摘要:
A driving circuit for a plurality of light-emitting diodes (LEDs) comprises a transformer, a driving module, and a protection module. The transformer has a primary coil and a secondary coil, wherein a first end of the primary coil is coupled to a voltage source. Furthermore, a second end of the primary coil of the transformer is coupled to the driving module. The driving module determines whether to deliver electrical power to the transformer according to a pulse-width modulation (PWM) signal and an error signal. The protection module is coupled to the secondary coil. When a driving voltage output by the transformer to the LEDs is less than a first preset voltage or greater than a second preset voltage, the protection module generates the error signal to the driving module.
摘要:
A current detecting circuit detects a resonant current in a primary side of a resonant converting circuit to generate a current detecting signal. An output detecting circuit generates a feedback signal according to the output voltage. A resonant controller generates a clock signal and adjusts an operating frequency of the clock signal in response to the feedback signal for modulating the output voltage of the resonant circuit. The resonant controller includes a resonance deviation protection unit which detects the current detecting signal according to a phase of the clock signal to determine whether the resonant circuit enters a region of zero current switching or not. When the resonant circuit enters the region of zero current switching, the resonant controller executes a corresponding protection process in response to that the resonant controller operates in a starting mode or a normal operating mode.
摘要:
A multi-phase DC-DC converter and a method of controlling a multi-phase DC-DC converter are disclosed. The multi-phase DC-DC converter is adapted to control a plurality of channels in a multi-phase DC-DC converting circuit for providing an output voltage. The multi-phase DC-DC converter comprises a constant on unit, a plurality of PWM units and a pulse width logic unit. The constant on unit determines a time point of generating a turning on signal indicative of a preset time period according to the output voltage. Each PWM unit generates a PWM signal, and a pulse width thereof is determined according to the turning on signal and currents of the channels. The pulse width logic unit controls the channels according to the corresponding PWM signals generated by the plurality of PWM units.
摘要:
A pulse width modulation signal controlling apparatus including a signal pin, a core circuit, a setting judging circuit, a signal adjusting and selecting circuit, and a timer circuit is disclosed. The signal pin is connected to a setting device for receiving an external input signal. The setting judging circuit receives and compares a setting signal with a reference value to generate a setting judgment result. The signal adjusting and selecting circuit couples the signal pin to the setting judging circuit and adjusts the external input signal into the setting signal according to the setting device in a first state, and couples the signal pin to the core circuit in a second state. The timer circuit controls the state of the signal adjusting and selecting circuit, wherein the timer circuit sets the signal adjusting and selecting circuit in the first state during a predetermined time period.
摘要:
An exemplary embodiment of the invention provides a set of an initial value of an error amplifying signal in the feedback control circuit for feedback control, so as to reduce the time and the amplitude of oscillation of the error amplifying signal. Accordingly, a feedback control circuit and a power converting circuit provided in an exemplary embodiment of the invention not only reduce the degree and the time of overshoot but also provide accurate and stable feedback control.
摘要:
A constant on-time period of a DC to DC buck converting controller is adjusted according to a level of a preset output voltage. Therefore, the DC to DC buck converting controller of the present invention is suitable for any applications with different requests of output voltages or different operating mode.
摘要:
An LED driving circuit includes a first and a second LED modules, a first and a second switching converters, an extreme voltage detecting and selecting circuit, a current balance circuit and a controller. The first switching converter transforms electric power of an input power supply into a first output voltage for lighting the first LED module. The second switching converter transforms electric power of the input power supply into a second output voltage for lighting the second LED module. The current balance circuit balances the currents flowing through the first and the second LED modules. The extreme voltage detecting and selecting circuit detects the first and the second LED modules and selects to output one of detecting results. The controller controls the transforming of the first switching converter and the second switching converter to light the first and the second LED modules in response to the outputted detecting result.
摘要:
A non-linear load driving circuit and a controller for controlling a conversion circuit to drive a non-linear load are provided. The controller includes a feedback unit, a pulse width control unit, and an overshoot reduction unit. The feedback unit generates a feedback signal according to a current feedback signal that represents a load current flowing through the non-linear load. The pulse width control unit generates a control signal according to the feedback signal to control a power output of the conversion circuit. The overshoot reduction unit generates an overshoot reduction signal when the load current changes from being smaller than to being greater than a predetermined value according to the current feedback signal. The pulse width control unit receives the overshoot reduction signal and reduces the duty cycle of the control signal accordingly. Thereby, stability of feedback control is improved and damage to circuit is prevented.
摘要:
A control circuit adapted to control a power converting circuit for stabilizing an output of the power converting circuit is provided. The control circuit includes a capacitor, a charging unit, a discharging unit, a feedback control unit, and a duty-cycle adjusting unit. The charging unit has a first current source coupled to the capacitor for charging the capacitor. The discharging unit is coupled to the capacitor for discharging the capacitor. The feedback control unit controls the charging unit to charge the capacitor according to a feedback signal which represents the output of the power converting circuit. The duty-cycle adjusting unit generates a control signal and adjusts a duty cycle of the control signal according to a voltage of the capacitor.
摘要:
A pulse width modulation signal controlling apparatus including a signal pin, a core circuit, a setting judging circuit, a signal adjusting and selecting circuit, and a timer circuit is disclosed. The signal pin is connected to a setting device for receiving an external input signal. The setting judging circuit receives and compares a setting signal with a reference value to generate a setting judgment result. The signal adjusting and selecting circuit couples the signal pin to the setting judging circuit and adjusts the external input signal into the setting signal according to the setting device in a first state, and couples the signal pin to the core circuit in a second state. The timer circuit controls the state of the signal adjusting and selecting circuit, wherein the timer circuit sets the signal adjusting and selecting circuit in the first state during a predetermined time period.