Rohm's synchronous buck converter IC claims the industry’s lowest minimum on-time



Controlling pulses in a very short period makes it possible to reduce the minimum ON time to an unprecedented 20ns, 6x shorter than the conventional level

ROHM recently announced the development of the BD51180TL, a step-down DC/DC converter featuring the lowest minimum ON time in the industry, making it ideal for high-power applications such as industrial equipment and automotive systems. In recent years, there is a growing trend towards electronification to meet the need to conserve energy in all areas, including the automotive market where attention has focused on 48V hybrid vehicle systems that take safety into account and provide better fuel economy than conventional 12V systems.

This is expected to increase the demand for DC/DC converters that can not only provide direct 3-5V output from 48V for driving control blocks and various functions, but are also capable of operating at high frequency (>2MHz) to prevent interference with AM radio bands and minimize the number of external components. To meet these market needs for high input, low output, and high switching frequency it is necessary to shorten the switching ON time.

Proprietary technology for controlling pulses in a very short time allowed ROHM to reduce the minimum ON time to an unprecedented 20ns – 6x shorter than conventional solutions – enabling stable step-down operation from 48V to 3.3V at a constant switching frequency of 2MHz. In addition, current mode control provides easy phase compensation required for constant voltage output with fewer external parts, contributing to greater end-product miniaturization while reducing customer design load. Integrating ROHM’s high voltage MOSFET expands the input voltage range to 65V, 4.6x higher than conventional products, ensuring compatibility with a wider range of applications. Additional features include multiple protection circuits and AEC-Q100 qualification that support the stringent reliability demands in the automotive and industrial equipment sectors.

Key Features
1. Breakthrough 20ns minimum ON-time control
Leveraging original technology for controlling pulses in a very short period makes it possible to reduce the minimum ON time to an unprecedented 20ns, 6x shorter than the conventional level. This ensures stable 3.3V output from 48V battery systems for driving various functions and control blocks while enabling 2MHz operation that prevents interference with AM radio band frequencies.
2. Easy phase compensation with current mode control
Switching power supplies such as DC/DC converters
typically include a feedback control circuit along with
phase compensation to prevent abnormal oscillation.
ROHM’s new IC employs current mode control
capable of controlling the current in very short pulse
widths, simplifying phase compensation while
reducing customer design load. Plus, only two
components are required to achieve stable operation over a wide input voltage range.
3. Expanded input voltage range
Integrating ROHM’s high voltage MOSFET makes it possible to expand the input voltage range by over 4.6x compared with conventional products, from 12V to 65V, enabling suitability for a wider range of applications – including high-voltage automotive systems and industrial equipment.
4. Compact high-heat dissipation package
Generally, increasing the breakdown voltage requires greater heat dissipation, making it difficult to decrease size. In contrast, the VQFN24SV4040 adopts a backside heat sink that reduces size to a compact 4.0x4.0x1.0mm, 54% smaller than conventional products,.
5. Multiple protection circuits
Standard protection circuits are built in to ensure safe operation and provide a greater degree of reliability.
・ AEC-Q100 Qualified
・ Over Current Protection
・ Input Under Voltage Lockout Protection
・ Input Over Voltage Protection
・ Output Overvoltage Protection
・ Thermal Shutdown
・ Short-Circuit Protection

ROHM Semiconductor