53results about How to "Avoid audio noise" patented technology

The invention discloses a switch voltage-stabilizing circuit which can regulate switching frequency as well as current peak, has high efficiency and has no audio-frequency noise generated in a state of light load, and method thereof. The switch voltage-stabilizing circuit comprises an energy storage component capable of storing energy; a switch electrically coupled to the energy storage component, wherein the energy storage component can store energy when the switch is on, and the energy stored in the energy storage component is transmitted to a load when the switch is off; a control circuit electrically coupled to the switch, wherein the control circuit compares current flowing through the switch with a current threshold, when the current flowing through the switch is more than the current threshold, the switch is off, and the control circuit determines on and off time of the switch according to the load of the switch voltage-stabilizing circuit, when the load becomes big, the on and off time of the switch is reduced, and when the load becomes small, the on and off time of the switch is increased. The current threshold is constant when the circuit has no light load and becomes low with the load reduced when the circuit has light load.

The invention provides a switching power supply, a control method of the switching power supply and a control chip. The control method of the switching power supply comprises the following steps: sampling preset output voltages to acquire sampling signals; generating an error voltage according to the sampling signals and a first reference voltage; judging a current state of the switching power supply according to the error voltage, a preset second reference voltage and a third reference voltage; if the error voltage is smaller than the second reference voltage and larger than the third reference voltage, and then the switching power supply is in a first state, and controlling the switching power supply according to the error voltage in a simulated pulse frequency modulation (PFM) mode; if the error voltage is smaller than the third reference voltage, and then the switching power supply is in a second state, and controlling the switching power supply according to the error voltage in a mixed mode of digital pulse width modulation (PWM) and digital PFM. The control method of the switching power supply can meet high accuracy of the output voltage of the switching power supply, and has high conversion efficiency in a full load range, and therefore dynamic response speed of the switching power supply is improved, and voice frequency noise in a light load state can be avoided.

The invention provides a controller for a non-complementary active clamp flyback converter. The controller comprises a frequency control unit, a pulse width control unit, a sequential control unit anda driving unit, uses a multi-mode control mode, and further comprises a wave peak detecting unit and a mode a determining unit. The wave peak detecting unit detects the peaks of an oscillating voltage at the drain end of a main switching tube, and turns on a clamp tube at the troughs in the non-complementary mode of the converter. The turning off of the clamp tube is determined by internally setturn-on time. The mode determining unit, according to feedback voltage FB, gives a mode switching signal to the sequential control unit according to a mode determining result signal. By using a DCM mode, the controller prevents the clamp tube from being turned on, reduces the peak-to-peak value of the excitation current when entering a frequency hopping mode, avoids audio noise, and optimizes no-load power consumption. Since the comparison process of the mode conversion is provided with a long time delay, the influence of mode switching on a converter control loop is reduced.

Disclosed are a switching regulator and a control circuit and a control method therefor. In one embodiment, by means of controlling a rectifying switch in a power stage with a second control signal which has a predetermined frequency and varies in accordance with the difference between a feedback voltage and a reference voltage, more energy may be shunted when a switching regulator operates in a light loaded or unloaded condition, so that audio noise is avoided.

The invention discloses a control circuit and control method of a Boost-Buck converter. The control method comprises the following steps of sampling an induction current, and accordingly generating a current sampling signal; controlling to receive the current sampling signal in a rise time interval of the induction current in each switching period; maintaining the maximum value of the current sampling signal to generate a sampling signal at the moment when the induction current is rise to an inductance current peak until the current switching period is finished; limiting the inductance current peak according to a second reference signal representing information of the maximum value of the inductance current, so that the induction current cannot be excessively fluctuated, and the fluctuation of an output voltage also can be relatively reduced; and meanwhile, adjusting the duty ratio of a switching device by a feedback control loop according to real-time error information between a compensation signal and a voltage signal representing the inductance current. Therefore, the dynamic response speed of the system is relatively high, the time required for restoring to a stable state again is shortened, the dynamic response speed of the system is increased, and the stability and the reliability of the system are improved.

The invention discloses a frequency soft clamp system for a quasi-resonant switching power supply and a method. The system is used for selecting a certain valley bottom where a power switch within a subsequent set time range is locked for switch-on through detecting the switching frequency within a set time range to achieve the effects that the switching frequency is limited within a certain range, and the power switch is locked in the certain valley bottom for switch-on within the set time range. The frequency soft clamp system for the quasi-resonant switching power supply and the method, which are disclosed by the invention, have the benefits that the power switch can be effectively prevented from being switched on between adjacent two valley bottoms in turn and is locked in the certain valley bottom for switch on within the certain time range, so that the audio frequency noise is effectively avoided, and the switching frequency is limited within the certain range.

