摘要:
The power output of a static DC--DC converter employing a current mode PWM controller is controlled upon the varying of the switching frequency, by detecting the sawtooth signal produced by the local oscillator generating a DC signal with an amplitude inversely proportional to the frequency. The power output is controlled by alternatively clamping the output voltage of the error amplifier of the PWM controller at a voltage proportional to the amplitude of the DC signal, or by offsetting the signal present on the current sensing resistor by a voltage corresponding to the difference between a constant voltage and the DC signal.
摘要:
The power supply device includes a DC-DC converter circuit having a power switch and a driving stage. The driving stage has a compensation terminal on which a compensation voltage is present, and which receives a biasing current. The driving stage includes a control circuit having an output terminal connected to a control terminal of the power switch and disconnection-detecting circuitry connected to the compensation terminal and generating a signal for permanent turning-off of the power switch when the biasing current drops below a current-threshold value. The driving stage moreover includes over-voltage detecting circuitry connected to the compensation terminal and generating a signal for temporary turning-off of the power switch when the compensation voltage exceeds a voltage-threshold value.
摘要:
A device for power factor correction in a forced switching power supply unit is provided. The device includes a converter and a control device coupled to the converter so as to obtain from an input alternating mains voltage a direct regulated voltage on the output terminal. The converter includes a power transistor, and the control device includes an error amplifier having its inverting terminal coupled to a first signal that is proportional to the regulated voltage and its non-inverting terminal coupled to a reference voltage. A drive circuit of the power transistor is coupled to the output terminal of the error amplifier. The control device also includes a circuit for generating a current signal that is representative of the effective input voltage. The current signal is coupled to the inverting terminal of the error amplifier to vary the regulated voltage in reply to variations in the effective input voltage.
摘要:
A device for power factor correction in a forced switching power supply unit is provided. The device includes a converter and a control device coupled to the converter so as to obtain from an input alternating mains voltage a direct regulated voltage on the output terminal. The converter includes a power transistor, and the control device includes an error amplifier having its inverting terminal coupled to a first signal that is proportional to the regulated voltage and its non-inverting terminal coupled to a reference voltage. A drive circuit of the power transistor is coupled to the output terminal of the error amplifier. The control device also includes a circuit for generating a current signal that is representative of the effective input voltage. The current signal is coupled to the inverting terminal of the error amplifier to vary the regulated voltage in reply to variations in the effective input voltage.
摘要:
A self-disabling and self-recovering converter includes a transformer connected to a power source and has an auxiliary winding for providing a self-supply voltage after start-up, and an integrated circuit having circuitry and a plurality of pins connected thereto. The converter also includes at least one external line and a sensor connected thereto for an electrical or physical quantity to be monitored. The at least one external line is biased through a first pin with the self-supply voltage, and is functionally coupled to a second pin when a threshold is surpassed. A sectionable voltage clamp chain is connected between the auxiliary winding and a voltage reference. A self-recovery circuit having a first input is connected to the auxiliary winding and a second input is connected through the second pin to the at least one external line. An output of the self-recovery circuit is connected to the sectionable voltage clamp chain for sectioning a portion thereof to the voltage reference for self-supplying the integrated circuit.
摘要:
A device corrects the power factor in forced switching power supplies and includes a converter and a control device to obtain a regulated voltage on an output terminal. The control device comprises an error amplifier having an inverting terminal (Vout) and a non-inverting terminal receiving a reference voltage. The device includes first and second resistances coupled in series with a conduction element positioned between the first resistance and the inverting terminal of the error amplifier and a fault detector suitable for detecting the electrical connection of the conduction element with the output terminal and suitable for detecting an output signal of the second resistance. The fault detector is suitable for supplying a malfunction signal upon detecting an electric disconnection of the conduction element from the output terminal or when the output signal of the second resistance tends to zero.
摘要:
A control device of a plurality of switching converters is disclosed; each converter comprises at least one power switch and is associated with a control circuit of the at least one power switch. The control device comprises means suitable for comparing a signal representative of the load of the plurality of converters with a plurality of reference signals and suitable for enabling or disabling at least one of said plurality of control circuits in response to said comparison.
摘要:
A device is provided for the correction of the power factor in forced switching power supplies. The device includes a converter, and a first control circuit coupled with the converter so as to obtain a regulated voltage on the output terminal from an alternating network input voltage. The converter includes a power transistor, and the first control circuit is suitable for driving the power transistor in every switching cycle comprising the turn-on time and the turn-off time of the power transistor. The device for the correction of the power factor further includes a second control circuit coupled to the first control circuit and capable of modulating the turn-off time of the power transistor.
摘要:
A circuit for reducing the variations of auto-supply voltage of a control circuit of a switching power supply, where the control circuit supplies an activation or deactivation signal of a power transistor, includes an auto-supply voltage generator, a controlled switch capable of selectively connecting the generator to the control circuit, and a driving circuit of the controlled switch that supplies a closing signal of the controlled switch after a predefined delay of time starting from the deactivation command.
摘要:
A circuit for reducing the variations of auto-supply voltage of a control circuit of a switching power supply, where the control circuit supplies an activation or deactivation signal of a power transistor, includes an auto-supply voltage generator, a controlled switch capable of selectively connecting the generator to the control circuit, and a driving circuit of the controlled switch that supplies a closing signal of the controlled switch after a predefined delay of time starting from the deactivation command.