Monolithic fan controller
First Claim
1. A monolithic fan controller comprising:
- a driver circuit for providing a pulse train for driving a fan motor, varying said pulse train controlling a speed of said fan motor;
a thermal sense circuit for receiving a signal relating to a temperature and, in response thereto, for varying said pulse train; and
a fan rotation sense circuit for detecting pulses created by fan motor rotation and for generating a signal indicating non-rotation of said fan motor in response to an absence of said detecting pulses.
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Accused Products
Abstract
Disclosed herein is a monolithic fan controller circuit which provides the following features: a special start-up routine for the fan; a fan fault detector; a thermal fault detector; an automatic speed controller; a minimum speed controller; a routine for attempting to clear temporary fan faults; and a controllable drive signal frequency. A start-up control circuit provides an initial high duty-cycle kick to the fan in order to initiate the rotation of the fan. A temperature sensor, which may be external or internal to the monolithic fan controller, supplies a signal which is proportional to measured temperature. This signal is used to control the output pulse width of a pulse-width modulator (PWM) or control the frequency of a pulse frequency modulator (PFM). The PWM or PFM output signal regulates the speed of the brushless (or brush) DC fan motor. In a preferred embodiment, the monolithic fan controller has 8 pins.
124 Citations
21 Claims
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1. A monolithic fan controller comprising:
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a driver circuit for providing a pulse train for driving a fan motor, varying said pulse train controlling a speed of said fan motor; a thermal sense circuit for receiving a signal relating to a temperature and, in response thereto, for varying said pulse train; and a fan rotation sense circuit for detecting pulses created by fan motor rotation and for generating a signal indicating non-rotation of said fan motor in response to an absence of said detecting pulses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method performed by a monolithic fan controller comprising the steps of:
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initiating a start-up routine for rotating a fan motor; temporarily issuing a maximum pulse train signal for driving said fan motor; detecting the existence of pulses relating to rotation of said fan motor for determining whether said fan motor is rotating in a desired manner; issuing a fault signal if it is detected that said fan motor is not rotating in said desired manner; and issuing a pulse train signal, below said maximum pulse train signal, for driving said fan motor at a speed for maintaining a desired temperature, if it is detected that said fan motor is rotating in said desired manner. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification