WO2022056923A1 - 恒流源采样电路和方法 - Google Patents

恒流源采样电路和方法 Download PDF

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Publication number
WO2022056923A1
WO2022056923A1 PCT/CN2020/116560 CN2020116560W WO2022056923A1 WO 2022056923 A1 WO2022056923 A1 WO 2022056923A1 CN 2020116560 W CN2020116560 W CN 2020116560W WO 2022056923 A1 WO2022056923 A1 WO 2022056923A1
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Prior art keywords
constant current
current source
module
resistor
terminal
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PCT/CN2020/116560
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English (en)
French (fr)
Inventor
赵龙武
赵德琦
吴壬华
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深圳欣锐科技股份有限公司
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Priority to CN202080008209.6A priority Critical patent/CN113272663B/zh
Priority to PCT/CN2020/116560 priority patent/WO2022056923A1/zh
Publication of WO2022056923A1 publication Critical patent/WO2022056923A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/14—Measuring resistance by measuring current or voltage obtained from a reference source
    • 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
    • G05F1/561—Voltage to current converters

Definitions

  • the present application relates to the field of electronic technology, in particular to a constant current source sampling circuit and method.
  • a constant current source circuit is a current source circuit in which the output current is kept constant.
  • the constant current source sampling circuit converts the resistance value of the resistance to be measured into a voltage value through a fixed constant current source, and then collects the voltage signal and converts the voltage signal into a digital signal through a single-chip microcomputer.
  • the reference voltage of the sampling range of the analog-to-digital converter of the single-chip microcomputer is generally 2.5V, and the resistance value of the resistance to be measured varies widely.
  • the existing constant current source sampling circuit when the resistance value of the resistance to be measured is small, the output voltage signal is weak and easily disturbed, and cannot meet the sampling accuracy requirements of the single-chip microcomputer; when the resistance value of the resistance to be measured is large, the output voltage signal is weak. The voltage signal exceeds the range limit of the single-chip microcomputer, the existing constant current source sampling circuit cannot guarantee the sampling accuracy and the sampling range, and the sampling efficiency is low.
  • the present application provides a constant current source sampling circuit and method, which can make the constant current source sampling circuit switch the current value of the constant current source through the control module, so as to satisfy the range and accuracy of the single-chip microcomputer. requirements to improve the sampling efficiency.
  • a constant current source sampling circuit which is applied to resistance sampling, wherein the constant current source sampling circuit includes: a constant current source circuit, a resistor to be sampled, a micro-control unit, a power supply and sampling voltage output;
  • the first end of the constant current source circuit is connected to the positive pole of the power supply; the second end of the constant current source circuit is connected to the first end of the resistor to be sampled and the output end of the sampled voltage; the The second end of the sampling resistor is connected to the negative pole of the power supply and the third end of the constant current source circuit; one end of the micro-control unit is connected to the sampling voltage output end, and the other end is connected to the constant current source circuit. The fourth end is connected.
  • the constant current source circuit includes: a first constant current source module, a second constant current source module and a control module;
  • the positive pole of the power supply is connected to the first end of the first constant current source module and the first end of the control module; the second end of the control module is connected to the first end of the second constant current source module; The third end of the control module is connected to the negative electrode of the power supply and the second end of the resistor to be sampled; the fourth end of the control module is connected to the micro-control unit; the first end of the second constant current source module The two terminals, the third terminal of the second constant current source module and the fourth terminal of the second constant current source module correspond to the corresponding second terminal of the first constant current source module, the first constant current source module The third end of the current source module and the fourth end of the first constant current source module are connected; the fifth end of the first constant current source module is connected to the fifth end of the second constant current source module and the The sampling voltage output terminal is connected;
  • the first constant current source module includes a load submodule, a constant current source submodule, and a bias voltage submodule;
  • the positive pole of the power supply is connected to the first end of the load sub-module and the first end of the bias voltage sub-module; the second end of the load sub-module and the second end of the second constant current source module connecting the first end of the constant current source sub-module; the second end of the bias voltage sub-module is connected to the second end of the constant current source sub-module and the third end of the second constant current source module; The third end of the constant current source sub-module is connected to the fourth end of the second constant current source module; the fourth end of the constant current source sub-module is connected to the fifth end of the second constant current source module and the sampling voltage output terminal.
  • the constant current source sub-module includes: a first transistor and a first resistor;
  • the second end of the load sub-module and the second end of the second constant current source module are connected to the collector end of the first triode; the second end of the bias voltage sub-module is connected to the second end of the first transistor.
  • the third terminal of the two constant current source modules is connected to the base terminal of the first transistor; the emitter terminal of the first transistor is connected to the first terminal of the first resistor and the second constant current source module.