A super audio mode control circuit and a switching converter using the same are disclosed. A rectifier switch of the switching converter is forced to be switched on according to a predetermined frequency in a low-load or no-load mode, and the on-time of the rectifier switch is controlled according to a compensation signal and the duty ratio of the switching converter. Thus, the switching converter does not produce audio noise in a low-load or no-load mode, and can work normally in a large parameter range. The on-time of the rectifier switch is continuously adjustable with the error signal and the duty ratio in a super audio mode. The accuracy and stability of output voltage at very wide duty ratio are ensured.

The invention discloses a switching power supply, a circuit and a method for controlling constant on-time. When the switching frequency of a switching circuit approximates to an audio frequency range, the switching power supply enters a sleep mode, and on-time of a switching tube is shortened to increase the switching frequency of the switching circuit, so that audio noise is avoided.

A power converter, and a control circuit and a circuit method thereof are disclosed. The power converter comprises a clock signal generation circuit, a modulation signal generation circuit, and a logic module which is connected with the clock signal generation circuit and the modulation signal generation circuit and used for generating an on-off control signal according to a working clock signal and a modulation signal, wherein when a ratio between an output voltage and an input voltage is less than a duty ratio corresponding to the working clock signal at a first frequency, the clock signal generation circuit controls the frequency of the working clock signal to be the first frequency, and when the ratio between the output voltage and the input voltage is greater than the duty ratio corresponding to the working clock signal at the first frequency, the clock signal generation circuit controls the frequency of the working clock signal to be a self-adaptive frequency. According to the power converter of the invention, through self-adaptive frequency reduction processing, turn-on time is adaptively prolonged in the case of ensuring certain minimum turn-off time, and the duty ratio ismaximized, thereby expanding the range of a working voltage and improving adjustable dynamic range of the output voltage.

A charge pump device includes a charge pump circuit, for generating an output voltage according to a driving signal, a comparing circuit, for generating a comparison result according to the output voltage and a reference voltage, a detecting circuit, for detecting a frequency range of a ripple of the output voltage according to the comparison result and generating a detection result, and a driving stage, for generating the driving signal according to the comparison result, and adjusting a driving capability corresponding to the driving signal according to the detection result.

Disclosed are a switching regulator and a control circuit and a control method therefor. In one embodiment, a switching control signal with decreasing on time is generated to control a power switch in a second mode so that audio noise can be avoided when the switching regulator operates in a light loaded or unloaded condition.

The invention discloses a switching power supply with constant on-time control, and a control circuit and a control method for the switching power supply. When the switching power supply enters a superaudio mode, a low-side switch tube is switched on to discharge an output capacitor, a complementary ramp compensation signal of which the voltage is raised from initial voltage is generated in the discharge stage, the algebraic sum of the complementary ramp compensation signal and reference voltage is compared with a feedback signal representing output voltage, the discharge time of the low-side switch tube is shortened, the switch-on of a high-side switch tube is accelerated, audio noise is avoided, and dipulse in the superaudio mode is eliminated, so that the output voltage ripple of the switching power supply is reduced, the loss of the high-side switch tube is reduced, and the efficiency of the switching power supply is improved.

The invention relates to the field of electronics and discloses a noise eliminating method and a noise eliminating circuit. The noise eliminating method comprises the following steps of sampling output voltage signals of a power-level circuit, and obtaining a current output feedback signal; and determining whether the frequency of a first driving signal currently input to the power-level circuit is in an audio range according to a current output feedback signal, if yes, disconnecting the power-level circuit and a circuit of the first driving signal, outputting a first low-frequency driving signal and a first high-frequency driving signal to the power-level circuit, wherein the frequency of the first low-frequency driving signal is lower than the lower limit of the audio, and the frequency of the first high-frequency driving signal is higher than the upper limit of the audio. The application of the technical scheme of the invention facilitates the reduction of the circuit noise and avoidance of the circuit loss.

The invention relates to a switching stabilizer for saving electricity, to improve the system efficiency at light load, wherein the first controller, based on the change of feedback signal, outputs one oscillating signal and one energy-saving signal; the second controller receives said oscillating signal and feedback signal, to output switching signal to control switch; the stop time of switching signal will increased along the decrease of load; when the switching signal is stopped, the energy-saving signal can stop the switch, and close not needed circuit in the stabilizer, to save energy.

