Infineon Technologies Austria Ag

Infineon Technologies Ag

Xiaowu Gong

Yong Siang Teo

Kok Kee Lim

Yi He

Siu Kam Kok

Tuck Meng Chan

Marc Fahlenkamp

Meng Kiat Jeoh

Andrey B Malinin

Anthony Sanders

Michael Herfurth

Wolfgang Furtner

Mingping Mao

Junyang Luo

Zan Wang

Winson Siew Teng Wong

Gerald Deboy

Mladen Ivankovic

Dong Li

Jing Hu

Fred Sawyer

Yaw Hann Thian

Wee Tar Richard Ng

Harmut Jasberg

In some examples, a controller is configured to control a power switch electrically connected in series with a winding. In some examples, the controller is also configured to control a pass switch electrically connected between an output node of the winding and a bus out node. In some examples, the controller includes a current source configured to selectively drive a charging current from an intermediate node between the power switch and the winding to a control terminal of the pass switch to turn on the pass switch.

Control of a pass switch by a current source

A flyback converter includes a primary-side switch connected to a primary-side winding of a transformer and a secondary-side switch connected to a secondary-side winding of the transformer. The flyback converter is operated by controlling the primary-side switch to store energy in the transformer during ON periods of the primary-side switch, switching on the secondary-side switch synchronously with switching off the primary-side switch to transfer energy from the transformer to the secondary side, determining an off time of the secondary-side switch based on a reflected input voltage measured at the secondary-side winding when the primary-side switch is on, accounting for a settling time of the reflected input voltage when determining the off time of the secondary-side switch so that the settling time has little or no effect on the off time, and switching off the secondary-side switch based on the off time.

Digital synchronous rectification control for flyback converter

A flyback converter includes a primary-side switch connected to a primary-side winding of a magnetic device and a secondary-side switch connected to a secondary-side winding of the magnetic device. The flyback converter is operated by controlling the primary-side switch to store energy in the magnetic device during ON periods of the primary-side switch, switching on the secondary-side switch synchronously with switching off the primary-side switch to transfer energy from the magnetic device to the secondary side, determining an off time of the secondary-side switch based on a reflected input voltage measured at the secondary-side winding when the primary-side switch is on, accounting for a settling time of the reflected input voltage when determining the off time of the secondary-side switch so that the settling time has little or no effect on the off time, and switching off the secondary-side switch based on the off time.

Method and apparatus for measuring at least one of output current and output power for isolated power converters

Voltage converter controllers, voltage converters and methods are discussed regarding the adjustment of an on-time of an auxiliary switch of a voltage converter. First and second voltages are measured before a primary switch of the voltage converter is turned on and while the primary switch is turned on, and the on-time is adjusted based on the voltages.

Voltage converter controller, voltage converter and method for operating a voltage converter

Techniques are provided for controlling a synchronous rectification (SR) switch within a switched-mode power converter. The SR switch rectifies an output voltage of the power converter, and incurs little power loss in doing so. An SR controller generates control signals, including a turn-off trigger, that control conductivity of the SR switch. Voltages provided to the SR controller are divided down, so that the SR controller inputs do not need to support excessively high voltage levels as may be present in the power converter. The divided voltages are integrated to create a volt-second metric that closely tracks current through a winding of the power converter and the SR switch. The volt-second metric is compared against a threshold to determine when to issue an SR switch turn-off trigger.

Synchronous rectification switch control with automatic compensation and reset

An example method includes storing a peak voltage level, a valley voltage level, and a frequency of a signal that corresponds to an alternating current (AC) signal across a capacitor; periodically determining whether a current peak voltage level of the signal is different than the stored peak voltage level of the signal or a current valley voltage level of the signal is different than the stored valley voltage level of the signal; determining, based on whether the current peak voltage level of the signal is different than the stored peak voltage level or the current valley voltage level of the signal is different than the stored valley voltage level, whether the AC signal has been removed from the capacitor; and in response to determining that the AC signal has been removed from the capacitor, discharging the capacitor.

Capacitor discharging

In some examples, a control circuit is configured to control a transistor, and the control circuit includes a leading-edge detection unit configured to detect a time interval that corresponds to a leading-edge current spike through the transistor, wherein the time interval is independent of temperature. In some examples, the control circuit also includes a blanking unit configured to prevent the control circuit from turning off the transistor during the time interval.

