STMICROELECTRONICS ASIA PACIFIC PTE LTD

A wireless power receiver includes a rectifier with first and second inputs coupled to first and second terminals of a receiver coil, and having a first output coupled to ground and a second output at which a rectified voltage is produced. A first switch is coupled between the second input and ground, and is controlled by a first gate voltage generated at a first node. A second switch is coupled between the first node and ground, and is controlled by a second gate voltage. The first gate voltage closes the first switch to couple the second input to ground when the rectified voltage is less than a threshold voltage, boosting the rectified voltage. The second gate voltage closes the second switch to cause the second gate voltage to be pulled to ground when the rectified voltage is greater than the threshold voltage, limiting the boosting of the rectified voltage.

An over-voltage protection circuit and methods of operation are provided. In one embodiment, a method includes monitoring a voltage at an output of a rectifier, a voltage at an output of a voltage regulator, or a combination thereof. The method further includes determining the over-voltage condition based on the monitoring; and in response to determining the over-voltage condition, regulating the voltage at the output of the rectifier in accordance with a voltage difference between the voltage at the output of the rectifier and the voltage at the output of the voltage regulator.

A power transmitter includes: a first switch coupled between a first node and a reference voltage node; a second switch configured to be coupled between a power supply and the first node; a coil and a capacitor coupled in series between the first node and the reference voltage node; a first sample-and-hold (S&H) circuit having an input coupled to the first node; and a timing control circuit configured to generate a first control signal, a second control signal, and a third control signal that have a same frequency, where the first control signal is configured to turn ON and OFF the first switch alternately, the second control signal is configured to turn ON and OFF the second switch alternately, and where the third control signal determines a sampling time of the first S&H circuit and has a first pre-determined delay from a first edge of the first control signal.

A bridge rectifier and associated control circuitry collectively form a “regtifier” which rectifies an input time varying voltage and regulates the rectified output voltage produced without the use of a traditional voltage regulator. To accomplish this, the gate voltages of transistors of the bridge rectifier that are on during a given phase may be modulated via analog control (to increase the on-resistance of those transistors) or via pulse width modulation (to turn off those transistors prior to the end of the phase). The transistors of the bridge rectifier that would otherwise be off during a given phase may be turned on to help dissipate excess power and thereby regulate the output voltage. This modulation is based upon both a voltage feedback signal and a current feedback signal.

A bridge rectifier is controlled by control circuitry to act a “regtifier” which both regulates and rectifies without the use of a traditional voltage regulator. To accomplish this, the gate voltages of transistors of the bridge that are on during a given phase may be modulated to dissipate excess power. Gate voltages of transistors of the bridge that are off during the given phase may alternatively or additionally be modulated to dissipate excess power. The regtifier may act as two half-bridges that each power a different voltage converter, with those voltage converters powering a battery. The voltage converters may be switched capacitor voltage converters that switch synchronously with switching of the two half-bridges as they perform rectification.

An over-voltage protection circuit and methods of operation are provided. In one embodiment, a method includes monitoring a voltage at an output of a rectifier, a voltage at an output of a voltage regulator, or a combination thereof. The method further includes determining the over-voltage condition based on the monitoring; and in response to determining the over-voltage condition, regulating the voltage at the output of the rectifier in accordance with a voltage difference between the voltage at the output of the rectifier and the voltage at the output of the voltage regulator.

A wireless power-reception system has a bridge rectifier with two high-side and two low-side transistors, linked to input-nodes and sense-resistors. During a first phase, a control circuit activates certain transistors for rectification, producing an output voltage, while modulating a gate voltage of a non-activated low-side transistor to dissipate excess power and regulate the output voltage. During a first given number of occurrences of the first phase, the control circuit determines the current through the low-side transistor having its gate voltage modulated based upon a voltage across a first sense resistor coupled between that low-side transistor and ground. During a second given number of occurrences of the first phase, the control circuit determines the current delivered to the load based upon a voltage across the first sense resistor and a voltage across a second sense resistor coupled between the other low-side transistor and ground.

A method for operating a wireless charging transmitter includes switching, by the wireless charging transmitter, an operating mode of a full bridge inverter of the wireless charging transmitter from a first mode to a second mode; and changing, by the wireless charging transmitter, an operating point of the wireless charging transmitter from a first operating point associated with the first mode to a second operating point associated with the second mode, the second operating point being selected to dampen a change in a rectifier voltage of a wireless charging receiver inductively coupled to the wireless charging transmitter.

A method for operating a wireless power transmitter includes: receiving a power control command from a wireless power receiver; computing a potential voltage change for a transmitter voltage of the wireless power transmitter in accordance with a target transmitter power and a present value of a transmitter current of the wireless power transmitter; comparing the potential voltage change with a discrete step size of a supply voltage; and in response to determining that the magnitude of the potential voltage change is equal to or larger than the discrete step size of the supply voltage, adjusting the transmitter power by: adjusting the supply voltage by one or more discrete steps; and controlling a power conversion circuit of the wireless power transmitter using a target current value computed in accordance with the target transmitter power and the adjusted supply voltage.

An over-voltage protection circuit and methods of operation are provided. In one embodiment, a method includes monitoring a voltage at an output of a rectifier, a voltage at an output of a voltage regulator, or a combination thereof. The method further includes determining the over-voltage condition based on the monitoring; and in response to determining the over-voltage condition, regulating the voltage at the output of the rectifier in accordance with a voltage difference between the voltage at the output of the rectifier and the voltage at the output of the voltage regulator.