Ultra-compact high efficiency power supplies target automotive applications

Ultra-compact high efficiency power supplies target automotive applications

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By eeNews Europe

The BD905xx series integrates a phase compensation circuit and feedback resistor, reducing the number of external parts considerably compared with conventional power supply ICs. This simplifies design load and contributes to end-product miniaturization.

In recent years the increasing popularity of electric and hybrid vehicles has led to more sophisticated electronic systems and a greater demand for microcontrollers and memory. Conventional LDO regulators are commonly used, but they feature poor efficiency and cannot meet higher current demands. As a result, DC/DC converters, which provide greater efficiency and higher current-handling capability, are becoming the preferred solution. However, they are not without their drawbacks, which include more external parts and consequently a larger mounting area, increasing circuit design complexity significantly. With the trend towards improved performance and decreasing model cycles in the automotive industry comes a need for easier-to-use, high efficiency power supply ICs that lighten the design load and minimize mounting area.

A primary factor in the number of external components used with power supply ICs is the phase compensation circuit required to maintain a stable output voltage. Normally external capacitors and resistors are used to set the desired characteristics. However, ROHM was able to optimize the phase compensation circuit internally, reducing parts count by 80% and contributing to more compact automotive systems. In addition, phase compensation adjustment, which is a common problem with power supply designs, is no longer required, shortening design times.

ROHM power supplies utilize synchronous rectification for high efficiency operation, in combination with Light Load Mode, ensuring superior performance with low current consumption under all load conditions.

The HTSOP-J8 package reduces volume by about 80% compared with conventional products. (6.0 mmx4.9 mm, t=1.0mm max.) The device’s low heat generation simplifies thermal design.  Loss is one tenth the level of conventional LDO regulators, resulting in minimal heat generation. This simplifies thermal countermeasures, making it ideal for microcontrollers and DDR memory used in today’s vehicles that require greater current consumption.

Synchronous rectification, coupled with Light Load Mode, results in over 90% efficiency (max.) under all load conditions for minimal current consumption.

ROHM is offering models in different output voltages and currents designed for various automotive systems (1.2 V for microcontroller cores, 1.5 V and 1.8 V for DDR memory).


Samples of the BD905xx series are available now with OEM quantities available in July 2013.

Visit ROHM Semiconductor at

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