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Industry Top-Class DC/DC Converter Enabling 80V and High Efficiency

High-Voltage DC/DC Converter to Enter the Market

- Part 1 -

  • 80V
  • Internal MOSFET
  • Manufacturing process
  • User dissatisfaction
  • Telecom 48V

Recently ROHM announced the "BD9G341AEFJ" that is a DC/DC converter IC with an internal high-voltage (80V) MOSFET. A high voltage of 80V places this device in the top class of the industry as a non-isolated DC/DC converter IC, and positions it as the model in the company's lineup of DC/DC converter ICs with the highest breakdown voltage. Simultaneously with the announcement of the "BD9G341AEFJ", ROHM declared its entry into the market for high-voltage DC/DC converters.

The demand for high-voltage DC/DC converters is growing steadily, driven by their increasing use in telecom-related areas, industrial equipment and also in applications employing battery stacks. However, only a limited number of manufacturers are supplying DC/DC converter ICs with voltages above 60 V, and users are not a little dissatisfied with the situation. We asked Mr. Tamagawa, a field application engineer at ROHM, about the background to development of the BD9G341AEFJ and its market positioning.

-I understand that this is a DC/DC converter IC with an 80V rated voltage. Isn't this quite high for a DC/DC converter?

A survey our company conducted indicated that 80V was among the highest in the industry for a DC/DC converter IC. Strictly speaking, this is a non-isolated type DC/DC converter IC with an internal power MOSFET.

As you are probably aware, there are numerous discrete components--MOSFETs, diodes, ICs for AC/DC converters, and the like--boasting rated voltages of 500 V or higher. For example, the rated voltage of the internal MOSFET in ROHM's ICs for AC/DC converters is 650 V. And by combining a high-voltage MOSFET and a DC/DC converter controller IC designed for use with an external power MOSFET, it is possible to configure a high-voltage DC/DC converter.

However, in order to achieve a high voltage of 80V for a single IC, rather than for discrete components, high-level manufacturing process technology is essential. ROHM's BiCDMOS process for high voltages, used in manufacturing the BD9G341AEFJ, is the industry’s leading-edge power process.

-I was aware that there are DC/DC converter ICs with a rated voltage of around 60 V, but had the impression that there aren't so many models, and that only a few manufacturers make them.

That's right. There are many manufacturers supplying DC/DC converter ICs, and a huge number of IC models are on the market. But when the rated voltage exceeds 40 V, suddenly there is a sharp drop in the number of device models available, and manufacturers who have lineups of hundreds of such ICs only offer a small number of devices rated at 60 V, and above 60 V, only a handful of ICs are available. And, not many manufacturers have product lineups rated at 60 V or higher. In fact, prior to developing this model, ROHM itself only offered models with rated voltages of 40 V or below, with only a few exceptions.

-Why are there so few high-voltage models?

Put simply, there are two conceivable reasons. One is the matter of demand, that is, the market scale. Applications that use high DC voltages as inputs have I think primarily been in industrial equipment, automobiles, and telecom-related products. Compared with consumer products, the market scale is small, and requirements are extremely strict. The other reason is that advanced technology is necessary to raise the voltages of ICs.

-Well then, why is ROHM entering the market for high-voltage DC/DC converter ICs?

Such important markets as industrial equipment, automobiles and telecom are what could be called key industries, and are among the focus areas for ROHM. Moreover, in recent years the diversification of battery voltages, including in automobiles, the use of battery stacks and other trends have led to increasing demand for DC/DC conversion from higher voltages. With this as background, we have become aware that customers are not a little dissatisfied with the current state of high-voltage DC/DC converter IC products.

-In what way are they dissatisfied?

Put simply, only a few manufacturers produce high-voltage DC/DC converter ICs, and models are limited, so that customers do not have many options. It may be difficult to satisfy the performance and functions required for a given application.

-Could you describe a specific example?

Let's consider a telecom application example. What is generally called the "telecom 48 V" for telecom products is an input voltage that, it is necessary to presume, includes considerable fluctuation, and as a rule, voltages in the range 36 V to 72 V (that is, 48 V -25%/+50%) must be assumed. There are some power supply ICs that declare support for telecom 48 V, but these are often, for example, products rated at 74 V that are extended version of product lineups with 60 V voltage. Perhaps it is anticipated that the worst case of 72 V does not occur often, but clearly there is almost no margin included. At present, there are almost no DC/DC converter ICs that properly cover this "telecom 48 V" range.

Given this situation, if an 80V product were available, it would be a safe option for use in telecom applications, and could probably address quite a bit of user dissatisfaction.

-How are 80V DC/DC converter ICs positioned among all DC/DC converter IC products?

This graphic presents a visual summary of the relation between the rated voltages of general DC/DC converter ICs and representative input power supplies. The order of the input power supplies is not simply based on their nominal voltages, but also on those voltages including the margin that is assumed to be necessary. And as mentioned earlier, as rated voltages rise, the number of product suppliers decreases, and the number of products and variation among products also drop off. In any case, at present a rated voltage of 80V puts a product in the top class of such devices.


Industry Top-Class DC/DC Converter Enabling 80V and High Efficiency

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Power Supply Design Technical Materials Free Download

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