material impact on the Company’s consolidated financial statements.

In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350). The pronouncement was issued to simplify the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. This pronouncement stipulates that an entity should perform a goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount, and will recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, with the loss recognized not exceeding the total amount of goodwill allocated to that reporting unit. The amendments in this pronouncement are to be applied on a prospective basis. This guidance will be effective for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019, with early adoption permitted for interim or annual goodwill impairment tests performed on testing dates after January 31, 2017. The adoption of this pronouncement is not expected to have a material impact on the Company’s consolidated financial statements.

In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805). This standard clarifies the definition of a business to assist entities with evaluating when a set of assets acquired or disposed of should be considered a business. The new standard requires an entity to evaluate if substantially all the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets; if so, the set would not be considered a business. The new standard also requires a business to include at least one substantive process and narrows the definition of outputs. The new standard is effective for interim and annual periods beginning after December 15, 2017, and may be adopted earlier. The standard would be applied prospectively to any transaction occurring on or after the adoption date. The impact of this standard will be dependent upon the specific facts and circumstances of any applicable future acquisitions or dispositions.

In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Asset Transfers Other Than Inventory (Topic 740). This accounting standard update is aimed at recognizing the income tax consequences of intra-entity transfers of assets other than inventory when they occur. This removes the exception to postpone recognition until the asset has been sold to an outside party. This ASU will be effective in the first quarter of fiscal year 2020. The standard update is required to be applied on a modified retrospective basis through a cumulative-effect adjustment to the Balance Sheet as of the beginning of the fiscal year of adoption. The Company is currently assessing the impact this pronouncement will have on its consolidated financial statements.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments (Topic 230). The primary purpose of this ASU is to reduce the diversity in practice that has resulted from the lack of consistent principles on this topic. This ASU is effective for fiscal years beginning after December 15, 2017. This ASU will be effective for the Company as of the beginning of fiscal year 2019. Early adoption is permitted in any interim or annual period. The Company is continuing to assess the overall impacts of the new standard. The Company does not expect the adoption of this pronouncement to have a material impact on its consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which will require that substantially all leases be recognized by lessees on their Balance Sheets as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. The new standard also will result in enhanced quantitative and qualitative disclosures, including descriptions of significant judgments made by management, to provide greater insight into the extent of expense recognized and expected to be recognized from existing leases. The standard requires modified retrospective adoption and will be effective for the Company as of the beginning of fiscal year 2020. The Company expects the valuation of right of use assets and lease liabilities, previously described as operating leases, to be the present value of the Company's forecasted future lease commitments. The Company is continuing to assess the overall impacts of the new standard, including the discount rate to be applied in these valuations.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which will require an entity to recognize revenue from the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance addresses, in particular, contracts with more than one performance obligation, as well as the accounting for some costs to obtain or fulfill a contract with a customer, and provides for additional disclosures with respect to revenues and cash flows arising from contracts with customers. Public entities are required to apply the amendments on either a full- or modified-retrospective basis for annual periods beginning after December 15, 2017 and for interim periods within those annual periods. This update will be effective for the Company beginning in the first quarter of fiscal year 2019. The Company plans to adopt the standard retrospectively with the cumulative effect of initially applying it recognized at the date of initial application ("modified retrospective" approach).

The Company’s assessment has identified a change in revenue recognition timing on the Company's component sales made to certain distributors where revenues are currently deferred and not recognized until the distributor sells the components to the distributor’s customers. The Company expects to recognize revenue when the Company delivers or "sells into" the distributor rather than deferring recognition until the distributor sells the components or "sells through" to the end customer.

On the date of initial application, the Company will remove the deferred net revenue on component sales made to certain distributors through a cumulative adjustment to retained earnings. The Company expects the revenue deferral to be offset by the acceleration of revenue recognition as control of the product transfers to its customer.

As the Company continues its assessment, it is also identifying and preparing to implement changes to accounting policies, business processes and internal controls to support the new accounting and disclosure requirements.