Abstract: An electric power-assist system for a manually operated vehicle, such as a bicycle, has a pedal with Hall sensors for producing a signal representing a rotational speed of the pedal, and an electric motor for power assisting the driving force of the bicycle. A speed counter, speed decision block, up/down counter, and comparator are provided so that the power assist by the electric motor increases or degreases, as the speed of the manual controlling device increases or decreases, respectively.

Abstract: An amplifier circuit that uses multiple power supplies includes a class D amplifier circuit, input bias generator and feedback network. By creating a voltage using the input bias generator at the non inverting terminal of the integrator, the inverting terminal of the integrator will follow the same voltage as the non inverting terminal. The offset voltage between the input signal DC bias and the input DC bias of the integrator will create an offset current flowing through the feedback resistors, thus resulting in the desired output DC bias.

Abstract: A method to determine the diameter and shape of the loaded optical disk without any additional sensor. By accelerating a disk for a certain period of time and then monitoring the rotational speed before the spindle lock, the diameter and shape of the loaded optical disk is detected.

Abstract: A smart overcurrent protection circuit is introduced. In case of successive current due to certain malfunctions flows in power transistor of a switching circuit a control signal is activated to stop power transistor switching. When overcurrent condition is no longer satisfied, the switching circuit is still able to return to normal operation.

Abstract: A differential input Class D audio power amplifier incorporating a differential error amplifier is introduced. In response of differential input signal, this differential error amplifier generates two error signals, which subsequently generates final output signal. This architecture makes it the effect of feedback signal error correction doubled, which helps in achieving good THD. In addition, input port of this architecture is also compatible with single-ended signal. A pop noise suppression technique for this differential input Class D audio power amplifier is also introduced.

Abstract: A output offset protection circuit provides protection of the load and the power amplifier through monitoring the temperature of the power transistor in the operational amplifier to detect fault conditions of an output block. In the output offset protection circuit, a sensor block monitors the temperature differences between the power transistors, while the output block is driving the load. Upon detection of the temperature differences reaching a 1st threshold level, the cutoff block sends a cutoff signal to a protection switch block, and the hysteresis block is activated. The hysteresis block shifts the threshold level lower to the 2nd threshold level. The sensor block continues to monitor the temperature differences until the 2nd threshold level is reached. Then the cutoff block is deactivated.

Abstract: A method of controlling the charge of the bootstrap capacitor during light load or no load conditions for a non-synchronous type of DC-DC converter consists of bootstrap capacitor voltage detector, light load detector and secondary switch controller. By turning on the secondary switch during the off-time of the power transistor when the bootstrap voltage is lower than the required value under light load condition, the bootstrap capacitor voltage will be able to charge back to the required value, yet minimizing the minimum current requirement for the DC-DC converter.

Abstract: A output offset protection circuit provides protection of the load and the power amplifier through monitoring the temperature of the power transistor in the operational amplifier to detect fault conditions of an output block. In the output offset protection circuit, a sensor block monitors the temperature differences between the power transistors, while the output block is driving the load. Upon detection of the temperature differences reaching a 1st threshold level, the cutoff block sends a cutoff signal to a protection switch block, and the hysteresis block is activated. The hysteresis block shifts the threshold level lower to the 2nd threshold level. The sensor block continues to monitor the temperature differences until the 2nd threshold level is reached. Then the cutoff block is deactivated.

Abstract: A method of controlling the charge of the bootstrap capacitor during light load or no load conditions for a non-synchronous type of DC-DC converter consists of bootstrap capacitor voltage detector, light load detector and secondary switch controller. By turning on the secondary switch during the off-time of the power transistor when the bootstrap voltage is lower than the required value under light load condition, the bootstrap capacitor voltage will be able to charge back to the required value, yet minimizing the minimum current requirement for the DC-DC converter.

Abstract: A voltage level detector (8) which activates itself by monitoring the voltage level (VSTB) at a standby pin (5) during power-up of an audio power amplifier (10), and can detect fault conditions of an output block (2), such as a short to ground at an output terminal (3), in contrast to conventional protection circuits that can operate only after power-up.

Abstract: A voltage level detector (8) activates itself through monitoring the voltage level (VSTB) at a standby pin (5) during power-up of an audio power amplifier (10), and can detect fault conditions of an output block (2), such as a short to ground at an output terminal (3), in contrast to conventional protection circuits that can operate only after power-up. In a voltage level detector (8), a second short-to-ground detection block (81) monitors the voltage levels (VSTB and Vout) at the standby pin (5) and the output terminal (3) during power-up. Upon detection of the voltage level (VSTB) reaching a first threshold level (Vth1) and a short to ground at the output terminal (3), the second short-to-ground detection block (81) activates a cutoff signal generating block (83). The recovery block (82) monitors the voltage level (VSTB) at the standby pin (5) during power-up.

Abstract: A voltage level detector (8) activates itself through monitoring the voltage level (VSTB) at a standby pin (5) during power-up of an audio power amplifier (10), and can detect fault conditions of an output block (2). Upon detection of the (VSTB) reaching a first threshold level (Vth1) and a short to ground at the output terminal (3), the second short-to-ground detection block (81) activates a the second cutoff signal generating block (83). The recovery block (82) monitors the voltage level (VSTB) at the standby pin (5) during power-up. Upon detection of the voltage level (VSTB) reaching a second threshold level (Vth2>Vth1), the recovery block (82) deactivates the cutoff signal generating block (83). The cutoff signal generating block (83) sends a cutoff signal (Sc) to a protection switch block (71) as a request for turn-off of protection switches (7A) on activation, and on the other hand, terminal the sending of the cutoff signal (Sc) on deactivation.