Abstract: A contactless, inductive charger having a generally planar surface is provided. An image, text or other visual indicator is disposed upon the substantially planar surface such that the visual indicator represents a preferred placement orientation for an electronic device for optimal inductive charging. The charger includes a primary coil positioned within the boundaries of the image, such that a user has a visual guide for placing the device on the charging surface for maximum efficiency in charging. The visual indicator, which may be a picture, outline, text or other directional indicator, may be geometrically similar to a shape of the electronic device or may be in the shape of a generic device. It may be disposed upon the charger by a method selected from the group consisting of painting, molding, silk screening, plating, vapor deposition and adhesive retention.

Abstract: This invention includes an improvement to a power regulation and thermal management circuit. The power regulation and thermal management circuit includes a pass element coupled serially between a power source and a load. A voltage sensing circuit senses the voltage across the serial element and selects a corresponding current path based upon the sense voltage from a plurality of current paths. The invention includes a timing circuit that periodically, temporarily overrides the selection of current paths. The timing circuit generates a test pulse that temporarily turns all of the current paths on, thereby preventing a discharge lockout condition. The power regulation and thermal management circuit also includes a linear regulator to terminate charging at the appropriate voltage.

Abstract: Voltage regulators are exposed to extreme amounts of voltage over short periods of time during an electrostatic discharge (ESD) event. Shunt regulators require protection from ESD events. Capacitors are passive devices that allow current flow when not in a steady-state condition. An apparatus and method compensates for the extreme voltages inherent in ESD events. By providing capacitance across the gate-drain junction of the shunt device in combination with a gate resistor, a voltage can be applied to the gate of the active device upon commencement of an ESD event, and cause the active device to “turn on” The “turned on” active device provides a pathway for the excess voltage from the ESD event to follow and discharge so as to avoid catastrophic failures.

Abstract: This invention includes an improvement to a power regulation and thermal management circuit. The power regulation and thermal management circuit includes a pass element coupled serially between a power source and a load. A voltage sensing circuit senses the voltage across the serial element and selects a corresponding current path based upon the sense voltage from a plurality of current paths. The invention includes a filtering circuit coupled serially between the voltage sensing circuit and the plurality of current paths to reduce noise on the sensed pass element voltage. The power regulation and thermal management circuit also includes a linear regulator to terminate charging at the appropriate voltage. The invention includes a peak detection circuit with the linear regulator to reduce noise caused by, for example, a pulsing load during charging.

Abstract: This invention provides a means of protecting power dissipating pass elements from exceeding their predetermined thermal limits. In one preferred embodiment, the circuit protects a pass element in a battery charging circuit from exceeding its threshold junction temperature by predicting temperature based upon the voltage across the pass element and the current flowing through it. From this predicted temperature, current is reduced to provide charging of a battery at a constant power. The circuit includes a voltage sensing circuit and a plurality of comparators for selecting a predetermined current based upon the output of the voltage sensing circuit. The circuit provides a piecewise linear approximation of proper pass element voltage and current values to maintain a suitable threshold junction temperature.

Abstract: A method and apparatus provide for improved crowbar protection in a shunt regulator circuit including a shunt device. An over-temperature protection circuit may be combined with a fast-crowbar protection circuit such that maximum protection from damaging thermal energy is provided to a shunt device. The fast-crowbar protection circuit estimates the thermal energy in the shunt device based upon an integration method. By integrating a measured power over time the rise in temperature can be estimated such that the crowbar protection is enabled before the thermal energy can damage the shunt device. The integration method can be approximated using a piece-wise linear approximation such that the estimation circuitry can be simplified. A series of comparators and timing/delay circuits are employed to measure a current level in the shunt device over a given duration. The timing/delay circuits have memory such that heat build up and heat dissipation are modeled.

Abstract: This invention provides a means of protecting power dissipating pass elements from exceeding their predetermined thermal limits. In one preferred embodiment, the circuit protects a pass element in a battery charging circuit from exceeding its threshold junction temperature by predicting temperature based upon the voltage across the pass element and the current flowing through it. From this predicted temperature, current is reduced to provide charging of a battery at a constant power. The circuit includes a voltage sensing circuit and a plurality of comparators for selecting a predetermined current based upon the output of the voltage sensing circuit. The circuit provides a piecewise linear approximation of proper pass element voltage and current values to maintain a suitable threshold junction temperature.

