TWI661648B - Charging circuit and charging-controlling method - Google Patents

Abstract

A charging control method includes receiving an input voltage, using a control unit to receive a detection voltage related to the input voltage, using the control unit to output a conduction voltage when the detection voltage falls within a working range, and generating a working voltage to the charging unit according to the conduction voltage. The test pin uses the charging unit to output the charging current when the detection pin receives the operating voltage, and the control unit does not output the on-voltage when the input voltage falls outside the working range.

Description

Charging circuit and charging control method

The invention relates to a charging technology, in particular to a charging circuit and a charging control method.

With the advancement of technology, portable electronic products such as mobile phones, notebook computers, or tablet computers are becoming more popular and more powerful. When external power is not available, portable electronic products must be powered by rechargeable batteries equipped with them.

When the power of the rechargeable battery is exhausted, the user can connect the charger to an external power source and use the charger to charge the rechargeable battery.

During the charging process, the charging integrated circuit (IC) inside the charger will detect the input voltage and limit the range of the input voltage to protect the safety of the back-end circuit, thus limiting the application range, such as the inability to use the external power provided by the car battery. Power supply, adapters with different voltages cannot be used directly, etc. In view of this, this case provides a charging circuit and a charging control method, in which the control unit replaces the charging IC to monitor the input voltage and controls the operation of the charging IC, thereby increasing the applicable input voltage range and avoiding uncharged Leakage current occurs at the output of the power supply.

In one embodiment, a charging control method includes receiving an input voltage, using a control unit to receive a detection voltage related to the input voltage, using the control unit to output a conduction voltage when the detection voltage falls within a working range, and The working voltage is connected to the detection pin of the charging unit. When the detection pin receives the working voltage, the charging unit is used to output the charging current, and when the input voltage falls outside the working range, the control unit is not used to output the conduction voltage.

In one embodiment, a charging circuit includes a power input terminal, a power output terminal, a voltage detection circuit, a control unit, a conversion unit, and a charging unit. The power input terminal is used to receive an input voltage. The power output terminal is used to output electric current. The voltage detection circuit is coupled to the power input terminal and is used to output a detection voltage according to the input voltage. The detection voltage is related to the input voltage. The control unit is coupled to the voltage detection circuit and is used to detect the voltage detection voltage. When the voltage detection voltage falls within the working range, the control unit outputs a turn-on voltage. When the voltage detection voltage falls outside the working range, the control unit does not output a turn-on voltage. The conversion unit is coupled to the control unit and configured to output an operating voltage according to the on-voltage. The charging unit is coupled between the power input terminal and the power output terminal. The charging unit has a detection pin, and the detection pin is coupled to the conversion unit. When the detection pin receives the operating voltage, the charging unit generates a charging current according to the input voltage.

The detailed features and advantages of the present invention are described in detail in the following embodiments. The content is sufficient for any person skilled in the art to understand and implement the technical content of the present invention, and according to the content disclosed in this specification, the scope of patent applications and the drawings. Anyone skilled in the relevant art can easily understand the related objects and advantages of the present invention.

1, the charging circuit 10 includes a power input terminal Ni, a power output terminal No, a control unit 110, a conversion unit 130, a charging unit 150, and a voltage detection circuit 170. The control unit 110 is electrically connected to the power input terminal Ni. The conversion unit 130 is coupled between the control unit 110 and the charging unit 150. The charging unit 150 is coupled between the power input terminal Ni and the power output terminal No. Here, the charging unit 150 has a detection pin Pdt, and the detection pin Pdt is coupled to the conversion unit 130. The voltage detection circuit 170 is coupled between the power input terminal Ni and the control unit 110. Here, the control unit 110 has a working range.

Referring to FIGS. 1 and 2, the power input terminal Ni receives an input voltage Vi from an external power supply (not shown) of the charging circuit 10 (step S11). The voltage detection circuit 170 captures the input voltage Vi to generate a detection voltage Vd related to the input voltage Vi (step S13). The control unit 110 receives the detection voltage Vd (step S15), and confirms whether the detection voltage Vd falls within the working range (step S16). Here, the detection voltage Vd and the input voltage Vi have a fixed proportional relationship.

When the detection voltage Vd falls within the working range, the control unit 110 outputs a turn-on voltage So to the conversion unit 130 (step S17). The conversion unit 130 generates an operating voltage Sa to the detection pin Pdt of the charging unit 150 according to the on-voltage So (step S19). When the detection pin Pdt receives the operating voltage Sa, the charging unit 150 generates a charging current Io according to the input voltage Vi (step S21).

When the detection voltage Vd falls outside the working range, the control unit 110 does not output the on-voltage So (step S18); at this time, the conversion unit 130 cannot generate the working voltage Sa to the detection pin Pdt of the charging unit 150 (step S20) ), So that the charging unit 150 stops operating (step S21).

In some embodiments, the charging unit 150 may include a charging integrated circuit (IC) 151, a switching circuit 153, and an output stage circuit 155. The charging IC 151 is electrically connected to the power input terminal Ni. The switching circuit 153 is electrically connected between the power input terminal Ni and the output stage circuit 155. Here, a current-sense resistor Rs1 is coupled between the power input terminal Ni and the switching circuit 153. The output stage circuit 155 is coupled between the output stage circuit 155 and the power output terminal No. Here, the output stage circuit 155 includes an output inductor L and a current-sense resistor Rs2. The output inductor L is coupled to the switching circuit 153, and the current-sense resistor Rs2 is coupled between the output inductor L and the power output terminal No. In some embodiments, the output stage circuit 155 further includes an output capacitor, and the output capacitor is coupled between the power output terminal No and the ground.

In the normal operating state of the charging IC 151, the charging IC 151 detects the input current Ii through the current sensing resistor Rs1, detects the charging current Io through the current sensing resistor Rs2, and / or detects the output voltage Vo, and The operation of the switching circuit 153 is controlled according to the detection results of the input current Ii, the charging current Io, and / or the output voltage Vo. Under the control of the charging IC 151, the switching circuit 153 receives the input current Ii via the current-sense resistor Rs1 and controls the charging and discharging time of the output inductor L based on the input current Ii, so that the output stage circuit 155 can output a stable DC output voltage, that is, via a power supply The output No provides the charging current Io to an external load (for example, a battery module).

In some embodiments, the switching circuit 153 includes a first transistor M1 and a second transistor M2. The control terminal G1 of the first transistor M1 and the control terminal G2 of the second transistor M2 are coupled to the charging IC 151. The first terminal D1 of the first transistor M1 is electrically connected to the power input terminal Ni via the current-sense resistor Rs1. The second terminal S1 of the first transistor M1 and the first terminal D2 of the second transistor M2 are coupled to each other, and are commonly coupled to the output inductor L of the output stage circuit 155 and the charging IC 151. The second terminal S2 of the second transistor M2 is coupled to the ground.

In some embodiments, the charging IC 151 has a plurality of external pins, and these pins include the aforementioned detection pin Pdt, input current sensing pin Pan, Pap, command input pin Ps2, and current limiting pin Pii. , Current feedback pin Pio, switch control pin Phd, Pld, drive output pin Prg, switch drive pin Pbt, Pph, and output current sense pin Psn, Psp.

The input current sensing pins Pan and Pap are electrically connected to both ends of the current sensing resistor Rs1, and the input current Ii is measured through the current sensing resistor Rs1. The output current-sense pins Psn and Psp are electrically connected to both ends of the current-sense resistor Rs2, and the charging current Io is measured via the current-sense resistor Rs2. The command input pin Ps2 is electrically connected to the control unit 110. When the control unit 110 determines that the detection voltage Vd falls within the working range, the control unit 110 outputs a control command Sc to a command input pin Ps2 in addition to the on-voltage So. In some embodiments, the command input pin Ps2 and the control unit 110 may be coupled through a bus. The bus may be, for example, but not limited to, a system management bus (System Management Bus, SMBus, or SMB).

The current-limiting pin Pii is electrically connected to the control unit 110 and receives a current limit from the control unit 110. The current feedback pin Pio is electrically connected to the control unit 110 and outputs a feedback current to the control unit 110 according to the input current Ii or the charging current Io. The switch control pins Phd and Pld are coupled to the control terminals G1 and G2 of the switch circuit 153. The charging IC 151 outputs a switching signal to the switching circuit 153 through the switching control pins Phd and Pld to control the switching circuit 153. The driving output pins Prg drive the driving pins Pbt and Pph respectively through external diodes and capacitor electrical connection switches. The charging IC 151 outputs a driving signal through the driving output pin Prg, and drives the output circuit of the internal switching signal through the switch driving pin Pbt and Pph. The switch driving pin Pph is further coupled to the switching circuit 153 (the second terminal S1 of the first transistor M1 and the first terminal D2 of the second transistor M2). In some embodiments, the first terminal D1 and the second terminal S1 of the first transistor M1 may be a drain and a source, respectively, and the control terminal G1 of the first transistor M1 may be a gate. In some embodiments, the first terminal D2 and the second terminal S2 of the second transistor M2 may be a drain and a source, respectively, and the control terminal G2 of the second transistor M2 may be a gate.

In some embodiments, the charging IC 151 has an allowable range, and the aforementioned operating voltage Sa falls within the allowable range. And, the operating range of the control unit 110 is larger than the allowable range. Here, the allowable range is a voltage range composed of the first voltage value and the second voltage value, and the first voltage value and the second voltage value are two fixed values different from each other. In other words, the operating voltage Sa is between the first voltage value and the second voltage value. In an exemplary embodiment, the first voltage value and the second voltage value may be 2.4V and 3.15V, respectively.

In some embodiments, the working range is a voltage range composed of the third voltage value and the fourth voltage value. The third voltage value may be smaller than the first voltage value, and / or the fourth voltage value may be smaller than the second voltage value. In an exemplary embodiment, the size of the operating range depends on the withstand voltage of the control unit 110.

In some embodiments, the charging IC 151 can detect whether the voltage signal received by the detection pin Pdt falls within the allowable range. Here, when the voltage signal received by the detection pin Pdt falls within the allowable range (ie, the detection pin Pdt receives the operating voltage Sa), the charging IC 151 generates an appropriate signal. Here, when the voltage signal received by the detection pin Pdt does not fall within the allowable range (ie, the detection pin Pdt does not receive the operating voltage Sa), the charging IC 151 does not generate an appropriate signal. In an exemplary embodiment, the working voltage Sa may be a voltage signal at a first level. In other words, when the voltage signal is a second level different from the first level, it means that the detection pin Pdt has not received the operating voltage Sa.

In some embodiments, the pin of the charging IC 151 may further include a notification pin (not shown), and the notification pin is used as a notification signal. In an exemplary example, the notification signal has different two levels (hereinafter referred to as the third level and the fourth level). Among them, the notification signal of the third level is an appropriate signal. In other words, when the notification pin outputs a notification signal at the fourth level, it means that the charging IC 151 has not generated a proper signal.

In some embodiments, the charging IC 151 may include a uniform circuit, an output circuit, a bus interface, a voltage-current comparison circuit, a selection circuit, a PWM (pulse width modulation) circuit, and a switching signal generation. Circuit.

The enabling circuit is coupled between the detection pin Pdt and the driving output pin Prg. The enabling circuit generates a driving signal according to the working voltage Sa received by the detection pin Pdt and outputs a driving signal through the driving output pin Prg. In an exemplary embodiment, the enabling circuit may include a first comparator, a second comparator, a logic element, and a generator. The first comparator is coupled to the detection pin Pdt. The first comparator compares the potential (eg, the operating voltage Sa) of the detection pin Pdt with a wake-up voltage value to generate a first comparison result. The second comparator is coupled to the power supply pin (not shown). The second comparator compares the detection pin Pdt with a power supply upper limit to generate a second comparison result. The logic element is coupled to the output of the first comparator, the output of the second comparator, and the input of the signal generator. The logic element generates a consistent energy signal to the signal generator according to the first comparison result and the second comparison result, so that the signal generator outputs a driving signal. The wake-up voltage value is a fixed value, for example, 0.6V. The upper limit of the power supply is a fixed value, for example, 3.75V.

