TECHNICAL FIELD

The present disclosure relates to an overvoltage protection apparatus, and in particular, to an overvoltage protection apparatus and method that prevent a high voltage power source from being mistakenly connected to a low voltage device.

BACKGROUND

An existing electronic product and device is generally powered by connecting an external power adapter between the product or device to be powered and a power source. However, without a uniform standard in the industry, various voltages are applied to devices provide by leading manufacturers, which results in a problem that when a customer mistakenly connects an adapter of a different manufacturer to a device, the device may be damaged because a voltage of the adapter does not match the device; in particular, when a high voltage adapter is mistakenly connected to a low voltage device, it may directly lead to overvoltage-caused burning of the low voltage device.

An existing solution for preventing a high voltage adapter from being mistakenly connected to a low voltage device is using a dedicated protection component, that is, using a dedicated chip for overvoltage protection, such as a fuse, on a device. However, the existing dedicated chip for overvoltage protection, such as the fuse, has a problem of supplying power by mistake, that is, when a high voltage adapter is connected and during a process in which an input voltage rises, a device is transiently powered, and the power source is disconnected only when the input voltage reaches a set protection value; therefore, the device is in a state of being transiently powered when the power source is connected, which affects user experience.

SUMMARY

Problem to be Resolved by the Present Disclosure

An objective of the present disclosure is to provide an overvoltage protection apparatus and method, which can ensure that a device is powered only when a correct and stable power source is connected.

Solutions Used for Resolving the Problem

To achieve the foregoing objective, a first aspect of the present disclosure provides an overvoltage protection apparatus, which includes a determining unit, having an input end connected to an input end of the apparatus and an output end connected to an input end of a soft-start unit, and configured to determine whether an input voltage at the input end of the apparatus exceeds a preset protection voltage, and send a result of the determining to the soft-start unit; and the soft-start unit, where an input end of the soft-start unit is separately connected to the output end of the determining unit and the input end of the apparatus, and an output end soft-start unit is connected to an output end of the apparatus, and if the determining unit determines that the input voltage does not exceed the preset protection voltage and remains stable in a preset delay time, the soft-start unit delivers the input voltage to the output end of the apparatus; otherwise, the soft-start unit does not deliver a voltage signal to the output end of the apparatus.

With reference to the first aspect, in a first possible implementation manner, the determining unit includes: a first transistor having a source connected to the input end of the apparatus and a drain connected to the input end of the soft-start unit; a Zener diode having a positive electrode connected to a gate of the first transistor and a negative electrode connected to a ground terminal; and a second resistor, connected between the source and the gate of the first transistor; and the soft-start unit includes a second transistor having a source connected to the input end of the apparatus, a gate connected to the drain of the first transistor, and a drain connected to the output end of the apparatus; a first resistor, connected between the gate of the second transistor and the ground terminal; and a capacitor, connected between the source and the gate of the second transistor.

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner, the first transistor is disconnected when the input voltage does not exceed the preset protection voltage, and the second transistor is conducted when the input voltage does not exceed the preset protection voltage and after the input voltage remains stable in a preset delay time.

With reference to the first possible implementation manner of the first aspect, in a third possible implementation manner, the first transistor is conducted when the input voltage exceeds the preset protection voltage, and the second transistor is disconnected when the input voltage exceeds the preset protection voltage.

With reference to the first possible implementation manner, the second possible implementation manner, or the third possible implementation manner of the first aspect, in a fourth possible implementation manner, the preset protection voltage depends on a sum of a Zener voltage of the Zener diode and a threshold voltage of the first transistor.

With reference to the first possible implementation manner, the second possible implementation manner, the third possible implementation manner, or the fourth possible implementation manner of the first aspect, in a fifth possible implementation manner, the first transistor and the second transistor are p-channel metal-oxide-semiconductor (PMOS) transistors.

A second aspect of the present disclosure provides an overvoltage protection method, which includes determining whether an input voltage exceeds a preset protection voltage; and if the input voltage does not exceed the preset protection voltage and remains stable in a preset delay time, delivering the input voltage; otherwise, skipping delivering a voltage signal.

Effects of the Present Disclosure

According to the apparatus and method provided by the present disclosure, a device is powered only when an input voltage does not exceed an allowable voltage range of the device and the input voltage is stable, which can efficiently avoid damage caused by a high voltage power source to a low voltage device, and can effectively avoid supplying power by mistake during a process in which the voltage rises, thereby avoiding a phenomenon of transient connection and disconnection.

In addition, the present disclosure is simple in design, low in cost, highly practical, and highly portable.

According to the following detailed description of the exemplary embodiments with reference to the accompanying drawings, other features and aspects of the present disclosure will become clear.