  • the fourth end of the first resistor; the second end of the first resistor is connected to the fifth end of the second constant current source module and the sampling voltage output end;
  • the bias voltage sub-module provides a bias voltage for the base of the first triode;
  • the load sub-module is the load resistance of the first triode;
  • the first constant current source module is used to control the first transistor to be in an amplification state, so that the current output by the emitter terminal of the first transistor is the output of the fifth terminal of the first constant current source module the current.
  • the load sub-module includes a second resistor and a second transistor
  • the positive electrode of the power supply is connected to the first end of the second resistor; the second end of the second resistor is connected to the emitter end of the second triode; the collector end of the second triode is suspended; The base terminal of the second triode and the second end of the second constant current source module are connected to the collector terminal of the first triode;
  • the second constant current source module includes a third resistor, a third transistor and a controllable precision voltage regulator;
  • the second end of the control module is connected to the first end of the third resistor; the second end of the third resistor is connected to the emitter end of the third triode; the base end of the third triode The base terminal of the second triode is connected to the collector terminal of the first triode; the collector terminal of the third triode is connected to the base terminal of the first triode and the cathode terminal of the controllable precision voltage regulator source; the reference terminal of the controllable precision voltage regulator source is connected to the emitter terminal of the first triode and the first terminal of the first resistor; the anode terminal of the controllable precision voltage regulator source The terminal is connected to the second end of the first resistor and the sampling voltage output end.
  • the first constant current The current output by the fifth terminal of the source module is the same as the current output by the fifth terminal of the second constant current source module.
  • the bias voltage sub-module includes a fourth resistor and a first capacitor connected in parallel;
  • the positive pole of the power supply is connected to the first end of the fourth resistor and the first end of the first capacitor; the second end of the fourth resistor and the second end of the first capacitor are connected to the first The base terminal of the triode, the collector terminal of the third triode, and the cathode terminal of the controllable precision voltage-stabilizing source;
  • the fourth resistor provides a bias voltage for the base of the first triode; the first capacitor provides a forward bias voltage for the base of the first triode when the circuit is turned on.
  • control module includes: a first switch tube, a second switch tube, a fifth resistor, a sixth resistor and a second capacitor;
  • the positive pole of the power supply is connected to the first end of the first switch tube, the first end of the fifth resistor and the first end of the second capacitor; the second end of the first switch tube is connected to the The first end of the second constant current source module; the third end of the first switch tube is connected to the second end of the fifth resistor, the second end of the second capacitor and the first end of the sixth resistor The second end of the sixth resistor is connected to the first end of the second switch tube; the second end of the second switch tube is connected to the negative electrode of the power supply and the second end of the resistor to be sampled; The third end of the second switch tube is connected to the micro-control unit;
  • the micro-control unit When the micro-control unit outputs the first voltage to the third end of the second switch tube, the first switch tube and the second switch tube are turned on, and the control module is in a connected state; when the When the micro-control unit outputs the second voltage or no voltage to the third end of the second switch tube, the first switch tube and the second switch tube are turned off, and the control module is in an off state.
  • the first switch tube includes any one of a relay, a triode, and a metal oxide semiconductor field effect MOS tube
  • the second switch tube includes any one of a relay, a triode, and a MOS tube.
  • a second aspect of the embodiments of the present application provides a constant current source sampling method, which is applied to the above constant current source sampling circuit, and the method may include:
  • the micro-control unit measures the initial resistance value of the resistor to be sampled, and determines the target resistance value range in which the initial resistance value falls;
  • the micro-control unit determines a target constant current value corresponding to the target resistance value interval according to the corresponding relationship between the resistance value interval set and the constant current value set;
  • the micro-control unit controls the second end of the constant current source circuit to output a constant current corresponding to the target constant current value, so as to measure the final resistance value of the resistor to be sampled.
  • the resistance value interval set includes a first resistance value interval and a second resistance value interval
  • the constant current value set includes a first constant current value and a second constant current value
  • the first resistance value The interval corresponds to the first constant current value
  • the second resistance interval corresponds to the second constant current value
  • the micro-control unit controls the second end of the constant current source circuit to output a constant current corresponding to the target constant current value, so as to measure the final resistance value of the resistor to be sampled, including: when When the target resistance value interval is the first resistance value interval, the micro-control unit controls the second end of the constant current source circuit to output a constant current corresponding to the first constant current value to measure the The final resistance value of the resistor to be sampled; when the target resistance value interval is the second resistance value interval, the micro-control unit controls the output of the second end of the constant current source circuit and the second constant current value corresponding constant current to measure the final resistance value of the resistance to be sampled.
