WO2016115703A1 - 限流保护电路和电子设备 - Google Patents

限流保护电路和电子设备 Download PDF

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Publication number
WO2016115703A1
WO2016115703A1 PCT/CN2015/071296 CN2015071296W WO2016115703A1 WO 2016115703 A1 WO2016115703 A1 WO 2016115703A1 CN 2015071296 W CN2015071296 W CN 2015071296W WO 2016115703 A1 WO2016115703 A1 WO 2016115703A1
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WIPO (PCT)
Prior art keywords
voltage
resistor
current
feedback
operational amplifier
Prior art date
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Ceased
Application number
PCT/CN2015/071296
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English (en)
French (fr)
Inventor
刘圣才
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Publication date
Application filed by Huawei Technologies Co Ltd filed Critical Huawei Technologies Co Ltd
Priority to JP2017538989A priority Critical patent/JP6474907B2/ja
Priority to US15/545,847 priority patent/US10411464B2/en
Priority to PCT/CN2015/071296 priority patent/WO2016115703A1/zh
Priority to EP15878381.1A priority patent/EP3242365B1/en
Priority to CN201580019716.9A priority patent/CN106463943B/zh
Publication of WO2016115703A1 publication Critical patent/WO2016115703A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current 
    • G05F1/46—Regulating voltage or current  wherein the variable actually regulated by the final control device is DC
    • G05F1/56—Regulating voltage or current  wherein the variable actually regulated by the final control device is DC using semiconductor devices in series with the load as final control devices
    • G05F1/565—Regulating voltage or current  wherein the variable actually regulated by the final control device is DC using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
    • G05F1/569—Regulating voltage or current  wherein the variable actually regulated by the final control device is DC using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection
    • G05F1/573—Regulating voltage or current  wherein the variable actually regulated by the final control device is DC using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection with overcurrent detector
    • G05F1/5735—Regulating voltage or current  wherein the variable actually regulated by the final control device is DC using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection with overcurrent detector with foldback current limiting

Definitions

  • Embodiments of the present invention relate to the field of circuits, and in particular, to a current limiting protection circuit and an electronic device.
  • Mobile handheld terminals such as smart phones and tablet computers are easy to carry and use.
  • users can perform video viewing, online reading, online games, instant messaging and other activities at any time.
  • Terminals are increasingly favored by users.
  • the battery life cannot meet the needs of users. Therefore, electronic products with external charging functions, such as charging treasures, have emerged. When these electronic products are externally charged, in order to ensure the safety of the equipment, the charging current is appropriately limited.
  • FIG. 1 is a schematic structural diagram of a current limiting scheme in the prior art.
  • a current limiting function is implemented by providing a dedicated linear current limiting chip 12 at a subsequent stage of the power chip 11, the specific principle is: when charging current When the current threshold is greater than the set current threshold, the on-resistance of the linear current-limiting chip 12 is linearly increased to lower the charging current until the charging current is equal to the set current threshold, thereby realizing the limitation of the charging current.
  • the prior art has the following drawbacks: increasing the on-resistance, that is, increasing the path loss, generating heat, in the over-current state, the external charging device is easily activated to turn off the external charging function, and the waste of resources and charging efficiency are caused. low.
  • the embodiment of the invention provides a current limiting protection circuit and an electronic device.
  • the constant voltage output is converted into a constant current output, which limits the charging current, saves resources, and improves charging efficiency.
  • an embodiment of the present invention provides a current limiting protection circuit, including: a power chip and a current limiting circuit electrically connected to the power chip;
  • the power chip has an output pin and a feedback pin
  • the current limiting circuit includes: a current sampling resistor, at least one voltage conversion resistor, and a first operation An amplifier, a triode, a first voltage dividing resistor, a second voltage dividing resistor, and a diode;
  • the output pin is connected to one end of the current sampling resistor; the negative input terminal of the first operational amplifier is connected to one end of the first voltage conversion resistor, and the other end of the first voltage conversion resistor and the current One end of the sampling resistor is connected; a forward input end of the first operational amplifier is connected to one end of the second voltage conversion resistor, and the other end of the second voltage conversion resistor is connected to the other end of the current sampling resistor; An output of the first operational amplifier is coupled to a base of the transistor, an emitter of the transistor is coupled to a negative input of the first operational amplifier, and a collector of the transistor and one end of a third voltage conversion resistor Connecting, the other end of the third voltage conversion resistor is grounded;
  • the first voltage dividing resistor is connected in series with the second voltage dividing resistor, one end of the first voltage dividing resistor is connected to the other end of the current sampling resistor, and one end of the second voltage dividing resistor is grounded;
  • the anode of the diode is connected to one end of the third voltage conversion resistor, and the cathode of the diode is respectively connected to the other end of the second voltage dividing resistor and the feedback pin;
  • the power chip is specifically configured to: convert the input first voltage into a second voltage, and output the second voltage to the current limiting circuit through the output pin;
  • the current limiting circuit is specifically configured to: detect a first current passing through the current sampling resistor; convert the first current into a third voltage through the voltage conversion resistor, the first operational amplifier, and the triode; Outputting a first reference voltage through the first voltage dividing resistor and the second voltage dividing resistor; outputting the feedback voltage to the feedback pin according to the third voltage and the first reference voltage;
  • the power chip is further configured to: when the feedback voltage is greater than the second reference voltage, lower the second voltage until the first current is preset; wherein the second reference voltage is internal to the power chip The preset voltage.
  • the current limiting circuit further includes a second operational amplifier
  • the anode of the diode is connected to one end of the third voltage conversion resistor, and the cathode of the diode is respectively connected to the other end of the second voltage dividing resistor and the feedback pin, corresponding to:
  • a positive input end of the second operational amplifier is connected to the other end of the second voltage dividing resistor, and a negative input end of the second operational amplifier is connected to one end of the third voltage converting resistor,
  • the output of the two operational amplifiers is coupled to the anode of the diode, and the cathode of the diode is coupled to the negative input of the second operational amplifier and the feedback pin, respectively.
  • the outputting the feedback voltage to the feedback pin according to the third voltage and the first reference voltage includes:
  • the feedback voltage is a difference between the third voltage and a forward voltage of the diode; or And if the third voltage is less than or equal to a sum of the first reference voltage and a forward voltage of the diode, the feedback voltage is the first reference voltage.
  • the outputting to the feedback pin according to the third voltage and the first reference voltage including:
  • the feedback voltage is the third voltage; or, if the third voltage is less than or equal to the first reference voltage, the feedback voltage is The first reference voltage is described.