The input terminal of the output circuit is coupled to the switch signal generating circuit, and the input terminal of the output circuit is coupled to the switch control pins Phd and Pld. The driving end of the output circuit is coupled to the enabling circuit and the switch driving pins Pbt and Pph. In other words, when the detection pin Pdt receives the operating voltage Sa, the enabling circuit generates a driving signal to drive the output circuit to output the switching signal generated by the switching signal generating circuit to the switching circuit 153 via the switching control pins Phd and Pld. Control terminals G1, G2. Conversely, when the detection pin Pdt does not receive the operating voltage Sa, the enable circuit does not generate a drive signal, so the output circuit is disabled; at this time, the charging IC 151 stops operating (ie, the charging unit 150 is prohibited from outputting the charging current Io ).

In some embodiments, the bus interface is coupled to the command input pin Ps2 and receives the control command Sc from the control unit 110 via the command input pin Ps2. The control command Sc may include a first current reference, a second current reference, a voltage reference, a selection signal, and a start signal.

The voltage and current comparison circuit is electrically connected to the command input pin Ps2, and is coupled to the input current-sense pins Pan, Pap, the current-limiting pin Pii, and the output current-sense pins Psn, Psp. The voltage and current comparison circuit detects the input current Ii according to the first current reference to generate a first detection result, detects the charging current Io according to the second current reference to generate a second detection result, and connects to the output current detection terminal according to the voltage reference detection. The output voltage Vo measured by the pin Psn generates a third detection result, and the detection input current Ii is limited according to the current received by the current-limiting pin Pii to generate a fourth detection result. In an exemplary embodiment, in the voltage-current comparison circuit, the first differential amplifier measures the input current Ii via the input current sensing pins Pan and Pap, and the second differential amplifier calculates the measured value of the input current Ii and the first differential amplifier. The first difference between a current reference (first detection result). The third differential amplifier measures the charging current Io via the output current-sensing pins Psn, Psp, and the fourth differential amplifier calculates a second difference between the measured value of the charging current Io and the second current reference (second Detection results). The fifth differential amplifier is coupled to the output current-sense pin Psn via a voltage dividing circuit. The fifth differential amplifier receives the feedback value of the output voltage Vo via the output current sensing pin Psn and the voltage dividing circuit, and calculates a third difference between the feedback value of the output voltage Vo and the voltage reference (third detection result). The sixth differential amplifier is coupled to the output of the current-limiting pin Pii and the third differential amplifier, and calculates a fourth difference between the measured value of the charging current Io and the current limit (fourth detection result). Then, the summing circuit integrates the first difference value, the second difference value, the third difference value, and the fourth difference value, and outputs it to the PWM circuit.

The selection circuit is coupled between the voltage-current comparison circuit and the current feedback pin Pio. The selection circuit outputs the measured value of the charging current Io or the measured value of the charging current Io according to the selection signal output voltage and current comparison circuit. Following the above example, the input terminal of the selection circuit is coupled to the output of the first differential amplifier and the output of the third differential amplifier, and the output terminal of the selection circuit is coupled to the current feedback pin Pio. The control terminal of the selection circuit is coupled to the bus interface.

The PWM circuit generates a PWM signal according to the first detection result, the second detection result, the third detection result, and the fourth detection result.

The switching signal generating circuit is coupled between the PWM circuit and the output circuit. The switch signal generating circuit generates a switch signal according to the PWM signal when receiving the start signal. In other words, when the control unit 110 determines that the detection voltage Vd falls within the working range, the control unit 110 outputs the on-voltage So and simultaneously outputs a control command Sc to the charging IC 151. The switching signal generating circuit in the charging IC 151 operates normally due to the start signal in the control command Sc. Conversely, when the control unit 110 determines that the detection voltage Vd does not fall into the working range, the control unit 110 does not output the on-voltage So, and does not output a control command Sc to the charging IC 151. The switching signal generating circuit in the charging IC 151 is disabled because it does not receive a start signal; at this time, the charging IC 151 stops operating (that is, the charging unit 150 is prohibited from outputting the charging current Io).