The invention relates to a dimming electronic ballast used in high strength discharge lamp and a method for selecting its working frequency. It comprises major loop of gas discharge lamp and control circuit connected with the major loop, where the major loop is composed of rectifier circuit with lowpass filter, PFC correction circuit, bridge inverter circuit and T-filter resonant circuit. It regulates the working frequency of switch tube of the bridge inverter circuit to make the working frequency greater than the upper limit frequency of sound resonance as the high strength gas discharge lamp outputs rating power and the working frequency of the high strength gas discharge lamp in the dimming course greater than the working frequency at the time of the high strength gas discharge lamp outputting the rating power.

Disclosed are a switching regulator and a control circuit and a control method therefor. In one embodiment, by means of controlling a rectifying switch in a power stage with a second control signal which has a predetermined frequency and varies in accordance with the difference between a feedback voltage and a reference voltage, more energy may be shunted when a switching regulator operates in a light loaded or unloaded condition, so that audio noise is avoided.

The invention discloses a quasi-resonant control switching power supply circuit and a switching power supply circuit control method. The purpose of preventing the generation of audio noises is achieved by adjusting the corresponding relationship between the peak current and the switching frequency. The quasi-resonant control switching power supply circuit comprises an energy storage element, a switch, a valley bottom detection circuit, a mode detection circuit and a peak signal adjustment circuit; wherein the energy storage element can store energy; the switch is electrically coupled to the energy storage element; the energy storage element stores energy when the switch is on, and the energy stored in the energy storage element is transmitted to the load when the switch is off; the valley bottom detection circuit is used for detecting whether the switching voltage at both sides of the switch is lower than the valley bottom reference signal or not; the mode detection circuit is used for detecting whether the switching power supply circuit is operated in the continuous current mode or not; and the peak signal adjustment circuit is used for adjusting the value of the peak signal under the condition of discontinuous current mode and non valley bottom conduction.

The invention discloses a DC-DC converter and a control method thereof. The DC-DC converter comprises a follow current tube and a control circuit, wherein the control circuit is used for controlling the follow current tube to be conducted continuously starting from the moment that the inductive current of the DC-DC converter is decreased to zero from positive current; and the follow current tube is disconnected until the inductive current becomes negative current and the negative current reaches a reference current value. The control method of the DC-DC converter comprises the following steps:starting from the moment that the inductive current is decreased to zero from positive current, controlling the follow current to be conducted continuously, and disconnecting the follow current tubeuntil the inductive current becomes negative current and the negative current reaches the reference current value. Audio-frequency noise caused by the fact that the switching frequency is decreased into an audio frequency range can be avoided effectively.

A charge pump device includes a charge pump circuit, for generating an output voltage according to a driving signal, a comparing circuit, for generating a comparison result according to the output voltage and a reference voltage, a detecting circuit, for detecting a frequency range of a ripple of the output voltage according to the comparison result and generating a detection result, and a driving stage, for generating the driving signal according to the comparison result, and adjusting a driving capability corresponding to the driving signal according to the detection result.

The invention provides a switching power supply control circuit, which is used for driving a first switch in a switching power supply to convert an input voltage into an output voltage, and comprises a turn-on time control unit, the turn-on time control unit receives a first signal and a second signal, the first signal represents the switching frequency of the first switch, and the second signal represents the current flowing through the first switch so as to generate a signal indicating the turn-off moment of the first switch; when the peak value of the current flowing through the first switch is lower than a preset current value, the turn-on time control unit determines the turn-off moment of the first switch according to the first signal so as to maintain the switching frequency of the first switch to be basically constant at a target frequency value. Therefore, generation of audio noise is effectively avoided, the output voltage can be stabilized and the high efficiency can be maintained when the load changes, and the safe operation of the switching power supply is ensured.

The invention relates to a control method for a voltage converter and a relevant voltage converter thereof. The control method comprises the following steps of: providing a setting used for a power saving mode; entering the power saving mode to enable the voltage converter to output preset energy according to the setting; entering a normal mode to judge whether the voltage converter needs to enter the power saving mode or not and to detect the output reaction of the voltage converter; and regulating the setting according to the output reaction so that the output reaction can be approximately maintained in a preset range.