  • an embodiment of the present invention provides an electronic device, including: a current limiting protection circuit and a power supply interface connected to the current limiting protection circuit; the power supply interface is configured to connect a load, and the electronic device is configured to Load supply
  • the current limiting protection circuit includes: a power chip and a current limiting circuit electrically connected to the power chip;
  • the power chip has an output pin and a feedback pin
  • the current limiting circuit includes: a current sampling resistor, at least one voltage conversion resistor, a first operational amplifier, a triode, a first voltage dividing resistor, a second voltage dividing resistor, and a diode;
  • the output pin is connected to one end of the current sampling resistor; the negative input terminal of the first operational amplifier is connected to one end of the first voltage conversion resistor, and the other end of the first voltage conversion resistor and the current One end of the sampling resistor is connected; a forward input end of the first operational amplifier is connected to one end of the second voltage conversion resistor, and the other end of the second voltage conversion resistor is connected to the other end of the current sampling resistor; An output of the first operational amplifier is coupled to a base of the transistor, an emitter of the transistor is coupled to a negative input of the first operational amplifier, and a collector of the transistor and one end of a third voltage conversion resistor Connecting, the other end of the third voltage conversion resistor is grounded;
  • the first voltage dividing resistor is connected in series with the second voltage dividing resistor, one end of the first voltage dividing resistor is connected to the other end of the current sampling resistor, and one end of the second voltage dividing resistor is grounded;
  • a cathode of the diode is connected to one end of the third voltage conversion resistor, the diode a negative electrode is respectively connected to the other end of the second voltage dividing resistor and the feedback pin;
  • the power chip is specifically configured to: convert the input first voltage into a second voltage, and output the second voltage to the current limiting circuit through the output pin;
  • the current limiting circuit is specifically configured to: detect a first current passing through the current sampling resistor; convert the first current into a third voltage through the voltage conversion resistor, the first operational amplifier, and the triode; Outputting a first reference voltage through the first voltage dividing resistor and the second voltage dividing resistor; outputting the feedback voltage to the feedback pin according to the third voltage and the first reference voltage;
  • the power chip is further configured to: when the feedback voltage is greater than the second reference voltage, lower the second voltage until the first current is preset; wherein the second reference voltage is internal to the power chip The preset voltage.
  • the current limiting circuit further includes a second operational amplifier
  • the anode of the diode is connected to one end of the third voltage conversion resistor, and the cathode of the diode is respectively connected to the other end of the second voltage dividing resistor and the feedback pin, corresponding to:
  • a positive input end of the second operational amplifier is connected to the other end of the second voltage dividing resistor, and a negative input end of the second operational amplifier is connected to one end of the third voltage converting resistor,
  • the output of the two operational amplifiers is coupled to the anode of the diode, and the cathode of the diode is coupled to the negative input of the second operational amplifier and the feedback pin, respectively.
  • the outputting the feedback voltage to the feedback pin according to the third voltage and the first reference voltage includes:
  • the feedback voltage is a difference between the third voltage and a forward voltage of the diode; or And if the third voltage is less than or equal to a sum of the first reference voltage and a forward voltage of the diode, the feedback voltage is the first reference voltage.
  • the outputting, according to the third voltage and the first reference voltage, to the feedback pin The feedback voltage, including:
  • the feedback voltage is the third voltage; or, if the third voltage is less than or equal to the first reference voltage, the feedback voltage is The first reference voltage is described.
  • the embodiment of the invention provides a current limiting protection circuit and an electronic device.
  • the current limiting protection circuit includes: a power chip and a current limiting circuit electrically connected to the power chip; the power chip has an output pin and a feedback pin, and the power chip inputs the input.
  • the first voltage is converted into a second voltage, and the second voltage is output to the current limiting circuit through the output pin, the current limiting circuit detects the first current passing through the current sampling resistor, and outputs a feedback voltage to the feedback pin, and the power chip is also used for When the feedback voltage is greater than the second reference voltage, the second voltage is lowered until the first current is preset, wherein the second reference voltage is a preset voltage inside the power chip.
  • the current limiting protection circuit provided by the embodiment of the invention reduces the output voltage and reduces the charging current when the charging current is over-current, so that the constant current output is converted into a constant current output when the charging current is over-current, thereby achieving the current limiting.
  • the purpose is to generate additional heat without additional path loss, which can continuously charge externally, save resources and improve charging efficiency.
  • FIG. 1 is a schematic structural view of a current limiting scheme in the prior art
  • Embodiment 1 of a current limiting protection circuit of the present invention
  • Embodiment 2 of a current limiting protection circuit of the present invention
  • FIG. 4 is a schematic structural diagram of Embodiment 1 of an electronic device according to the present invention.
  • the current limiting protection circuit may include a power chip 21 and a current limiting circuit electrically connected to the power chip 21.
  • the power chip 21 has an output pin VOUT and a feedback pin FB.
  • the current limiting circuit includes: a current sampling resistor R6, at least one voltage conversion resistor, a first operational amplifier U2, a transistor T1, a first voltage dividing resistor R7, a second voltage dividing resistor R8, and a diode D1.
  • the output pin VOUT is connected to one end of the current sampling resistor R6.
  • the negative input terminal 2 of the first operational amplifier U2 is connected to one end of the first voltage conversion resistor R4, and the other end of the first voltage conversion resistor R4 is connected to one end of the current sampling resistor R6.
  • the forward input terminal 3 of the first operational amplifier U2 is connected to one end of the second voltage conversion resistor R3, and the other end of the second voltage conversion resistor R3 is connected to the other end of the current sampling resistor R6.
  • the output terminal 1 of the first operational amplifier U2 is connected to the base of the transistor T1, the emitter of the transistor T1 is connected to the negative input terminal 2 of the first operational amplifier U2, the collector of the transistor T1 and one end of the third voltage conversion resistor R5. Connected, the other end of the third voltage conversion resistor R5 is grounded.
  • the first voltage dividing resistor R7 is connected in series with the second voltage dividing resistor R8. One end of the first voltage dividing resistor R7 is connected to the other end of the current sampling resistor R6, and one end of the second voltage dividing resistor R8 is grounded.
  • the anode of the diode D1 is connected to one end of the third voltage converting resistor R5, and the cathode of the diode D1 is connected to the other end of the second voltage dividing resistor R8 and the feedback pin FB, respectively.
  • the power chip 21 is specifically configured to: convert the input first voltage V in into a second voltage V out , and output a second voltage V out to the current limiting circuit through the output pin VOUT.
  • the current limiting circuit is specifically configured to: detect a first current I passing through the current sampling resistor R6, convert the first current I into a third voltage Vcov through the voltage conversion resistor, the first operational amplifier U2, and the transistor T1, and pass the first partial voltage
  • the resistor R7 and the second voltage dividing resistor R8 output a first reference voltage Vth , and output a feedback voltage VFB to the feedback pin FB according to the third voltage Vcov and the first reference voltage Vth .
  • the power chip is further configured to: when the feedback voltage V FB is greater than the second reference voltage V FB — thth , lower the second voltage V out until the first current I is preset.
  • the second reference voltage V FB_th is a preset voltage inside the power chip 21 .
  • the power chip 21 can convert the input voltage into a required voltage constant output, that is, convert the input first voltage V in into a second voltage V out and output it constantly through the output pin VOUT.
  • the energy input source of the power chip 21 is the battery Vbat, and the inductor L1 and the capacitor C1 cooperate with the power chip 21 to realize the conversion of the input voltage to the output voltage.
  • the energy input source of the power chip 21 may be a battery or other energy input source, which is not limited in the present invention.
  • a second power source voltage V out chip 21 according to the feedback pin FB can also receive the feedback voltage V FB and a second reference voltage V FB_th adjusted output.
  • the second reference voltage V FB_th is a preset voltage inside the power chip 21 . Specifically, when the feedback voltage V FB is smaller than the second reference voltage V FB_th , the power module 21 will increase the output second voltage V out ; when the feedback voltage V FB is greater than the second reference voltage V FB_th , the power module 21 will decrease The outputted second voltage V out ; when the feedback voltage V FB is equal to the second reference voltage V FB_th , the power module 21 will keep outputting the second voltage V out without adjustment. It can be seen that when the power chip 21 is stably operated, the feedback voltage V FB will be equal to the second reference voltage V FB_th .
  • the power chip 21 inputs the second voltage V out to the current limiting circuit, wherein the current sampling resistor R6 can detect the first current I passing through the resistor, and the first current I is the charging current.
  • the first voltage conversion resistor R4 Converting the first current I into a third voltage V cov by the first voltage conversion resistor R4, the second voltage conversion resistor R3, the third voltage conversion resistor R5, the first operational amplifier U2, and the transistor T1, specifically, the third voltage conversion
  • the voltage at one end of the resistor R5 is the third voltage V cov .
