TWI704737B - Over power protection circuit, charger and over power protection method - Google Patents

Abstract

An over power protection circuit, a charger and an over power protection method are provided. The over power protection circuit includes a power controller and a voltage raising circuit. The voltage raising circuit is configured to detect an alternating-current (AC) high voltage signal and increasing a voltage value of a target voltage signal from a first voltage value lower than a threshold value to a second voltage value higher than the threshold value according to the AC high voltage signal. The power controller is configured to activate an over power protection mechanism in response to the voltage value of the target voltage signal being higher than the threshold value.

Description

Overpower protection circuit, charger and overpower protection method

The present invention relates to a circuit protection technology, and particularly relates to an overpower protection circuit, a charger and an overpower protection method.

Generally speaking, the over power protection of the charger is based on the current detection pin of the power control chip to determine whether to activate. When the voltage value of the voltage on the current detection pin exceeds a critical value, the power control chip will activate the over-power protection and stop charging to avoid damage to the internal circuit due to excessive charging current and/or voltage. This process is the over-power protection of the charger.

However, when the input power supply is high-voltage alternating current, the voltage value of the voltage caused by the high-voltage alternating current on the current detection pin may be small (for example, less than the above threshold), resulting in the above-mentioned over-power protection when over-power occurs The mechanism cannot be activated automatically, causing problems related to charging safety.

The present invention provides a power protection circuit, a charger and an overpower protection method, which can effectively improve the above problems.

An embodiment of the present invention provides an overpower protection circuit, which includes a power supply controller and a voltage boost circuit. The voltage boost circuit is coupled to the power controller. The voltage boosting circuit is used for detecting an AC high voltage signal and increasing the voltage value of the target voltage signal from a first voltage value lower than a threshold value to a second voltage value higher than the threshold value according to the AC high voltage signal, and The power controller is used for activating an over power protection mechanism in response to the voltage value of the target voltage signal being higher than the threshold value.

An embodiment of the present invention further provides a charger, which includes a charger module and an overpower protection circuit. The overpower protection circuit is coupled to the charger module. The overpower protection circuit is used for detecting an AC high voltage signal and increasing the voltage value of the target voltage signal from a first voltage value lower than a threshold value to a second voltage value higher than the threshold value according to the AC high voltage signal; And the overpower protection circuit is further used to activate an overpower protection mechanism in response to the voltage value of the target voltage signal being higher than the threshold value.

An embodiment of the present invention also provides an overpower protection method for a charger, which includes: detecting an AC high-voltage signal; according to the AC high-voltage signal, increasing the voltage value of the target voltage signal from a first voltage value lower than a critical value to a higher value A second voltage value at the threshold; and in response to the voltage value of the target voltage signal being higher than the threshold, an overpower protection mechanism is activated.

Based on the above, the embodiment of the present invention can detect the AC high voltage signal and increase the voltage value of the target voltage signal from the first voltage value lower than the threshold value to the second voltage value higher than the threshold value according to the AC high voltage signal . Then, in response to the voltage value of the target voltage signal being higher than the threshold value, the overpower protection mechanism of the charger can be automatically activated to provide overpower protection of the charger. In this way, the traditional over-power protection of the charger cannot be automatically performed against the AC high-voltage signal, and the safety of the charger in use can be effectively improved.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail in conjunction with the accompanying drawings.

Fig. 1 is a functional block diagram of a charger according to an embodiment of the present invention. Please refer to FIG. 1, the charger 10 can be installed in any type of electronic device to provide charging power to the electronic device. In this embodiment, a flyback charger is used as an example of the charger 10. For example, the charger 10 can perform AC-DC conversion and/or DC-DC conversion of the input signal. However, in another embodiment, the charger 10 can also be other types of chargers, and the present invention is not limited.

The charger 10 includes a charger module 11 and an overpower protection circuit 12. In this embodiment, the charger module 11 is a flyback charger module, and its specific circuit structure is shown in FIG. 2, and the circuit structure of the charger module 11 is not limited to this. The charger module 11 can be used to perform operations such as rectification, AC-DC conversion and/or DC-DC conversion of input signals. The overpower protection circuit 12 is coupled to the charger module 11. The over power protection circuit 12 can detect the AC high voltage signal and automatically activate the over power protection mechanism according to the AC high voltage signal. For example, after the overpower protection mechanism is activated, the charger module 11 can stop charging, so as to protect the electronic circuit in the charger 10 and improve the safety of the charger 10 in use.

