Speed control circuit of brushless DC fan motor
First Claim
1. A speed control circuit of a brushless DC fan motor which is driven by a drive circuit, and controlled in the rotational speed thereof by controlling the voltage of a control input terminal of the drive circuit comprising:
- a differential amplifier in which the voltage signal for controlling the speed is inputted in a first input terminal and the reference voltage signal is inputted in a second input terminal, wherein the differential amplifier is linear in the input-output characteristic, and can set a rise characteristic of a desired gradient, and give the voltage signal from the output terminal of the differential amplifier to the control input terminal of the drive circuit.
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Accused Products
Abstract
There is provided a brushless DC fan motor which can eliminate an oscillator for PWM, control the motor speed at a low cost with high accuracy, and efficiently adjust the temperature in a housing for electronic appliances when radiating the heat in the housing. The brushless DC fan motor with the rotational speed thereof controlled by controlling the voltage of a control input terminal of a drive circuit comprises a differential amplifier in which the voltage signal for controlling the speed is inputted in a first input terminal and the reference voltage signal is inputted in a second input terminal. The differential amplifier is linear in the input-output characteristic, and can set the rise characteristic of a desired gradient, and control the motor speed with high accuracy without using the PWM signal for the input signal. The voltage signal from the output terminal of the differential amplifier is given to the control input terminal of the drive circuit.
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Citations
6 Claims
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1. A speed control circuit of a brushless DC fan motor which is driven by a drive circuit, and controlled in the rotational speed thereof by controlling the voltage of a control input terminal of the drive circuit comprising:
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a differential amplifier in which the voltage signal for controlling the speed is inputted in a first input terminal and the reference voltage signal is inputted in a second input terminal, wherein the differential amplifier is linear in the input-output characteristic, and can set a rise characteristic of a desired gradient, and give the voltage signal from the output terminal of the differential amplifier to the control input terminal of the drive circuit. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification