BD9227F：Step-down DC-DC Converter to Drive DC Fan Motor : Integrated Discrete Components for Higher Precision, Efficiency and Smaller Size

As with other electronic equipment, in recent years there have been mounting demands for intelligent, compact, and highly efficient motors. Nearly 50% of the world consumption of electric power is used to drive motors, and there is an urgent need to respond to these demands.

The BD9227F is the industry’s first* power supply IC capable of controlling the rotational speed of DC fan motors with the high precision that would be difficult using conventional discrete components, achieved by linear control of the output voltage according to a PWM signal generated by the MCU. Through control optimization achieved by component integration, efficiency is dramatically improved, the number of components is decreased and faster switching is possible to enable miniaturization of peripheral components, so that the footprint can be reduced drastically. (*ROHM survey as of Nov. 18, 2016)

The BD9227F is a non-synchronous (diode) rectifying PWM-control step-down converter with 20 V input and 1 A output, optimized for DC fan motor power supplies. It incorporates a high-side power MOSFET, and the operating frequency is fixed at 1 MHz. Phase compensation is simplified by current-mode control and there are few external components; a ceramic output capacitor can be used. It is also equipped with overcurrent and overvoltage protection, thermal shutdown, and undervoltage lockout functions, and uses a compact SOP8 package. Its main features are as follows.

BD9227F

Discrete Components Integrated into IC

Conventional power supplies for DC fan motors, installed in refrigerators and other products, have mainly been configured using discrete components. By integrating these components into ICs, it has been possible to achieve high-precision control, enhanced efficiency, and more compact peripherals, resulting from fewer components and faster operation. Compared with discrete-component designs, efficiency has been increased by 19%, and footprint has been slashed by 75%.