Abstract: This invention includes an improvement to a power regulation and thermal management circuit. The power regulation and thermal management circuit includes a pass element coupled serially between a power source and a load. A voltage sensing circuit senses the voltage across the serial element and selects a corresponding current path based upon the sense voltage from a plurality of current paths. The invention includes a timing circuit that periodically, temporarily overrides the selection of current paths. The timing circuit generates a test pulse that temporarily turns all of the current paths on, thereby preventing a discharge lockout condition. The power regulation and thermal management circuit also includes a linear regulator to terminate charging at the appropriate voltage.

Abstract: This invention includes an improvement to a power regulation and thermal management circuit. The power regulation and thermal management circuit includes a pass element coupled serially between a power source and a load. A voltage sensing circuit senses the voltage across the serial element and selects a corresponding current path based upon the sense voltage from a plurality of current paths. The invention includes a filtering circuit coupled serially between the voltage sensing circuit and the plurality of current paths to reduce noise on the sensed pass element voltage. The power regulation and thermal management circuit also includes a linear regulator to terminate charging at the appropriate voltage. The invention includes a peak detection circuit with the linear regulator to reduce noise caused by, for example, a pulsing load during charging.

Abstract: A protection circuit (100) and protection device (300) for protecting a rechargeable (lithium-based) battery cell or cells from overcharging. A voltage regulator element (110, 310) is connected in parallel with the battery cell or cells (5) and is thermally coupled to a thermal element (120, 322, 326) connected in series with the charging current supply. The voltage regulator element (110, 310) prevents overcharging of the battery (5) by shunting current away from the battery when a predetermined voltage across the battery is exceeded. Moreover, the thermal element (120, 322, 326) prevents failure of the voltage regulator element (110, 310) by open circuiting the current path when the heat dissipated by the voltage regulator element (110, 310), thermally coupled to the thermal element (120, 322, 326) causes the thermal element to enter a high resistance state.

Abstract: This invention includes a circuit that approximates the thermal behavior of a fuse or other electronic device that is coupled in series with the circuit. In one preferred embodiment, the circuit protects a fuse coupled in series with a rechargeable battery from clearing during soft short conditions. Thus, when the instantaneous current is temporarily above the current rating of the fuse, yet the root mean squared current is below the current rating of the fuse, the circuit works to estimate the heating of the fuse element and limit the current to a root mean squared value that is less than the current rating of the fuse. One embodiment includes a programmable comparator that actuates a counter which, in turn, increments to estimate heating of the element when the current exceeds a predetermined threshold.

Abstract: This invention includes a current limiting circuit comprised of an array of switch-fuse pairs. Switches are coupled in series with fuses to form fuse-switch pairs. The fuse switch pairs are coupled in parallel forming an equivalent fuse. A current censing circuit senses the current flowing in the equivalent fuse. When the current exceeds a predetermined threshold, the current sense circuit actuates a control circuit that clears the fuses by opening all the transistors save one. This forces the entire current through a single fuse, causing it to clear. Each fuse is cleared in similar fashion in much the same way that a zipper is opened one tooth at a time. In other words, under normal conditions, all switches are on and each fuse carries Ta/n amps, where Ta is the current rating of the fuse and n is the number of fuses. If all but one transistor is turned off, then Ta amps would flow through a single fuse. If the fuse were rated for 2Ta/n, the fuse would clear.

Abstract: This invention includes a trickle charging circuit that works with a series charging element to charge battery cells with a low, constant current when the voltage of the cell is below a predetermined operational range. The trickle charging circuit includes a control transistor that is actuated by a current source when both the power supply and undervoltage battery cell are coupled. The trickle charging continues until a minimum operational voltage of the cell is reached. The invention includes a means for rapid charging the cell once the cell voltage is within a preferred operational range. The circuit includes means for charging at other currents, like mid-rate currents, as well.

