Abstract: A system for sensing a current through a transistor is provided and a DC-DC converter including one or more such systems. The system includes a transistor module, including: a primary transistor electrically connected between a first and a second terminal; and a secondary transistor electrically connected between the first and a third terminal, a control terminal of the secondary transistor is electrically connected to a control terminal of the primary transistor. The system includes a current sensing module electrically connected to the transistor module and having an output terminal. The system is operable in a first mode in which the current sensing module outputs, at the output terminal, a first output signal indicative of a current through the primary transistor in a first current direction based on a voltage difference between the third and the second terminal, the first current direction being from the first to the second terminal.

Abstract: Operating power converters. Some of the methods include: storing energy in a transformer arranged for flyback operation, the storing by making conductive a primary switch coupled to a primary winding of the transformer; and then ceasing the storing of energy; determining on time of the primary switch during the storing of energy, the determining creates a value indicative of charge time; transferring energy from the transformer to a load through a secondary winding of the transformer; measuring discharge time of the energy from the transformer during the transferring, the measuring of the discharge time creates a value indicative of discharge time; calculating a value indicative of output voltage of the power converter using the value indicative of charge time and the value indicative of discharge time; and then compensating a charge time of a subsequent energy storage cycle, the compensation based on the value indicative of output voltage.

Abstract: Operating power converters. Some of the methods include: storing energy in a transformer arranged for flyback operation, the storing by making conductive a primary switch coupled to a primary winding of the transformer; and then ceasing the storing of energy; determining on time of the primary switch during the storing of energy, the determining creates a value indicative of charge time; transferring energy from the transformer to a load through a secondary winding of the transformer; measuring discharge time of the energy from the transformer during the transferring, the measuring of the discharge time creates a value indicative of discharge time; calculating a value indicative of output voltage of the power converter using the value indicative of charge time and the value indicative of discharge time; and then compensating a charge time of a subsequent energy storage cycle, the compensation based on the value indicative of output voltage.

Abstract: In one form, a power factor correction (PFC) controller, comprising includes a regulation circuit, a dead-time detection circuit, and a pulse width modulator. The regulation circuit provides a control voltage in response to a feedback voltage received at a feedback input terminal, wherein the feedback voltage is proportional to an output voltage. The dead-time detection circuit has an input coupled to a zero current detection input terminal, and an output for providing a dead-time signal. The pulse width modulator is responsive to the control voltage and the dead-time signal to provide a drive signal that controls conduction of a switch to improve a power factor of an offline converter, wherein the pulse width modulator modulates both an on-time and a switching period of the drive signal using the dead-time signal in a discontinuous conduction mode.

Abstract: An integrated circuit power factor controller includes a pulse width modulator and a line sensing circuit. The pulse width modulator has a first input for receiving a feedback signal, a second input for receiving a line sense signal, and an output for providing a drive signal having a duty cycle formed in response to the feedback signal and the line sense signal. The line sensing circuit has an input for receiving the drive signal, and an output coupled to the second input of the pulse width modulator for providing the line sense signal. The line sensing circuit forms the line sense signal in response to measuring a duty ratio of the drive signal. In another form, an offline converter includes an integrated circuit power factor controller that provides a line sense signal in response to a duty ratio of the drive signal without measuring a voltage on the input line.

Abstract: An integrated circuit power factor controller includes a feedback input terminal for receiving a feedback signal representative of an output voltage, a control terminal for receiving an error signal and adapted to be coupled to a compensation network, a drive terminal for providing a drive signal and adapted to be coupled to a transistor, and a pulse width modulator. The pulse width modulator is coupled to the feedback input terminal, the control terminal, and the drive terminal, and provides the drive signal having a duty cycle formed in response to the feedback signal. The pulse width modulator includes a line sensing multiplier having a first input for receiving the error signal, a second input for receiving the drive signal, and an output for providing a multiplied signal, and the pulse width modulator further provides the drive signal in response to the multiplied signal.

Abstract: In accordance with an embodiment, a converter includes a power factor controller that varies the switching frequency of a switching transistor in accordance with a signal representative of power at the input of the converter.

