Chapter 1
Introduction
1.1 Introduction
This document describes the implementation of a DC brushless fan controller using the Freescale ultra low cost MC9RS08KA2
VARIABLE RESISTOR
(TO EMULATE A TEMPERATURE SENSOR)
MC9RS08KA2
MCU IN
SOIC PACKAGE
BUZZER
Figure 1-1. The MC9RS08KA2 DC Fan Reference Design
The DC fan used is a brushless DC motor fan. It is widely used in chip cooling or system ventilation applications. In the market, most of the DC fans are of the constant air flow design. As the high performance electronic products continue to increase, cooling requirement becomes more and more sophisticated. MCU approach provides a cost effective solution to this application. There are several advantages of a MCU based design over traditional solutions.
1.Instead of having a constant air flow the MCU provides enough processing power to modify the fan speed according to environment changes such as the temperature of the target system.
2.Fault detection can easily be implemented by the MCU. For example, the MCU can detect for the air flow blocking or motor jam, the motor driver can be stopped completely to avoid further damage.
3.Buzzer alarm or digital output acknowledgement can be generated under the faulty situation.
The MCU chosen for this purpose must be low cost and it must provide small geometry package to integrate into the fan controller printed circuit board (PCB). The MC9RS08KA2 is ideal for this application.
Variable Speed DC Fan Control using the MC9RS08KA2, Rev. 0
Freescale Semiconductor | 7 |
