DC/DC converter controls DC fan motor speed

Typically, DC fan motor power supply blocks used in refrigerators and other equipment are primarily configured using discrete components, making it difficult to provide high accuracy control or carry out high frequency drive, says the company. As a result, larger coils and output capacitors are required for the peripheral circuit, increasing the mounting area required.

According to the company, the BD9227F is the industry’s first power supply IC capable of controlling the rotational speed of DC fan motors. Accuracy is assured by linearly varying the output voltage based on the PWM duty signal generated by the microcontroller. It offers more accurate control compared with conventional discrete configurations, says the company, where there is no output voltage linearity with respect to the pulse duty supplied to the PWM terminal, making it difficult to accurately control the motor rotational speed.

This IC also leverages proprietary IC analogue circuit design technology, for circuit optimization and high frequency (1MHz) drive. This supports the use of smaller peripheral components (i.e. coil, output capacitor), reducing footprint by 75%, and also improves power conversion efficiency by 19% (at 300mA output). All combine to deliver greater accuracy, increased miniaturisation, and higher power conversion efficiency in DC fan motor applications, says the company.

Finally, integrating a high-side PMOS makes it possible to generate an output voltage at 100% duty, which, the company points out, is rare for an IC.

The BD9227F is supplied in an SOP8 (5.0 x 6.2 x 1.7mm) and operates at -40 to +85°C.