  • the voltage of one end of the first voltage conversion resistor R4 is equal to the voltage of one end of the second voltage conversion resistor R3.
  • the transistor T1 is used to constitute an operational amplifier negative feedback
  • the second voltage conversion resistor R3 is used to compensate a bias current of the input end of the first operational amplifier U2.
  • Output feedback pin FB to the feedback voltage V FB in particular, the anode of the diode D1 according to a third voltage with the first reference voltage V CoV V th voltage is a first reference voltage V th, the diode D1 as a third voltage of the positive voltage V Cov , and the cathode of the diode D1 is connected to the feedback pin FB, and the feedback voltage V FB is output to the feedback pin FB .
  • the third voltage V cov will be less than or equal to the sum of the first reference voltage V th and the forward voltage V D1 of the diode D1, the diode D1 is turned off, and the feedback voltage V FB is the first reference.
  • the third voltage V cov When the first current I is overcurrent, the third voltage V cov will be greater than the sum of the first reference voltage V th and the forward voltage V D1 of the diode D1 , the diode D1 is turned on, and the feedback voltage V FB is the third voltage V cov
  • V FB V cov -V D1
  • the feedback voltage V FB will be greater than the second reference voltage V FB_th
  • the power chip 21 will lower the second voltage V out until feedback
  • the power chip 21 performs current limiting by dynamically adjusting the output voltage, when the charging current is over-current, the charging current is reduced by lowering the output voltage, no additional heat is generated by additionally increasing the path loss, and the external charging can be continued, saving resources and improving charging. effectiveness.
  • the parameters of the power chip, the battery, the resistor, the capacitor, and the inductor shown in FIG. 2 are only examples, and the specific models and parameters can be adjusted according to the requirements of the power chip and the product.
  • the back end may be connected to a load for supplying power to the load, and the load may be an external load or a load inside the electronic device, which is not limited by the present invention. .
  • An embodiment of the present invention provides a current limiting protection circuit, including a power chip and a current limiting circuit electrically connected to the power chip.
  • the power chip has an output pin and a feedback pin, and the power chip converts the input first voltage into a second. Voltage, and outputting a second voltage to the current limiting circuit through the output pin, the current limiting circuit detects the first current through the current sampling resistor, and outputs a feedback voltage to the feedback pin, and the power chip is further used when the feedback voltage is greater than the second reference voltage And decreasing the second voltage until the first current is preset, wherein the second reference voltage is a preset voltage inside the power chip.
  • the current limiting protection circuit provided by the embodiment of the invention reduces the output voltage and reduces the charging current when the charging current is over-current, so that the constant current output is converted into a constant current output when the charging current is over-current, thereby achieving the current limiting.
  • the purpose is to generate additional heat without additional path loss, which can be continuously externally charged and save resources. Increased charging efficiency.
  • FIG. 3 is a schematic structural diagram of a second embodiment of a current protection circuit according to the present invention. This embodiment provides another feasible structure of the current limiting circuit based on the first embodiment. As shown in FIG. 3, the current limiting protection circuit may include a power chip 21 and a current limiting circuit electrically connected to the power chip 21.
  • the power chip 21 has an output pin VOUT and a feedback pin FB.
  • the current limiting circuit includes: a current sampling resistor R6, at least one voltage conversion resistor, a first operational amplifier U2, a transistor T1, a first voltage dividing resistor R7, a second voltage dividing resistor R8, and a diode D1.
  • the output pin VOUT is connected to one end of the current sampling resistor R6.
  • the negative input terminal 2 of the first operational amplifier U2 is connected to one end of the first voltage conversion resistor R4, and the other end of the first voltage conversion resistor R4 is connected to one end of the current sampling resistor R6.
  • the forward input terminal 3 of the first operational amplifier U2 is connected to one end of the second voltage conversion resistor R3, and the other end of the second voltage conversion resistor R3 is connected to the other end of the current sampling resistor R6.
  • the output terminal 1 of the first operational amplifier U2 is connected to the base of the transistor T1, the emitter of the transistor T1 is connected to the negative input terminal 2 of the first operational amplifier U2, the collector of the transistor T1 and one end of the third voltage conversion resistor R5. Connected, the other end of the third voltage conversion resistor R5 is grounded.
  • the first voltage dividing resistor R7 is connected in series with the second voltage dividing resistor R8. One end of the first voltage dividing resistor R7 is connected to the other end of the current sampling resistor R6, and one end of the second voltage dividing resistor R8 is grounded.
  • the positive input terminal 3 of the second operational amplifier U3 is connected to the other end of the second voltage dividing resistor R8, and the negative input terminal 2 of the second operational amplifier U3 is connected to one end of the third voltage converting resistor R5, and the second operational amplifier U3 is connected.
  • the output terminal 1 is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the negative input terminal 3 of the second operational amplifier U3 and the feedback pin FB, respectively.
  • the current limiting circuit further includes a second operational amplifier U3. Outputting a feedback voltage V FB to the feedback pin FB according to the third voltage V cov and the first reference voltage V th .
  • the voltage of the forward input terminal of the second operational amplifier U3 is the first reference voltage V th
  • the second operational amplifier The voltage of the negative input terminal 2 of U3 is the third voltage V cov
  • the cathode of the diode D1 is connected to the feedback pin FB
  • the feedback voltage V FB is output to the feedback pin FB .
  • the third voltage V cov When the first current I is not overcurrent, the third voltage V cov will be less than or equal to the first reference voltage V th , ie, the voltage of the negative input terminal 2 of the second operational amplifier U3 is less than or equal to the second operational amplifier U3
  • the constant voltage output is maintained, and the feedback voltage V FB is the first reference voltage V th and is equal to the second reference voltage V FB_th .
  • the third voltage V cov will be greater than the first reference voltage V th , ie, the voltage of the negative input terminal 2 of the second operational amplifier U3 is greater than the forward input terminal 3 of the second operational amplifier U3.
  • the power chip 21 performs current limiting by dynamically adjusting the output voltage, when the charging current is over-current, the charging current is reduced by lowering the output voltage, no additional heat is generated by additionally increasing the path loss, and the external charging can be continued, saving resources and improving charging. effectiveness.
  • An embodiment of the present invention provides a current limiting protection circuit, including a power chip and a current limiting circuit electrically connected to the power chip.
  • the power chip has an output pin and a feedback pin, and the power chip converts the input first voltage into a second. Voltage, and outputting a second voltage to the current limiting circuit through the output pin, the current limiting circuit detects the first current through the current sampling resistor, and outputs a feedback voltage to the feedback pin, and the power chip is further used when the feedback voltage is greater than the second reference voltage And decreasing the second voltage until the first current is preset, wherein the second reference voltage is a preset voltage inside the power chip.
  • the current limiting protection circuit provided by the embodiment of the invention reduces the output voltage and reduces the charging current when the charging current is over-current, so that the constant current output is converted into a constant current output when the charging current is over-current, thereby achieving the current limiting.
  • the purpose is to generate additional heat without additional path loss, which can continuously charge externally, save resources and improve charging efficiency.
  • FIG. 4 is a schematic structural diagram of Embodiment 1 of an electronic device according to the present invention.
  • the electronic device 100 may include a current limiting protection circuit 101 and a power supply interface 102 connected to the current limiting protection circuit 101.
  • the power supply interface 102 is used to connect the load 200 to enable the electronic device 100 to supply power to the load 200. .
  • the current limiting protection circuit 101 can be the current limiting protection circuit shown in FIG. 2 , and the current limiting protection circuit 101 includes a power chip 21 and a current limiting circuit electrically connected to the power chip 21 .
