Buck Converters (Synchronous & Integrated FET)

ROHM's switching regulator series (DC/DC converter) are available with or without integrated FET (boost/buck/boost-buck) and from single-channel to multi-channel system power supply configurations for broad compatibility.
Buck Converters (Synchronous)

New product: 3.5V to 40V input 1-channel step-down switching regulator for automotive application BD9P series

The "BD9P series" is a switching regulator of high efficiency and fast response operation, which outputs stable DC voltage from 0.8V to 8.5V from a maximum input voltage of 40V. These regulators provide stable operation even when the supply voltage from battery fluctuates. The overshoot voltage at the time of input voltage fluctuation is reduced to 1/10 or less than that of a standard product, thereby reducing the capacity of an additional capacitor that has been used as an overshoot measure.

"BD9P series" adopts a new control method to reduce the current consumption of the circuit to 1/3 of the conventional level, and achieves the industry's top class efficiency from light load to high load.
The BD9P series achieves both a fast response time and high efficiency, which are generally considered to be incompatible, and achieves a conversion efficiency of not only 92% at high load (at an output current of 1 A), but also a high efficiency of 85% at light load (at 1 mA).
"BD9P series" has a high efficiency design that contributes to low power consumption not only when the vehicle is running, but also when the engine is stopped.

Furthermore, by combining the "BD9P series" with the "BD9S series" secondary power supply IC connected to the back-end of the "BD9P series", it is possible to construct an even more efficient and faster-responding power supply circuit for vehicles.
The automotive reference designs proposed by ROHM are available on the ROHM website.
In addition to the solution board and various design support tools, ROHM offers the "ROHM Solution Simulator", a web simulation environment that allows users to verify the characteristics of the "BD9P series". "It is now available to the public.
It enables peripheral circuits to be designed and simulated close to real-world conditions, greatly reducing the development load when considering product design.


1. Stable operation without overshooting during battery voltage fluctuations

Sudden changes in battery voltage caused by cranking or other events may cause extreme situations in which the supply voltage is lower than the output voltage setting.
In such cases, the overshoot voltage that occurs in the output voltage when the voltage returns to its normal value becomes a design issue.

"BD9P series" reduces the output voltage overshoot to less than 1/10th of the output voltage of standard products and enables stable operation of the equipment.
The additional capacitor required as a countermeasure against overshoot in standard products can be reduced.

2. High efficiency over a wide range of load currents, contributing to low power consumption in applications

"BD9P series" achieves both high-speed response and high efficiency, which are generally considered to be incompatible.
Power supply ICs with conventional technology require a large drive current to ensure fast response, making it difficult to achieve both fast response and high efficiency under light loads.

"BD9P series" adopts a new control method and achieves a fast enough response even at a lower drive current than standard products. The conversion efficiency at high load is 92% (at output current of 1 A) and 85% (at 1 mA) at light load.
The industry's top-class efficiency from light load to high load contributes to low power consumption in applications both when the engine is off and when the vehicle is running.

3. The Nano Pulse ControlTM provides high step-down ratio and stable operation.

"The BD9P series uses ROHM's proprietary ultra-fast pulse control technology "Nano Pulse ControlTM". This technology enables constant operation at a switching frequency of 2.2 MHz without affecting the AM radio band (1.84 MHz Max.), while providing a stable output voltage of 3.3 to 5.0 V to drive back-end devices, even at high voltages of up to 40 V.
In addition, the internal clock generator has a spread spectrum function to reduce the peak noise generated. This product is ideal for automotive applications that require high levels of radiated noise.

4. Tools that contribute significantly to reducing set development time

ROHM's reference designs and ROHM Solution Simulator contribute significantly to the reduction of development time in the design stages of circuit design, board design, noise design, thermal design and simulation.
ROHM's reference designs, including the new ”BD9P series”, are now available on its website.

Reference Design(REFRPT001)

A reference design that uses the "BD9P series" as the primary power supply and the "BD9S series" as the secondary power supply has been released on our website.
This circuit configuration covers the power supply systems necessary for ADAS and infotainment functions.
The board design of the reference board "REFRPT001-EVK-001" has been subjected to EMC testing and thermal design in addition to standard electrical characteristics measurements, which can be confirmed in an evaluation report (application note).
A variety of design support tools are also available, including design data, simulation models of on-board products and schematic symbols for PCB CAD. We hope you will find these tools valuable in your design and implementation.