Abstract: A fusing device with an adjustable current rating. The fusing device has a common conductive trace, a plurality of individual conductive traces, and a plurality of fusible links. Each fusible link electrically connects the common conductive trace with a corresponding individual conductive trace, and each fusible link has a current rating. The current ratings of the plurality of fusible links are substantially identical to each other or different. Each fusible link can have one or more fusible elements. The fusible elements can be coupled in parallel or in series. Optionally, at least one fusible element can be trimmed through an intermediate terminal. Fusible links can be disposed in a same surface of a substrate or in different surfaces of the substrate.

Abstract: This invention includes a circuit that approximates the thermal behavior of a fuse or other electronic device that is coupled in series with the circuit. In one preferred embodiment, the circuit protects a fuse coupled in series with a rechargeable battery from clearing during soft short conditions. Thus, when the instantaneous current is temporarily above the current rating of the fuse, yet the root mean squared current is below the current rating of the fuse, the circuit works to estimate the heating of the fuse element and limit the current to a root mean squared value that is less than the current rating of the fuse. One embodiment includes a programmable comparator that actuates a counter which, in turn, increments to estimate heating of the element when the current exceeds a predetermined threshold.

Abstract: This invention is a series current regulator with an on-silicon temperature sensing means which forms an improved over current battery protection device. The invention regulates current in a pass element linearly while sensing the junction temperature of the pass element. If the temperature of the pass element reaches a predetermined threshold, the on-silicon temperature sensing means actuates a switch which causes the pass element to go into an open, or high-impedance, mode. The invention offers advantages over positive temperature coefficient (PTC) devices including smaller size, lower manufacturing defect incidents, improved performance, and improved circuit integration characteristics. The temperature response of a PTC can be exactly replicated with the present invention. Further, the invention offers advantages over PTC devices including faster trip time and lower leakage current.

Abstract: This invention includes a battery overprotection device comprising a thermal resistor, a zener diode, a pass element and a control circuit. The thermal resistor is used as an over-temperature limiting device, rather than an overcurrent device. By thermally coupling the thermal resistor to the zener diode, the thermal resistor protects the zener diode from “burning up” as a result of continuous power dissipation. When the zener is subjected to continuous power dissipation, its temperature rises. As the temperature rises, the thermal resistor's impedance increases, thereby reducing the power dissipation in the zener. The zener/thermal resistor combination serves as an auxiliary safety circuit for the transistor and control circuit.

Abstract: In a fault-tolerant integrated power circuit, a plurality of power transistors, each having a power source electrically coupled to a common source line, a power gate and a power drain electrically coupled to a common drain line, is capable of driving a power current from the source line to the drain line. A first plurality of control transistors, each having a first source, a first gate and a first drain, is disposed so that the first drain of each of the first plurality of control transistors is electrically coupled to a corresponding power gate of a different one of the power transistors. A first transistor control circuit generates a first control signal that is electrically coupled to each first gate of the first plurality of control transistors.

Abstract: This invention is a battery charging system that charges rechargeable battery cells by tracking a voltage profile charging curve across time. As all lithium based, like voltage cells have the same voltage profile across time, regardless of capacity, the invention presents a preferred embodiment of a universal charger capable of charging lithium batteries of varying capacities. Current is treated as a variable dependent upon voltage. Thus, in a preferred embodiment, cells of varying capacities will be charged at an optimal rate, thereby optimizing battery performance. One embodiment uses frequency selection to vary the rate of change in the output voltage of the system, thereby tracking the voltage profile charging curve across time.

Abstract: A battery charging and protection circuit that features a single transistor to control current flow in two directions. The circuit comprises first and second input terminals to which a charging current is coupled, wherein a voltage between the first and second input terminals is limited to a maximum value. The circuit has first and second output terminals to which at least one rechargeable battery cell is coupled. A single transistor is coupled in series between the first input terminal and the first output terminal and is operated to control current flow both in a direction from the first input terminal to the first output terminal, and in a direction from the first output terminal to the first input terminal.