  • the power chip 21 has an output pin VOUT and a feedback pin FB.
  • the current limiting circuit includes: a current sampling resistor R6, at least one voltage conversion resistor, a first operational amplifier U2, a transistor T1, a first voltage dividing resistor R7, a second voltage dividing resistor R8, and a diode D1.
  • the output pin VOUT is connected to one end of the current sampling resistor R6.
  • the negative input terminal 2 of the first operational amplifier U2 is connected to one end of the first voltage conversion resistor R4, and the other end of the first voltage conversion resistor R4 is connected to one end of the current sampling resistor R6.
  • the forward input terminal 3 of the first operational amplifier U2 is connected to one end of the second voltage conversion resistor R3, and the other end of the second voltage conversion resistor R3 is connected to the other end of the current sampling resistor R6.
  • the output terminal 1 of the first operational amplifier U2 is connected to the base of the transistor T1, the emitter of the transistor T1 is connected to the negative input terminal 2 of the first operational amplifier U2, the collector of the transistor T1 and one end of the third voltage conversion resistor R5. Connected, the other end of the third voltage conversion resistor R5 is grounded.
  • the first voltage dividing resistor R7 is connected in series with the second voltage dividing resistor R8. One end of the first voltage dividing resistor R7 is connected to the other end of the current sampling resistor R6, and one end of the second voltage dividing resistor R8 is grounded.
  • the anode of the diode D1 is connected to one end of the third voltage converting resistor R5, and the cathode of the diode D1 is connected to the other end of the second voltage dividing resistor R8 and the feedback pin FB, respectively.
  • the power chip 21 is specifically configured to: convert the input first voltage V in into a second voltage V out , and output a second voltage V out to the current limiting circuit through the output pin VOUT.
  • the current limiting circuit is specifically configured to: detect a first current I passing through the current sampling resistor R6, convert the first current I into a third voltage Vcov through the voltage conversion resistor, the first operational amplifier U2, and the transistor T1, and pass the first partial voltage
  • the resistor R7 and the second voltage dividing resistor R8 output a first reference voltage Vth , and output a feedback voltage VFB to the feedback pin FB according to the third voltage Vcov and the first reference voltage Vth .
  • the power chip is further configured to: when the feedback voltage V FB is greater than the second reference voltage V FB — thth , lower the second voltage V out until the first current I is preset.
  • the second reference voltage V FB_th is a preset voltage inside the power chip 21 .
  • outputting the feedback voltage V FB to the feedback pin FB according to the third voltage V cov and the first reference voltage V th may include:
  • the feedback voltage is the difference between the third voltage V cov and the forward voltage V D1 of the diode D1; If the third voltage V cov is less than or equal to the sum of the first reference voltage V th and the forward conduction voltage V D1 of the diode D1, the feedback voltage is the first reference voltage V th .
  • the current limiting protection circuit 101 can also be the current limiting protection circuit shown in FIG. 3, and the current limiting protection circuit 101 can further include a second operational amplifier U2.
  • the anode of the diode D1 is connected to one end of the third voltage converting resistor R5, and the cathode of the diode D1 is respectively connected to the other end of the second voltage dividing resistor R8 and the feedback pin FB, corresponding to:
  • the positive input terminal 3 of the second operational amplifier U3 is connected to the other end of the second voltage dividing resistor R8, and the negative input terminal 2 of the second operational amplifier U3 is connected to one end of the third voltage converting resistor R5, and the second operational amplifier U3 is connected.
  • the output terminal 1 is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the negative input terminal 3 of the second operational amplifier U3 and the feedback pin FB, respectively.
  • outputting the feedback voltage to the feedback pin according to the third voltage V cov and the first reference voltage V th may include:
  • the feedback voltage is the third voltage V cov ; or, if the third voltage V cov is less than or equal to the first reference voltage V th , the feedback voltage is the first reference voltage V Th .
  • An embodiment of the present invention provides an electronic device, including a current limiting protection circuit and a power supply interface connected to the current limiting protection circuit, wherein the power supply interface is used for loading, and the electronic device supplies power to the load, wherein the current limiting protection circuit includes a power chip and a current limiting circuit electrically connected to the power chip, the power chip has an output pin and a feedback pin, and the power chip converts the input first voltage into a second voltage, and outputs a second voltage to the current limiting circuit through the output pin, The flow circuit detects the first current passing through the current sampling resistor, and outputs a feedback voltage to the feedback pin.
  • the power chip is further configured to: when the feedback voltage is greater than the second reference voltage, lower the second voltage until the first current is preset, where The second reference voltage is a preset voltage inside the power chip.
  • the power chip when the charging current is over-current, the power chip reduces the output voltage to reduce the charging current, so that the constant current output is converted to the constant current output when the charging current is over-current, thereby achieving the current limiting purpose. No additional heat is added to generate additional heat, which can be continuously externally charged, saving resources and improving charging efficiency.

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Abstract

一种限流保护电路（101）和电子设备（100），限流保护电路包括：电源芯片（21）和与电源芯片电连接的限流电路；限流电路用于：检测充电电流，向电源芯片输出反馈电压；电源芯片用于：当反馈电压大于第二参考电压时，降低输出电压直至充电电流为预设值，其中，第二参考电压为电源芯片内部的预设电压。

Description

限流保护电路和电子设备 技术领域
本发明实施例涉及电路领域，尤其涉及一种限流保护电路和电子设备。
背景技术
智能手机、平板电脑等移动手持终端携带使用方便，而且，随着移动手持终端向多功能化以及高效率化发展，用户可以随时进行视频观看、网上阅读、网上游戏、即时通信等活动，移动手持终端越来越受到用户的青睐。相比于移动手持终端的使用便利性，其电池续航时间却无法满足用户的需求，因此也应运而生了带有对外充电功能的电子产品，例如充电宝等。这些电子产品在对外充电时，为了确保设备的安全性，会对充电电流做适当的限流设置。
图1为现有技术中电流限流方案的结构示意图，如图1所示，通过在电源芯片11的后级设置一个专用的线性限流芯片12实现限流功能，具体原理为：当充电电流大于设定的电流门限时，线性增大线性限流芯片12的导通阻抗从而降低充电电流，直至充电电流等于设定的电流门限，从而实现对充电电流的限制。
但是，现有技术存在如下缺陷：增大导通阻抗即增加通路损耗，产生热量，在过流状态下容易导致对外充电设备启动热保护而关闭对外充电功能，而且造成了资源浪费、充电效率变低。
发明内容
本发明实施例提供一种限流保护电路和电子设备，当充电电流过流时由恒压输出转换为恒流输出，限制了充电电流，节省了资源，提高了充电效率。
第一方面，本发明实施例提供一种限流保护电路，包括：电源芯片和与所述电源芯片电连接的限流电路；
所述电源芯片具有输出管脚和反馈管脚；
所述限流电路包括：电流采样电阻、至少一个电压转换电阻、第一运算 放大器、三极管、第一分压电阻、第二分压电阻和一二极管；
所述输出管脚与所述电流采样电阻的一端连接；所述第一运算放大器的负向输入端与第一电压转换电阻的一端连接，所述第一电压转换电阻的另一端与所述电流采样电阻的一端连接；所述第一运算放大器的正向输入端与第二电压转换电阻的一端连接，所述第二电压转换电阻的另一端与所述电流采样电阻的另一端连接；所述第一运算放大器的输出端与所述三极管的基极连接，所述三极管的发射极与所述第一运算放大器的负向输入端连接，所述三极管的集电极与第三电压转换电阻的一端连接，所述第三电压转换电阻的另一端接地；
所述第一分压电阻与所述第二分压电阻串联，所述第一分压电阻的一端与所述电流采样电阻的另一端连接，所述第二分压电阻的一端接地；
所述二极管的正极与所述第三电压转换电阻的一端连接，所述二极管的负极分别与所述第二分压电阻的另一端和所述反馈管脚连接；
所述电源芯片具体用于：将输入的第一电压转换为第二电压，并通过所述输出管脚输出所述第二电压至所述限流电路；
所述限流电路具体用于：检测通过所述电流采样电阻的第一电流；通过所述电压转换电阻、所述第一运算放大器和所述三极管将所述第一电流转换为第三电压；通过所述第一分压电阻和所述第二分压电阻输出第一参考电压；根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压；
所述电源芯片还用于：当所述反馈电压大于第二参考电压时，降低所述第二电压直至所述第一电流为预设置；其中，所述第二参考电压为所述电源芯片内部的预设电压。
结合第一方面，在第一方面的第一种可能的实现方式中，所述限流电路还包括第二运算放大器；
所述二极管的正极与所述第三电压转换电阻的一端连接，所述二极管的负极分别与所述第二分压电阻的另一端和所述反馈管脚连接，相应为：
所述第二运算放大器的正向输入端与所述第二分压电阻的另一端连接，所述第二运算放大器的负向输入端与所述第三电压转换电阻的一端连接，所述第二运算放大器的输出端与所述二极管的正极连接，所述二极管的负极分别与所述第二运算放大器的负向输入端和所述反馈管脚连接。
结合第一方面，在第一方面的第二种可能的实现方式中，所述根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压，包括：
