Current magnitude sensing circuit
First Claim
1. An apparatus adapted to monitor its operation, the apparatus comprising:
- a device adapted to operate when supplied power;
a pulse detection circuit for generating a trigger signal depending on the frequency of periodic drops in current magnitude of a current flowing through the device relative to a first frequency value, and for canceling the trigger signal depending on the frequency of periodic drops in current magnitude of the current flowing through the device relative to a second frequency value which is different than the first frequency value, wherein the trigger signal comprises a variable analog voltage; and
a pulse decision circuit coupled to the pulse detection circuit for providing an output signal indicative of the frequency of periodic drops in the current magnitude of the current flowing through the device in response to the trigger signal, wherein the output signal indicates whether the device is operating properly.
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Accused Products
Abstract
A current magnitude sensing circuit for detecting a malfunction of a DC brushless fan. The current magnitude sensing circuit detects drops in the current magnitude in windings of a fan motor. Depending on the frequency of the current drops in the fan current, the current magnitude sensing circuit outputs either a high or a low voltage signal. The current magnitude sensing circuit operates by charging a capacitor beyond a certain voltage and thereby providing a high fan fail output signal when a fan is spinning too slowly for proper cooling of a device. Another capacitor is charged at a different time constant for setting the fan fail output of the current magnitude circuit low for indicating that the fan is spinning sufficiently fast.
43 Citations
14 Claims
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1. An apparatus adapted to monitor its operation, the apparatus comprising:
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a device adapted to operate when supplied power; a pulse detection circuit for generating a trigger signal depending on the frequency of periodic drops in current magnitude of a current flowing through the device relative to a first frequency value, and for canceling the trigger signal depending on the frequency of periodic drops in current magnitude of the current flowing through the device relative to a second frequency value which is different than the first frequency value, wherein the trigger signal comprises a variable analog voltage; and a pulse decision circuit coupled to the pulse detection circuit for providing an output signal indicative of the frequency of periodic drops in the current magnitude of the current flowing through the device in response to the trigger signal, wherein the output signal indicates whether the device is operating properly. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus adapted to monitor its operation, the apparatus comprising:
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a device adapted to operate when supplied power; a pulse detection circuit for generating a trigger signal indicative of the frequency of periodic drops in current magnitude of a current flowing through the device relative to a first frequency value, and for canceling the trigger signal depending on the frequency of periodic drops in current magnitude of the current flowing through the device relative to a second frequency value which is different than the first frequency value, wherein the trigger signal comprises a variable analog voltage; and a processor coupled to the pulse detection circuit for providing an output signal indicative of the frequency of periodic drops in the current magnitude of the current flowing through the device in response to the trigger signal, wherein the output signal indicates whether the device is operating properly.
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13. A process for sensing a frequency of periodic drops in current magnitude of a current flowing through a device, the process comprising the steps of:
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providing a trigger signal depending on the frequency of periodic drops in current magnitude of a current flowing through a device relative to a first frequency value, wherein the trigger signal comprises a variable analog voltage; generating an output signal indicative of the frequency of periodic drops in the current magnitude of the current flowing through a device relative to the trigger signal; and canceling the trigger signal depending on the frequency of periodic drops in current magnitude of the current flowing through a device relative to a second frequency value which is different than the first frequency value, wherein the output signal indicates whether the device is operating properly.
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14. An apparatus for sensing a frequency of periodic drops in current magnitude of a current flowing through a device, the apparatus comprising:
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means for generating a trigger signal depending on the frequency of periodic drops in current magnitude of a current flowing through the device relative to a first frequency value, wherein the trigger signal comprises a variable analog voltage; means for generating an output signal indicative of the frequency of periodic drops in the current magnitude of a current flowing through the device relative to the trigger signal; and means for canceling the trigger signal depending on the frequency of periodic drops in current magnitude of a current flowing through the device relative to a second frequency value which is different than the first frequency value, wherein the output signal indicates whether the device is operating properly.
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Specification