CN-115333051-B - Input power control and protection

Abstract

The present disclosure relates to input power control and protection. The present disclosure describes a system and method for protecting an electronic device from high voltages that may exceed the tolerance limits of circuitry within the electronic device. The protection circuit blocks high voltages from the device components by gating techniques. Such gating techniques may similarly be used to control whether the electronic components receive power when the control unit detects an error condition.

Inventors

• DING YAO
• Alan Jayadev Rao

Assignees

• 谷歌有限责任公司

Dates

Publication Date

20260508

Application Date

20220909

Priority Date

20211122

Claims (14)

1. 1. A voltage protection circuit for an electronic device, comprising: A control line coupled to the first transistor; an input power line; A power interrupt transistor coupled to the input power line and electrically coupled to the first transistor; wherein receipt of a square wave signal at the first transistor through the control line causes the power interrupt transistor to turn off, thereby interrupting the flow of power on the input power line, The voltage protection circuit further includes: A capacitor coupled across the junction of the first transistor, wherein receipt of the square wave signal at the first transistor causes the capacitor to drain out, and A second transistor coupled between the capacitor and the power interrupt transistor, wherein the second transistor is turned on when the capacitor is drained.
2. 2. The voltage protection circuit of claim 1 wherein the power interrupt transistor is turned off when the second transistor is turned on.
3. 3. The voltage protection circuit of claim 1 further comprising a resistor coupled between the input power line and the second transistor, the resistor having an ohmic value based on a voltage tolerance of the electronic device, wherein receipt of a voltage exceeding a threshold triggers activation of the second transistor.
4. 4. The voltage protection circuit of claim 1 wherein the control line is coupled to a control unit and the square wave signal is received from the control unit in response to detecting an error.
5. 5. The voltage protection circuit of claim 1 wherein the first transistor is a MOSFET.
6. 6. An electronic device, comprising: An input port; Electronic assembly, and A voltage protection circuit between the input port and the electronic component, the voltage protection circuit comprising: A control line coupled to the first transistor; an input power line; a power interrupt transistor coupled across the input power line and electrically coupled to the first transistor; wherein receipt of a square wave signal at the first transistor through the control line causes the power interrupt transistor to turn off, thereby interrupting the flow of power on the input power line, The voltage protection circuit further includes: a capacitor across the junction of the first transistor, wherein receipt of the square wave signal at the first transistor causes the capacitor to drain out, and A second transistor coupled between the capacitor and the power interrupt transistor, wherein the second transistor turns on when the capacitor is drained.
7. 7. The electronic device of claim 6, wherein the power interrupt transistor is turned off when the second transistor is turned on.
8. 8. The electronic device of claim 6, wherein the voltage protection circuit further comprises a resistor coupled between the input power line and the second transistor, the resistor having an ohmic value based on a voltage tolerance of the electronic device, wherein receipt of a voltage exceeding a threshold triggers activation of the second transistor.
9. 9. The electronic device of claim 6, wherein the control line is coupled to a control unit and the square wave signal is received from the control unit in response to detecting an error.
10. 10. The electronic device of claim 6, wherein the electronic device is a wearable electronic device.
11. 11. A method of operating an electronic device, comprising: receiving a voltage at a power line of the electronic device, the power line coupled between an input of the electronic device and a circuit; detecting, at a control unit, when an error condition exists; In response to detecting the error condition, transmitting a square wave signal to a first transistor through a control line, the square wave signal causing a power interrupt transistor to turn off, the power interrupt transistor preventing the circuit of the electronic device from receiving the voltage, Wherein transmitting the square wave signal causes a capacitor coupled across the first transistor to discharge, and Wherein discharging the capacitor activates a second transistor, the activation of the second transistor causing the power interrupt transistor to turn off.
12. 12. The method of claim 11, wherein the control line remains stable when the control unit does not detect the error condition.
13. 13. The method of claim 11, further comprising activating a second transistor when the received voltage exceeds a predetermined threshold.
14. 14. The method of claim 13, further comprising turning off the second transistor when the received voltage no longer exceeds the predetermined threshold.

Description

Input power control and protection Technical Field The present disclosure relates to input power control and protection. Background Wearable products are typically physically small housings with elegant industrial designs. Circuits within such products often have voltage input limitations. A typical voltage supplied by a USB type-a charging cable may be around 5V, which may be within voltage input limits. However, other USB type C power supplies, such as type C compliant with PD, may deliver up to 20V after negotiation, which may exceed the voltage input limit of the circuit. Such excessive power delivery can lead to damage to the circuitry and the wearable product. Disclosure of Invention The present disclosure provides input voltage protection without blocking the power path. In particular, the AC signal is used to turn off a transistor coupled across the power path such that power does not pass through the transistor. Such a transistor may also be turned off in response to receiving a voltage exceeding a predetermined threshold. One aspect of the present disclosure provides a voltage protection circuit for an electronic device including a control line coupled to a first transistor, an input power line, and a power interrupt transistor coupled across the input power line and electrically coupled to the first transistor, wherein receipt of a square wave signal at the first transistor through the control line causes the power interrupt transistor to turn off, thereby interrupting power flow on the input power line. The voltage protection circuit may further include a capacitor coupled across the junction of the first transistor, wherein receipt of the prescription wave signal at the first transistor results in the capacitor being drained. The circuit may further include a second transistor coupled between the capacitor and the power interrupt transistor, wherein the second transistor turns on when the capacitor is drained. When the second transistor is on, the power interruption transistor is off. According to some examples, the voltage protection circuit may further include a resistor coupled between the power line input and the second transistor, the resistor having an ohmic value based on a voltage tolerance of the electronic device, wherein receipt of a voltage exceeding a threshold triggers activation of the second transistor. According to some examples, a control line may be coupled to the control unit and receive a square wave signal from the control unit in response to detecting an error. Another aspect of the present disclosure provides an electronic device including an input port, an electronic component, and a voltage protection circuit located between the input port and the electronic component. The voltage protection circuit includes a control line coupled to the first transistor, an input power line, a power interrupt transistor coupled across the input power line and electrically coupled to the first transistor, wherein receipt of a square wave signal at the first transistor by the control line turns the power interrupt transistor off, thereby interrupting power flow on the input power line. Yet another aspect of the present disclosure provides a method of operating an electronic device, comprising receiving a voltage at a power line of the electronic device, the power line being coupled between an input of the electronic device and a circuit, detecting at a controller unit when an error condition exists, and transmitting, in response to detecting the error condition, a square wave signal to a first transistor through a control line, the square wave signal causing a power interrupt transistor to turn off, the power interrupt transistor preventing the circuit of the electronic device from receiving the voltage. Transmitting the square wave signal may discharge a capacitor coupled across the first transistor. Discharging the capacitor may activate the second transistor, activation of which causes the power interrupt transistor to turn off. According to some examples, the control line remains stable when the control unit does not detect an error condition. According to some examples, the method may further comprise activating the second transistor when the received voltage exceeds a predetermined threshold. Still further, the method may include turning off the second transistor when the received voltage no longer exceeds the predetermined threshold. Drawings Fig. 1A is a functional block diagram illustrating an example system in accordance with aspects of the present disclosure. FIG. 1B is an example pictorial diagram of the system of FIG. 1A. Fig. 2 is an example circuit diagram according to aspects of the present disclosure. Fig. 3 is a flow chart illustrating an example method in accordance with aspects of the present disclosure. Fig. 4 is a flow chart illustrating an example method in accordance with aspects of the present disclosure. Detailed Description The present disclosure describes sys