583 results about "RC circuit" patented technology

Voltage regulators often have coupled output inductors because coupled output inductors provide improvements in cost and efficiency. Coupled inductors are often used in multi-phase voltage regulators. Feedback control of voltage regulators often requires accurate and responsive sensing of output current. Provided is a technique for accurately sensing the magnitude of output current in coupled inductors. An RC circuit (comprising a resistor and capacitor in series) is connected in parallel with the coupled inductor. The inductor has a leakage inductance Lk and a DC (ohmic) resistance of DCR. The resistor and capacitor are selected such that an RC time constant is equal to an L/R time constant of Lk/DCR. With the matching time constants, a sum of voltages on the capacitors is accurately proportional to a sum of currents flowing in the output inductors. Also provided is a technique for sensing current when an uncoupled center tap inductor is present.

A system is disclosed for enhancing the stimulation signal bandwidth for a touch sensor panel and maintaining relatively uniform touch sensitivity over the touch sensor panel surface. In one embodiment, a bandwidth enhancement circuit is coupled in parallel to a sensor circuit. The sensor circuit includes a source of stimulating voltage, a drive line, a sense line, and a charge amplifier. The drive line and the sense line are coupled with each other by a mutual capacitance Csig. The bandwidth enhancement circuit can be a RC circuit coupled in parallel to the sensor circuit. The bandwidth enhancement circuit can be represented by two serially coupled resistors, each of which is also coupled to ground on one end, and two capacitors. In particular, one of the capacitors couples the bandwidth enhancement circuit to the drive line, and the other capacitor couples the bandwidth enhancement circuit to the sense line.

A user interface (210) includes an RC circuit (213). The RC circuit (213) includes a variable capacitance. The variable capacitance is produced by a sensing member (310) in cooperation with a user's finger (311). When a user makes a selection with the user interface (210), the user places a finger (311) in close proximity and in a facing relationship to a section, or discrete surface (320, 322, 324), of the sensing member (310). The discrete surfaces (320, 322, 324) can correspond to keys of a keypad (138) or to directions of a directional button (1030), for example. The time constant of the RC circuit (213) varies according to which discrete surface (320, 322, 324) is determining the capacitance of the RC circuit (213). A controller (118) determines the user's selection based on the time constant of the RC circuit (213).

An output buffer having a controlled output slew rate comprises a first predriver circuit having a first RC circuit and a first output node and a second predriver circuit having a second RC circuit and a second output node. A buffer input node is coupled to the first and second predriver circuits. The output buffer further includes an output circuit having first and second input nodes and a third output node, where the first and second input nodes are coupled, respectively, to the first and second output nodes. The time constants of the RC circuits control a signal slew rate at the third output node of the output circuit, and the value of R may be selected to provide a predetermined, controlled slew rate range at the third output node. A selection circuit aids in the selection of an appropriate value for R.

A protection circuit is disclosed that protects a semiconductor device from damage due to an electrostatic discharge. One such protection circuit comprises a vertical pnp hetero-junction bipolar transistor (HBT) connected between terminals such as supply terminals of the device, configured to conduct during an electrostatic discharge. The protection circuit also comprises a trigger circuit, such as a transient activated RC circuit connected between the terminals to detect the electrostatic discharge and control the transistor based on the detected electrostatic discharge. A Darlington transistor pair in the trigger circuit can be used to multiply the effective capacitance and HBT drive current. The HBT transistor absorbs energy from the electrostatic discharge and clamps the over-voltage across the terminals. The protection circuit may also be used across other I/O terminals of the device.

The invention relates to a PWM buck convertor with overcurrent protection function, which comprises a control circuit, a first switching tube connected between an input power source and an inductor, and a current-limit circuit, wherein the current-limit circuit is used for sampling current signals on the first switching tube and outputting overcurrent signals; the control circuit judges whether the overcurrent signals are greater than a preset current maximum to control the connection and cut off of the first switching tube; and the PWM buck convertor is provided with the current-limit circuit, so that a power tube is cut off when the current is increased to the preset current maximum to protect a chip and ensure the normal work of a switch power supply. Furthermore, a capacitor in an RC circuit outputs sampling voltage so as to avoid the influence of power supply voltage vibration on the current-limit circuit in the direct sampling process; when the overcurrent happens, the cut-off time of the power tube is fixed so as to avoid the repeat starting of the power tube in short time and reduce power consumption; and two shifts of cut-off time are automatically selected according to the output voltage of the buck convertor so as to ensure the stability of the output voltage.