Abstract: A circuit and method for detecting a brown-out condition and providing a feed-forward transfer function in a power supply circuit. A comparison circuit is coupled to a delay element through a latch. A second delay element is connected between the first delay element and an input of the latch. The output of the first delay element is connected to a clamping circuit via a logic circuit. A first voltage is compared with a reference voltage to generate a comparison voltage, which is transmitted through the latch and the first delay element. The comparison voltage is monitored at an output of the first delay element. A brown-out condition occurs if the comparison voltage being monitored at the output of the first delay element results from the first voltage being less than the reference voltage.

Abstract: In accordance with an embodiment, a converter includes a power factor controller that varies the switching frequency of a switching transistor in accordance with a signal representative of power at the input of the converter.

Abstract: A method for regulating an output voltage of a converter is provided in which a switching frequency of a switching device is limited in response to a signal that is representative of a magnitude of a current from an input of the converter and to a sense signal generated in response to an input voltage signal.

Abstract: In one embodiment, a method of forming a power supply controller includes forming the power supply controller to receive an input signal that is representative of an ac signal, and forming the power supply controller to form an average value of an output current over a period of a drive signal that is formed by the power supply controller to have a waveshape of substantially one of a squared version of the input signal or a waveshape of the input signal.

Abstract: An off-line power converter includes an integrated circuit power factor controller including a multi-function input terminal, a drive terminal for providing a drive signal to a gate of a drive transistor, a processing circuit coupled to the multi-function input terminal and, based on a signal received from the multi-function input terminal, providing at least one current signal representative of a current conducted in the off-line power converter, and at least one voltage signal representative of a voltage provided to a load, and a controller for providing the drive signal selectively in response to the at least one current signal and the at least one voltage signal.

Abstract: A method and circuit for generating a clock signal. A power factor correction circuit has n channels operating out of phase and independently. The circuit is able to generate a clock signal for each channel according to the current cycle duration of each channel.

Abstract: A circuit and method for detecting a brown-out condition and providing a feed-forward transfer function in a power supply circuit. A comparison circuit is coupled to a delay element through a latch. A second delay element is connected between the first delay element and an input of the latch. The output of the first delay element is connected to a clamping circuit via a logic circuit. A first voltage is compared with a reference voltage to generate a comparison voltage, which is transmitted through the latch and the first delay element. The comparison voltage is monitored at an output of the first delay element. A brown-out condition occurs if the comparison voltage being monitored at the output of the first delay element results from the first voltage being less than the reference voltage.

Abstract: In one embodiment, a method of forming a power supply controller includes forming the power supply controller to receive an input signal that is representative of an ac signal, and forming the power supply controller to form an average value of an output current over a period of a drive signal that is formed by the power supply controller to have a waveshape of substantially one of a squared version of the input signal or a waveshape of the input signal.

Abstract: A method and circuit for protecting against an over current condition. A conduction time of one or more transistors is reduced during the over current condition. The conduction time is reduced in an amount that is an increasing function of the amount of the over current. The conduction time may be reduced proportionally to the excess current.

Abstract: A circuit and method for detecting a brown-out condition and providing a feed-forward transfer function in a power supply circuit. A comparison circuit is coupled to a delay element through a latch. A second delay element is connected between the first delay element and an input of the latch. The output of the first delay element is connected to a clamping circuit via a logic circuit. A first voltage is compared with a reference voltage to generate a comparison voltage, which is transmitted through the latch and the first delay element. The comparison voltage is monitored at an output of the first delay element. A brown-out condition occurs if the comparison voltage being monitored at the output of the first delay element results from the first voltage being less than the reference voltage.

Abstract: In one embodiment, a power supply controller is configured to adjust a peak value of a primary current through a power switch responsively to a difference between a demagnetization time and a discharge time of the parasitic leakage inductance of a transformer.

Abstract: An off-line power converter includes an integrated circuit power factor controller including a multi-function input terminal, a drive terminal for providing a drive signal to a gate of a drive transistor, a processing circuit coupled to the multi-function input terminal and, based on a signal received from the multi-function input terminal, providing at least one current signal representative of a current conducted in the off-line power converter, and at least one voltage signal representative of a voltage provided to a load, and a controller for providing the drive signal selectively in response to the at least one current signal and the at least one voltage signal.

Abstract: In accordance with an embodiment, a converter includes a power factor controller that varies the switching frequency of a switching transistor in accordance with a signal representative of power at the input of the converter.