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Fast transient response DC/DC converter IC

Fujitsu Microelectronics Europe has announced a new two-channel DC/DC converter IC with fast transient response times, for use in digital products such as LCD TVs, and digital video recorders. The MB39A145 IC utilises a ‘bottom detection comparator method’ and includes new comparator circuits that provide changes in voltage for changes in current to realise a more stable, low ripple output voltage. This improved stability subsequently reduces the number of external components that are needed, such as condensers, thus reducing space. The IC also includes PFM (pulse frequency modulation) that operates in currents below 100mA, enabling the IC to provide high efficiency in all current ranges and reduce the power consumption of end equipment in stand-by mode. The IC was jointly developed by Fujitsu Microelectronics and Fujitsu VLSI.

The bottom detection comparator method compares the output voltage to a reference voltage using a high-speed comparator. The result is that variations in the generated output voltage are reduced to a minimum when the load is high. In low current ranges below 100mA, or in stand-by mode, the integrated PFM function reduces the power used, thus contributing to a reduction in power consumption of the equipment that it is being used in. As audio equipment requires low frequency noise measures, the prohibit audio frequency function can set the minimum frequency to 30kHz so that low frequency noise from the power supply is reduced. With enhanced comparator circuits, which provide changes in voltage for changes in current, it is possible to operate the IC even with no ripple in the output voltage. The improved stability reduces the number of external components needed on the output, thus reducing the size of power supply systems and making their design easier.