Note 7 - Segment, Significant Customers and Geographic Information (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

	Three Months Ended March 31,
Customer	2021			2020
Distributor A		26	%		23	%
Distributor B		16	%		*
Direct customer A		*			10	%

	March 31,			December 31,
Customer	2021			2020
Distributor A		25	%		24	%
Distributor B		18	%		21	%
Value-added reseller A		11	%		13	%
Direct customer A		*			10	%

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

	Three Months Ended March 31,
Country or Region	2021		2020
China	$	153,383	$	105,737
Taiwan		30,445		16,540
Europe		20,380		13,072
South Korea		19,287		10,944
Southeast Asia		11,497		8,780
Japan		12,049		6,890
United States		7,302		3,737
Other		112		78
Total	$	254,455	$	165,778

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

	Three Months Ended March 31,
Product Family	2021		2020
DC to DC	$	241,429	$	156,875
Lighting Control		13,026		8,903
Total	$	254,455	$	165,778

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

	March 31,		December 31,
Country	2021		2020
China	$	167,625	$	151,752
United States		101,891		101,768
Taiwan		18,435		18,797
Other		9,790		9,211
Total	$	297,741	$	281,528