Nano Pulse Control™ROHM Develops Ultra-High-Speed Pulse Control Technology
for the Era of 48V DC-DC Converters

48V power systems are already widely utilized in various industries, including wireless communication base stations, industrial robots, and emergency power supplies for forklifts. And following the enactment of stringent CO₂ emissions regulations, their introduction in the automotive sector is expected to accelerate rapidly as well.

ROHM’s ultra-high-speed pulse control technology, Nano Pulse Control™, enables gan to overcome major challenges. (Source: ROHM)

CO₂ emissions regulations introduced in Europe in 2020 have spurred the emergence of mild hybrid vehicles (HEVs). A noteworthy aspect of this development is the power supply system. Until now, HEVs have operated on 12V DC power. However, Germany and other European automakers are intensifying efforts to transition to a 48V power supply system. Why increase the voltage from 12V to 48V? To start with, 48V enables higher drive motor output while reducing size. Additionally, components such as electromagnetic solenoids and motors for AC, power windows, and wipers can be miniaturized.
48V systems have also been standardized by the International Organization for Standardization (ISO). ISO 21780 specifies the requirements and test methods for electrical and electronic components used in automotive 48V power supply systems. This environment is prompting many automakers to make the shift.

Challenges in converting 48V to 3.3V

Transitioning to a 48V power system requires overcoming a considerable challenge. Namely, supplying low DC voltages such as 3.3V or even 2.5V for the various ECUs located throughout HEVs. Converting from high to low DC voltages has proven problematic until now.
Using conventional DC-DC converters to step down 48V input to 3.3V output involves a two-stage process. First, the 48V is stepped down to an intermediate voltage of 12V at a switching frequency of 2.2MHz (to avoid interference with the AM radio band). The next stage converts the 12V input to 3.3V. This means that two DC-DC converters are needed – each requiring its own power IC – one more than existing 12V systems.

Power supply IC requirements

The role of the power supply IC is to convert voltage input from a battery or other source into a stable voltage that allows electronic circuits and semiconductor devices to operate properly. This must be carried out with as few components as possible, as space constraints make additional parts unacceptable. Therefore, there is a significant demand for DC-DC converters with a wide step-down range capable of directly stepping down from 48V battery input to output voltages as low as 3.3V.
So how can the step-down range of a DC-DC converter be expanded? The key lies in the pulse width that controls the timing of the switching operation. The narrower the pulse width, the smaller the duty cycle and the wider the step-down range. Conversely, the wider the pulse width, the longer the ON switching time and the larger the duty cycle, resulting in a narrower step-down range.
Decreasing the pulse width increases susceptibility to noise, so unless measures are taken to stabilize the waveform even in the presence of noise, practical use cannot be guaranteed. Given these challenges, developing a power IC capable of directly stepping down from 48V to 3.3V is extremely difficult.
Of course, using two power ICs allows for direct step-down from 48V to 3.3V, but as mentioned earlier, increasing the number of ICs is not permissible.

A new technology that overcomes these challenges

Improving power supply IC performance involves optimizing the pulse width. A novel technology has emerged that accomplishes this. Developed by Japanese semiconductor manufacturer ROHM, Nano Pulse Control™ enables operation with an extremely short ON-time as low as 9ns. Power supply ICs incorporating this technology have already been commercialized.
As a result, direct step-down from input voltages as high as 48V to 3.3V or even 1.2V is possible. This eliminates the need for a two-step process, requiring only one power supply IC. In other words, a ‘single-chip design’ becomes achievable. What’s more, switching frequencies as high as 4MHz allow external components such as coils to be miniaturized.
Power supply ICs incorporating Nano Pulse Control™ are ideal for automotive 48V power systems. Of course, they can also be used in other applications where 48V systems are anticipated, such as industrial equipment, robots, and forklifts.

DC-DC Converter IC Pulse Width Comparison (High-Voltage Products for Automotive and Industrial Equipment)
Enables Ultra-high-speed pulse control in high-frequency ranges. (Source: ROHM)

Maximizing the performance of GaN devices

The applicability of Nano Pulse Control™ extends beyond 48V power supply systems. ROHM is advancing this technology further by incorporating it into power control ICs for GaN devices. GaN is characterized by excellent switching properties that enable extremely fast switching operation. As such, it is being increasingly adopted in a variety of applications. But until now, there has not been a power control IC capable of high-speed operation that could fully leverage the benefits of GaN. Utilizing Nano Pulse Control™ makes it possible to maximize the performance of GaN devices, which ROHM believes are on the verge of a major breakthrough.
ROHM is also developing and commercializing GaN devices under the EcoGaN™ brand. These products boast low ON resistance and high switching performance, improving power savings while reducing the size of power circuits. Combining EcoGaN™ with Nano Pulse Control™ allows ROHM to reduce mounting area by 86%, achieving significant miniaturization.
ROHM currently offers EcoGaN™ DC-DC control ICs that utilize Nano Pulse Control™ for driving GaN devices. Integrating EcoGaN™ enables significant reductions in power consumption and size across a range of applications, including wireless base stations, data centers, FA equipment, and drones.

ROHM establishes ultra-high-speed control IC technology to maximize the performance of GaN components. (Source: ROHM)

Power Supply Solution with GaN Components and Nano Pulse Control™ Technology Reduces the mounting area of the power circuit by 86%, enabling significant miniaturization. (Source: ROHM)

Innovative ‘Nano’ power supply technologies achieve unprecedented energy savings and miniaturization

In addition to Nano Pulse Control™, ROHM’s Nano Series features two other groundbreaking technologies: Nano Energy™ and Nano Cap™. Nano Energy™ is an ultra-low power consumption technology that achieves an industry-low current consumption of 180nA for power supply ICs along with up to 90% conversion efficiency at a load current of 10uA. While Nano Cap™ is a stable control technology that suppresses voltage fluctuations within ±5% even when the output capacitance is reduced by 1/10th. These three proprietary technologies have already been integrated into various analog ICs, including gate drivers, power management ICs, op amps, and comparators.

Driving technology forward and surpassing limits

Before the development of Nano Pulse Control™, the pulse width of ROHM’s power supply ICs was already among the industry's smallest at 120ns. But relentless efforts to improve performance have propelled ROHM to the forefront of the field. Meanwhile, as market demands for energy efficiency, miniaturization, enhanced safety, low power consumption, and higher functionality continue to grow, technologies currently seen as reaching their limits may well be surpassed in the future.

Nano Pulse Control™, EcoGaN™, Nano Energy™ and Nano Cap™ are trademarks or registered trademarks of ROHM Co., Ltd.