First Step Down DC/DC Converter IC For Efficient operation

ROHM has recently announced the development of a DC/DC converter IC featuring very low ON time. This enables direct step-down conversion to 3.3V or 5V from the input voltage range which includes 48V used in the automotive and industrial sectors. This step-down ratio allows the BD51180TL to eliminate the need for intermediate conversion utilizing a secondary power supply IC, while current mode control helps in phase compensation, lightening design load, efficiency, and contributing to end-product miniaturization.

In recent years, there is a growing need to conserve energy in all areas, including the automotive sector where attention has focused on 48V systems for hybrid vehicles that take safety into account and provide better fuel economy than conventional 12V systems. Normally, 2 step-down stages are necessary to create an intermediate voltage such as 12V. High frequency of over 2MHz is needed to prevent interference with AM radio bands. To meet market needs for high input, low output, and high-frequency operation the switching ON time needs to be minimized. However, conventional methods are susceptible to noise, making it difficult to reduce ON time.

With this proprietary technology the minimum ON time of about 20ns – 6x shorter than conventional solutions – enabling stable step-down operation from 48V to 3.3V at a constant switching frequency of 2MHz has been achieved. The 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 MOSFET expands the input voltage range to 65V, 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.

Leveraging technology for controlling pulses in a short period makes it possible to reduce the minimum ON time to about 20ns. 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. Current mode control simplifies phase compensation

Switching power supplies such as DC/DC converters typically include a feedback circuit and require phase compensation to prevent abnormal oscillation. ROHM’s new IC employs current mode control capable of controlling the current using very short pulse widths, simplifying phase compensation while reducing design load. In addition, two components are required to ensure stable operation over a wide input voltage range.

Integrating ROHM’s MOSFET makes it possible to expand the input voltage range by over 4.6x vs conventional products, from 12V to 65V, enabling compatibility with a wider range of applications – including industrial equipment and automotive systems.

Typically, increasing the breakdown voltage requires greater heat dissipation, making it difficult to reduce size. However, ROHM’s VQFN24SV4040 package adopts a backside heat sink that reduces size to a compact 4.0×4.0x1.0mm form factor – 54% smaller than conventional products – by significantly improving heat dissipation.

5. Multiple protection functions improve safety and reliability
Standard protection circuits are built in to ensure safe operation and provide a greater degree of reliability.
• AEC-Q100 qualified
• Overcurrent protection
• Input undervoltage lockout protection
• Input overvoltage protection
• Output overvoltage protection
• Thermal shutdown
• Short-circuit protection

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Terminology
• DC/DC Converter
A type of power supply IC that converts one DC voltage to another DC voltage (usually lower, although boost converters exist that increase the voltage).
• Pulse
Refers to a constant-width square wave. Control of voltage or current is performed by changing the width.
• Phase Compensation
A type of circuit used to maintain constant voltage and ensure stable power supply operation.