In this embodiment, the over power protection circuit 12 includes a power controller 121 and a voltage boost circuit 122. The power controller 121 is coupled to the charger module 11 and the voltage boost circuit 122. The power controller 121 is also called a power control chip. For example, the power controller 121 may include a pulse width modulation (Pulse Width Modulated, PWM) control chip. The power controller 121 can be used to control the charger module 11 to start or stop charging.

The voltage boost circuit 122 can be used to detect the voltage signal V0 from the charger module 11. For example, the voltage signal V0 can be coupled to the input terminal of the charger module 11. The voltage signal V0 can reflect whether the input power of the charger module 11 is an AC high voltage signal. When the voltage signal V0 reflects that the input power of the charger module 11 is an AC high voltage signal, the voltage boosting circuit 122 can change the voltage value of the voltage signal VT (also known as the target voltage signal) from below a certain threshold according to the voltage signal V0 The voltage value (also referred to as the first voltage value) of is increased to another voltage value (also referred to as the second voltage value) higher than the critical value. In one embodiment, this threshold is also called an overpower voltage trigger value, which is used to activate the overpower protection mechanism. In response to the voltage value of the voltage signal VT being higher than the threshold, the power controller 121 can automatically activate the over-power protection mechanism. On the other hand, when the input power of the charger module 11 is not an AC high voltage signal, the voltage boost circuit 122 may not actively boost the voltage value of the voltage signal VT.

2 is a schematic diagram of the internal circuit structure of the charger according to an embodiment of the present invention. Please refer to FIG. 2, the charger module 11 may include power input terminals AC- and AC+, a bridge rectifier BD, a capacitor (also called an input capacitor) Cin, a transformer TR, and a diode (also called an output diode) Do, capacitor (also known as output capacitor) Co, diode (also known as auxiliary diode) Daux, and capacitor (also known as auxiliary voltage stabilizing capacitor) Caux. The AC input terminals AC- and AC+ are used to receive input signals. The bridge rectifier BD is used to rectify the input signal. After the cooperative operation of the capacitor Cin, the transformer TR, the diode Do, the diode Daux and the capacitor Caux, the voltage signal Vo can be output as a charging power source.

The power controller 121 can detect the voltage signal VT on the current detection pin CS and determine whether the voltage value of the voltage signal VT is higher than a threshold value. If the voltage value of the voltage signal VT is higher than this critical value, the power controller 121 can adjust the output signal of the control pin GD to cut off the transformer TR (and/or the charger module 11) via the switch (also called the main switch) Q Other electronic components). In one embodiment, cutting off the output of the transformer TR (and/or other electronic components in the charger module 11) can be regarded as activating the overpower protection mechanism.

For example, under normal circumstances (that is, when the voltage value of the voltage signal VT is not higher than the critical value), the power controller 121 can maintain the output signal of the control pin GD at a logic high. When the output signal of the control pin GD is at logic high, the switch Q can be turned on and the transformer TR can normally output the voltage signal Vo. However, under special circumstances (that is, when the voltage value of the voltage signal VT is higher than the threshold), the power controller 121 can adjust the output signal of the control pin GD to logic low. When the output signal of the control pin GD is logic low, the switch Q can be cut off so that the transformer TR cannot normally output the voltage signal Vo.

Traditionally, when the input signal of the charger module 11 is an AC high-voltage signal (that is, the input signal of the charger module 11 includes high-voltage AC), the current flowing through the switch Q may be small and the voltage value of the voltage signal VT may be less than The above-mentioned critical value causes the over-power protection mechanism set when the over-power occurs to fail to start smoothly, thereby causing damage to the internal circuit and/or causing safety problems. However, in this embodiment, when the input signal of the charger module 11 is an AC high voltage signal, the voltage value of the voltage signal VT on the current detection pin CS of the power controller 121 can be actively increased to be higher than the above threshold Value to automatically activate the over-power protection mechanism, thereby effectively improving the above-mentioned safety problem.

In an embodiment, the voltage boost circuit 122 of FIG. 1 may include the detection circuit (also referred to as the AC high voltage detection circuit) 21, the voltage stabilizing circuit 22, and the impedance circuit 23 of FIG. The detection circuit 21 is coupled to the charger module 11. The detection circuit 21 can generate a voltage signal (also referred to as a control voltage signal) V1 in response to the voltage signal V0.

