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DC/DC converter controls DC fan motor speed and saves space

Offering a 75% reduction in mounting area compared with that of discrete configurations, the buck DC/DC converter is optimised for DC fan motor power supplies used in applications such as cold air circulation in refrigerators.

Typically, such DC fan motor power supply blocks are configured using discrete components, making it difficult to provide high accuracy control or carry out high frequency drive, says the company. Consequently, larger coils and output capacitors are needed for the peripheral circuit, which increases the mounting area required.

The BD9227F power supply IC controls the rotational speed of DC fan motors. It ensures accuracy through linearly varying the output voltage based on the PWM duty signal generated by the microcontroller. According to the company, it offers more accurate control compared with conventional discrete configurations, 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.

The IC also leverages proprietary IC analogue circuit design technology, to optimise the circuit and high frequency (1MHz) drive. This allows 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), claims the company. All combine to deliver greater accuracy, increased miniaturisation, and higher power conversion efficiency in DC fan motor applications, says the company.

A high-side PMOS facilitates the generation of 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). Operating temperature range is -40 to 85°C.

 



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