Note 7 - Segment and Geographic Information (Tables)

6 Months Ended

Jun. 30, 2018

Notes Tables

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

	Revenue												Accounts Receivable
	Three Months Ended June 30,						Six Months Ended June 30,						June 30,			December 31,
Customer	2018			2017			2018			2017			2018			2017
A (distributor)		20	%		17	%		20	%		17	%		19	%		16	%
B (distributor)		10	%		*			10	%		*			15	%		*
C (value-added reseller)		*			*			*			*			*			15	%

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

	Three Months Ended June 30,				Six Months Ended June 30,
Country or Region	2018		2017		2018		2017
China	$	81,207	$	62,325	$	154,072	$	118,409
Taiwan		18,150		17,286		34,541		32,161
Europe		12,651		9,593		24,116		17,501
Korea		8,853		8,154		18,640		16,315
Southeast Asia		7,977		6,925		17,002		13,297
Japan		6,486		4,945		12,100		9,771
United States		4,274		2,888		8,029		4,930
Other		163		82		411		176
Total	$	139,761	$	112,198	$	268,911	$	212,560

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

	Three Months Ended June 30,				Six Months Ended June 30,
Product Family	2018		2017		2018		2017
DC to DC	$	127,496	$	102,187	$	246,765	$	193,611
Lighting Control		12,265		10,011		22,146		18,949
Total	$	139,761	$	112,198	$	268,911	$	212,560

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

	June 30,		December 31,
Country	2018		2017
China	$	95,152	$	89,472
United States		67,116		65,618
Taiwan		16,879		17,238
Bermuda		7,075		7,522
Other		736		388
Total	$	186,958	$	180,238