Industry Top-Class DC-DC Converter Enabling 80V and High EfficiencyHigh Voltages Alone Do Not Resolve User Problems

－Well then, I’d like to ask more specific equations about the BD9G341AEFJ. Could you please begin with a summary.

The MOSFET within the BD9G341AEFJ is an N-channel device rated at 80 V/3.5 A. The IC conversion method is a voltage step-down method known as diode rectification or asynchronous rectification. Using only a few external components such as resistors and capacitors, a Schottky barrier diode and an inductor, a high-performance, high-voltage DC-DC converter can easily be configured.

This device employs current mode control, so that phase compensation is simple and fast transient response is obtained. The switching frequency can be set in the range of 50 kHz to 750 kHz, so that size and efficiency can be optimized. Nearly all the protective functions used in the DC-DC converters of recent years are included.

I have prepared the features, main specifications, and an application circuit example for the device; please have a look.

－It seemed to me that the high voltage must make this a special product in some way, but the configuration is quite simple.

In general, high-voltage DC-DC converters frequently achieve a high voltage by using a circuit configuration that includes an external high-voltage MOSFET, but by incorporating a MOSFET, the BD9G341AEFJ eliminates the need to select a MOSFET. The footprint is thus reduced to the extent that there is no external MOSFET. In addition to the high voltage, this IC offers a full set of the features and functions required of a leading-edge DC-DC converter IC.

－So the IC includes other features and functions in addition to the high rated voltage.

The BD9G341AEFJ was developed placing emphasis on the following four main areas:

1．Achieving an industry top-level high voltage rating of 80 V
2．Attaining the highest efficiency in the industry for an 80 V-class DC-DC converter device
3．Boosting equipment reliability through protection functions to prevent breakdown and improve
   safety
4．Reducing footprint and simplifying design through a compact package and reduced number of
   external components

－And achieving a high voltage rating of 80V using an internal MOSFET was a challenge?

As explained at the beginning, the high voltage rating of 80V was achieved using ROHM’s industry-leading 0.6 μm BiCDMOS power process. The 80V products could not be manufactured without this advanced process; this is also clear from the fact that high-voltage products on the market do not extend to the 80 V level. And a voltage rating of 80 V is necessary to be able to reliably support the 48V input voltages that are common in the telecom and industry fields. 80 V can provide a sufficient margin to protect from sudden surges and the like, so that reliability can be further improved in applications where power supply conditions are exacting and high availability is required.

－Where efficiency is concerned, I have heard that efficiency is worse when stepping down from a high input voltage to a low voltage?

－Breakdown prevention and safety improvements are important when handling high voltages.

－The fourth area is miniaturization and simplification of design; these are goals that in recent times have become essential.

－Please give us a final summary.

When considering the requirements of the telecom and industrial equipment markets, it has been difficult to construct power supplies with sufficient margins using existing high-voltage DC-DC converter ICs. It was under these circumstances that ROHM entered the market for high-voltage DC-DC converter ICs on the strength of a new IC boasting a rated voltage of 80 V, putting it in the top tier of the industry. With this, user options for high-voltage DC-DC converter ICs can be said to have expanded.

However, it is essential that the demands of recent years for reduced power consumption and shortened time to market be addressed as well. The BD9G341AEFJ was developed on the understanding that merely raising the rated voltage to 80 V would not be sufficient to resolve user dissatisfaction and other problems.

At present we are developing derivative products to expand our lineup of high-voltage DC-DC converter products, so please expect further expansion of our product line.