Switching power supplies have been spreading rapidly because they have the advantage of small size, light weight, and high efficiency.Technical Innovation has been remarkable in this size reduction, particularly in high frequency application to switching frequency that is key technology for size reduction. With future progress in size, weight, and efficiency, further extension of the switching power supply market can be expected.

Power supply controller ICs demand high quality and reliability. Fuji Electric has developed bipolar and Bi-CMOS processes to meet the requirements of these ICs. This paper outlines the bipolar and Bi-CMOS processes and introduces element devices applied in power supply controller ICs.

Switching power supplies are now used in various devices and its technology is making steady progress. Controller ICs (integrated circuits) are also changing to new generation ones following their trend. Fuji Electric is developing series of control ICs for switching power supplies to cope with the situation.
This paper outlines the trend of circuit technology and Fuji Electric's lineup of controller ICs and typical examples.

The requirement of electronic systems for smaller size and lower power consumption has pushed the mounted DC-DC converters to reduce peripheral components, apply high frequency and use MOSFET construction.
To meet this requirement, Fuji Electric has developed series of controller ICs (integrated circuits) matching each circuit system. This paper outlines ICs for bipolar transistor drive and MOSFET drive, citing examples of application circuits.

It is essential for portable telephones using batteries for power supply to reduce power consumption other than for function circuits required during waiting periods.
Fuji Electric has developed a power supply integrated circuit for portable telephones that can cut off the output of a series regulator provided in each function circuit and reduce its internal power consumption.

There has been an increasing demand for power factor correction in electronic systems using commercial power supply. An active filter circuit making a practical application of switching power supply technology attracts attention as a countermeasure. To cope with the situation, Fuji Electric has developed an integrated circuit (IC) for active filter controllers.
This paper outlines a method of designing a converter circuit used for active filters,
Its controller IC and application.

As portable electronic equipment became popular, switching power supplies have come into wide use for the source owing to the advantage of small size and high efficiency. Most of the portable equipment selects one of two modes, that is, either commercial AC for office and indoor use or DC for car and outdoor use. To meet such switching power supplies using two input modes, Fuji Electric has developed power hybrid ICs in which a MOSFET is used for the main switching element and the DC-side switching power supply incorporates a reverse-current protecting function against AC power supply.

Since an air bag system used for vehicles aims to protect people in them, a DC-DC converter used in the system is regarded as a most important component and required to be highly reliable. Further, to make the system small and highly functional, a DC-DC converter is also required to be small and have high efficiency. This paper introduces Fuji Electric's newly developed, small size, high efficiency, high reliability DC-DC converter for air bag systems.

Fuji Electric has developed a power IC on which a power MOSFET with blocking voltage of 650V and current of 2A and a control and protective circuit. The IC incorporates a overcurrent protection and thermal shutdown circuit and a pre-regulator circuit and can realize reduction in size, improvement in reliability, and simplification in power supply design for 100-240V AC switching power supplies. The IC is based on a standard CMOS process and the power MOSFET has a construction of our own reconciling high blocking voltage and low on-resistance. The bipolar transistor and CMOS also integrated on a chip make up a precisely controlled analog circuit.

Remarkable technical progress in IC packaging is going on toward diversification and sophistication.
This paper outlines the technical progress and various technologies of Fuji Electric's IC packaging, including low thermal resistance packages, transparent molding packages, and tape carrier packages.
Also it refers to bump technology which is one of Fuji Electric's characteristic IC technologies.

This paper outlines Fuji Electric's quality assurance activities dividing them into the stages of new product development, preparation for production, production, and delivery, and describes the following three items to which priority is given now:
(1)Planning a fault analysis method for power supply ICs and grasping the mechanism of faults,
(2)Completing design inspection, and
(3)Completing application service.

As working environments for switching power supplies became severer year after year, MOSFETs as main switching devices have been in still severer working conditions. Therefore, high Avalanche ruggedness against destruction is indispensable to MOSFETs. Fuji Electric has developed a power a MOSFET with high Avalanche ruggedness meeting the requirement, which is outlined in this paper.

With the rapid diffusion and development of electronic systems, switching power supplies have demanded smaller size, higher efficiency, and lower cost. Currently, power factor improvement is taken up, and active filter circuit application is under technical investigation.
To meet the market needs, in addition to the former low loss fast diode(LLD) series, Fuji Electric has developed new 600V LLD with reverse recovery time(t_rr) of 50ns and VF of 1.5V which greatly improved the former fast diode characteristics. This paper outlines the new diode.