The invention discloses a power supply method and power supply apparatus preventing audio noise. The power supply apparatus preventing the audio noise comprises a voltage input end, a power switch circuit, a voltage output end, a pulse width modulation signal generation circuit and a pulse intermittent frequency detection circuit. The pulse width modulation signal generation circuit controls the power switch circuit by means of pulse width modulation signals to enable the power supply apparatus preventing the audio noise to enter a pulse intermittent mode; the pulse intermittent frequency detection circuit detects a pulse intermittent frequency of the power switch circuit; if the pulse intermittent frequency falls into an audio scope, the pulse intermittent frequency detection circuit notifies the pulse width modulation signal generation circuit that the pulse intermittent frequency falls into the audio scope; and the power supply apparatus preventing the audio noise leaves the pulse intermittent mode so as to prevent the audio noise.

Disclosed are a switching power supply controlled by a constant conduction period, a control circuit and a control method thereof. When the switching power supply enters the super-audio mode, turn on the low-side switching tube to discharge the output capacitor, and generate a supplementary slope compensation signal whose voltage rises from the initial voltage during the discharge phase, and combine the supplementary slope compensation signal with the The algebra of the reference voltage is compared with the feedback signal representing the output voltage, which shortens the discharge time of the low-side switch and accelerates the conduction of the high-side switch. While avoiding audio noise, it eliminates the dual Pulse, thereby reducing the output voltage ripple of the switching power supply, reducing the loss of the high-side switching tube, and improving the efficiency of the switching power supply.

The present invention discloses a switching regulator. The switching regulator converts an input voltage to an output voltage. The switching regulator includes: a power stage circuit, which switches at least one power switch thereof according to a driving signal to convert the input voltage to the output voltage; and a control circuit, which is coupled to the power stage circuit, for generating the driving signal according to a feedback signal. The power stage circuit includes: an active circuit, which includes the power switch and at least one inductor, and is controlled by a driving signal to convert the input voltage to a middle voltage; and a passive circuit, which is coupled to the active circuit, and includes a charge pump for converting the middle voltage to the output voltage.

A digital video camera (10) includes a microphone (34). When audio data fetched through a microphone (34) and an A / D converter (36), and a plurality of screens of JPEG data generated by a JPEG codec (32) are subjected to a recording process in parallel with each other, an error of the audio data between a real processing amount (=8043 bytes / second) and a virtual processing amount (=8040 bytes / second) of the audio data is calculated by a CPU (52) every 30 frames. When the calculated error is above a threshold value, the number of frames of the JPEG data to be recorded in a recording medium (50) is adjusted by thinning-out / interpolation.

The invention discloses a control circuit and a control method for a buck-boost converter, which samples the inductor current and generates a current sampling signal based on it; controls the receiving current sampling in the rising time interval of the inductor current in each switching cycle signal; from the moment when the inductor current rises to the peak value of the inductor current to the end of the current switching cycle, the maximum value of the current sampling signal is maintained to generate a sampling signal; the inductor current is limited by the second reference signal representing the maximum value information of the inductor current Peak value, so that the inductor current will not fluctuate too much, so the fluctuation of the output voltage will be relatively reduced; at the same time, the feedback control loop can adjust the switching device according to the real-time error information between the compensation signal and the voltage signal representing the inductor current Therefore, the dynamic response speed of the system is faster, shortening the time required to return to a stable state again improves the dynamic response speed, stability and reliability of the system.

The invention discloses a control method, a controller and a switching converter. By controlling a rectifier switch to be on for first time and then, triggering a power switch to be on for second timein each switching period under a superaudio mode, and adjusting the first time according to a regulation signal corresponding to the output voltage to enable the switching period of the switching converter to be kept in a set period, the switching converter can be prevented from having audio noise under the superaudio mode, and meanwhile, stability of the system is enhanced, and efficiency of thesystem is improved.

A power supply apparatus (10) includes a voltage input side (102), a power switch circuit (104), a voltage output side (106), a pulse width modulation signal generating circuit (108) and a burst frequency detection circuit (110). According to a pulse width modulation signal (114), the pulse width modulation signal generating circuit (108) controls the power switch circuit (104), so that the power supply apparatus (10) enters a burst mode. The burst frequency detection circuit (110) detects a burst frequency of the power switch circuit (104). The burst frequency detection circuit (110) informs the pulse width modulation signal generating circuit (108) that the burst frequency is in an audio frequency range if the burst frequency is in the audio frequency range. The power supply apparatus (10) leaves from the burst mode to avoid audio noise.