Design support tools available to the public

Design data (circuit diagram, BOM, PCB data, etc.)
Simulation models (SPICE models and models for thermal simulation)
PCB library (symbols and footprints for CAD tools, etc.)

ROHM Solution Simulator

ROHM's web simulator, the "ROHM Solution Simulator", allows users to simulate the frequency response, load response and power supply response of the "BD9P series" simply by accessing a web page.
You can set up the conditions in the simulator on the web site and easily run the simulation and check the results.
You can save the time and effort of constructing a new simulation environment for the initial stage of development, such as confirmation of the characteristics under the desired conditions.

In addition, a simulation environment is available to confirm the basic characteristics of the reference board "REFRPT001-EVK-001" in the configuration of primary and secondary power supply. We can support your development with a variety of design support tools.

REFRPT001 / Load Response for 5.0V power tree sub-circuit (Login Required)
REFRPT001 / Load Response for 3.3V power tree sub-circuit (Login Required)

Application examples

ADAS sensors, cameras and radar
◇ Applications such as car infotainment, clusters, and body control modules (BCM) that require
miniaturization, high efficiency, and high reliability in automobiles.


Primary switching regulator BD9P series

Part No. Absolute Max. Ratings Input Voltage Range Output Voltage Max. Output Current Output Voltage Accuracy Operating Frequency Operating Temperature Range Package
NEW  BD9P105EFV-C 42V 3.5V~40.0V 0.8V~8.5V 1.0A ±1.75% 2.2MHz -40℃~
NEW  BD9P105MUF-C 0.8V~8.5V VQFN20FV4040
NEW  BD9P135EFV-C 3.3V(Typ.) HTSSOP-B20
NEW  BD9P135MUF-C 3.3V(Typ.) VQFN20FV4040
NEW  BD9P155EFV-C 5.0V(Typ.) HTSSOP-B20
NEW  BD9P155MUF-C 5.0V(Typ.) VQFN20FV4040
NEW  BD9P205EFV-C 0.8V~8.5V 2.0A HTSSOP-B20
NEW  BD9P205MUF-C 0.8V~8.5V VQFN20FV4040
NEW  BD9P235EFV-C 3.3V(Typ.) HTSSOP-B20
NEW  BD9P235MUF-C 3.3V(Typ.) VQFN20FV4040
NEW  BD9P255EFV-C 5.0V(Typ.) HTSSOP-B20
NEW  BD9P255MUF-C 5.0V(Typ.) VQFN20FV4040

Secondary switching regulator BD9S series

Part No. Absolute Max. Ratings Input Voltage Range Output Voltage Max. Output Current Output Voltage Accuracy Operating Frequency Operating Temperature Range Package
BD9S000NUX-C 7V 2.7V~ 5.5V 0.8V ~VIN 0.6A ±1.5% 2.2MHz -40℃~
BD9S100NUX-C 0.8V ~VIN 1.0A VSON008X2020
BD9S110NUX-C 1.2V(Typ) 1.0A VSON008X2020
BD9S111NUX-C 1.8V(Typ) 1.0A VSON008X2020
BD9S200MUF-C 0.8V ~VPVINx0.8V 2.0A VQFN16FV3030
BD9S201NUX-C 0.8V ~VIN 2.0A VSON008X2020
BD9S300MUF-C 0.8V ~VIN 3.0A VQFN16FV3030
BD9S400MUF-C 0.8V ~VPVINx0.8V 4.0A VQFN16FV3030

Design Model

Primary switching regulator BD9P series

Secondary switching regulator BD9S series

Part No. SPICE Model Thermal Model Footprint / Symbol 3D STEP Model Calculation-sheet
BD9S000NUX-C available - available available -
BD9S100NUX-C available - available available -
BD9S110NUX-C - - available available -
BD9S111NUX-C - - available available -
BD9S200MUF-C - - available available -
BD9S201NUX-C available available available available -
BD9S300MUF-C available available available available -
BD9S400MUF-C available available available available -