若所述第三电压大于所述第一参考电压与所述二极管的正向导通电压之和，则所述反馈电压为所述第三电压与所述二极管的正向导通电压的差值；或者，若所述第三电压小于等于所述第一参考电压与所述二极管的正向导通电压之和，则所述反馈电压为所述第一参考电压。
结合第一方面的第一种可能的实现方式，在第一方面的第三种可能的实现方式中，所述根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压，包括：
若所述第三电压大于所述第一参考电压，则所述反馈电压为所述第三电压；或者，若所述第三电压小于等于所述第一参考电压，则所述反馈电压为所述第一参考电压。
第二方面，本发明实施例提供一种电子设备，包括：限流保护电路和与所述限流保护电路连接的供电接口；所述供电接口用于连接负载，使所述电子设备向所述负载供电；
所述限流保护电路包括：电源芯片和与所述电源芯片电连接的限流电路；
所述电源芯片具有输出管脚和反馈管脚；
所述限流电路包括：电流采样电阻、至少一个电压转换电阻、第一运算放大器、三极管、第一分压电阻、第二分压电阻和一二极管；
所述输出管脚与所述电流采样电阻的一端连接；所述第一运算放大器的负向输入端与第一电压转换电阻的一端连接，所述第一电压转换电阻的另一端与所述电流采样电阻的一端连接；所述第一运算放大器的正向输入端与第二电压转换电阻的一端连接，所述第二电压转换电阻的另一端与所述电流采样电阻的另一端连接；所述第一运算放大器的输出端与所述三极管的基极连接，所述三极管的发射极与所述第一运算放大器的负向输入端连接，所述三极管的集电极与第三电压转换电阻的一端连接，所述第三电压转换电阻的另一端接地；
所述第一分压电阻与所述第二分压电阻串联，所述第一分压电阻的一端与所述电流采样电阻的另一端连接，所述第二分压电阻的一端接地；
所述二极管的正极与所述第三电压转换电阻的一端连接，所述二极管的 负极分别与所述第二分压电阻的另一端和所述反馈管脚连接；
所述电源芯片具体用于：将输入的第一电压转换为第二电压，并通过所述输出管脚输出所述第二电压至所述限流电路；
所述限流电路具体用于：检测通过所述电流采样电阻的第一电流；通过所述电压转换电阻、所述第一运算放大器和所述三极管将所述第一电流转换为第三电压；通过所述第一分压电阻和所述第二分压电阻输出第一参考电压；根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压；
所述电源芯片还用于：当所述反馈电压大于第二参考电压时，降低所述第二电压直至所述第一电流为预设置；其中，所述第二参考电压为所述电源芯片内部的预设电压。
结合第二方面，在第二方面的第一种可能的实现方式中，所述限流电路还包括第二运算放大器；
所述二极管的正极与所述第三电压转换电阻的一端连接，所述二极管的负极分别与所述第二分压电阻的另一端和所述反馈管脚连接，相应为：
所述第二运算放大器的正向输入端与所述第二分压电阻的另一端连接，所述第二运算放大器的负向输入端与所述第三电压转换电阻的一端连接，所述第二运算放大器的输出端与所述二极管的正极连接，所述二极管的负极分别与所述第二运算放大器的负向输入端和所述反馈管脚连接。
结合第二方面，在第二方面的第二种可能的实现方式中，所述根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压，包括：
若所述第三电压大于所述第一参考电压与所述二极管的正向导通电压之和，则所述反馈电压为所述第三电压与所述二极管的正向导通电压的差值；或者，若所述第三电压小于等于所述第一参考电压与所述二极管的正向导通电压之和，则所述反馈电压为所述第一参考电压。
结合第二方面的第一种可能的实现方式，在第二方面的第三种可能的实现方式中，所述根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压，包括：
若所述第三电压大于所述第一参考电压，则所述反馈电压为所述第三电压；或者，若所述第三电压小于等于所述第一参考电压，则所述反馈电压为所述第一参考电压。
本发明实施例提供一种限流保护电路和电子设备，限流保护电路包括：电源芯片和与电源芯片电连接的限流电路，电源芯片具有输出管脚和反馈管脚，电源芯片将输入的第一电压转换为第二电压，并通过输出管脚输出第二电压至限流电路，限流电路检测通过电流采样电阻的第一电流，向反馈管脚输出反馈电压，电源芯片还用于当反馈电压大于第二参考电压时，降低第二电压直至第一电流为预设置，其中，第二参考电压为电源芯片内部的预设电压。本发明实施例提供的限流保护电路，当充电电流过流时，电源芯片将降低输出电压从而降低充电电流，使得在充电电流过流时由恒压输出转换为恒流输出，从而达到限流目的，没有额外增加通路损耗产生额外热量，可以持续对外充电，节省了资源，提高了充电效率。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作一简单地介绍，显而易见地，下面描述中的附图是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1为现有技术中电流限流方案的结构示意图；
图2为本发明限流保护电路实施例一的结构示意图；
图3为本发明限流保护电路实施例二的结构示意图；
图4为本发明电子设备实施例一的结构示意图。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
图2为本发明限流保护电路实施例一的结构示意图，如图2所示，该限流保护电路可以包括：电源芯片21和与电源芯片21电连接的限流电路。
其中，电源芯片21具有输出管脚VOUT和反馈管脚FB。
其中，限流电路包括：电流采样电阻R6、至少一个电压转换电阻、第一运算放大器U2、三极管T1、第一分压电阻R7、第二分压电阻R8和一二极管D1。
输出管脚VOUT与电流采样电阻R6的一端连接。第一运算放大器U2的负向输入端2与第一电压转换电阻R4的一端连接，第一电压转换电阻R4的另一端与电流采样电阻R6的一端连接。第一运算放大器U2的正向输入端3与第二电压转换电阻R3的一端连接，第二电压转换电阻R3的另一端与电流采样电阻R6的另一端连接。第一运算放大器U2的输出端1与三极管T1的基极连接，三极管T1的发射极与第一运算放大器U2的负向输入端2连接，三极管T1的集电极与第三电压转换电阻R5的一端连接，第三电压转换电阻R5的另一端接地。
第一分压电阻R7与第二分压电阻R8串联，第一分压电阻R7的一端与电流采样电阻R6的另一端连接，第二分压电阻R8的一端接地。
二极管D1的正极与第三电压转换电阻R5的一端连接，二极管D1的负极分别与第二分压电阻R8的另一端和反馈管脚FB连接。
电源芯片21具体用于：将输入的第一电压Vin转换为第二电压Vout，并通过输出管脚VOUT输出第二电压Vout至限流电路。
限流电路具体用于：检测通过电流采样电阻R6的第一电流I，通过电压转换电阻、第一运算放大器U2和三极管T1将第一电流I转换为第三电压Vcov，通过第一分压电阻R7和第二分压电阻R8输出第一参考电压Vth，根据第三电压Vcov与第一参考电压Vth向反馈管脚FB输出反馈电压VFB。
电源芯片还用于：当反馈电压VFB大于第二参考电压VFB_th时，降低第二电压Vout直至第一电流I为预设置。其中，第二参考电压VFB_th为电源芯片21内部的预设电压。
本实施例提供的限流保护电路，工作原理如下：
电源芯片21可以将输入的电压转换为需要的电压恒定输出，即将输入的第一电压Vin转换为第二电压Vout通过输出管脚VOUT恒定输出。在本实施例中，电源芯片21的能量输入源为电池Vbat，电感L1和电容C1配合电源芯片21实现输入电压到输出电压的转换。需要说明的是，电源芯片21的能量输入源可以为电池，也可以是其他能量输入源，本发明对此不加以限制。
电源芯片21还可以根据反馈管脚FB接收的反馈电压VFB以及第二参考电压VFB_th来调整输出的第二电压Vout。其中，第二参考电压VFB_th为电源芯片21内部的预设电压。具体地，当反馈电压VFB小于第二参考电压VFB_th时，电源模块21将增大输出的第二电压Vout；当反馈电压VFB大于第二参考电压VFB_th时，电源模块21将降低输出的第二电压Vout；当反馈电压VFB等于第二参考电压VFB_th时，电源模块21将保持输出第二电压Vout不做调整。可见，当电源芯片21稳定工作时，反馈电压VFB将与第二参考电压VFB_th相等。
电源芯片21将第二电压Vout输入至限流电路，其中，电流采样电阻R6可以检测出通过该电阻的第一电流I，该第一电流I即为充电电流。
通过第一电压转换电阻R4、第二电压转换电阻R3、第三电压转换电阻R5、第一运算放大器U2和三极管T1将第一电流I转换为第三电压Vcov，具体地，第三电压转换电阻R5的一端的电压为第三电压Vcov。根据第一运算放大器U2虚短可知：第一电压转换电阻R4的一端的电压与第二电压转换电阻R3的一端的电压相等。根据第一运算放大器U2虚断可知：输入端没有电流，第二电压转换电阻R3的一端的电压与电流采样电阻R6的另一端的电压相等，即，第一电压转换电阻R4的一端的电压与电流采样电阻R6的另一端的电压相等，也就是说，第一电压转换电阻R4两端的电压差与电流采样电阻R6两端的电压差相等，即IR4*R4＝I*R6。根据第一运算放大器U2虚断可知：输入端没有电流，通过第一电压转换电阻R4的电流与通过第三电压转换电阻R5的电流近似相等，即IR4＝IR5。所以，通过第三电压转换电阻R5的电流为IR5＝IR4＝(I*R6)/R4，第三电压转换电阻R5的一端的电压为VR5＝IR5*R5＝(I*R6*R5)/R4，即，第三电压为Vcov＝VR5＝(I*R6*R5)/R4。其中，三极管T1用于构成运放负反馈，第二电压转换电阻R3用于补偿第一运算放大器U2输入端的偏置电流。
