Note 1 Description of Business	12 Months Ended
Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations [Text Block]	1. Description of Business We design, develop, manufacture and market power semiconductors, digital and analog integrated circuits, or ICs, and systems and radio frequency, or RF, power semiconductors. Power semiconductors are used primarily in controlling energy in motor drives, power conversion including uninterruptible power supplies, or UPS, and switch mode power supplies, or SMPS, and medical electronics. Our power semiconductors convert electricity at relatively high voltage and current levels to create efficient power as required by a specific application. Our target market includes segments of the power semiconductor market that require medium to high power semiconductors, with a particular emphasis on high power semiconductors. Our power semiconductors include power metal-oxide-silicon field-effect transistors, or Power MOSFETs, insulated-gate bipolar transistors, or IGBTs, thyristors and rectifiers, including fast-recovery epitaxial diodes, or FREDs. Our ICs include solid state relays, or SSRs, for telecommunications applications and power management and control ICs, such as current regulators, motion controllers, digital power modulators and drivers, and microcontrollers such as embedded flash microcontrollers and 8-bit microcontrollers. Our systems include laser diode drivers, high voltage pulse generators and modulators, and high power subsystems, sometimes know as stacks, that are principally based on our high power semiconductor devices. We sell products in North America, Europe and Asia through an organization that includes direct sales personnel, independent representatives and distributors. We are headquartered in Northern California with principal operations in California, Massachusetts, Germany, the Philippines and the United Kingdom. Each site has manufacturing, research and development and sales and distribution activities. We also make use of subcontract manufacturers for fabrication of wafers and for assembly and test operations.

Note 1 Description of Business

12 Months Ended

Mar. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

1. Description of Business

We design, develop, manufacture and market power semiconductors, digital and analog integrated circuits, or ICs, and systems and radio frequency, or RF, power semiconductors.

Power semiconductors are used primarily in controlling energy in motor drives, power conversion including uninterruptible power supplies, or UPS, and switch mode power supplies, or SMPS, and medical electronics. Our power semiconductors convert electricity at relatively high voltage and current levels to create efficient power as required by a specific application. Our target market includes segments of the power semiconductor market that require medium to high power semiconductors, with a particular emphasis on high power semiconductors. Our power semiconductors include power metal-oxide-silicon field-effect transistors, or Power MOSFETs, insulated-gate bipolar transistors, or IGBTs, thyristors and rectifiers, including fast-recovery epitaxial diodes, or FREDs. Our ICs include solid state relays, or SSRs, for telecommunications applications and power management and control ICs, such as current regulators, motion controllers, digital power modulators and drivers, and microcontrollers such as embedded flash microcontrollers and 8-bit microcontrollers. Our systems include laser diode drivers, high voltage pulse generators and modulators, and high power subsystems, sometimes know as stacks, that are principally based on our high power semiconductor devices.

We sell products in North America, Europe and Asia through an organization that includes direct sales personnel, independent representatives and distributors. We are headquartered in Northern California with principal operations in California, Massachusetts, Germany, the Philippines and the United Kingdom. Each site has manufacturing, research and development and sales and distribution activities. We also make use of subcontract manufacturers for fabrication of wafers and for assembly and test operations.