Over voltage protection for wireless power receiver circuits
Methods and apparatuses for controlling a rectified voltage outputted by a rectifier circuit is described. In response to an occurrence of an overvoltage condition, an apparatus can regulate a gate-source voltage of a low-side switching element of the rectifier circuit to control the rectified voltage. The apparatus can include an operational amplifier that can compare a reference voltage and with a scaled voltage measured at a node between the low-side switching element and a high-side switching element of the rectifier circuit. The operational amplifier can output a voltage to regulate a gate-source voltage of a low-side switching element. The apparatus can further include a current sensor configured to sense current flowing through the low-side switching element. A power dissipation of the low-side switching element can be controlled based on the current being sensed by the current sensor.
1. An apparatus comprising:
a rectifier circuit configured to output a rectified voltage; and
a controller connected to the rectifier circuit, the controller being configured to regulate a gate-source voltage of a low-side switching element of the rectifier circuit to control the rectified voltage,
wherein the controller comprises an operational amplifier connected to the low-side switching element,
wherein the rectifier circuit is connected to a coil of a receiver,
wherein an inverting input of the operational amplifier is connected to a reference voltage,
wherein a non-inverting input of the operational amplifier is connected to a node in the rectifier circuit, the node is connected to the coil, a drain terminal of the low-side switching element, and a source terminal of a high-side switching element of the rectifier circuit, and
wherein the controller further comprises:
a first resistor connected between the non-inverting input of the operational amplifier and the node; and
a second resistor connected to the non-inverting input of the operational amplifier, a source terminal of the low-side switching element, and a ground terminal,
wherein a maximum value of the rectified voltage is set based on the reference voltage and a ratio of a resistance of the first resistor to a resistance of the second resistor.
2. The apparatus of claim 1 ,
wherein the controller is configured to:
detect an occurrence of an overvoltage condition in the rectifier circuit; and
regulate the gate-source voltage of the low-side switching element in response to detecting the occurrence of the overvoltage condition in the rectifier circuit.
3. The apparatus of claim 1 wherein the receiver is a wireless power receiver.
4. The apparatus of claim 1 , wherein the controller is configured to regulate the gate-source voltage of the low-side switching element by limiting the rectified voltage to a specific level.
5. The apparatus of claim 1 ,
wherein an auxiliary input of the operational amplifier is connected to an output of a current sensor that senses current flowing through the low-side switching element, and
wherein a power dissipation of the low-side switching element is controlled based on the current being sensed by the current sensor.
6. An apparatus comprising:
a receiver configured to receive alternating current (AC) power;
a rectifier circuit configured to convert the AC power into a rectified voltage;
a controller connected to the rectifier circuit, the controller being configured to regulate a gate-source voltage of a low-side switching element of the rectifier circuit to control the rectified voltage,
wherein the controller comprises an operational amplifier connected to the low-side switching element,
wherein an inverting input of the operational amplifier is connected to a reference voltage,
wherein a non-inverting input of the operational amplifier is connected to a node in the rectifier circuit, the node is connected to a coil of the receiver, a drain terminal of the low-side switching element, and a source terminal of a high-side switching element of the rectifier circuit, and
wherein the controller further comprises:
a first resistor connected between the non-inverting input of the operational amplifier and the node; and
a second resistor connected to the non-inverting input of the operational amplifier, a source terminal of the low-side switching element, and a ground terminal,
wherein a maximum value of the rectified voltage is set based on the reference voltage and a ratio of a resistance of the first resistor to a resistance of the second resistor.
7. The apparatus of claim 6 , wherein the controller is configured to:
detect an occurrence of an overvoltage condition in the rectifier circuit; and
regulate the gate-source voltage of the low-side switching element in response to detecting the occurrence of the overvoltage condition in the rectifier circuit.
8. The apparatus of claim 6 , wherein the receiver is a wireless power receiver.
9. The apparatus of claim 6 , wherein the controller is configured to regulate the gate-source voltage of the low-side switching element by limiting the rectified voltage to a specific level.
10. The apparatus of claim 6 ,
wherein an auxiliary input of the operational amplifier is connected to an output of a current sensor that senses current flowing through the low-side switching element, element; and
wherein a power dissipation of the low-side switching element is controlled based on the current being sensed by the current sensor.
11. A method comprising:
regulating a gate-source voltage of a low-side switching element of a rectifier circuit to control a rectified voltage being outputted by the rectifier circuit, wherein regulating the gate-source voltage of the low-side switching element of the rectifier circuit comprises:
regulating the gate-source voltage of the low-side switching element using an operational amplifier, wherein a maximum value of the rectified voltage is set based on a reference voltage and a ratio of a resistance of a first resistor to a resistance of a second resistor,
wherein the first resistor is connected between a non-inverting input of the operational amplifier and a node, the node is connected to a coil of a receiver, a drain terminal of the low-side switching element, and a source terminal of a high-side switching element of the rectifier circuit, and
wherein the second resistor is connected to the non-inverting input of the operational amplifier, a source terminal of the low-side switching element, and a ground terminal.
12. The method of claim 11 , further comprising:
detecting an occurrence of an overvoltage condition in the rectifier circuit; and
in response to detecting the occurrence of the overvoltage condition in the rectifier circuit, regulating the gate-source voltage of the low-side switching element by limiting the rectified voltage to a specific level.
13. The method of claim 11 , further comprising:
controlling a power dissipation of the low-side switching element based on an amount of current flowing through the low-side switching element.