High-efficiency DC/DC converter for car audio applications

January 28, 2016 // By Christoph Hammerschmidt
Not only since electric cars are looming, power efficiency is a big topic for automotive electronics designers. Rohm’s BD49101AEFS-M power supply IC for car infotainment systems boasts the lowest power consumption in the industry: Instead of the industry’s average of 13.3W it consumes just 4.66W.

Suppressing heat generation makes it possible to adopt a surface mount package without requiring an external heat sink, simplifying thermal designs while contributing to 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 centered around a linear regulator which suffers from poor efficiency, reducing the operating efficiency of the entire system. In response, ROHM’s DC/DC converter-based system power supply IC provides much greater efficiency, enabling support for the latest high-performance car audio systems.

Typically, high-efficiency DC/DC converters require many external parts, leading to increased costs along with larger mounting area. In contrast, ROHM conducted a thorough review of the entire system and optimally combined a DC/DC converter and linear regulator in order to minimize the dual converter design and improve efficiency while reducing costs. As a result, power consumption of the entire system during operation is reduced to industry-low levels.

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