In an embodiment, referring to FIGS. 1 and 3, the conversion unit 130 may be a voltage dividing circuit, and the voltage dividing circuit includes two voltage dividing elements (hereinafter referred to as a first voltage dividing element R11 and a second voltage dividing element). R12). The first terminal of the second voltage-dividing element R12 is coupled to a voltage source (which provides a predetermined voltage VCC), and the second terminal of the second voltage-dividing element R12 is coupled to the control unit 110, the detection pin Pdt and the first voltage-dividing element. First end of the pressing element R11. The second terminal of the first voltage-dividing element R11 is coupled to the ground. Here, the on-voltage So is a high level, and the operating voltage Sa is a divided voltage of the predetermined voltage VCC on the first voltage-dividing element R11. Conversely, when the control unit 110 determines that the detection voltage Vd does not fall into the working range, the control unit 110 directly pulls down the potential of the detection pin Pdt to a low level, that is, does not output the on-voltage So.

In another embodiment, referring to FIG. 1 and FIG. 4, the conversion unit 130 may be a voltage dividing circuit, and the voltage dividing circuit includes two voltage dividing elements (hereinafter referred to as a first voltage dividing element R21 and a second voltage dividing element). Element R22). The first terminal of the second voltage dividing element R22 is coupled to the control unit 110, and the second terminal of the second voltage dividing element R22 is coupled to the detection pin Pdt of the charging unit 150 and the first terminal of the first voltage dividing element R21. The second terminal of the first voltage dividing element R21 is coupled to the ground. Here, the operating voltage Sa is a divided voltage of the on-voltage So on the first voltage dividing element R21.

In an embodiment, referring to FIGS. 1 and 5, the voltage detecting circuit 170 may be a voltage dividing circuit, and the voltage dividing circuit includes two voltage dividing elements (hereinafter referred to as the third voltage dividing element R31 and the fourth voltage dividing element). Pressure element R32). The fourth voltage-dividing element R32 and the third voltage-dividing element R31 are connected in series between the power input terminal Ni and the ground. The contact between the third voltage-dividing element R31 and the fourth voltage-dividing element R32 is coupled to the control unit 110. Here, the detection voltage Vd is a divided voltage of the input voltage Vi, that is, a divided voltage of the input voltage Vi on the third voltage dividing element R31.

In some embodiments, the charging circuit 10 may further include a voltage stabilization circuit 190. The voltage stabilization circuit 190 is coupled between the power input terminal Ni and the charging unit 150. That is, the voltage stabilization circuit 190 receives the input voltage Vi via the power input terminal Ni and provides a stable input voltage Vi to the back-end circuit (charging unit 150) accordingly. In an exemplary embodiment, the voltage stabilization circuit 190 is one or more audit diodes connected in parallel between the power input terminal Ni and the charging unit 150.

In some embodiments, the control unit 110 may be implemented by a microcontroller.

In some embodiments, the power output terminal No of the charging circuit 10 is adapted to be coupled to a battery module 20, as shown in FIGS. 1 and 6. For example, in an exemplary case, assuming that the charging circuit 10 is an internal circuit of an independent charging device (such as a charger, a charging stand, etc.), the power output terminal No may be suitable for electrically connecting the battery module 20 A connector. Here, the charging circuit 10 outputs the generated charging current Io to the battery module 20 through the connector, thereby charging the battery module 20. In another example, when the charging circuit 10 is a circuit built in an electronic device (such as a portable electronic product such as a mobile phone, a notebook computer, or a tablet computer), the power output terminal No may be a line connection. Point, and this line contact is electrically connected to the battery module 20. Here, the charging circuit 10 can output the generated charging current Io to the battery module 20, so as to charge the battery module 20.

In some embodiments, the power input terminal Ni of the charging circuit 10 is adapted to be coupled to an adapter circuit 30, as shown in FIGS. 1 and 3. The adapter circuit 30 is used to provide an input voltage Vi. Here, the circuit architecture of the adapter circuit 30 is well known in the art, so it will not be described in detail.

