Abstract:
A start-up circuit with low standby power loss for power converters according to present invention comprises a first diode and a second diode coupled to an input voltage of the power converter. A start-up resistor is coupled to the join of the first diode and the second diode. A high-voltage switch is coupled to the start-up resistor to generate a power source. A control circuit generates a switching signal for switching a transformer. A detection circuit generates a disable signal in response to the input voltage to disable the switching signal. A winding of the transformer is coupled to the power source to generate the power for the power source. The high-voltage switch is turned off to cut off the start-up resistor for saving the power loss once the voltage of the power source is higher than a threshold.
Abstract:
A synchronous rectifier for a switching power converter is provided and includes a power transistor, a diode, and a control circuit. The power transistor and the diode are coupled to a transformer and an output of the power converter for the rectification. The control circuit generates a drive signal to switch on the power transistor once the diode is forward biased. The control circuit includes a phase-lock circuit. The phase-lock circuit generates an off signal to switch off the power transistor in response to a pulse width of the drive signal. The pulse width of the drive signal is shorter than a turned-on period of the diode. The phase-lock circuit further reduces the pulse width of the drive signal in response to a feedback signal. The feedback signal is correlated to an output load of the power converter.
Abstract:
An adaptive synchronous rectification control circuit and a control method are developed. The control circuit comprises an adaptive circuit that generates a reference signal in response to a detection signal of a power converter. A clamped circuit clamps the reference signal at a threshold voltage if the reference signal equals or is greater than the threshold voltage. A switching circuit generates a control signal to control a synchronous switch of the power converter in response to the detection signal and the reference signal. The control method generates the reference signal in response to the detection signal. The reference signal is clamped at the threshold voltage if the reference signal equals or is greater than the threshold voltage. The method further generates the control signal to control the synchronous switch of the power converter in response to the detection signal and the reference signal.
Abstract:
A trim circuit for a power supply controller includes: a control circuit; at least a capacitance type programmable circuit connection; and a switching circuit, under control of the control circuit, the switching circuit selectively coupling the capacitance type programmable circuit connection to anyone of an operation voltage and a programming voltage, for determining a programming state of the capacitance type programmable circuit connection.
Abstract:
A controller for a power converter includes a clamping circuit, a switching circuit and a pulse generator. The clamping circuit is coupled to an input terminal of the controller for detecting a detection signal from a transformer. The switching circuit generates a switching signal to switch the transformer in response to the detection signal for regulating the power converter. A maximum level of the detection signal is clamped to be under a level of a threshold voltage during an off-period of the switching signal. Since the maximum level of the detection signal is clamped and the oscillating energy of the reflected signal is discharged, the speed of detecting the detection signal is increased. Therefore, the regulation of the primary-side controlled power converter can be improved accordingly.
Abstract:
A synchronous rectifier for a switching power converter is provided and includes a power transistor, a diode, and a control circuit. The power transistor and the diode are coupled to a transformer and an output of the power converter for the rectification. The control circuit generates a drive signal to switch on the power transistor once the diode is forward biased. The control circuit includes a phase-lock circuit. The phase-lock circuit generates an off signal to switch off the power transistor in response to a pulse width of the drive signal. The pulse width of the drive signal is shorter than a turned-on period of the diode. The phase-lock circuit further reduces the pulse width of the drive signal in response to a feedback signal. The feedback signal is correlated to an output load of the power converter.
Abstract:
A control circuit includes a detection circuit to detect the short-circuited of a current sense terminal of the power converter. It includes a comparator, a verification circuit and a timer circuit. The comparator receives an input signal for generating a sense signal. The input signal represents the switching current of a power switch. The sense signal is enabled when the input signal is lower than a threshold. The verification circuit generates a protection signal in response to the sense signal or/and -a delay signal. The protection signal is generated when the current sense terminal is short-circuited, in which the power switch and the sense signal are enabled after the time delay of the delay signal. The protection signal turns off the power switch for the protection.
Abstract:
A control circuit with protection circuit for power supply according to the present invention comprises a peak-detection circuit and a protection circuit. The peak-detection circuit detects an AC input voltage and generates a peak-detection signal. The protection circuit generates a reset signal to reduce the output of the power supply in response to the peak-detection signal. The present invention can protect the power supply in response to the AC input voltage effectively through the peak-detection circuit.
Abstract:
A control circuit includes a detection circuit to detect the short-circuited of a current sense terminal of the power converter. It includes a comparator, a verification circuit and a timer circuit. The comparator receives an input signal for generating a sense signal. The input signal represents the switching current of a power switch. The sense signal is enabled when the input signal is lower than a threshold. The verification circuit generates a protection signal in response to the sense signal or/and -a delay signal. The protection signal is generated when the current sense terminal is short-circuited, in which the power switch and the sense signal are enabled after the time delay of the delay signal. The protection signal turns off the power switch for the protection.
Abstract:
A control circuit with protection circuit for power supply according to the present invention comprises a peak-detection circuit and a protection circuit. The peak-detection circuit detects an AC input voltage and generates a peak-detection signal. The protection circuit generates a reset signal to reduce the output of the power supply in response to the peak-detection signal. The present invention can protect the power supply in response to the AC input voltage effectively through the peak-detection circuit.