The voltage stabilizing circuit 22 is coupled to the detecting circuit 21 and can receive the voltage signal V1. When the voltage signal V0 reflects that the input power of the charger module 11 is an AC high voltage signal, the voltage stabilizing circuit 22 can generate a voltage signal (also referred to as a reference voltage signal) V2 in response to the voltage signal V1. In addition, when the voltage signal V0 reflects that the input power of the charger module 11 is not an AC high voltage signal, the voltage stabilizing circuit 22 may not generate the voltage signal V2.

The impedance circuit 23 is coupled to the voltage stabilizing circuit 22 and the power controller 121. The impedance circuit 23 can increase the voltage value of the voltage signal VT from the first voltage value to the second voltage value in response to the voltage signal V2. For example, the first voltage value may reflect the original voltage value of the signal output from the transformer TR to the switch Q, and the second voltage value may reflect the voltage value raised by the original voltage value affected by the voltage signal V2. The first voltage value may be lower than the above-mentioned threshold value, and the second voltage value may be higher than the above-mentioned threshold value to activate the over power protection mechanism. Or, from another perspective, the difference between the first voltage value and the second voltage value may be affected by the voltage value of the voltage signal V2. For example, the higher the voltage value of the voltage signal V2, the greater the difference between the first voltage value and the second voltage value (that is, the voltage value of the voltage signal V2 can be positively correlated with the first voltage value and the second voltage value The difference between).

In an embodiment, the detection circuit 21 may include a diode (also called a first unidirectional diode) Din, an impedance element (also called a first impedance element) R1, and an impedance element (also called a second Impedance element) R2. The first end of the diode Din is coupled to the charger module 11 to detect the voltage signal V0. The impedance elements R1 and R2 may each include one or more resistors. The first end of the impedance element R1 is coupled to the second end of the diode Din to receive the voltage signal V0. The second end of the impedance element R1 is coupled to the first end of the impedance element R2, and the second end of the impedance element R2 can be grounded.

In one embodiment, the impedance elements R1 and R2 can form a voltage divider circuit. The voltage divider circuit can detect the voltage signal V0 through the diode Din and generate the voltage signal V1 in response to the voltage signal V0. For example, the voltage signal V1 can be generated at the second end of the impedance element R1 (or between the impedance elements R1 and R2).

In an embodiment, the voltage stabilizing circuit 22 may include a switch (also referred to as an auxiliary switch) Qaux, a sensing diode ZD, and a diode (also referred to as a second unidirectional diode) Din2. The switch Qaux is coupled to the detection circuit 21 to receive the voltage signal V1. When the input power of the charger module 11 is not an AC high voltage signal, the voltage value of the voltage signal V1 is not higher than the turn-on voltage of the switch Qaux and the switch Qaux is not turned on.

It should be noted that when the input power of the charger module 11 is an AC high voltage signal, the voltage value of the voltage signal V1 can be higher than the turn-on voltage of the switch Qaux to turn on the switch Qaux. When the switch Qaux is turned on, the signal path between the charger module 11 (such as the diode Daux) and the sensing diode ZD can also be turned on. The first end of the sensing diode ZD is coupled to the switch Qaux and the diode Din2. The second end of the ZD diode can be grounded. The sensing diode ZD can generate a voltage signal V2 at its first terminal in response to the turn-on of the switch Qaux. The voltage signal V2 can be provided to the impedance circuit 23 through the diode Din2.

In one embodiment, the voltage signal V2 can reflect the breakdown voltage of the sensing diode ZD. For example, suppose that the breakdown voltage of the ZD is 1 Volt. In response to the turn-on of the switch Qaux, the sensing diode ZD can lock the voltage value of the voltage signal V2 at 1 volt (ie, the breakdown voltage of the sensing diode ZD).

In one embodiment, the impedance circuit 23 includes an impedance element (also referred to as a third impedance element) Rcs1 and an impedance element (also referred to as a fourth impedance element) Rcs2. The first end of the impedance element Rcs1 can be coupled to the first end of the impedance element Rcs2 and the voltage stabilizing circuit 22 to receive the voltage signal V2. The second end of the impedance element Rcs1 can be coupled to the switch Q and the power controller 121. The second end of the impedance element Rcs2 can be grounded. The voltage signal VT is generated at the second end of the impedance element Rcs1. From another perspective, the impedance elements Rcs1 and Rcs2 can also form a voltage divider circuit. The voltage divider circuit can increase the voltage value of the voltage signal VT from the first voltage value to the second voltage value in response to the voltage signal V2, so that the power controller 121 activates the overpower protection mechanism.