To sum up, according to the charging circuit and charging control method of any embodiment of the present invention, the control unit 110 replaces the charging IC to monitor the input voltage Vi, and controls the operation of the charging IC 151 according to it, thereby increasing the applicable input voltage. The range of Vi can also avoid leakage current at the output end of the power supply when it is not charged.

Although the technical content of the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art and making some changes and retouching without departing from the spirit of the present invention should be covered by the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent application.

10‧‧‧Charging circuit

110‧‧‧control unit

130‧‧‧ conversion unit

150‧‧‧ Charging unit

151‧‧‧Charging integrated circuit (IC)

153‧‧‧Switch circuit

155‧‧‧Output stage circuit

170‧‧‧voltage detection circuit

190‧‧‧Regulator

20‧‧‧ Battery Module

30‧‧‧ adapter circuit

Ni‧‧‧ Power Input

No‧‧‧Power output

Vi‧‧‧ input voltage

Ii‧‧‧Input current

Vo‧‧‧ output voltage

Io‧‧‧Charging current

Vd‧‧‧ Detection voltage

So‧‧‧on voltage

Sa‧‧‧Working voltage

Sc‧‧‧Control command

Pdt‧‧‧ Detect Pin

Pan, Pap‧‧‧input current sensing pin

Ps2‧‧‧command input pin

Pii ‧‧‧ current limiting pin

Pio‧‧‧Current feedback pin

Phd, Pld‧‧‧ switch control pin

Prg‧‧‧ drive output pin

Pbt, Pph‧‧‧ switch drive pin

Psn, Psp‧‧‧ output current sensing pin

Rs1‧‧‧Current-sense resistor

Rs2‧‧‧Current-sense resistor

M1‧‧‧First transistor

D1‧‧‧ the first end

S1‧‧‧ second end

G1‧‧‧Control terminal

M2‧‧‧Second transistor

D2‧‧‧ the first end

S2‧‧‧Second End

G2‧‧‧Control terminal

L‧‧‧Output inductor

R11‧‧‧The first voltage dividing element

R12‧‧‧Second Voltage Dividing Element

R21‧‧‧The first voltage dividing element

R22‧‧‧Second Voltage Dividing Element

R31‧‧‧third voltage divider

R32‧‧‧Fourth voltage dividing element

S11 ~ S21‧‧‧‧step

FIG. 1 is a schematic diagram of a charging circuit according to an embodiment of the present invention. FIG. 2 is a flowchart of a charging control method according to an embodiment of the present invention. FIG. 3 is a schematic circuit diagram of an embodiment of the conversion unit of FIG. 1. FIG. 4 is a schematic circuit diagram of another embodiment of the conversion unit of FIG. 1. FIG. 5 is a circuit diagram of an embodiment of the voltage detection circuit of FIG. 1. FIG. 6 is a functional block diagram of an application example of the charging circuit of FIG. 1.

Claims (10)

