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Fujitsu Microelectronics Europe (FME) has brought out a 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 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 in turn reduces component count.

The IC also includes pulse frequency modulation (PFM), which 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.

Today’s AV equipment incorporates large screens, multiple functions and advanced video-compression technologies.

These features are supported by ICs that provide multiple functions at high-speed.

Power supplies for these ICs have to handle the requirements of large currents and fast transient response times.

The MB39A145 DC/DC converter IC was developed to meet these needs.

When turning on AV equipment, such as a large-screen TV, or when there are rapid changes in contrast in the scenes of a video, fast transient response times and a large current supply are necessary.

Fujitsu’s new DC/DC converter IC provides these features by utilising a ‘bottom detection comparator method’ that 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.

Additionally, as audio equipment requires low-frequency noise measures, the Prohibit Audio Frequency (PAF) 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 MB39A145 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.

Fujitsu Semiconductor

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