DC/DC buck converter IC for ADAS ensures best-in-class operational stability

ROHM has developed the BD9S402MUF-CDC/DC buck converter IC with integrated MOSFET (switching regulator), designed for increasingly advanced automotive applications, such as infotainment systems and ADAS (Advanced Driver Assistance Systems) equipped with on-board cameras and sensors.

In recent years, safety requirements in the automotive industry have become increasingly stringent, hand in hand with the continuous advancement of technological innovation in accident prevention and autonomous driving systems.

In the wake of this trend, SoCs and microcontrollers that control ADAS equipped with cameras and on-board sensors imply greater sophistication and thus require power ICs that can operate more stably even under significant fluctuations in load current.

To meet these needs, in 2017 ROHM created Nano Pulse Control, an ultra-fast pulse width control technology that provides low output voltage at high switching frequencies, and then in 2021 introduced QuiCur, a high-speed load response technology that ensures stable operation.

Thanks to QuiCur technology, the IC boasts a stability of operation that puts it at the top of its class compared to secondary DC/DC converter ICs with equivalent performance intended for automotive.

The new BD9S402MUF-C supports low output voltages as low as 0.6 V and an output current of 4 A at switching frequencies above 2 MHz in a compact format that lends itself well to increasingly sophisticated secondary power supply applications for high-performance microcontrollers and SoCs.

But that's not all: it features QuiCur, the proprietary high-speed load response technology that enables stable operation at 30 mV, an industry record (measurement conditions: input voltage 5 V, output voltage 1.2 V, output electrical capacitance 44 µF, load current variation 0 to 2 A/2 µs).

In other words, with a 25% reduction in output voltage fluctuation compared to standard class-leading products with equivalent functionality, it is the ideal solution for use in the most advanced ADAS systems under severe power conditions that require stable operation within 5% even at low output voltage.

The BD9S402MUF-C also features a new load response performance selection function that allows users to easily switch the priority between "voltage fluctuation" (for industry-leading operation stability) and "electrical capacitance reduction" (to ensure 22 µF operation stability) by acting on the settings via the terminal.

Users can thus greatly reduce the resources required for power circuit design due to the stable operation that can be easily achieved not only in the initial design phase, but also when changes are made to models or in specifications.

ROHM plans to expand the line-up of power ICs equipped with QuiCur technology in the future to support a wider range of applications.

Details of the new product

The BD9S402MUF-C, in addition to meeting thebasic requirements of secondary DC/DC converter ICs in ADAS for operation at speeds of 2 MHz or higher and output current of 4 A, features Nano Pulse Control, the unique ultra-fast pulse-width control technology created by ROHM that provides a next-generation output voltage reduced to as low as 0.6 V-a much lower value than the 1.0 V usually required by current SoCs and microcontrollers.

It also integrates QuiCur, the high-speed load response technology that ensures extremely stable operation.

The ability to contain output voltage variations to within 5 percent even at low voltages, below 1.0 V, makes it an ideal tool for secondary power supplies in more advanced ADAS systems.

The BD9S402MUF-C is also equipped with a load response performance selection function that, taking advantage of QuiCur technology features, allows users to easily switch the priority between "voltage fluctuation" (for industry-leading operating stability) and "electrical capacitance reduction" (to ensure 22 µF operating stability) by acting on the High/Low settings of the GAIN pin.

For example, theuser can set the GAIN pin to High if the high-performance SoC's power supply needs to handle rapid load fluctuations, or the user can set the GAIN pin to Low to achieve a good balance between capacitor cost and performance when a microcontroller's power supply does not need to account for extremely accurate voltage fluctuations.

This helps to significantly increase design flexibility for application designers, as stable operation can be easily achieved both in the initial design phase and during changes to models or specifications.

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