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

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.

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.

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 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.

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.

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.

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.