Patent ID: 6380704
Filing Date: 2002-04-30
Classification: F04D,H02P,Y02B

Abstract:
A fan linear speed controller for controlling the rotation speed of a fan by an external fan control voltage (FANC), comprising:a temperature sensor unit having a thermistor for detecting the ambient temperature around said fan to generate a thermally sensitive voltage (VRI); a linear speed control unit for receiving said fan control voltage (FANC) and said thermally sensitive voltage (VRI) to generate an output voltage (OUT) for applying to said fan, wherein said output voltage (OUT) is proportional to said fan control voltage (FANC) when said thermally sensitive voltage (VRI) is lower than a preset threshold voltage (VT) and said fan control voltage (FANC) is higher than a preset reference voltage (VR), wherein the linear speed control unit comprises: a logic controller for receiving said fan control voltage (FANC), said thermally sensitive voltage (VR1), said reference voltage (VR), said threshold voltage (VT) and an input voltage (VIN) that is a preset portion of said fan control voltage (FANC) for selectively supplying said input voltage (VIN); and a voltage level shifter connected to said logic controller for receiving said input voltage (VIN) from said logic controller and transforming said received input voltage (VIN) to said output voltage (OUT) to drive said fan.