Abstract: Disclosed is a universal primary-only output current regulation for a flyback converter. A controller determines a peak sense resistor voltage responsive to a desired average output current for the flyback converter during a continuous conduction mode of operation. After a power switch transistor is cycled on, the controller monitors a sense resistor voltage to determine when the sense resistor voltage equals the peak sense resistor voltage. The controller switches off the power switch transistor when the sense resistor voltage equals the peak sense resistor voltage to maintain an average output current for the flyback converter equal to the desired average output current.

Abstract: Disclosed is a system for determining a primary switching event in an isolated converter having a primary-side and a secondary-side. The system includes a primary-switch (PS) on the primary-side, a synchronous rectifier (SR) on the secondary-side, an integration circuit, and a SR controller. The integration circuit is in signal communication with the SR on the secondary-side and the SR controller is in signal communication with the SR and the integration circuit. The SR is configured to produce a drain-to-source voltage (VDS) and the integration circuit is configured to integrate a difference between the VDS and a output voltage (VOut) (produced by the secondary-side) over time to produce a VDS over time value (VTime). The SR controller is configured to determine if the VDS is greater than a first threshold voltage (VTH) and determine the primary switching event when the VTime is greater than a second threshold voltage (VSTH).

Abstract: A flyback converter is disclosed that times a detection time for each cycle of a power switch transistor. The detection time ends when a sense resistor voltage exceeds a threshold voltage. Over a half cycle of an AC input voltage to the flyback converter measures a series of detection time and determines a minimum detection time from the series of detection times. If the minimum detection time exceeds a brownout delay, a brownout condition exists. If the minimum detection time is less than an overvoltage delay, an overvoltage condition exists.

Abstract: Disclosed is a universal input voltage detection system for a flyback converter having a transformer coupled between an input and an output of the flyback converter. The transformer includes a primary winding coupled to the input of the flyback converter to receive an input voltage and a secondary winding coupled to the output of the flyback converter. The universal input voltage detection system comprises a controller, coupled to a switch, at a primary winding side of the transformer. The switch is coupled to the primary winding of the transformer and a current through the primary winding is generated when the switch is turned on. The controller is configured to operate in either continuous conduction mode (CCM) or discontinuous conduction mode (DCM) and indirectly detect the input voltage to the flyback converter based on the current through the primary winding generated while the switch is turned on.

Abstract: A switch detection circuit is provided that senses the voltage on a rectifying component for rectifying a secondary winding current through a secondary winding of a flyback converter's transformer to determine whether a power switch transistor attached to a primary winding of the transformer has ceased cycling.

Abstract: The feedback loop of a switching power converter controller is provided with an averaging circuit that averages either an output voltage, an error signal, or a control voltage. Regardless of which feedback signal is averaged, the averaging occurs over a first cycle of a rectified input voltage to form an averaged signal that is used by the feedback loop in a subsequent cycle of the rectified input voltage.

Abstract: A switching power converter is provided that communicates with a mobile device to receive a value of a load detection current. The switching power converter adjusts the cycling of a power switch until a constant current mode of operation is entered with a known output current driving the mobile device. The switching power converter subtracts the load current from the output current to measure a soft-short circuit current.

Abstract: A device for determining impedance at a data pin of a communication interface. In one embodiment, the device includes a current source configured to selectively inject a test current to the data pin. The device also includes a sensing circuit for sensing a first test voltage corresponding to a voltage at the data pin without the test current injected, and a second test voltage corresponding to another voltage at the data pin with the test current injected. The sensing circuit determines the impedance at the data pin based on the first test voltage and the second test voltage.

Abstract: A power converter and method to detect a light load condition at an output of the power converter are presented. The power converter may have an inductor and a resistive element connected between an input of the power converter and an input of the inductor. The power converter may have a first chopping unit to generate a chopped voltage signal at an output of said first chopping unit, wherein the chopped voltage signal is generated by chopping an inductor voltage at the input of said inductor based on a duty cycle of the power converter. The power converter may have a reference current source, wherein the reference current source and a replica resistive element are arranged in series. The power converter may have a comparator unit to generate, based on the reference potential and based on the chopped voltage signal, a signal indicative of said light load condition.

Abstract: A flyback converter is disclosed having a secondary side controller that generates an input current for an optocoupler diode by driving a variable resistor with a control voltage. The secondary side controller varies a variable resistance for the variable resistor to compensate for current transfer ratio gain variations for the optocoupler.

Abstract: A flyback converter is provided with a controller that is configured to analyze the reflected feedback voltage waveforms to determine the presence of a ground connection fault for the auxiliary winding.

Abstract: A power system and related methods provide sense resistor fault detection and safe operation of switching power converters and connected devices such as portable electronic devices powered by the switching power converter. The power system detects an open circuit or short circuit condition of the sense resistor and controls output current of the switching power converter to ensure safe operating conditions of the power system and connected equipment. The power system can also detect initial inrush current of the connected equipment and detect a duty cycle of the switching power converter to positively detect a short circuit condition of the sense resistor.

Abstract: A flyback converter controller is provided with secondary-side controller that adjusts a discharge current form an output voltage rail during a communication period with a primary-side controller to maintain the output voltage within regulation.

Abstract: A flyback converter control architecture is provided in which primary-only feedback techniques are used to ensure smooth startup and detection of fault conditions. During steady-state operation, secondary-side regulation is employed. In addition, current limits are monitored during steady-state operation using primary-only feedback techniques to obviate the need for a secondary-side current sense resistor.

Abstract: A switching power supply controller for a switching power supply is provided that measures an input voltage through an application of a load during an input voltage measurement period following connection of the switching power supply to an AC mains. Based upon the measured input voltage, the controller adjusts a start-up delay period so that the start-up delay period is substantially constant despite variations in an AC line voltage for the AC mains.

Abstract: A system for improving a power factor (PF) of a power converter in signal communication with a rectifier and an electromagnetic interference capacitor is disclosed. The system includes a controller and a threshold detector. The threshold detector is configured to measure and compare a rectified voltage against a threshold voltage and the controller is configured to set the power converter to a stop-mode. The power converter is set to the stop-mode at a stop-time that is less than a first zero-crossing time. The controller is further configured to set the power converter to a run-mode at a time that is past the first zero-crossing time.

Abstract: An adaptive pulse width modulation threshold is provided for a flyback converter that controls the transition between the pulse frequency mode of operation and the pulse width modulation mode of operation. The adaptive pulse width modulation mode is adapted responsive to an output voltage for the flyback converter.

Abstract: A synchronous rectifier controller method is provided for controlling the on and off periods of a synchronous rectifier (SR) switch transistor in a switching power converter. The method includes a first step of monitoring an unfiltered to control whether the SR switch transistor is turned on during a first part of a power switch cycle. The method also includes a second step of monitoring a filtered SR switch signal to control whether the SR switch is turned on during a remaining second part of the power switch cycle.

Abstract: A flyback converter communication channel is provided that comprises a pair of capacitors. A transmitter on a first side of a transformer for the flyback converter transmits a transmitter signal over a first one of the capacitors. The transmitter also transmits a complement of the transmitter signal over a second one of the capacitors. A receiver on a second side of the transformer controls a switch transistor responsive to a high-pass-filtered difference of the received signals from the pair of capacitors.

Abstract: An adaptive pulse frequency modulation for a switching power converter is provided that varies the switching frequency across a cycle of a rectified input voltage for the switching power converter From a beginning of the cycle of the rectified input voltage, the switching frequency decreases from a maximum value to a minimum value at a mid-point of the cycle and then increases from the mid-point back to the maximum value at an end of the cycle.