In one embodiment, assuming that the impedance elements Rcs1 and Rcs2 provide impedances of 500 milliohms (mΩ) and 10 milliohms, respectively, the breakdown voltage of the audit diode ZD is 1 volt and is used to trigger the threshold of the over-power protection mechanism The value is 1.5 volts. When the input power of the charger module 11 is an AC low-voltage signal (for example, low-voltage AC power), the switch Qaux is not turned on, and the voltage signal V2 is not generated. At this time, based on the characteristics of the AC low-voltage signal, the current value of the signal passing through the switch Q can be, for example, 3 amperes (A) and the voltage value of the voltage signal VT can be, for example, 1.53V (ie 3A×(500mΩ+10mΩ)=1.53V) ). In this example, the voltage value (for example, 1.53 volts) of the voltage signal VT is higher than the critical value (for example, 1.5 volts), so the power controller 121 can automatically activate the over power protection mechanism.

In one embodiment, when the input power of the charger module 11 is an AC high-voltage signal (for example, high-voltage AC), the voltage value of the voltage signal V1 may be higher than the turn-on voltage of the switch Qaux. Therefore, the switch Qaux can be turned on in response to the voltage signal V1, and the voltage signal V2 can be generated. For example, the voltage value of the voltage signal V2 may be 1 volt to reflect the breakdown voltage of the audit diode ZD. At this time, based on the characteristics of the AC high voltage signal, the current value of the signal passing through the switch Q can be, for example, 1 ampere and the voltage value of the voltage signal VT can be changed from the original 0.51 volt (ie 1A×(500mΩ+10mΩ)=0.51V) Raise to 1.51 volts (ie 1A×(500mΩ+10mΩ)+1V=1.51V). It should be noted that the voltage value (for example, 1.51 volt) of the boosted voltage signal VT may be higher than the threshold (for example, 1.5 volt), so the power controller 121 can also automatically activate the over power protection mechanism.

Fig. 3 is a flowchart of an over-power protection method according to an embodiment of the present invention. Referring to FIG. 3, in step S301, an AC high voltage signal is detected. In step S302, the voltage value of the target voltage signal is increased from a first voltage value lower than a threshold value to a second voltage value higher than the threshold value according to the AC high voltage signal. In step S303, in response to the voltage value of the target voltage signal being higher than the threshold value, an overpower protection mechanism of the charger is activated.

The steps in Figure 3 have been described in detail as above, and will not be repeated here. It is worth noting that each step in FIG. 3 can be implemented as multiple program codes or circuits, and the present invention is not limited. In addition, the method in FIG. 3 can be used in conjunction with the above exemplary embodiments, or can be used alone, and the present invention is not limited.

In summary, the embodiment of the present invention can detect an AC high voltage signal and increase the voltage value of the target voltage signal from the first voltage value lower than the threshold value to the second voltage value higher than the threshold value according to the AC high voltage signal. Voltage value. Then, in response to the voltage value of the target voltage signal being higher than the threshold value, the overpower protection mechanism of the charger can be automatically activated to provide overpower protection of the charger. In this way, the traditional over-power protection of the charger cannot be automatically performed against the AC high-voltage signal, and the safety of the charger in use can be effectively improved.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention shall be determined by the scope of the attached patent application.

10: Charger 11: Charger module 12: Overpower protection circuit 121: Power Controller 122: voltage boost circuit 21: Detection circuit 22: voltage regulator circuit 23: Impedance circuit AC-, AC+: power input BD: Bridge rectifier Cin, Co, Caux: capacitance TR: Transformer Do, Daux, Din, Din2: Diode R1, R2, Rcs1, Rcs2: impedance components V0, V1, V2, VT, Vo: voltage signal Q, Qaux: switch ZD: Sensing diode GD: control pin CS: Current detection pin S301~S303: steps

Fig. 1 is a functional block diagram of a charger according to an embodiment of the present invention. 2 is a schematic diagram of the internal circuit structure of the charger according to an embodiment of the present invention. Fig. 3 is a flowchart of an over-power protection method according to an embodiment of the present invention.

