Ultra-compact high-efficiency supplies address automotive applications



ROHM's latest family of compact, high efficiency power supplies are designed to drive DDR memory, microcontrollers, and other advanced subsystems in automotive applications. D905xx power supply ICs integrate a phase-compensation circuit and feedback resistor, reducing the number of external parts considerably compared with conventional devices. 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 successfully 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 time significantly. The power supplies use synchronous rectification for high efficiency operation, in combination with Light Load Mode, ensuring superior performance with low current consumption under all load conditions. Key Features Built-in phase compensation circuit and feedback resistors The BD905xx series integrates an optimized phase compensation circuit that reduces the number of external components considerably, simplifying set design while minimizing mounting area. Compact package The HTSOP-J8 package reduces volume by approx. 80% compared with conventional products. (6.0mmx4.9mm, t=1.0mm max.) Low heat generation simplifies thermal design Loss is 1/10th that 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 and Light Load Mode Synchronous rectification, coupled with Light Load Mode, results in over 90% efficiency (max.) under all load conditions for minimal current consumption. ROHM Semiconductor