Abstract: A multimode receiver can include on or more of an over-voltage protection circuit or a high frequency mode switch. As such, some embodiments of a multi-mode receiver includes a rectifier; a high frequency circuit coupled to the rectifier; a low frequency circuit coupled to the rectifier; and a switching circuit coupled to disable at least a portion of the low frequency circuit while the multi-mode receiver operates in high frequency mode. In some embodiments, the multimode receiver further includes a high-voltage protection circuit coupled to the high frequency circuit that detunes the high frequency circuit when a high-voltage condition is detected.

Abstract: A multimode receiver can include on or more of an over-voltage protection circuit or a high frequency mode switch. As such, some embodiments of a multi-mode receiver includes a rectifier; a high frequency circuit coupled to the rectifier; a low frequency circuit coupled to the rectifier; and a switching circuit coupled to disable at least a portion of the low frequency circuit while the multi-mode receiver operates in high frequency mode. In some embodiments, the multimode receiver further includes a high-voltage protection circuit coupled to the high frequency circuit that detunes the high frequency circuit when a high-voltage condition is detected.

Abstract: A power circuit includes a plurality of LED strings, each LED string having multiple LEDs connected in series. A plurality of magnetic amplifiers, reset current sources, and a control circuit are used to drive each LED string with equal current and to independently regulate the amount of voltage supplied to each LED to maximize efficiency. One magnetic amplifier, one reset current source, and one current sink are dedicated to each LED string. The control circuit measures the voltage drop across each LED string and determines an amount of reset control current in response to the measured voltage drop. The reset control current is supplied by the reset current source to the magnetic amplifier dedicated to the regulated LED string. The amount of reset control current supplied to the magnetic amplifier dictates the amount of voltage supplied to the LED string.

Abstract: A power circuit include a plurality of LED strings, each LED string having multiple LEDs connected in series. A plurality of magnetic amplifiers, reset current sources, and a control circuit are used to drive each LED string with equal current and to independently regulate the amount of voltage supplied to each LED to maximize efficiency. One magnetic amplifier, one reset current source, and one current sink are dedicated to each LED string. The control circuit measures the voltage drop across each LED string and determines an amount of reset control current in response to the measured voltage drop. The reset control current is supplied by the reset current source to the magnetic amplifier dedicated to the regulated LED string. The amount of reset control current supplied to the magnetic amplifier dictates the amount of voltage supplied to the LED string.

Abstract: The present invention contemplates a variety of improved techniques for the fast switching of current through, among others, LED loads. A current shunting device is utilized to divert current away from a load at high speed when activated, thus enabling the control of the amount current that flows through the load.

Abstract: The present invention contemplates a variety of improved techniques for the fast switching of current through, among others, LED loads. A current shunting device is utilized to divert current away from a load at high speed when activated, thus enabling the control of the amount current that flows through the load.

Abstract: Class D amplifiers and methods of amplification wherein a load is periodically coupled to a positive power supply connection through a first switch or a negative power supply connection through a second switch for a period responsive to an input signal. A third switch couples the load to a circuit ground connection during times when the load is not coupled to either the positive or the negative power supply connection. This provides a load current recirculation path through the ground connection, which together with the inductance of the load, tends to maintain the load current when both the first and second switches are open. Loads such as speakers may be directly connected to the amplifier output, or may be coupled to the amplifier output through a filter. Various exemplary control methods, including use of feedback, are disclosed.

Abstract: Secondary side synchronous rectifier driver circuits with adaptive turn-off of each of a pair of synchronous rectifiers in the secondary circuit of isolated and non-isolated transformer coupled power supplies having a continuous inductor current. When a respective turnoff signal is received from the controller, each synchronous rectifier driver senses the synchronous rectifier switch current, and holds the respective synchronous rectifier switch on until the current in the switch goes to zero, indicating a proper charging or discharging of the transformer leakage inductance. This may be done, for example for a FET synchronous rectifier, by sensing the drain-source voltage and turning the FET off when the drain-source voltage goes to zero. This minimizes synchronous rectifier body diode or external Schottky diode conduction and energy loss. Other current sensing techniques may also be used, including but not limited to, current sense resistors and current sensing transformers.

Abstract: Hot swappable pulse width modulation power supply circuits preferably realized in integrated circuit form. The hot swap circuits provide for de-bouncing, controlled charging of the input capacitor of the power supply circuit and soft-start of the pulse width modulator after charging the input capacitor. Other features include a low voltage lockout, and an output for coupling to a synchronous rectifier driver to synchronize synchronous rectifiers on the secondary side of a coupling transformer in isolated systems. The hot swap capability may be disabled through an enable pin, or not implemented by not connecting the integrated circuit in a manner to use the hot swap capability.

Abstract: A circuit for supplying power to a fluorescent lamp comprising a buck regulator with a high side drive. A dc battery is coupled to a drain of a first transistor. A source of the first transistor is coupled to an inverter for powering the lamp. A first control signal is coupled to a primary winding of a transformer. A first terminal of a secondary winding of the transformer is coupled to the anode of a diode. The cathode of the diode is coupled to the gate of the first transistor. A second terminal of the secondary winding of the transformer is coupled to the source of first transistor. The first control signal is activated to bias the first transistor through the transformer by charging the gate to a voltage higher than the control voltage due to the transformer turns ratio. A diode is coupled to capture a charge on the gate. A second transistor is coupled to the gate of the first transistor to drain the captured charge to ground, turning off the first transistor when a second control signal is activated.