Note 5 - Segment Information (Tables)

3 Months Ended

Mar. 31, 2014

Segment Reporting [Abstract]

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

	Three Months Ended March 31,
Customer	2014			2013
A		26	%		34	%
B		10	%		*

Schedule of Accounts Receivable by Major Customers [Table Text Block]

Customer	March 31, 2014			December 31, 2013
A		24	%		32	%
B		16	%		17	%

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]

	Three Months Ended March 31,
Country and Region	2014		2013
China	$	36,859	$	26,779
Taiwan		9,064		7,519
Europe		4,591		3,950
Korea		2,736		2,418
United States		2,603		1,901
Japan		2,141		1,521
Southeast Asia		2,013		7,329
Other		54		53
Total	$	60,061	$	51,470

Revenue from External Customers by Products and Services [Table Text Block]

	Three Months Ended March 31,
Product Family	2014		2013
DC to DC products	$	53,935	$	46,442
Lighting control products		6,126		5,028
Total	$	60,061	$	51,470

Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]

Country	March 31, 2014		December 31, 2013
China	$	39,093	$	41,557
United States		31,753		24,719
Other		210		205
Total	$	71,056	$	66,481