The invention discloses a lithium-battery variable fractional order and equivalent circuit model and an identification method thereof. The lithium-battery variable fractional order and equivalent circuit comprises a run time circuit and a battery I-V characteristic circuit, wherein a capacitor in the battery I-V characteristic circuit is a variable fractional order capacitor. A second order RC circuit model is generalized to a non-integer order, and the model parameters and the number of fractional order of different SOC are identified based on a least square method, so that the fractional order and equivalent circuit varying order according to the SOC is obtained. The instruction of fractional order realizes the continuous change of the order number of the model, so that the model is relatively stable, good in dynamic property and high in precision. The variation of fractional order realizes more freedom and more flexibility and innovation of the model. As the number of RC networks is not increased, the fractional order model effectively solves the contradiction between the accuracy and practicality of the model, is suitable for various working conditions of batteries, and has high practical value. The invention provides a precise battery model easy to realize for precise estimation of SOC.

Provided is a switched-mode power supply. The power supply includes: a DC voltage input terminal; a driver switching element connected to the input terminal; an inductor connected to the driver switching element; an output terminal connected to the inductor and outputting output voltage different from the input voltage; and an integrated circuit outputting control pulses used for on-off control of the driver switching element. The integrated circuit has: a ripple injection circuit adding a ripple component to a feedback voltage of the output voltage; a voltage comparator comparing the summed voltage with a predetermined voltage; and a control pulse generator generating the control pulse based on an output of the voltage comparator. The ripple injection circuit has an integrator outputting an integral of the voltage at the node between the driver switching element and the inductor, and a series RC circuit connected to the output end of the integrator.

A method of remote sensing a charge includes charging or discharging a capacitor of an RC circuit to a predetermined threshold voltage using a power source. A response signal is provided from a communications module to a handheld computing device comprising a reader system once the capacitor reaches the predetermined threshold voltage. An amount of time taken for the handheld computing device to receive the response signal is determined using a processor. The processor determines charge information using the amount of time.

A micropower RC oscillator having stable frequency characteristics with varying temperature includes a number of inverting circuits which are driven by an external driving voltage and connected in series with each other and an RC circuit having a resistor disposed in between a head-inverter and a tail inverter to form a closed loop and a capacitor disposed between the tail-inverter and the head-inverter. The resistor comprises a plurality of unit resistors constituting of a P+ diffusion resistor and a polysilicon resistor having opposing characteristics with respect to temperature variation at a predetermined ratio. A resistance regulator controls the resistance of the resistor by decoding an external resistance setting data to select a unit resistor that determines the oscillation frequency effectively. A driving voltage circuit receives a reference signal having the voltage level which is stable against the temperature variation by using a current source and a load having opposing characteristics with respect to the temperature variation and provides as a driving voltage of the RC oscillating circuit after increasing a fan-out capacity of the reference signal. An output level shifting circuit can be added to the rear side of the RC oscillating circuit to adjust the voltage level of the oscillation signal with the appropriate standard required at a receiving end.

An indication and sectionalizing method of the small current grounding fault of the power system relates to the detecting field of the grounding fault of the power system. The method is characterized in that the back zero sequence equivalent capacity of the detecting point is estimated, simultaneously the related information of the transient phase voltage and the transient zero sequence current caused by the fault is utilized as the basis of the fault indication and sectionalizing. The back zero sequence equivalent capacity of the detecting point is estimated according to the collected transient phase voltage and the transient zero sequence current after the fault, and whether the fault detecting device is actuated to alarm is determined according the value of the zero sequence capacitor. The method has the advantages of only need of one phase voltage transformer for realization, effective decrease of the production cost, obtaining the phase voltage signal for the cable line via the sheet iron that is covered on the line and grounded via the RC circuit, being simple and feasible, higher amplitude of the transient signal than that of the stationary signal and easy detecting, and no influence from the grounding mode of the neutral point of the system.