  • the micro-control unit determines the constant current value output by the constant current source circuit by detecting the initial resistance value of the resistance to be sampled, and the voltage at the output terminal of the sampling voltage is the constant current value and the sampling resistance.
  • the sampling voltage meets the requirements of the sampling range and sampling accuracy of the micro-control unit, which improves the sampling efficiency of the constant current source sampling circuit.
  • 1 is a schematic structural diagram of a constant current source sampling circuit in an embodiment of the application
  • FIG. 2 is a schematic diagram of a specific structure of a constant current source sampling circuit in an embodiment of the application
  • FIG. 3 is a schematic diagram of a specific structure of another constant current source sampling circuit in an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a specific structure of another constant current source sampling circuit in an embodiment of the application.
  • FIG. 5 is a schematic flowchart of a method for sampling a constant current source according to an embodiment of the present application.
  • FIG. 1 is a schematic structural diagram of a constant current source sampling circuit according to an embodiment of the present application.
  • the present application provides a constant current source sampling circuit, including a constant current source circuit 210, a power supply 220, a resistance to be sampled 230, a sampling voltage output terminal (represented by Vout in FIG. 1), and a microcontroller unit (MCU).
  • a constant current source sampling circuit including a constant current source circuit 210, a power supply 220, a resistance to be sampled 230, a sampling voltage output terminal (represented by Vout in FIG. 1), and a microcontroller unit (MCU).
  • MCU microcontroller unit
  • the first terminal 211 of the constant current source circuit 210 is connected to the positive pole of the power supply 220, the second terminal 212 of the constant current source circuit 210 is connected to the first terminal 231 of the resistor 230 to be sampled and the sampling voltage output terminal Vout Connected, the second end 232 of the resistance to be sampled 230 is connected to the negative electrode of the power supply 220 and the third end 213 of the constant current source circuit 210, one end of the micro-control unit MCU is connected to the output end Vout of the sampled voltage, the micro The other end of the control unit MCU is connected to the fourth end 214 of the above-mentioned constant current source circuit 210 .
  • the resistance to be sampled 230 is a connection confirmation function (CC) resistance Rcc
  • the constant current source circuit 210 is applied to the electric vehicle conduction charging system
  • the connection confirmation function of the electric vehicle conduction charging system is performed by
  • the charging gun is connected to resistors Rcc with different resistance values to realize the judgment of the connection status of the vehicle interface and the capacity of the charging cable of the charging pile.
  • the above-mentioned micro-control unit MCU is used to measure the initial resistance value of the resistor 230 to be sampled under the condition that the second terminal 212 of the above-mentioned constant current source circuit 210 outputs the initial constant current value, and determine the target resistance value range in which the initial resistance value falls. , and determine the target constant current value corresponding to the above target resistance value interval according to the corresponding relationship between the resistance value interval set and the constant current value set, and control the second terminal 212 of the constant current source circuit 210 to re-output the target constant current value corresponding to the above target constant current value corresponding constant current to measure the final resistance value of the resistance 230 to be sampled.
  • the above-mentioned constant current source circuit 210 includes a plurality of parallel constant current source modules, each constant current source module is controlled by the control module corresponding to the constant current source module to work or not, and the control module of each constant current source module is controlled by the control module.
  • the above-mentioned micro-control unit MCU controls, when any of the above-mentioned constant-current source modules work, the constant-current source module in the working state outputs a constant current, and the current output by the constant-current source circuit 210 is the output current of the multiple constant-current source modules in the working state Sum.
  • the micro control unit MCU determines the constant current value of the constant current source circuit by detecting the initial resistance value of the resistor 230 to be sampled, and the voltage of the sampling voltage output terminal Vout is the product of the constant current value and the resistance value of the resistor 230 to be sampled , so that the resistances 230 to be sampled in different resistance value intervals correspond to different constant current values, so that the sampling voltage meets the sampling range and sampling accuracy requirements of the microcontroller unit MCU, and the sampling efficiency of the constant current source sampling circuit is improved.
  • the above-mentioned resistance value interval set includes a first resistance value interval and a second resistance value interval
  • the above-mentioned constant current value set includes a first constant current value and a second constant current value
  • the above-mentioned first resistance value interval is the same as the above-mentioned The first constant current value corresponds
  • the second resistance value interval corresponds to the second constant current value.
  • the microcontroller MCU controls the second terminal 212 of the constant current source circuit 210 to output a constant current corresponding to the first constant current value, so as to measure the above The final resistance value of the resistor 230 to be sampled.
  • the microcontroller MCU controls the second terminal 212 of the constant current source circuit 210 to output a constant current corresponding to the second constant current value, so as to measure the above The final resistance value of the resistor 230 to be sampled.