Adaptive leading-edge blanking

Synchronous rectification control for flyback converter

Circuits and methods within a switched-mode power supply (SMPS) controller are provided. The SMPS controller includes an SMPS power stage which is integrated within the same package, and which has a first power switch. The first power switch is used to supply current to a power supply for the SMPS controller during a start-up phase of the SMPS, thereby charging this power supply prior to normal operational mode of the SMPS. A lead of the SMPS controller is connected to a control terminal of the first power switch during the start-up phase. After the start-up phase, this same lead is instead routed to an input source voltage monitor, and is used for detecting overvoltage or undervoltage conditions at the SMPS input power source.

Switched-mode power supply controller using a single pin for both input voltage sensing and control of power supply charging

A power converter includes a controller. The controller is configured to charge a capacitor of the controller based on a peak voltage applied to a primary-side winding of a transformer of the power converter. The controller is also configured to apply a discharge current defined by a first amount of current to the capacitor, and responsive to discharging the capacitor to a reference voltage level, determine, based on a feedback voltage generated by a primary-side auxiliary winding of the transformer, whether a discharge time of the capacitor is equal to a discharge time of the secondary-side winding. The controller is further configured to responsive to determining that the discharge time of the capacitor is not equal to the discharge time of the secondary-side winding, adjust the discharge current from the first amount of current to a second amount of current. The second amount of current is indicative of a predicted discharge time of a secondary-side winding of the transformer.

Knee point detection for power converter control

In one example, a method includes activating, by a controller of a power converter, a switch of the power converter that controls an amount of energy provided by the power converter; receiving, by an input of the controller, a signal that represents an amount of current flowing through the switch; responsive to determining that the amount of current flowing through the switch is greater than or equal to a threshold amount of current, deactivating, by the controller, the switch; and responsive to determining that an amount of time elapsed since activation of the switch is greater than a threshold amount of time, deactivating, by the controller, the switch.

Power converter damage protection

In some examples, a circuit is configured to receive an input signal and deliver, based on the input signal, a charging current to a capacitor. The circuit may be further configured to receive an output voltage that indicates a charge on the capacitor. The circuit may be further configured to determine that the output voltage is shorted to a reference ground. The circuit may be further configured to reduce, based on determining that the output voltage is shorted to the reference ground, the charging current.

Protection and management of a power supply output shorted to ground

A controller of a power converter is described that after switching-on a primary switch of a power converter, detects a voltage that is indicative of a primary current through the primary switch and responsive to determining that the voltage exceeds a direct-current (DC) voltage threshold, switches-off the primary switch. The controller stores a peak value of the voltage while switching-off the primary switch, and responsive to determining that the peak value is higher or lower than a range of target values associated with the peak value of the voltage, the controller adjusts at least one of the DC voltage threshold or the range of target values for a subsequent switching cycle of the primary switch.

Power limiting for flyback converter

In some embodiments, a power system includes an integrated circuit (IC). The IC includes a first switching transistor having a load path coupled between a sensing terminal of the IC and a first terminal of the IC. The first terminal of the IC is configured to be coupled to a first load path terminal of a second switching transistor. The IC also includes a first diode coupled between the first terminal of the IC and a second terminal of the IC. The second terminal is configured to be coupled to an auxiliary winding of the power system. The IC further includes a first driver circuit having an output coupled to a third terminal of the IC. The third terminal is configured to be coupled to a control node of the second switching transistor.

System and method for a cascode switch

A flyback converter is described that in some examples includes an integrated circuit that includes a delta-sigma converter and a cascaded integrator-comb filter configured to determine: a proportional factor, an integral factor, and a derivative factor associated with a secondary-side voltage across a secondary-side winding of the converter. The integrated circuit uses each factor to control a secondary switching element to perform synchronous rectification. In some examples, the flyback converter includes an auxiliary winding at the primary side of the transformer and a knee point voltage detection unit. The knee point voltage detection unit is configured to determine, based on an analog input indicative of a voltage at the auxiliary winding, an integral of value and detect, based on the integral value, a knee point voltage associated with the voltage at the auxiliary winding. A controller may use the detected knee point to control a primary side switch.

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Singapore, Singapore

Xiaowu Gong