XML 15 R1.htm IDEA: XBRL DOCUMENT v3.22.1
Cover Page - USD ($)
$ in Billions
 12 Months Ended
Mar. 25, 2022
May 06, 2022
Sep. 24, 2021
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Mar. 25, 2022    
Current Fiscal Year End Date --03-25    
Document Transition Report false    
Entity File Number 001-39675    
Entity Registrant Name ALLEGRO MICROSYSTEMS, INC.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 46-2405937    
Entity Address, Address Line One 955 Perimeter Road    
Entity Address, City or Town Manchester,    
Entity Address, State or Province NH    
Entity Address, Postal Zip Code 03103    
City Area Code 603    
Local Phone Number 626-2300    
Title of 12(b) Security Common Stock, par value $0.01 per share    
Trading Symbol ALGM    
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     $ 1.9
Entity Common Stock, Shares Outstanding (in shares)   190,500,630  
Documents Incorporated by Reference Portions of the registrant’s proxy statement for its 2022 Annual Meeting of Stockholders to be filed pursuant to Regulation 14A within 120 days of the end of the registrant’s fiscal year ended March 25, 2022 are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein.    
Entity Central Index Key 0000866291    
Amendment Flag false    
Document Fiscal Year Focus 2022    
Document Fiscal Period Focus FY