1222 results about "High input" patented technology

A power factor corrected (pfc) ac-dc converter has a modified boost input and a modified buck output. Unlike the prior art boost input, the boost switch returns to the output, not to ground. Unlike the prior art buck output stage, a third switch connects to the input. This allows much of the input current to pass through the converter to the output. There is no input current measurement, but nearly ideal power factor correction is achieved through “natural modulation.” A preferred pfc ac-dc converter uses a variable dc-dc transformer on its output, as a post regulator, to provide dielectric isolation and to provide voltage level shifting. The output of the pfc ac-dc converter has the control characteristics of a buck converter, so it is a natural mate for the variable dc-dc transformer. An ac-dc buck converter is most efficient at its maximum duty cycle. It cannot regulate for a lower input voltage, but it can reduce its duty-cycle to control for higher input voltages. A variable dc-dc transformer is most efficient at its maximum ratio. It cannot regulate for a higher input voltage, but it can reduce its effective turns ratio to control for a lower input voltage. With a small overlap in their control ranges, both parts of the power system can operate at maximum efficiency. The variable dc-dc transformer controls the output voltage for nominal and low input voltage. The ac-dc buck converter limits over-voltage transients.

A preamplifier having extremely high input impedance amplifies the electrical signal output from an electret condenser microphone (ECM) without suffering from the effects of a DC leakage current at the input. The preamplifier circuit includes a pair of cross-coupled PN junction diodes setting the input impedance, a PMOS device, and a load resistor configured similarly to a conventional preamplifier. A capacitor is placed between the input and the cross-coupled diodes such that a DC path no longer exists to bias the cross-coupled diodes. Therefore, leakage currents are prevented from upsetting the DC operating point of the preamplifier and biasing the cross-coupled diodes. Consequently, small signal gain distortion, excessive demodulation products and increased noise can be avoided.

A living body measuring sensor (1) is made to contact a body surface of a measuring subject through capacitance coupling using a cloth (6) between a metal electrode (2) and the body surface as the capacitance, a living body electric signal is extracted from the metal electrode (2), and an elctrocardiographic waveform is outputted based on an output of the living body measuring sensor (1) using an impedance converter having a high input impedance and a low output impedance.

The invention relates to a high power factor DCM Boost PFC converter comprising a main power circuit and a control circuit. The main power circuit comprises an input voltage source vin, an EMI filter, a diode rectification circuit RB, a Boost inductor Lb, a switch tube Qb, a diode Db, an output capacitor Co and a load RLd. The high power factor DCM Boost PFC converter is characterized in that the control circuit adopts an output signal which adopts duty ratio as changing rule to drive the switch tube Qb. Adopting the varying duty ratio control, the high power factor DCM Boost PFC converter can improve the PF value to about 1 in the AC input voltage range of 90-265 V, increase the inductance capacity, obviously decrease the inductive current ripple, obviously reduce the effective value of the inductive current and correspondingly reduce the effective value of the current of the switch tube, has high input power factor and small output voltage ripple and contains less input current harmonic waves. The conduction loss of the high power factor DCM Boost PFC converter is reduced, and the efficiency is improved.

The invention discloses a DC/DC converter. The DC/DC converter includes a square wave generator, which is used to output a series of voltage in form of square wave. The said square wave generator includes a serial capacitor which is connected to serial inductor and parallel inductor. Primary side of transformer is cascaded to a serial inductor in the DC/DC converter, then connected to an inductorin parallel. Secondary side of transformer is connected to a rectification circuit so as to provide a rectified DC voltage for output load circuit. The first characteristic resonance frequency of theserial capacitor and the serial inductor are expressed as fs. The second characteristic resonance frequency of the serial capacitor and the serial inductor as well as parallel inductor are expressed as fn where fs>fn. Switching of variable frequency in the converter carries out the output adjustment. Based on frequency switching between first and second characteristic resonance frequency, the converter realizes high conversion efficiency when working under high input voltage.

The invention discloses a switch converter with constant connection time control, and a control circuit and method thereof. A compensation control signal is generated according to the input voltage or a control signal, and a compensation signal is adjusted according to the compensation control signal so that the compensation signal can be adjusted to a proper value within a wide input range. Compared with the prior art, jittering and subharmonic oscillation under low input can be avoided, and dynamic response and load adjusting rate under high input are improved.

A control circuit and method are provided for a flyback converter converting an input voltage to an output voltage, to compensate for an entry point of a burst mode of the flyback converter, so that the entry point is not affected by the input voltage, and audible noise resulted from a higher input voltage is reduced without impacting the light load efficiency of the flyback converter.

Systems, methods, and apparatus for use in biasing and driving high voltage semiconductor devices using only low voltage transistors are described. The apparatus and method are adapted to control multiple high voltage semiconductor devices to enable high voltage power control, such as power amplifiers, power management and conversion and other applications wherein a first voltage is large compared to the maximum voltage handling of the low voltage control transistors. Timing of control signals can be adjusted via internal and/or external components so as to minimize shoot trough currents in the high voltage devices. A DC/DC power conversion implementation from high input voltage to low output voltage using a novel level shifter which uses only low voltage transistors is also provided. Also presented is a level shifter in which floating nodes and high voltage capacitive coupling and control enable the high voltage control with low voltage transistors.

The invention provides a method for correcting error-prone words in voice interaction. The method comprises the steps of context recognition, automatic error correction based on semantic restriction, and artificial error correction based on semantic feedback. Through voice interaction with users and perception and recognition of the context of a topic, automatic error correction of an entity with a specific meaning can be achieved by using the named entity recognition technology within the limited semantic range, additional semantics can be obtained through artificial feedback so as to conduct error correction, and higher input efficiency and more convenient wrong word correction than existing voice recognition software are realized.

The invention discloses a system for providing over-current protection for a switching power converter. The system comprises a front-edge blanking circuit, a linear compensation circuit and an over-current protection comparer, wherein the front-edge blanking circuit is configured to generate a front-edge blanking effect on a detection signal of a current which flows through an external switching tube of the switching power converter; the linear compensation circuit is configured for performing linear compensation on a threshold voltage of the over-current protection comparer; and the over-current protection comparer is configured for generating an over-current protection comparison signal. By a linear compensation over-current protection circuit, the time delay of a system internal over-current protection output signal is taken into consideration, so the permanent damage of a switching tube of a metal-oxide semiconductor field effect transistor (MOSFET) caused by large-current conduction which may be generated at a high input voltage is avoided; and a maximum output power is stabilized, so the maximum power planarization of a power system can be realized in a full-voltage input range.