COMMITMENTS - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Total outstanding purchase obligation	$ 1,600
Total rent expense, net of sublease income	866	$ 834	$ 878
Wafer purchase commitment
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Outstanding commitment for purchase of wafer inventory	$ 1,100	$ 1,600
Minimum
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Capital leases, term	2 years
Maximum
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Capital leases, term	3 years