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 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 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: Systems, devices, and methods are provided to enable power converters to use two or more sensing elements to reliably detect a short circuit (or soft-short circuit) existing in the power converter and distinguish these conditions from other operating conditions, such as low voltage conditions or normal operating conditions. The disclosed embodiments enable the accurate detection of fault conditions, such as short circuits or soft short conditions, using a number of sensing elements, such as sense resistors and the inherent resistance of switching devices, while preventing the detection of false positives due to other factors such as low input voltage.

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 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 synchronous rectifier controller for controlling the on and off periods of a synchronous rectifier switch transistor in a switching power converter. In particular, the synchronous rectifier controller is configured to adaptively enable and disable a deglitch filter for filtering a turn-on signal for the synchronous rectifier switch transistor. In this fashion, the synchronous rectifier switch transistor may be switched on more rapidly during periods when the deglitch filter is disabled for greater efficiency yet the switching power converter is protected by the deglitch filter when it is not disabled.

Abstract: A synchronous rectifier controller for controlling the on and off periods of a synchronous rectifier switch transistor in a switching power converter. In particular, the synchronous rectifier controller is configured to adaptively enable and disable a deglitch filter for filtering a turn-on signal for the synchronous rectifier switch transistor. In this fashion, the synchronous rectifier switch transistor may be switched on more rapidly during periods when the deglitch filter is disabled for greater efficiency yet the switching power converter is protected by the deglitch filter when it is not disabled.

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 switching power converter provides regulated voltage to a load. The switching power converter comprises a transformer including a primary winding coupled to an input voltage and a secondary winding coupled to an output of the switching power converter. The switching power converter further comprises a power switch coupled to the primary winding and a rectifier coupled to the secondary winding. Current is generated in the primary winding responsive to the power switch being turned on and not generated responsive to the power switch being turned off. A detection circuit measures a voltage across the rectifier. If the detection circuit detects a decrease in the voltage across the rectifier outside of a blanking period, the detection circuit generates a current pulse in the secondary winding of the transformer.

Abstract: A flyback converter is provided with a synchronous rectifier (SR) controller including a pulse linear regulator (PLR) charging path and an LDO charging path. The SR controller is configured to monitor the switching period and/or duty cycle of a power switch in the flyback converter to select between the PLR and LDO charging paths.

Abstract: A synchronous rectifier controller for controlling the on and off periods of a synchronous rectifier switch transistor in a switching power converter. In particular, the synchronous rectifier controller is configured to adaptively enable and disable a deglitch filter for filtering a turn-on signal for the synchronous rectifier switch transistor. In this fashion, the synchronous rectifier switch transistor may be switched on more rapidly during periods when the deglitch filter is disabled for greater efficiency yet the switching power converter is protected by the deglitch filter when it is not disabled.

Abstract: A line ripple compensation technique is provided for a switching power converter operating in both a pulse frequency mode of operation and a pulse width modulation mode of operation.

Abstract: An adaptive valley mode switching power converter is provided that switches on a power switch within valley periods of a resonant voltage oscillation for the power switch. Each valley period is determined with regard to a valley threshold voltage.

Abstract: A power switch transistor for a switching power converter is maintained on during a re-startup period by a zener breakdown voltage following a fault condition for the switching power converter. A source voltage from the power switch transistor is used to charge a VCC capacitor that stores a power supply voltage for a controller for the switching power converter.

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 switching power converter may include a power switch coupled to a primary winding of a transformer, and a primary controller configured to turn on and off the power switch, a synchronous rectifier switch coupled to a secondary winding of a transformer, and a synchronous rectifier controller configured to turn on and off the synchronous rectifier switch. The synchronous rectifier controller may monitor a voltage across the synchronous rectifier switch. The synchronous rectifier controller may determine a period of a resonant oscillation of the voltage across the synchronous rectifier switch following at least one cycling off of the synchronous rectifier switch. The synchronous rectifier controller may adjust the minimum off-time period for the synchronous rectifier switch based on the period of the resonant oscillation. The synchronous rectifier controller may adaptively adjust a minimum off-time period for the synchronous rectifier switch.

Abstract: A startup circuit is provided for establishing the Vcc voltage level of a switching power converter. The startup circuit uses a switch controller and path switching transistor to provide a two-stage Vcc capacitor charging that reduces startup time while avoiding short circuit damage through the alternate usage of a high impedance charging path and a low-impedance charging path.

Abstract: A synchronous rectifier controller for controlling the on and off periods of a synchronous rectifier switch transistor in a switching power converter. In particular, the synchronous rectifier controller is configured to adaptively enable and disable a deglitch filter for filtering a turn-on signal for the synchronous rectifier switch transistor. In this fashion, the synchronous rectifier switch transistor may be switched on more rapidly during periods when the deglitch filter is disabled for greater efficiency yet the switching power converter is protected by the deglitch filter when it is not disabled.

Abstract: A flyback converter is provided with a synchronous rectifier (SR) controller including a pulse linear regulator (PLR) charging path and an LDO charging path. The SR controller is configured to monitor the switching period and/or duty cycle of a power switch in the flyback converter to select between the PLR and LDO charging paths.