Special Charges (Details) (USD $)	3 Months Ended				9 Months Ended	12 Months Ended			3 Months Ended	12 Months Ended	3 Months Ended					12 Months Ended			3 Months Ended		12 Months Ended	3 Months Ended						12 Months Ended
	Jul. 30, 2011	Apr. 30, 2011	Jan. 29, 2011	Jan. 30, 2010	Jul. 31, 2010	Oct. 30, 2010	Oct. 31, 2009	Nov. 01, 2008	Jan. 30, 2010 Closure of Wafer Fabrication Facility in Sunnyvale [Member]	Oct. 30, 2010 Closure of Wafer Fabrication Facility in Sunnyvale [Member]	Jul. 30, 2011 Reduction of Operating Costs [Member]	Apr. 30, 2011 Reduction of Operating Costs [Member]	Jan. 29, 2011 Reduction of Operating Costs [Member]	Jan. 30, 2010 Reduction of Operating Costs [Member]	Jan. 31, 2009 Reduction of Operating Costs [Member]	Oct. 30, 2010 Reduction of Operating Costs [Member]	Oct. 31, 2009 Reduction of Operating Costs [Member]	Nov. 01, 2008 Reduction of Operating Costs [Member]	Nov. 01, 2008 Reduction of operating costs, Severance and fringe benefit costs, foreign locations for 19 engineering, and selling, marketing, general and administrative (SMG&A) employees [Member] NumberOfEmployees	Jan. 30, 2010 Reduction of operating costs, Severance and fringe benefit costs, foreign locations for 149 engineering and SMG&A employees [Member] NumberOfEmployees	Oct. 31, 2009 Reduction of operating costs, Severance and fringe benefit costs, foreign locations for 245 manufacturing employees and 302 engineering and SMG&A employees [Member] NumberOfEmployees	Jul. 30, 2011 Closure of a Wafer Fabrication Facility in Cambridge [Member]	Apr. 30, 2011 Closure of a Wafer Fabrication Facility in Cambridge [Member]	Jan. 29, 2011 Closure of a Wafer Fabrication Facility in Cambridge [Member]	Jan. 30, 2010 Closure of a Wafer Fabrication Facility in Cambridge [Member]	Oct. 31, 2009 Closure of a Wafer Fabrication Facility in Cambridge [Member] NumberOfEmployees	Jan. 31, 2009 Closure of a Wafer Fabrication Facility in Cambridge [Member] NumberOfEmployees	Oct. 30, 2010 Closure of a Wafer Fabrication Facility in Cambridge [Member]	Oct. 31, 2009 Closure of a Wafer Fabrication Facility in Cambridge [Member]
Summary of the Company's special charges, Income Statement
Workforce reductions						$ 10,908,000	$ 34,029,000	$ 1,627,000								$ 10,908,000	$ 26,583,000	$ 1,627,000	$ 1,600,000	$ 10,900,000	$ 26,600,000						$ 9,200,000		$ 7,446,000
Facility closure costs						5,064,000	2,468,000			375,000					2,100,000		2,411,000											4,689,000	57,000
Non-cash impairment charge						487,000	15,468,000									487,000	839,000												14,629,000
Other items						24,000	500,000									24,000	500,000
Total Fiscal Charges					16,483,000	16,483,000	52,465,000	1,627,000		375,000				11,400,000		11,419,000	30,333,000	1,627,000							4,700,000		22,100,000	4,689,000	22,132,000
Summary of the Company's special charges and accruals related to ongoing actions, Balance Sheet
Accruals related to ongoing actions, balance	3,345,000	5,182,000	7,509,000								2,969,000	4,236,000	5,546,000									376,000	946,000	1,963,000
Severance payments	(844,000)	(1,808,000)	(1,757,000)								(468,000)	(1,288,000)	(1,300,000)									(376,000)	(520,000)	(457,000)
Facility closure costs		(50,000)	(560,000)																				(50,000)	(560,000)
Effect of foreign currency on accrual	(4,000)	21,000	(10,000)								(4,000)	21,000	(10,000)
Accruals related to ongoing actions, balance	2,497,000	3,345,000	5,182,000			7,509,000					2,497,000	2,969,000	4,236,000			5,546,000						0	376,000	946,000				1,963,000
Special Charges (Textuals) [Abstract]
Charge related to lease obligation costs for facilities ceased using by Company									400,000																3,400,000
Write-off of property, plant and equipment no longer used																	800,000									1,700,000
Contract termination costs																	500,000
Clean-up and closure costs that were expensed as incurred																	300,000								1,300,000
Number of manufacturing employees																					245						175
Additional charge related cost reduction					16,483,000	16,483,000	52,465,000	1,627,000		375,000				11,400,000		11,419,000	30,333,000	1,627,000							4,700,000		22,100,000	4,689,000	22,132,000
Impairment of intellectual property, related to the Company's decision to abandon efforts to develop a particular expertise in power management				500,000
Number of engineering and SMGA (selling, marketing, general and administrative) employees																			19	149	302						9
Impairment charge of manufacturing assets																											12,900,000
Number of employees who voluntarily left the company or found alternative employment																										51
Special charge for clean-up cost																										100,000
Reversed amount of severance accrual																										$ 1,800,000