Note 13 - Segment Information (Tables)

12 Months Ended

Dec. 31, 2013

Segment Reporting [Abstract]

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

	Year Ended December 31,
Country and Region	2013		2012		2011
China	$	141,400	$	124,278	$	113,469
Taiwan		34,248		27,477		23,634
Southeast Asia		21,760		21,641		14,789
Europe		15,351		16,201		14,416
Korea		9,992		9,434		14,183
United States		7,525		5,711		4,422
Japan		7,495		8,516		10,681
Other		320		555		925
Total	$	238,091	$	213,813	$	196,519

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

	Year Ended December 31,
Product Family	2013		2012			2011*
DC to DC products	$	211,337	$	188,736	$	170,032
Lighting control products		26,754		25,077		26,487
Total	$	238,091	$	213,813	$	196,519

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

	As of December 31,
	2013		2012
China	$	41,557	$	37,071
United States		24,719		23,163
Other		205		202
Total	$	66,481	$	60,436