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

3 Months Ended

Mar. 31, 2020

Notes Tables

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

	Revenue						Accounts Receivable
	Three Months Ended March 31,						March 31,			December 31,
Customer	2020			2019			2020			2019
Distributor A		23	%		23	%		28	%		24	%
Distributor B		*			*			13	%		11	%
Value-added reseller A		*			*			16	%		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	2020		2019
China	$	105,737	$	76,198
Taiwan		16,540		21,347
Europe		13,072		12,984
South Korea		10,944		9,611
Southeast Asia		8,780		8,672
Japan		6,890		6,642
United States		3,737		5,806
Other		78		103
Total	$	165,778	$	141,363

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

	Three Months Ended March 31,
Product Family	2020		2019
DC to DC	$	156,875	$	132,711
Lighting Control		8,903		8,652
Total	$	165,778	$	141,363

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

	March 31,		December 31,
Country	2020		2019
China	$	119,904	$	113,888
United States		96,982		94,671
Taiwan		17,341		17,652
Other		2,580		2,104
Total	$	236,807	$	228,315