通过第一分压电阻R7和第二分压电阻R8输出第一参考电压Vth，具体地，第二分压电阻R8的另一端的电压为第一参考电压为Vth，第一分压电阻R7的一端的电压为Vout_1，第一分压电阻R7和第二分压电阻R8串联，所以，第二分压电阻R8的另一端的电压为VR8＝IR8*R8＝(Vout_1*R8)/(R7+R8)，即，第一参考电压为Vth＝VR8＝(Vout_1*R8)/(R7+R8)。
根据第三电压Vcov与第一参考电压Vth向反馈管脚FB输出反馈电压VFB， 具体地，二极管D1负极的电压为第一参考电压Vth，二极管D1正极的电压为第三电压Vcov，而且，二极管D1的负极与反馈管脚FB连接，向反馈管脚FB输出反馈电压VFB。当第一电流I没有过流时，第三电压Vcov将小于或等于第一参考电压Vth与二极管D1的正向导通电压VD1之和，二极管D1截止，反馈电压VFB为第一参考电压Vth，即VFB＝Vth，此时，电源芯片21将工作在稳定状态保持恒压输出，反馈电压VFB为第一参考电压Vth且与第二参考电压VFB_th相等。当第一电流I过流时，第三电压Vcov将大于第一参考电压Vth与二极管D1的正向导通电压VD1之和，二极管D1导通，反馈电压VFB为第三电压Vcov与二极管正向导通电压VD1的差值，即VFB＝Vcov-VD1，此时，反馈电压VFB将大于第二参考电压VFB_th，电源芯片21将降低第二电压Vout直至反馈电压VFB等于第二参考电压VFB_th，即VFB_th＝VFB＝Vcov-VD1＝(I*R6*R5/R4)-VD1，即I＝(VFB_th+VD1)*R4/(R5*R6)，此时电源芯片21输出恒定电流，即当电流过流时，电源芯片21由恒压输出转换为恒流输出，从而达到限流的目的。由于电源芯片21通过动态调整输出电压进行限流，当充电电流过流时通过降低输出电压从而降低充电电流，不会额外增加通路损耗产生额外热量，可以持续对外充电，节省了资源，提高了充电效率。
需要说明的是，图2所示的电源芯片、电池、电阻、电容、电感的参数只是示例，具体型号和参数可以根据电源芯片和产品需求进行调整。
需要说明的是，本发明实施例提供的限流保护电路，后端可以连接负载，用于向负载供电，负载可以为外部负载，也可以为电子设备内部的负载，本发明对此不加以限制。
本发明实施例提供了一种限流保护电路，包括电源芯片和与电源芯片电连接的限流电路，电源芯片具有输出管脚和反馈管脚，电源芯片将输入的第一电压转换为第二电压，并通过输出管脚输出第二电压至限流电路，限流电路检测通过电流采样电阻的第一电流，向反馈管脚输出反馈电压，电源芯片还用于当反馈电压大于第二参考电压时，降低第二电压直至第一电流为预设置，其中，第二参考电压为电源芯片内部的预设电压。本发明实施例提供的限流保护电路，当充电电流过流时，电源芯片将降低输出电压从而降低充电电流，使得在充电电流过流时由恒压输出转换为恒流输出，从而达到限流目的，没有额外增加通路损耗产生额外热量，可以持续对外充电，节省了资源， 提高了充电效率。
图3为本发明电流保护电路实施例二的结构示意图，本实施例在实施例一的基础上，提供了限流电路的另一种可行结构。如图3所示，该限流保护电路可以包括：电源芯片21和与电源芯片21电连接的限流电路。
其中，电源芯片21具有输出管脚VOUT和反馈管脚FB。
其中，限流电路包括：电流采样电阻R6、至少一个电压转换电阻、第一运算放大器U2、三极管T1、第一分压电阻R7、第二分压电阻R8和一二极管D1。
输出管脚VOUT与电流采样电阻R6的一端连接。第一运算放大器U2的负向输入端2与第一电压转换电阻R4的一端连接，第一电压转换电阻R4的另一端与电流采样电阻R6的一端连接。第一运算放大器U2的正向输入端3与第二电压转换电阻R3的一端连接，第二电压转换电阻R3的另一端与电流采样电阻R6的另一端连接。第一运算放大器U2的输出端1与三极管T1的基极连接，三极管T1的发射极与第一运算放大器U2的负向输入端2连接，三极管T1的集电极与第三电压转换电阻R5的一端连接，第三电压转换电阻R5的另一端接地。
第一分压电阻R7与第二分压电阻R8串联，第一分压电阻R7的一端与电流采样电阻R6的另一端连接，第二分压电阻R8的一端接地。
第二运算放大器U3的正向输入端3与第二分压电阻R8的另一端连接，第二运算放大器U3的负向输入端2与第三电压转换电阻R5的一端连接，第二运算放大器U3的输出端1与二极管D1的正极连接，二极管D1的负极分别与第二运算放大器U3的负向输入端3和反馈管脚FB连接。
本实施例中的电源芯片21以及相应元件的功能与实施例一类似，此处不再赘述。
在本实施例中，限流电路还包括第二运算放大器U3。根据第三电压Vcov与第一参考电压Vth向反馈管脚FB输出反馈电压VFB，具体地，第二运算放大器U3的正向输入端的电压为第一参考电压Vth，第二运算放大器U3的负向输入端2的电压为第三电压Vcov，而且，二极管D1的负极与反馈管脚FB连接，向反馈管脚FB输出反馈电压VFB。当第一电流I没有过流时，第三电压Vcov将小于或等于第一参考电压Vth，即，第二运算放大器U3的负向输入 端2的电压小于或等于第二运算放大器U3的正向输入端3的电压，二极管D1负极的电压VFB将跟随等于第二运算放大器U3的正向输入端3的电压，即VFB＝Vth，此时，电源芯片21将工作在稳定状态保持恒压输出，反馈电压VFB为第一参考电压Vth且与第二参考电压VFB_th相等。
当第一电流I过流时，第三电压Vcov将大于第一参考电压Vth，即，第二运算放大器U3的负向输入端2的电压大于第二运算放大器U3的正向输入端3的电压，二极管D1负极的电压VFB将跟随等于第二运算放大器U3的负向输入端2的电压，即VFB＝Vcov，此时，反馈电压VFB将大于第二参考电压VFB_th，电源芯片21将降低第二电压Vout直至反馈电压VFB等于第二参考电压VFB_th，即VFB_th＝VFB＝Vcov＝(I*R6*R5)/R4，即I＝(VFB_th*R4)/(R5*R6)，此时电源芯片21输出恒定电流，即当电流过流时，电源芯片21由恒压输出转换为恒流输出，从而达到限流的目的。由于电源芯片21通过动态调整输出电压进行限流，当充电电流过流时通过降低输出电压从而降低充电电流，不会额外增加通路损耗产生额外热量，可以持续对外充电，节省了资源，提高了充电效率。
本发明实施例提供了一种限流保护电路，包括电源芯片和与电源芯片电连接的限流电路，电源芯片具有输出管脚和反馈管脚，电源芯片将输入的第一电压转换为第二电压，并通过输出管脚输出第二电压至限流电路，限流电路检测通过电流采样电阻的第一电流，向反馈管脚输出反馈电压，电源芯片还用于当反馈电压大于第二参考电压时，降低第二电压直至第一电流为预设置，其中，第二参考电压为电源芯片内部的预设电压。本发明实施例提供的限流保护电路，当充电电流过流时，电源芯片将降低输出电压从而降低充电电流，使得在充电电流过流时由恒压输出转换为恒流输出，从而达到限流目的，没有额外增加通路损耗产生额外热量，可以持续对外充电，节省了资源，提高了充电效率。
图4为本发明电子设备实施例一的结构示意图。请同时参照图2至图4，该电子设备100可以包括限流保护电路101和与限流保护电路101连接的供电接口102，供电接口102用于连接负载200，使电子设备100向负载200供电。
其中，限流保护电路101可以是图2所示的限流保护电路，该限流保护电路101包括：电源芯片21和与电源芯片21电连接的限流电路。
其中，电源芯片21具有输出管脚VOUT和反馈管脚FB。
其中，限流电路包括：电流采样电阻R6、至少一个电压转换电阻、第一运算放大器U2、三极管T1、第一分压电阻R7、第二分压电阻R8和一二极管D1。
输出管脚VOUT与电流采样电阻R6的一端连接。第一运算放大器U2的负向输入端2与第一电压转换电阻R4的一端连接，第一电压转换电阻R4的另一端与电流采样电阻R6的一端连接。第一运算放大器U2的正向输入端3与第二电压转换电阻R3的一端连接，第二电压转换电阻R3的另一端与电流采样电阻R6的另一端连接。第一运算放大器U2的输出端1与三极管T1的基极连接，三极管T1的发射极与第一运算放大器U2的负向输入端2连接，三极管T1的集电极与第三电压转换电阻R5的一端连接，第三电压转换电阻R5的另一端接地。
第一分压电阻R7与第二分压电阻R8串联，第一分压电阻R7的一端与电流采样电阻R6的另一端连接，第二分压电阻R8的一端接地。
二极管D1的正极与第三电压转换电阻R5的一端连接，二极管D1的负极分别与第二分压电阻R8的另一端和反馈管脚FB连接。
电源芯片21具体用于：将输入的第一电压Vin转换为第二电压Vout，并通过输出管脚VOUT输出第二电压Vout至限流电路。
限流电路具体用于：检测通过电流采样电阻R6的第一电流I，通过电压转换电阻、第一运算放大器U2和三极管T1将第一电流I转换为第三电压Vcov，通过第一分压电阻R7和第二分压电阻R8输出第一参考电压Vth，根据第三电压Vcov与第一参考电压Vth向反馈管脚FB输出反馈电压VFB。
电源芯片还用于：当反馈电压VFB大于第二参考电压VFB_th时，降低第二电压Vout直至第一电流I为预设置。其中，第二参考电压VFB_th为电源芯片21内部的预设电压。
