Buck-boost power supply chipset stabilises start-stop vehicle systems
Claimed to provide the lowest current consumption in the industry and stable transient response characteristics, Rohm has introduced a buck-boost power supply chipset for automotive electronic control units (ECUs).
The chipset integrates a buck DC/DC converter with boost functionality (BD8P250MUF-C) and a dedicated boost IC (BD90302NUF-C). The primary chip (BD8P250MUF-C) uses Rohm’s buck-boost control technology, Quick Buck Booster. This is designed to enable the configuration of a buck-boost power supply without degrading buck power supply characteristics by simply adding the dedicated BD90302NUF-C boost IC to the subsequent stage.
The result, says Rohm, is an industry-best no-load current consumption of eight microA and ±100mV output voltage fluctuation utilising an output capacitance 44 microF (70 per cent less current consumption and 50 per cent less output capacitance compared to conventional products). It contributes to improved stability and energy savings in applications where significant input voltage drops occur in a short period of time, such as start-stop vehicle systems, says Rohm.
Quick Buck Booster technology also allows a common board design that integrates both buck-boost and buck power supply topologies along with the requisite peripheral components and noise countermeasures, reducing development time and labour by 50 per cent, compared to conventional methods which require separate buck-boost and buck power supply boards.
In vehicles equipped with start-stop functionality that turns the engine/motor off when idle, a buck-boost power supply is required to prevent malfunctions due to low battery voltage during idling and battery fluctuations (cranking) immediately after start-stop operation. Rohm developed a buck-boost power supply chipset using proprietary automotive technology centred on Quick Buck Booster control that overcomes the current consumption and responsiveness issues related to start-stop systems. According to the company, the BD8P250MUF-C buck DC/DC converter integrated in the chipset uses Quick Buck Booster control technology to easily switch to buck-boost operation without degrading buck performance, which has superior
The chipset with Quick Buck Booster technology makes it possible to provide a common design that combines both buck and buck-boost power supply operation on a single board along with peripheral components and noise countermeasures. To switch from buck to buck-boost operation is achieved by simply adding a dedicated boost IC. According to Rohm, this reduces design load by as much as 50 per cent compared with conventional methods using separate power supply boards.
To meet market demands, the BD8P250MUF-C integrates a spread spectrum function as a countermeasure against noise (EMI), allowing it to clear the international standard (CISPR 25) for noise in the automotive sector. At the same time, Rohm’s original ultra-high-speed pulse control technology Nano Pulse Control is used to enable high speed operation at 2.2MHz that eliminates the effects on the AM radio band (1.84MHz maximum), making it possible to achieve stable 5.0V output for ECU drive from high-voltage 36V input. This ensures low EMI while enabling low voltage output from high voltage input without AM radio band interference, contributing to stable operation in automotive systems sensitive to noise.
Samples are available now, with OEM quantities expected January 2019.
