New high-efficiency system power supply IC for vehicle audio applications

To meet the expanding needs of the automotive audio market for multifunction power supplies, Rohm has developed a system power supply IC that features the lowest power consumption in the industry. The BD49101AEFS-M leverages proprietary expertise in car audio power system design to achieve an optimized system based on a high-efficiency DC-DC converter. As a result, power consumption is reduced by 65%, from 13.3W with Rohm’s conventional products, to an industry-leading 4.66W, says the company. Suppressing heat generation makes it possible to adopt a surface mount package without requiring an external heat sink, simplifying thermal designs considerably while contributing to greater space savings. In addition, integrating all system power supplies required for car audio systems on a single chip - including for USB with a cable impedance function - contributes to a lighter design load. In recent years, along with the continued computerization has come a greater need for reducing power consumption and improving fuel consumption in vehicles. However, at the same time, the growing demand for power consumption to meet the expanding functionality of car infotainment systems (i.e. USB and Bluetooth) is becoming of increased concern. And conventional car audio system power supply ICs, although generally easy to design, are often centred around a linear regulator which suffers from poor efficiency, reducing the operating efficiency of the entire system. In response, the company's DC-DC converter-based system power supply IC provides much greater efficiency, enabling support for the latest high-performance car audio systems. In DC/DC converters, because efficiency drops when the load current deceases (i.e. during standby), the BD49101AEFS-M integrates a low-current linear regulator dedicated for continuously powering the MCU. During standby operation the IC switches from the DC/DC converter to the linear regulator, reducing quiescent current that flows when the engine is idle to 100uA (typ.). The optimized DC-DC converter-based configuration suppresses heat generation and makes it possible to offer the BD49101AEFS-M in a compact surface-mount package with small backside heatsink. This eliminates the need for thermal counter measures and results in 14x less volume compared with conventional products. When charging USB devices it is necessary to compensate for the drop in voltage caused by the cable wiring resistance. In response, ROHM includes a built-in compensation function that maintains the cable end voltage, minimizing charging time and ensuring compliance with USB standards. In addition, an output terminal is included for notifying the MCU of over-current conditions, says the company.