Fan control circuit
AssigneeHewlett-Packard Development Company, L.P.
InventorJérome Krief
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Abstract
The invention relates to a motor control circuit for a computer system fan motor, comprising a temperature sensor, a sensor amplifier, a fan command for applying a voltage to the fan motor according to the output of the sensor amplifier, and feedback control means. The circuit of claim also comprises means for stopping the supply of voltage across the fan motor terminals, irrespective of the output of the temperature measuring means. The sensor amplifier allows easy setting of the parameters of the voltage according to the temperature measured by the temperature sensor.
Claims22
A motor control circuit for a computer system fan motor, comprising a temperature measuring circuit for outputting a signal representative of the voltage to be applied across fan motor terminals, and a feedback control arrangement for applying a voltage across fan motor terminals according to said signal,
- wherein the feedback control arrangement comprises subtraction circuitry, fan control circuitry, and a feedback loop, said subtraction circuitry receiving the signal outputted by said temperature sensing circuit and a signal outputted by said feedback loop, and outputting to the fan control circuitry a signal representative of a difference between the signal outputted by said temperature sensing circuit and the signal outputted by said feedback loop, said fan control subtraction circuit applying across said fan motor terminals a voltage representative of the signal supplied by the subtraction circuitry, said feedback loop outputting to said subtraction circuitry a signal representative of the voltage applied to the fan motor terminals.
A computer comprising a fan motor connected to a circuit, the circuit comprising:
- a temperature measuring circuit for outputting a signal representative of the voltage to be applied across fan motor terminals;
- a capacitor in parallel to the fan motor terminals;
- and
- feedback control means for applying a voltage across fan motor terminals according to said signal.
A motor control circuit for a computer system fan motor wherein the voltage applied to the fan motor varies between a lower voltage and a higher voltage, comprising:
- a temperature measuring circuit for outputting a signal representative of the voltage to be applied across fan motor terminals, the temperature measuring circuit comprising a thermistor and a sensor amplifier, the sensor amplifier comprising a comparator for comparing the voltage across the thermistor with a reference voltage and for outputting a difference signal representative of the difference between the voltage across the thermistor and the reference voltage, said sensor amplifier comprising circuitry for adding to said difference signal a signal representative of a lower value of said signal;
- a feedback control arrangement for applying a voltage across fan motor terminals according to said signal, the feedback control arrangement comprising subtracting circuitry, fan control circuitry, and a feedback loop, said subtracting circuitry receiving the signal outputted by said temperature sensing circuit and a signal outputted by said feedback loop, and outputting to the fan control circuitry a signal representative of the difference between the signal outputted by said temperature sensing circuit and the signal outputted by said feedback loop, said fan control circuit applying across said fan motor terminals a voltage representative of the signal supplied by the subtracting circuitry, said feedback loop outputting to said subtracting circuitry a signal representative of the voltage applied to the fan motor terminals.
A computer comprising a fan motor connected to a circuit, wherein the voltage applied to the fan motor varies between a lower voltage and a higher voltage, the circuit comprising:
- a temperature measuring circuit for outputting a signal representative of the voltage to be applied across fan motor terminals, the temperature measuring circuit comprising a thermistor and a sensor amplifier, the sensor amplifier comprising a comparator for comparing the voltage across the thermistor with a reference voltage and for outputting a difference signal representative of the difference between the voltage across the thermistor and the reference voltage, said sensor amplifier comprising circuitry for adding to said difference signal a signal representative of a lower value of said signal;
- a capacitor in parallel to the fan motor terminals;
- and
- a feedback control arrangement for applying a voltage across fan motor terminals according to said signal, the feedback control arrangement comprising subtracting circuitry, fan control circuitry, and a feedback loop, said subtracting circuitry receiving the signal outputted by said temperature sensing circuit and a signal outputted by said feedback loop, and outputting to the fan control circuitry a signal representative of the difference between the signal outputted by said temperature sensing circuit and the signal outputted by said feedback loop, said fan control circuit applying across said fan motor terminals a voltage representative of the signal supplied by the subtracting circuitry, said feedback loop outputting to said subtracting circuitry a signal representative of the voltage applied to the fan motor terminals.
A motor control circuit for a computer system fan motor, comprising a temperature measuring circuit for outputting a signal representative of the voltage to be applied across fan motor terminals, a capacitor in parallel to the fan motor terminals, and a feedback control arrangement for applying a voltage across fan motor terminals according to said signal.
Dependencies are inferred from the claim text.