Mirror element drive circuit with fault protection
First Claim
1. A rearview mirror element drive circuit, comprising:
- a controller configured to receive an actual element voltage signal, an actual element current signal and an element drive transistor power dissipation signal, said controller is further configured to detect a fault condition by comparing said actual element voltage signal to a desired voltage value, comparing said actual element current to a desired current value, comparing said element drive transistor power dissipation signal to a maximum power value, a sub-combination thereof or a combination thereof.
1 Assignment
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Accused Products
Abstract
In at least one embodiment a fault sense circuit includes a current sense device, a voltage sense device, a power sense device, a sub-combination thereof or a combination thereof. The current sense device is positioned to sense a drive current provided to a load by a drive circuit. The voltage sense device is coupled across the current sense device and receives a threshold signal at a first input and provides an output signal on an output whose value is dependent upon whether a sense signal at a second input is above or below the threshold signal. A level of the threshold signal changes in response to a voltage level of a power supply that supplies the drive current to the drive circuit.
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Citations
59 Claims
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1. A rearview mirror element drive circuit, comprising:
a controller configured to receive an actual element voltage signal, an actual element current signal and an element drive transistor power dissipation signal, said controller is further configured to detect a fault condition by comparing said actual element voltage signal to a desired voltage value, comparing said actual element current to a desired current value, comparing said element drive transistor power dissipation signal to a maximum power value, a sub-combination thereof or a combination thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A rearview mirror element drive circuit, comprising:
a controller configured to receive an actual element voltage signal, said controller is further configured to detect a fault condition by comparing said actual element voltage signal to a desired voltage value. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A rearview mirror element drive circuit, comprising:
a controller configured to receive an actual element voltage signal and an actual element current signal, said controller is further configured to detect a fault condition by comparing said actual element voltage signal to a desired voltage value and by comparing said actual element current signal to an actual element current signal. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A rearview mirror element drive circuit, comprising:
a controller configured to receive an actual element current signal, said controller is further configured to detect a fault condition by comparing said actual element current signal to a desired current value. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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47. A rearview mirror element drive circuit, comprising:
a controller configured to receive an element drive transistor power dissipation signal, said controller is further configured to detect a fault condition by comparing said element drive transistor power dissipation signal to a desired voltage value. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59)
Specification