Short-circuit detection for half-bridge peak-and-hold pre-driver
First Claim
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1. An apparatus for detecting faults on outputs of a half-bridge, peak-and-hold pre-driver (driver) having a high side output and a low side output, the apparatus comprising:
- a first current sensor coupled between a first switch, which turns on and off responsive to signals received by the first switch from the driver, and a power supply, the first current sensor providing a first signal representing current flowing into a load from the power supply when the first switch is on;
a first peak detector coupled to the first current sensor and providing a first output signal representing a substantially instantaneous peak value of current flowing into the load from the power supply when the first switch is on;
a second current sensor coupled between a second switch, which turns on and off responsive to signals received by the second switch from the driver, and a reference potential for the power supply, the second current sensor providing a second signal representing current flowing out of the load and into the reference potential;
a second peak detector coupled to the second current sensor and providing a second output signal corresponding to a substantially instantaneous peak value of current flowing out of the load and into the reference potential node;
a comparator coupled to the first and second peak detectors and coupled to the driver, the comparator configured to turn off the driver within a predetermined amount of time, when the first output signal from the first peak detector exceeds the second output signal from the second peak detector by an amount greater than a first predetermined threshold amount.
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Abstract
Current sensors measure current flowing into and out of an inductive load such as a solenoid coil and provide signals to a processor when the difference between the two measured currents exceeds a threshold. A solenoid coil and electronic devices driving it are protected from damage caused by a short circuit at the connections to the coil.
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Citations
11 Claims
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1. An apparatus for detecting faults on outputs of a half-bridge, peak-and-hold pre-driver (driver) having a high side output and a low side output, the apparatus comprising:
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a first current sensor coupled between a first switch, which turns on and off responsive to signals received by the first switch from the driver, and a power supply, the first current sensor providing a first signal representing current flowing into a load from the power supply when the first switch is on; a first peak detector coupled to the first current sensor and providing a first output signal representing a substantially instantaneous peak value of current flowing into the load from the power supply when the first switch is on; a second current sensor coupled between a second switch, which turns on and off responsive to signals received by the second switch from the driver, and a reference potential for the power supply, the second current sensor providing a second signal representing current flowing out of the load and into the reference potential; a second peak detector coupled to the second current sensor and providing a second output signal corresponding to a substantially instantaneous peak value of current flowing out of the load and into the reference potential node; a comparator coupled to the first and second peak detectors and coupled to the driver, the comparator configured to turn off the driver within a predetermined amount of time, when the first output signal from the first peak detector exceeds the second output signal from the second peak detector by an amount greater than a first predetermined threshold amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of detecting faults on the outputs of a half-bridge, peak-and-hold pre-driver (driver) having a high side output and a low side output, the method comprising:
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monitoring current flowing into a load from a power supply, the current from the power supply and flowing into the load passing through a first switch, which turns on and off to modulate the current flowing into the load, responsive to signals provided to the first switch by the driver, generating a first load current signal, which represents the current flowing into the load when the first switch is on; determining a peak in the magnitude of the current flowing through the load when the first switch is on; monitoring current flowing from the load into a reference potential through a second switch, which turns on and off responsive to signals provide to the second switch by the driver, generating a second load current signal representing the current flowing from the load to the reference potential when the second switch is on; determining a peak in the magnitude of the current flowing out of the load and into the reference potential when the second switch is on; and providing signals to the first and second switches that reduces or shuts off current passing through them, when a peak in the magnitude of the current flowing into the load from the power supply while the first switch is on, exceeds by a predetermined amount, a peak in the magnitude of the current flowing out of the load and into the reference potential when the second switch is on. - View Dependent Claims (10)
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11. The method of step 9, wherein determining a peak in the magnitude of the current flowing through the load when the first switch is on is performed by a first peak detector, wherein determining a peak in the magnitude of the current flowing out of the load and into the reference potential when the second switch is on is performed by a second peak detector, wherein the first and second peak detectors each comprise a diode, which is connected between a current sensor and, a capacitance and resistance connected in parallel to each other, the parallel connected resistance and capacitance being connected between the diode and the reference potential.
Specification