Alpha Omega Semiconductor Inc.

Alpha and Omega Semiconductor (Cayman) Ltd.

Alpha and Omega Semiconductor International LP

Zhiye Zhang

Allen Chang

Kuang Ming Chang

Gilbert Lee

Mark Tomas

Son Tran

Zhinan Wei

Yu-Cheng Chang

Gilbert S Z Lee

A controller for a switching regulator incorporates a protection circuit to limit the negative current to a negative current threshold while operating the switching regulator to sink current from the load without damage to the power switches. In some embodiments, in response to the negative current reaching the negative current threshold, the protection circuit turns off the low-side power switch and turns on the high-side power switch for a maximum time period. In the event the negative current has not recovered, the high-side power switch and the low-side power switch are both turned off while the high-side power switch conducts the negative current through the high-side power switch body diode. When the negative current recovers to a recovery level, the low-side power switch can then be turned on. The protection circuit repeats the process each time the negative current is detected to have reached the negative current threshold.

Switching regulator implementing negative current protection

A control circuit for a switching regulator implementing a fixed frequency constant on-time control scheme incorporates a reference voltage generator to generate a reference voltage ramp that varies over substantially the entire switching period. In one embodiment, the reference voltage increases from an initial voltage value at the start of each switching period towards the end of the switching period and is reset to the initial voltage value at the end of each switching period. The reference voltage ramp ensures stable feedback control operation in the switching regulator without introducing voltage offset for all output voltage values. The control circuit enables the switching regulator to apply constant on-time control scheme while using an output capacitor having any ESR value, including an output capacitor with low or zero ESR.

Constant on-time switching regulator for zero ESR output capacitor without output voltage offset

A current detection circuit for detecting a current in a Switch Mode Power Supply (SMPS) having a first switch and a second switch coupled in series and an output filter including an inductor and a capacitor coupled to a switch node formed by the first and second switches, has a current sensing circuit for sensing a current across the second switch and generating a current sensing signal indicating current information of the second switch, and a current emulation circuit for emulating current information of the first switch. The current emulation circuit includes an inductance sensing circuit for acquiring a real-time rate of change in inductor current and an AC emulation circuit for computing the AC portion of the current information of the first switch based on the real-time rate of change in inductor current.

Accurate high-side current emulation with auto-conversion for smart power stage applications

A fault tolerant power supply system includes at least one load switch circuit configured to connect, using a main switch, an input voltage to an output node of the load switch circuit when the load switch circuit is turned on and at least one power channel coupled to the load switch circuit to receive the input voltage. The power channel is configured as a buck converter and includes at least a high-side power switch and a low-side power switch. The fault tolerant power supply system is configured to measure a current flowing through the main switch of the load switch circuit, to determine that the current flowing through the main switch of the load switch circuit has exceeded a current limit threshold, and to disable the main switch of the load switch circuit and the low-side power switch of the power channel in response to the determination that the current flowing in the main switch has exceeded the current limit threshold.

Fault tolerant power supply incorporating intelligent load switch to provide uninterrupted power

A fault tolerant power supply system includes at least one load switch configured to connect an input voltage to an output node of the load switch when the load switch is turned on and at least one power channel coupled to the load switch to receive the input voltage. The power channel is configured as a buck converter and includes at least a high-side power switch and a low-side power switch. The fault tolerant power supply system is configured to measure a current flowing through the low-side power switch, to determine that the current flowing through the low-side power switch has exceeded a current limit threshold, and to disable the low-side power switch and the load switch in response to the determination that the current flowing in the low-side power switch has exceeded the current limit threshold.

Fault tolerant power supply incorporating intelligent gate driver-switch circuit to provide uninterrupted power

A switching regulator controller for a buck switching regulator incorporates a multi-mode adaptive modulator configured to automatically select between a first operation mode and a second operation mode as a function of the output voltage being generated. In one embodiment, the switching regulator controller compares the output voltage to a comparator reference voltage and is configured to operate in a selected operation mode based on the output voltage. In this manner, a single switching regulator controller can be used in multiple instances of an electronic system to supply circuitry that may have different operational requirements. In one embodiment, the switching regulator controller is configured to operation in a PWM/PFM mode and a PWM mode as a function of the output voltage, which indicates the circuit application to which the switch regulator controller is used to supply.

Switching regulator with adaptive PWM/PFM modulator

A control circuit for a switching regulator implements constant on-time control scheme with synchronous rectification and applies dual control loops to improve light load efficiency and enhance transient response. In one embodiment, the control circuit includes a first control loop configured to control a one-shot timer to generate a control signal to turn on the main switch when the feedback voltage is below a first reference voltage and a minimum off-time duration has expired. The control circuit further includes a second control loop configured to control the one-shot timer to generate the control signal to turn on the main switch when the feedback voltage is below a second reference voltage and the minimum off-time duration has expired and a low-side current signal has a first state indicative of a light load condition at the output node.

Constant on-time switching regulator implementing dual control loops

A control circuit for a switching regulator implements constant on-time control scheme with synchronous rectification and applies an integrated standard and light load control loop to improve light load efficiency and enhance transient response. In one embodiment, the control circuit includes a reference voltage selection circuit configured to select, based on a low-side current signal, a first reference voltage for standard load condition and a second reference voltage for light load condition as a selected reference voltage. The second reference voltage is greater than the first reference voltage. The control circuit further includes a control loop configured to generate a control signal to turn on the main switch when the feedback voltage is below the selected reference voltage and the minimum off-time duration has expired.

Constant on-time switching regulator implementing light load control

A high efficiency single-inductor dual-control loop power converter (SIDL) is proposed for converting unregulated DC input into regulated DC output to a power load. The SIDL includes: A PWM switching power regulating loop for converting the unregulated DC input into the regulated DC output. The power-efficiency maximizing loop includes: a power shunt transistor in parallel connection with the power diode and a real-time control loop adjusting, in response to a freewheeling current through the power diode, conductance of the power shunt transistor in a manner that a higher freewheeling current results in a higher conductance of the power shunt transistor.

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San Jose, CA, United States of America

Zhiye Zhang