Line of 24 ICs with Integrated FETs for AC-DC Converters Introduced
ROHM Semiconductor has announced the development of power supply ICs for ac-dc converters in primary power supplies for home appliances and ac adapters. The BM2xxx/F series consists of 24 models that utilize a proprietary low ON resistance super-junction (SJ) MOSFET and feature circuit optimization, resulting in industry-leading efficiency and low noise. In addition, a surface mount type is available in the SOP8 package that contributes to set miniaturization. ROHM is working on expanding its lineup to achieve high efficiency in a wide range of home electronics, including appliances, TVs, and monitors.
These ICs offer high efficiency operation for greater energy savings. In order to improve efficiency a proprietary high performance super junction MOSFET is utilized, while exhaustive optimization of the driver circuitry enabled the company to maximize MOSFET performance. As a result, ROHM products cleared the 86.35% efficiency rating required by Energy Star 6.0. Efficiencies of more than 87% are possible by simply replacing conventional products with ROHM ICs (100Vac, 25W applications), while greater than 90% can be achieved through optimization of peripheral components.
The internal SJ MOSFET features a voltage resistance of 650V, low ON resistance (4.0Ω even with the SOP8 package), low gate charge Qg, and high-speed switching capability. In addition, standby power consumption is less than 20mW (@100Vac) for a 25W adapter and only 30mW @ 230Vac – significantly less than the 100mW required by the Version 6.0 Energy Star. And even lower consumption is possible by adjusting the peripheral circuitry.
AC-DC systems typically use a planar-type MOSFET, which is difficult to miniaturize due to problems associated with heat dissipation. In contrast, ROHM uses a SJ MOSFET and integrate a number of protection functions, enabling the company to offer a variety of package types in the 8W and under class, from conventional DIP7 to surface mount SOP8 (6.2x5.0x1.5mm) that reduces mounting area by 47% for easier design and board layout.
AC-DC converters, used to configure the primary power supply in electronic devices, must meet market needs for improved energy and space savings along with greater convenience. Generally, there is a strong demand for power supply ICs in ac-dc converters to be Energy Star compliant and provide high efficiency operation that includes standby power. Also, the increased number of components leads to a larger mounting area, presenting additional challenges regarding design complexity and time.
In response, ROHM utilized power supply technology cultivated from developing LDOs, dc-dc converters, and the like along with discrete transistor analog power technology to develop the BM2Pxxx/F series, optimized for ac adapters, home electronics, and office equipment up to 25W that require high efficiency operation in a compact form factor. Samples are already available, OEM quantities as of September 2013.