A charging control method includes: receiving an input voltage; using a control unit to receive a detection voltage related to the input voltage; when the detection voltage falls within a working range, using the control unit to output a turn-on voltage; and according to the turn-on The voltage generates a working voltage to a detection pin of a charging unit; when the detection pin receives the working voltage, using the charging unit to output a charging current based on the input voltage; and when the detection voltage falls on the When the working range is outside, the control unit is not used to output the on-voltage. The step of generating the working voltage according to the on-voltage is to generate the working voltage by dividing the on-voltage. A charging control method includes: receiving an input voltage; using a control unit to receive a detection voltage related to the input voltage; when the detection voltage falls within a working range, using the control unit to output a turn-on voltage; and according to the turn-on The voltage generates a working voltage to a detection pin of a charging unit; when the detection pin receives the working voltage, using the charging unit to output a charging current based on the input voltage; and when the detection voltage falls on the When the operating range is outside, using the control unit does not output the on-voltage; wherein the step of generating the working voltage according to the on-voltage is to generate the working voltage by dividing a predetermined voltage in the presence of the on-voltage, and using the The step of the control unit not outputting the on-voltage is to use the control unit to pull down the voltage of the detection pin to ground. The charging control method according to claim 1 or 2, wherein the charging unit has an allowable range, the operating voltage falls within the allowable range, and the operating range is greater than the allowable range. The charging control method according to claim 1 or 2, further comprising: dividing the input voltage to generate the detection voltage. The charging control method according to claim 1 or 2, further comprising: using the control unit to output a first current reference, a second current reference, a voltage reference, and a current limit to the charging unit; using the charging unit Detecting an input current according to the first current reference to generate a first detection result, detecting the charging current according to the second current reference to generate a second detection result, and detecting an output voltage according to the voltage reference to Generating a third detection result, and detecting the charging current according to the current limit to generate a fourth detection result; and using the charging unit according to the first detection result, the second detection result, and the third The detection result and the fourth detection result control the output of the charging current. A charging circuit includes: a power input terminal receiving an input voltage; a power output terminal outputting a charging current; a voltage detection circuit coupled to the power input terminal and outputting a detection voltage according to the input voltage, wherein the The detection voltage is related to the input voltage; a control unit is coupled to the voltage detection circuit and detects the detection voltage according to a working range, wherein when the detection voltage falls within the working range, the control unit outputs a turn-on voltage, And when the detection voltage falls outside the working range, the control unit does not output the on-voltage; a conversion unit is coupled to the control unit and outputs a working voltage according to the on-voltage; and a charging unit is coupled to the Between the power input terminal and the power output terminal, the charging unit has a detection pin, the detection pin is coupled to the conversion unit, and when the detection pin receives the working voltage, the charging unit is based on The input voltage generates the charging current; wherein the conversion unit includes a first voltage-dividing element and a second voltage-dividing element, and a first terminal of the second voltage-dividing element Connected to the control unit, the second end of the second voltage-dividing element is coupled between the detection pin and the first end of the first voltage-dividing element, and the second end of the first voltage-dividing element is coupled to ground And the operating voltage is a partial voltage of the on-voltage on the first voltage dividing element. A charging circuit includes: a power input terminal receiving an input voltage; a power output terminal outputting a charging current; a voltage detection circuit coupled to the power input terminal and outputting a detection voltage according to the input voltage, wherein the The detection voltage is related to the input voltage; a control unit is coupled to the voltage detection circuit and detects the detection voltage according to a working range, wherein when the detection voltage falls within the working range, the control unit outputs a turn-on voltage, And when the detection voltage falls outside the working range, the control unit does not output the on-voltage; a conversion unit is coupled to the control unit and outputs a working voltage according to the on-voltage; and a charging unit is coupled to the Between the power input terminal and the power output terminal, the charging unit has a detection pin, the detection pin is coupled to the conversion unit, and when the detection pin receives the working voltage, the charging unit is based on The input voltage generates the charging current; wherein the conversion unit includes a first voltage-dividing element and a second voltage-dividing element, and a first terminal of the second voltage-dividing element Connected to a predetermined voltage, the second terminal of the second voltage dividing element is coupled to the control unit, the detection pin is connected to the first terminal of the first voltage dividing element, and the second terminal of the first voltage dividing element is coupled To the ground, and the operating voltage is a partial voltage of the predetermined voltage on the first voltage dividing element. The charging circuit according to claim 6 or 7, wherein the charging unit has an allowable range, the operating voltage falls within the allowable range, and the operating range is greater than the allowable range. The charging circuit according to claim 6 or 7, wherein the voltage detecting circuit comprises a plurality of voltage dividing elements, the voltage dividing elements are electrically connected between the power input terminal and the ground, and the connection between the voltage dividing elements The point is coupled to the control unit, and the voltage detection voltage is a divided voltage of the input voltage. The charging circuit according to claim 6 or 7, wherein the control unit outputs a first current reference, a second current reference, a voltage reference, and a current limit to the charging unit, and the charging unit is based on the first current Reference detection of an input current to generate a first detection result, detection of the charging current according to the second current reference to generate a second detection result, detection of an output voltage according to the voltage reference to generate a third detection Measurement results, and detecting the charging current according to the current limit to generate a fourth detection result, and according to the first detection result, the second detection result, the third detection result, and the fourth detection As a result, the output of the charging current is controlled.