可选的，根据第三电压Vcov与第一参考电压Vth向反馈管脚FB输出反馈电压VFB，可以包括：
若第三电压Vcov大于第一参考电压Vth与二极管D1的正向导通电压VD1之和，则反馈电压为第三电压Vcov与二极管D1的正向导通电压VD1的差值；或者，若第三电压Vcov小于等于第一参考电压Vth与二极管D1的正向导通电 压VD1之和，则反馈电压为第一参考电压Vth。
可选的，限流保护电路101还可以是图3所示的限流保护电路，该限流保护电路101还可以包括第二运算放大器U2。
二极管D1的正极与第三电压转换电阻R5的一端连接，二极管D1的负极分别与第二分压电阻R8的另一端和反馈管脚FB连接，相应为：
第二运算放大器U3的正向输入端3与第二分压电阻R8的另一端连接，第二运算放大器U3的负向输入端2与第三电压转换电阻R5的一端连接，第二运算放大器U3的输出端1与二极管D1的正极连接，二极管D1的负极分别与第二运算放大器U3的负向输入端3和反馈管脚FB连接。
可选的，根据第三电压Vcov与第一参考电压Vth向反馈管脚输出反馈电压，可以包括：
若第三电压Vcov大于第一参考电压Vth，则反馈电压为第三电压Vcov；或者，若第三电压Vcov小于等于第一参考电压Vth，则反馈电压为第一参考电压Vth。
其中，限流保护电路101的具体工作原理和技术效果与前述实施例类似，此处不再赘述。
本发明实施例提供了一种电子设备，包括限流保护电路和与限流保护电路连接的供电接口，供电接口用于负载，使电子设备向负载供电，其中，限流保护电路包括电源芯片和与电源芯片电连接的限流电路，电源芯片具有输出管脚和反馈管脚，电源芯片将输入的第一电压转换为第二电压，并通过输出管脚输出第二电压至限流电路，限流电路检测通过电流采样电阻的第一电流，向反馈管脚输出反馈电压，电源芯片还用于当反馈电压大于第二参考电压时，降低第二电压直至第一电流为预设置，其中，第二参考电压为电源芯片内部的预设电压。本发明实施例提供的电子设备，当充电电流过流时，电源芯片将降低输出电压从而降低充电电流，使得在充电电流过流时由恒压输出转换为恒流输出，从而达到限流目的，没有额外增加通路损耗产生额外热量，可以持续对外充电，节省了资源，提高了充电效率。
最后应说明的是：以上各实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述各实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改， 或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的范围。

Claims (8)

  1. 一种限流保护电路，其特征在于，包括：电源芯片和与所述电源芯片电连接的限流电路；所述电源芯片具有输出管脚和反馈管脚；
    所述限流电路包括：电流采样电阻、至少一个电压转换电阻、第一运算放大器、三极管、第一分压电阻、第二分压电阻和一二极管；
    所述输出管脚与所述电流采样电阻的一端连接；所述第一运算放大器的负向输入端与第一电压转换电阻的一端连接，所述第一电压转换电阻的另一端与所述电流采样电阻的一端连接；所述第一运算放大器的正向输入端与第二电压转换电阻的一端连接，所述第二电压转换电阻的另一端与所述电流采样电阻的另一端连接；所述第一运算放大器的输出端与所述三极管的基极连接，所述三极管的发射极与所述第一运算放大器的负向输入端连接，所述三极管的集电极与第三电压转换电阻的一端连接，所述第三电压转换电阻的另一端接地；
    所述第一分压电阻与所述第二分压电阻串联，所述第一分压电阻的一端与所述电流采样电阻的另一端连接，所述第二分压电阻的一端接地；
    所述二极管的正极与所述第三电压转换电阻的一端连接，所述二极管的负极分别与所述第二分压电阻的另一端和所述反馈管脚连接；
    所述电源芯片具体用于：将输入的第一电压转换为第二电压，并通过所述输出管脚输出所述第二电压至所述限流电路；
    所述限流电路具体用于：检测通过所述电流采样电阻的第一电流；通过所述电压转换电阻、所述第一运算放大器和所述三极管将所述第一电流转换为第三电压；通过所述第一分压电阻和所述第二分压电阻输出第一参考电压；根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压；
    所述电源芯片还用于：当所述反馈电压大于第二参考电压时，降低所述第二电压直至所述第一电流为预设置；其中，所述第二参考电压为所述电源芯片内部的预设电压。
  2. 根据权利要求1所述的限流保护电路，其特征在于，所述限流电路还包括第二运算放大器；
    所述二极管的正极与所述第三电压转换电阻的一端连接，所述二极管的负极分别与所述第二分压电阻的另一端和所述反馈管脚连接，相应为：
    所述第二运算放大器的正向输入端与所述第二分压电阻的另一端连接，所述第二运算放大器的负向输入端与所述第三电压转换电阻的一端连接，所述第二运算放大器的输出端与所述二极管的正极连接，所述二极管的负极分别与所述第二运算放大器的负向输入端和所述反馈管脚连接。
  3. 根据权利要求1所述的限流保护电路，其特征在于，所述根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压，包括：
    若所述第三电压大于所述第一参考电压与所述二极管的正向导通电压之和，则所述反馈电压为所述第三电压与所述二极管的正向导通电压的差值；或者，若所述第三电压小于等于所述第一参考电压与所述二极管的正向导通电压之和，则所述反馈电压为所述第一参考电压。
  4. 根据权利要求2所述的限流保护电路，其特征在于，所述根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压，包括：
    若所述第三电压大于所述第一参考电压，则所述反馈电压为所述第三电压；或者，若所述第三电压小于等于所述第一参考电压，则所述反馈电压为所述第一参考电压。
  5. 一种电子设备，其特征在于，包括：限流保护电路和与所述限流保护电路连接的供电接口；所述供电接口用于连接负载，使所述电子设备向所述负载供电；
    所述限流保护电路包括：电源芯片和与所述电源芯片电连接的限流电路；
    所述电源芯片具有输出管脚和反馈管脚；
    所述限流电路包括：电流采样电阻、至少一个电压转换电阻、第一运算放大器、三极管、第一分压电阻、第二分压电阻和一二极管；
    所述输出管脚与所述电流采样电阻的一端连接；所述第一运算放大器的负向输入端与第一电压转换电阻的一端连接，所述第一电压转换电阻的另一端与所述电流采样电阻的一端连接；所述第一运算放大器的正向输入端与第二电压转换电阻的一端连接，所述第二电压转换电阻的另一端与所述电流采样电阻的另一端连接；所述第一运算放大器的输出端与所述三极管的基极连接，所述三极管的发射极与所述第一运算放大器的负向输入端连接，所述三极管的集电极与第三电压转换电阻的一端连接，所述第三电压转换电阻的另一端接地；
    所述第一分压电阻与所述第二分压电阻串联，所述第一分压电阻的一端与所述电流采样电阻的另一端连接，所述第二分压电阻的一端接地；
    所述二极管的正极与所述第三电压转换电阻的一端连接，所述二极管的负极分别与所述第二分压电阻的另一端和所述反馈管脚连接；
    所述电源芯片具体用于：将输入的第一电压转换为第二电压，并通过所述输出管脚输出所述第二电压至所述限流电路；
    所述限流电路具体用于：检测通过所述电流采样电阻的第一电流；通过所述电压转换电阻、所述第一运算放大器和所述三极管将所述第一电流转换为第三电压；通过所述第一分压电阻和所述第二分压电阻输出第一参考电压；根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压；
    所述电源芯片还用于：当所述反馈电压大于第二参考电压时，降低所述第二电压直至所述第一电流为预设置；其中，所述第二参考电压为所述电源芯片内部的预设电压。
  6. 根据权利要求5所述的电子设备，其特征在于，所述限流电路还包括第二运算放大器；
    所述二极管的正极与所述第三电压转换电阻的一端连接，所述二极管的负极分别与所述第二分压电阻的另一端和所述反馈管脚连接，相应为：
    所述第二运算放大器的正向输入端与所述第二分压电阻的另一端连接，所述第二运算放大器的负向输入端与所述第三电压转换电阻的一端连接，所述第二运算放大器的输出端与所述二极管的正极连接，所述二极管的负极分别与所述第二运算放大器的负向输入端和所述反馈管脚连接。
  7. 根据权利要求5所述的电子设备，其特征在于，所述根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压，包括：
    若所述第三电压大于所述第一参考电压与所述二极管的正向导通电压之和，则所述反馈电压为所述第三电压与所述二极管的正向导通电压的差值；或者，若所述第三电压小于等于所述第一参考电压与所述二极管的正向导通电压之和，则所述反馈电压为所述第一参考电压。
  8. 根据权利要求6所述的电子设备，其特征在于，所述根据所述第三电压与所述第一参考电压向所述反馈管脚输出所述反馈电压，包括：
    若所述第三电压大于所述第一参考电压，则所述反馈电压为所述第三电 压；或者，若所述第三电压小于等于所述第一参考电压，则所述反馈电压为所述第一参考电压。
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