Abstract: A flyback converter is provided that includes a high-side synchronous rectifier switch transistor. A secondary-side synchronous rectifier controller powered by a power supply voltage controls a cycling on and off of the high-side synchronous rectifier switch transistor. An active control of the charging of the power supply voltage uses an auxiliary capacitor that is charged from a charge source while a power switch transistor in a first switching state. When the power switch transistor is in a second switching state that is the complement of the first switching state, the active control coupes the auxiliary capacitor to a power supply capacitor that stores the power supply voltage.

Abstract: A flyback converter includes a synchronous rectifier switch transistor controlled by a controller. The controller cycles the synchronous rectifier switch transistor to lower an output voltage by transferring energy from a secondary-side output capacitor to a primary-side input capacitor.

Abstract: A switching power converter is provided that adaptively changes the on-time period for an auxiliary switch transistor to locate a boundary between sufficient and insufficient energy.

Abstract: A flyback converter is provided that dynamically adjusts a drain threshold voltage for a current cycle of a synchronous rectifier switch transistor based upon operating conditions in a previous cycle of the synchronous rectifier switch transistor. A differential amplifier drives a gate voltage of the synchronous rectifier switch transistor during an on-time of the current cycle so that a drain voltage of the synchronous rectifier switch transistor equals the drain threshold voltage during a regulated portion of the current cycle.

Abstract: A system for turning off a synchronous rectifier (SR) based on a primary switch (PS) turn-on detection in a flyback converter having a primary-side and a secondary-side is disclosed. The system comprises the PS on the primary-side, the SR on the secondary-side, a spike detector, and a SR controller. The SR is configured to produce a drain-to-source voltage (VDS). The spike detector is in signal communication with an output capacitor (Cout) on the secondary-side and the spike detector is configured to detect a voltage spike of an output voltage (VOut) across the Cout that is indicative of the PS being turned-on. The SR controller is in signal communication with the SR and the spike detector and the SR controller is configured to turn-off the SR based on the spike detector detecting the voltage spike of the VOut.

Abstract: A flyback converter is provided that includes a high-side synchronous rectifier switch transistor. A secondary-side synchronous rectifier controller powered by a power supply voltage controls a cycling on and off of the high-side synchronous rectifier switch transistor. An active control of the charging of the power supply voltage uses an auxiliary capacitor that is charged from a charge source while a power switch transistor in a first switching state. When the power switch transistor is in a second switching state that is the complement of the first switching state, the active control coupes the auxiliary capacitor to a power supply capacitor that stores the power supply voltage.

Abstract: An isolated switching power converter having a primary-side and secondary-side in signal communication with an input and an output is disclosed. The isolated switching power converter comprises a transformer, primary-side switch, secondary-side switch, primary-side controller, and secondary-side controller. The transformer includes a primary-winding and a secondary-winding in signal communication with the input and output. The primary-side switch is in signal communication with the primary-winding and the secondary-side switch is in signal communication with the secondary-winding. The primary-side controller is on the primary-side and the secondary-side controller is on the secondary-side.

Abstract: A standby power system for a flyback converter is disclosed. The flyback converter includes a primary-side, a secondary-side, an output terminal at the secondary-side, and a secondary-side controller, where the output terminal is configured to electrically connect to a load. The standby power system comprises a comparator at the secondary-side, an opto-coupler in signal communication with the primary-side, the secondary-side, and the comparator, and a cable detach detector (or load detector). The cable detach detector is configured to determine whether a device is electrically connected to the flyback converter through a charging cable and to set the flyback converter into a standby mode if the deice is disconnected from the charging cable.

Abstract: A flyback converter includes a synchronous rectifier switch transistor controlled by a controller. The controller cycles the synchronous rectifier switch transistor to lower an output voltage by transferring energy from a secondary-side output capacitor to a primary-side input capacitor.

Abstract: A flyback converter is provided that dynamically adjusts a drain threshold voltage for a current cycle of a synchronous rectifier switch transistor based upon operating conditions in a previous cycle of the synchronous rectifier switch transistor. A differential amplifier drives a gate voltage of the synchronous rectifier switch transistor during an on-time of the current cycle so that a drain voltage of the synchronous rectifier switch transistor equals the drain threshold voltage during a regulated portion of the current cycle.

Abstract: A secondary-side control loop for a flyback converter is provided that generates a secondary-side control signal during normal operation using a compensator. In periods of significant load changes, the compensator is bypassed so that the secondary-side control signal is generated as an open-loop signal.

Abstract: A standby power system for a flyback converter is disclosed. The flyback converter includes a primary-side, a secondary-side, an output terminal at the secondary-side, and a secondary-side controller, where the output terminal is configured to electrically connect to a load. The standby power system comprises a comparator at the secondary-side, an opto-coupler in signal communication with the primary-side, the secondary-side, and the comparator, and a cable detach detector (or load detector). The cable detach detector is configured to determine whether a device is electrically connected to the flyback converter through a charging cable and to set the flyback converter into a standby mode if the deice is disconnected from the charging cable.

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: An isolated switching power converter having a primary-side and secondary-side in signal communication with an input and an output is disclosed. The isolated switching power converter comprises a transformer, primary-side switch, secondary-side switch, primary-side controller, and secondary-side controller. The transformer includes a primary-winding and a secondary-winding in signal communication with the input and output. The primary-side switch is in signal communication with the primary-winding and the secondary-side switch is in signal communication with the secondary-winding. The primary-side controller is on the primary-side and the secondary-side controller is on the secondary-side.

Abstract: A flyback converter is provided that dynamically adjusts a drain threshold voltage for a current cycle of a synchronous rectifier switch transistor based upon operating conditions in a previous cycle of the synchronous rectifier switch transistor. A differential amplifier drives a gate voltage of the synchronous rectifier switch transistor during an on-time of the current cycle so that a drain voltage of the synchronous rectifier switch transistor equals the drain threshold voltage during a regulated portion of the current cycle.

Abstract: A flyback converter is provided that dynamically adjusts a drain threshold voltage for a current cycle of a synchronous rectifier switch transistor based upon operating conditions in a previous cycle of the synchronous rectifier switch transistor. A differential amplifier drives a gate voltage of the synchronous rectifier switch transistor during an on-time of the current cycle so that a drain voltage of the synchronous rectifier switch transistor equals the drain threshold voltage during a regulated portion of the current cycle.

Abstract: A system for turning off a synchronous rectifier (SR) based on a primary switch (PS) turn-on detection in a flyback converter having a primary-side and a secondary-side is disclosed. The system comprises the PS on the primary-side, the SR on the secondary-side, a spike detector, and a SR controller. The SR is configured to produce a drain-to-source voltage (VDS). The spike detector is in signal communication with an output capacitor (Cout) on the secondary-side and the spike detector is configured to detect a voltage spike of an output voltage (VOut) across the Cout that is indicative of the PS being turned-on. The SR controller is in signal communication with the SR and the spike detector and the SR controller is configured to turn-off the SR based on the spike detector detecting the voltage spike of the VOut.

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 integrating 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 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.