The invention relates to a dimming method applicable to traditional dimmers and an LED dimmable drive power. The method comprises the following steps: converting PWM signals determined by the phase ofthe angle of flow into DC signals through a phase test circuit after being filtered by a RC circuit, and magnifying the signals to control the changes of the resistance value of a constant-current sampling resistor so as to regulate the magnitude of the LED current. The invention can regulate the brightness of an LED bulb by the traditional dimmer, so that people can conveniently change the traditional incandescent bulb lamp into the LED bulb lamp with the ideal stepless dimming function. The LED has the characteristics of long service life, no mercury pollution or ultraviolet pollution, highlight efficiency, shock resistance, energy saving and the like, and belongs to a new generation of green light sources. Therefore, the invention has the advantages of favorable dimming effect (1-100%of continuous stepless dimming), soft light color, environmental protection and energy saving.

The circuit comprises: a watch-dog chip (U1) whose dog-feeding input end (WDI) is connected to the dog-feeding signal source, and whose reset output end (RST) is used for outputting a reset signal; a first order RC circuit connected to the power failure detection input (PFI) of the watch-dog chip (U1) and used for adjusting the time length in which the input voltage of said PFI is made to equal to the reference voltage; the power failure detection output end (PFO) is connected to the reset input end (MR); the state of both PFO and MR are the same high level or low level. The invention can be used for disabling the watch-dog when the CPU is powered on.

An improved snubber is electrically switched to close a current path to a capacitor (C) in a series connected RC circuit at the onset of an abrupt voltage change otherwise producing ringing in a resonant circuit to which the snubber circuit is connected. The current path to the capacitor (C) is then interrupted before the capacitor (C) discharges and thereafter at each such voltage change in the resonant circuit the capacitor (C) is no longer charged from its totally discharged state but nevertheless damps the ringing by virtue of current flow to the nearly completely charged capacitor (C). By preventing complete charging and discharging of the capacitor (C) in the RC circuit every cycle, power dissipation in the resistance of the snubber circuit is greatly reduced.

Apparatus and methods for eliminating DC offset in a wireless communication device operable on a continuous basis or on a sampled basis. In a receive channel, the output of a forward variable gain amplifier is fed back to an RC circuit to charge the capacitor (C) to a voltage dependent on the DC offset in the variable gain amplifier output. The voltage on the capacitor is amplified and summed with the input to the variable gain amplifier. The RC circuit is configured to provide a high gain feedback at DC and very low frequencies, but very low gain at signal frequencies. Preferably the output of the forward variable gain amplifier is fed back to the RC circuit with a gain that is inversely proportional to the forward gain. Disconnection of the capacitor and feedback of the capacitor voltage provides sampled operation. Various embellishments and sample applications are disclosed.

The invention relates to a true root mean square value detection-based soil moisture sensor, which comprises a power supply filter circuit, an active crystal oscillator, a Schmidt trigger, a signal attenuator, a probe and a true root mean square value detector. The Schmidt trigger shapes a high-frequency sine wave or square wave signal output by the active crystal oscillator into a standard waveform square wave signal, the amplitude of the standard waveform square wave signal is reduced by the signal attenuator, a resistor-capacitor (RC) circuit consisting of the signal attenuator and the probe is charged and discharged periodically, a periodic charging and discharging curve waveform is obtained on the probe, and the true root mean square value detector converts a waveform signal on the probe into equivalent direct current voltage serving as a sensor output signal. When soil moisture is different, the equivalent capacitance of the probe is different, the charging and discharging waveforms are different, and the final output signals are different, so that the soil moisture is measured according to the principle. The soil moisture sensor has the characteristics of simple structure, small volume, low power consumption, low cost, high soil adaptability, simple input/output interface and the like, is easy to apply and facilitates the development of secondary instruments.

A method of transforming a first topology to a reduced topology is disclosed. One preferred embodiment of the present invention includes a method of transforming a circuit from a first topology to a reduced topology, said first topology comprising a plurality of inter-connected circuit elements. The method comprises the steps of: (a) identifying one or more circuit elements; (b) analyzing the effect of reducing one or more of said identified circuit elements on the topological and physical characteristics of said circuit; and (c) if the effect satisfies a first standard, generating a second topology reflecting the reduction of one or more identified circuit elements.