10: Charger

11: Charger module

12: Overpower protection circuit

121: Power Controller

122: voltage boost circuit

V0, VT: voltage signal

Claims (11)

An overpower protection circuit includes: a power controller; and a voltage boost circuit coupled to the power controller, wherein the voltage boost circuit includes: an AC high voltage detection circuit coupled to the power controller; A voltage stabilizing circuit is coupled to the AC high voltage detection circuit; and an impedance circuit is coupled to the voltage stabilizing circuit and the power controller, wherein the AC high voltage detection circuit is used for detecting an AC high voltage signal and responding to it The AC high voltage signal generates a control voltage signal, the voltage stabilizing circuit is used to generate a reference voltage signal in response to the control voltage signal, and the impedance circuit is used to respond to the reference voltage signal to convert a voltage of a target voltage signal The value increases from a first voltage value lower than a threshold value to a second voltage value higher than the threshold value, and the difference between the first voltage value and the second voltage value is affected by a reference voltage signal Influenced by the voltage value, the power controller is used to activate an over-power protection mechanism in response to the voltage value of the target voltage signal being higher than the threshold value. The overpower protection circuit described in item 1 of the scope of patent application, wherein the AC high voltage detection circuit includes: a first unidirectional diode; and A voltage divider circuit coupled to the first unidirectional diode, wherein the voltage divider circuit is used to detect the AC high voltage signal through the first unidirectional diode and generate it in response to the AC high voltage signal The control voltage signal. According to the overpower protection circuit described in claim 2, wherein the voltage divider circuit includes: a first impedance element; and a second impedance element, wherein the first end of the first impedance element is coupled to the The first unidirectional diode, the second end of the first impedance element is coupled to the first end of the second impedance element, and the control voltage signal is generated at the second end of the first impedance element. According to the overpower protection circuit described in claim 1, wherein the voltage stabilizing circuit includes: a switch coupled to the AC high voltage detection circuit; an audit diode coupled to the switch; and The second unidirectional diode is coupled to the switch, the audit diode and the impedance circuit, wherein the switch is used to turn on in response to the control voltage signal, and the audit diode is used to respond to The switching of the switch provides the reference voltage signal to the impedance circuit through the second unidirectional diode. In the overpower protection circuit described in item 4 of the scope of patent application, the reference voltage signal reflects a breakdown voltage of the audit diode. The overpower protection circuit according to the first item of the scope of patent application, wherein the impedance circuit includes: a third impedance element; and a fourth impedance element, wherein the first end of the third impedance element is coupled to the voltage regulator The circuit and the first end of the fourth impedance element are used for receiving the reference voltage signal, and the target voltage signal is generated at the second end of the third impedance element. A charger includes: a charger module; and an over power protection circuit coupled to the charger module, wherein the over power protection circuit is used to detect an AC high voltage signal and respond to the AC high voltage signal A control voltage signal is generated, the overpower protection circuit is further used to generate a reference voltage signal in response to the control voltage signal, and the overpower protection circuit is further used to respond to the reference voltage signal to generate a target voltage signal The voltage value is increased from a first voltage value lower than a threshold value to a second voltage value higher than the threshold value, wherein the difference between the first voltage value and the second voltage value is affected by the reference voltage signal A voltage value is affected, and the overpower protection circuit is further used to activate an overpower protection mechanism in response to the voltage value of the target voltage signal being higher than the threshold value. An over-power protection method for a charger, and the over-power protection method includes: detecting an AC high-voltage signal; In response to the AC high voltage signal, a control voltage signal is generated; in response to the control voltage signal, a reference voltage signal is generated; in response to the reference voltage signal, a voltage value of a target voltage signal is changed from a voltage value lower than a threshold value The first voltage value is increased to a second voltage value higher than the critical value, wherein the difference between the first voltage value and the second voltage value is affected by a voltage value of the reference voltage signal; and in response to the target The voltage value of the voltage signal is higher than the critical value and an over power protection mechanism is activated. For the overpower protection method described in claim 8, wherein the step of generating the control voltage signal in response to the AC high voltage signal includes: generating the control voltage signal by a voltage divider circuit in response to the AC high voltage signal . For the overpower protection method described in claim 8, wherein the step of generating the reference voltage signal in response to the control voltage signal includes: turning on a switch in response to the control voltage signal; The body generates the reference voltage signal in response to the turn-on of the switch. In the overpower protection method described in item 10 of the scope of patent application, the reference voltage signal reflects a breakdown voltage of the audit diode.

Images