Ikko Harada

Emergency power supply for small computer systems

A small size emergency power supply was investigated. This was realized by adopting a quick detector of momentary power failure and a compact DC-DC converter. The power failure detector has a novel type of T-V (time-voltage) conversion using an SC (switched capacitor) integrator and can detect power failures at its earliest stage. The DC-DC converter was constructed by an SC transformer in which the voltage of each stage increases according to the form of the Fibonacci sequence. The proposed power supply is supplied with power from chargeable batteries for several minutes, while the computer system saves important data to an auxiliary memory such as a disk and can complete its emergency quit operation. The circuit configurations, operations and experimental results are presented.<<ETX>>

Power supply for electroluminescence aiming integrated circuit

For promoting the application of electroluminescent (EL) devices, a thin-plate-typ DC-AC converter is required. For this purpose, a novel type of power supply that uses switched capacitor (SC) transformers is presented. This power supply generates on AC voltage of more than 100 V with several hundred hertz by using two types of SC transformers. This scheme has the following advantages: (1) it operates on a low battery voltage, (2) it realizes a very large transformer ratio, (3) it is capable of realization in an IC form as a thin plate type power supply that is capable of being unified onto the back of an EL device, and (4) it generates a sinusoidal voltage in a novel way by selection of voltages. The circuit configurations, operations, and basic experimental results are presented.<<ETX>>

Programmable ring type switched-capacitor DC-DC converters

New dc–dc converters are presented whose step-up and step-down ratio can be controlled easily by changing their external clocks. These converters consist of switched capacitors that form a ring connected by MOSFET switches (“ring-type SC”). The proposed circuits have the following features: (1) Their step-up and step-down ratios can be controlled programmably by changing the patterns of clocks because of their symmetry structure. (2) They can treat a wide input voltage range from low voltage to high voltage without changing their structures. (3) Various output voltages can be supplied by using DIP-switches or a computer control. (4) They can contribute to lower the costs of production, since they correspond to various input and output voltages with the same circuit. (5) A soft start circuit of the control apparatus can be easily realized. (6) They can be implemented in one-chip IC form together with other signal processing circuits such as a system-on-chip or a system integration including power supplies, since generation of a magnetic field is extremely low due to the coilless construction.

Multi-output SC type DC-DC converter using a flexible capacitor ring operation

By using a switched-capacitor technique, a multi-output DC-DC power converter is investigated. This is featured by the flexibility in the step-up/-down voltage conversion ratio by adopting a novel capacitor ring circuit. Its circuit configuration, theoretical consideration and experimental results are presented.

Digital type power-failure detector with wide AC frequency response

A proposed quick detector possesses the period data as a digital counter value, and has the novel feature that, when an AC power failure lasts more than one cycle, a power failure signal is generated. The following advantages also exist: this detector can detect a power failure about 100 ms faster than a conventional detector, which checks power failures by means of DC voltage drop for a 60 Hz power source; it operates on a wide AC frequency range, and therefore operates on AC frequencies including not only commercial power but also a high-frequency subdistribution system in buildings, vessels and aircraft; an auxiliary pulse synchronous to the AC power source before it fails is generated during the power failure; the detector is constructed without analog devices such as an operational amplifier and is realized in an IC form.<<ETX>>