Controlling a thermally sensitive over-current protector
First Claim
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1. A circuit for over-current protection, comprising:
- a current sense and control circuit to be coupled to monitor a load current, and provide a control signal that is responsive to the monitored load current exceeding a predetermined threshold for a predetermined time interval;
an automatically resettable, thermally sensitive over-current protector that conducts the load current;
an electrical heating element that is in proximity to the resettable, thermally sensitive over-current protector and is to conduct a heating current, being separate from the load current; and
a current source circuit having a control input coupled to receive the control signal, wherein the current source circuit is coupled to the electrical heating element that is in proximity to the resettable, thermally sensitive, over-current protector, wherein the current source circuit is to raise the heating current through the electrical heating element in accordance with the control signal to a high enough level that causes the over-current protector to trip.
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Abstract
A method for controlling a thermally sensitive over-current protector is described. A battery current is monitored. It is then determined whether or not the monitored current has exceeded a predetermined threshold during the entirety of a predetermined time interval. If yes, then a current source is signaled to raise its current, so as to increase the heat being generated by a heating element that is being driven by the current source thereby tripping the thermally sensitive over-current protector. Other embodiments are also described and claimed.
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Citations
23 Claims
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1. A circuit for over-current protection, comprising:
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a current sense and control circuit to be coupled to monitor a load current, and provide a control signal that is responsive to the monitored load current exceeding a predetermined threshold for a predetermined time interval; an automatically resettable, thermally sensitive over-current protector that conducts the load current; an electrical heating element that is in proximity to the resettable, thermally sensitive over-current protector and is to conduct a heating current, being separate from the load current; and a current source circuit having a control input coupled to receive the control signal, wherein the current source circuit is coupled to the electrical heating element that is in proximity to the resettable, thermally sensitive, over-current protector, wherein the current source circuit is to raise the heating current through the electrical heating element in accordance with the control signal to a high enough level that causes the over-current protector to trip. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A battery pack circuit comprising:
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a positive battery pack terminal and a negative battery pack terminal; an automatically resettable thermally sensitive over-current protector coupled in series with one of the positive or negative battery pack terminals to conduct battery charging current and battery discharging current; an electrical heating element in proximity with the over-current protector that is to conduct a heating current separate from the battery charging current and the battery discharging current being conducted by the over-current protector; a current sense and control circuit coupled to monitor battery pack current through the positive pack terminal or the negative pack terminal and provide a control signal that is responsive to the monitored current exceeding a predetermined threshold for a predetermined time interval; and a current source circuit having a control input coupled to receive the control signal, wherein the current source circuit is coupled to the electrical heating element and is to raise the heating current through the electrical heating element in accordance with the control signal to a high enough level that trips the over-current protector. - View Dependent Claims (12, 13, 14, 15)
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16. A portable electronic system comprising:
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a) a touch screen system; b) a communications network interface; c) electro-acoustic transducer interface circuitry; d) a programmable processor coupled to the touch screen, communications network interface and electro-acoustic transducer circuitry and programmed to run a touchscreen graphical user interface, a telephony application, and a digital audio player application; e) a battery to supply battery current for powering the elements a)-d); f) an automatically resettable, thermally sensitive, over-current protector in series with the battery and the elements a)-d) so as to conduct battery current; g) an electrical heating element in proximity with the over-current protector that is to conduct a heating current separate from the battery current; h) a current sense and control circuit coupled to monitor the battery current, and provide a control signal that is responsive to the monitored current exceeding a predetermined threshold for a predetermined time interval; and i) a variable current source circuit having a control input coupled to receive the control signal, wherein the current source circuit is coupled in series with the electrical heating element and is to raise the heating current through the electrical heating element in accordance with the control signal, wherein the current sense and control circuit is to select the heating current as any one of a plurality of discrete current levels and signal the variable current source circuit to raise the heating current to the selected level, which is a high enough level that causes the over-current protector to trip. - View Dependent Claims (17, 18, 19)
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20. A method for controlling an automatically resettable, thermally sensitive over-current protector, comprising:
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monitoring battery current through the automatically resettable, thermally sensitive over-current protector; and determining whether or not the monitored current has exceeded a predetermined threshold during the entirety of a predetermined time interval, wherein if the threshold has been determined to be exceeded, then a current source is signaled to raise a heating current through a heating element, which is separate from the monitored battery current, to a high enough level thereby tripping the automatically resettable, thermally sensitive over-current protector. - View Dependent Claims (21, 22, 23)
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Specification