Cover Page - USD ($) $ in Billions	12 Months Ended
	Jan. 30, 2022	Mar. 11, 2022	Aug. 01, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Current Fiscal Year End Date	--01-30
Document Transition Report	false
Entity File Number	001-06395
Entity Registrant Name	SEMTECH CORP
Entity Central Index Key	0000088941
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	95-2119684
Entity Address, Address Line One	200 Flynn Road
Entity Address, City or Town	Camarillo
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	93012-8790
City Area Code	805
Local Phone Number	498-2111
Title of 12(b) Security	Common Stock par value $0.01 per share
Trading Symbol	SMTC
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 3.1
Entity Common Stock, Shares Outstanding		64,106,315
Documents Incorporated by Reference	Portions of the registrant’s Proxy Statement in connection with registrant’s 2022 annual meeting of stockholders to be filed with the Securities and Exchange Commission no later than 120 days after the end of the registrant’s fiscal year ended January 30, 2022 are incorporated by reference into Part III hereof.
Document Period End Date	Jan. 30, 2022