  • the constant current source circuit 210 shown in FIG. 2 includes a first constant current source module 310 , a second constant current source module 330 and a control module 320 .
  • the positive pole of the power supply 220 is connected to the first end 311 of the first constant current source module 310 and the first end 321 of the control module 320 , and the second end 322 of the control module 320 is connected to the first end of the second constant current source module 330 .
  • Terminal 331 the third terminal 323 of the control module 320 is connected to the negative pole of the power supply 220 and the second terminal 232 of the resistor 230 to be sampled
  • the fourth terminal 324 of the control module 320 is connected to the micro-control unit MCU
  • the second constant current source The second end 332 , the third end 333 and the fourth end 334 of the module 330 are respectively connected to the second end 312 , the third end 313 and the fourth end 314 of the first constant current source module 310 .
  • the fifth terminal 315 of the module 310 is connected to the fifth terminal 335 of the second constant current source module 330 and the sampling voltage output terminal Vout.
  • the above-mentioned control module 320 is used to control whether the above-mentioned second constant current source module 330 works.
  • the micro control unit MCU controls the control module 320 to be in a connected state, so that the fifth terminal 315 of the first constant current source module 310 outputs a constant current corresponding to the second constant current value , the fifth terminal 335 of the second constant current source module 330 outputs a constant current corresponding to a third constant current value, and the first constant current value is equal to the sum of the second constant current value and the third constant current value.
  • the micro-control unit MCU controls the control module 320 to be in an off state, so that the fifth terminal 315 of the first constant current source module 310 outputs a constant current corresponding to the second constant current value, Since the control module 320 is in an off state, the second constant current source module 330 is in an open state, and at this time, the second constant current source module 330 has no current output.
  • the above-mentioned constant current source circuit 210 may further include a first control module, the first control module is located between the first constant current source module 310 and the power supply 220 , and the first control module is used to control the first control module. An on-off state of the constant current source module 310 .
  • the second terminal 212 of the constant current source circuit 210 When the micro control unit MCU controls the first control module to be in the connected state and the control module 320 is in the disconnected state, the second terminal 212 of the constant current source circuit 210 outputs a constant current corresponding to the second constant current value; When a control module is in the connected state and the control module 320 is in the connected state, the second terminal 212 of the constant current source circuit 210 outputs a constant current corresponding to the first constant current value.
  • the first constant current source module 310 includes a load sub-module 410 , a constant current source sub-module 430 and a bias voltage sub-module 420 .
  • the positive pole of the power supply 220 is connected to the first terminal 411 of the load sub-module 410 and the first terminal 421 of the bias voltage sub-module 420 .
  • the second end 332 of the second constant current source module 330 is connected to the first end 431 of the constant current source sub-module 430 .
  • the second end 422 of the bias voltage sub-module 420 is connected to the second end 432 of the constant current source sub-module 430 and the third end 333 of the second constant current source module 330, and the third end 433 of the constant current source sub-module 430 is connected to the third end 433 of the constant current source sub-module 430.
  • the fourth terminal 334 of the two constant current source modules 330 and the fourth terminal 434 of the constant current source sub-module 430 are connected to the fifth terminal 335 of the second constant current source module 330 and the sampling voltage output terminal Vout.
  • the constant current source sub-module 430 includes: a first transistor Q1 and a first resistor R1 .
  • the second end of the load sub-module 410 and the second end of the second constant current source module 330 are connected to the collector end of the first transistor Q1, and the second end of the bias voltage sub-module 420 is connected to the second end of the second transistor Q1.
  • the third terminal of the constant current source module 330 is connected to the base terminal of the first transistor Q1, and the emitter terminal of the first transistor Q1 is connected to the first terminal of the first resistor R1 and the second constant current source module 330.
  • the fourth end of the first resistor R1 is connected to the fifth end of the second constant current source module 330 and the sampling voltage output end Vout.
  • the bias voltage sub-module 420 provides a bias voltage for the base of the first transistor Q1, and the load sub-module 410 is the load resistance of the first transistor Q1.
  • the first constant current source module 310 is used to control the first transistor Q1 to be in an amplifying state, so that the current output by the emitter terminal of the first transistor Q1 is the output of the fifth terminal of the first constant current source module 310 the current.
  • the above-mentioned load sub-module 410 includes a second resistor R2 and a second transistor Q2.
  • the positive pole of the power supply 220 is connected to the first end of the second resistor R2, the second end of the second resistor R2 is connected to the emitter terminal of the second transistor Q2, and the collector terminal of the second transistor Q2 is suspended.
  • the base terminal of the second transistor Q2 is connected to the second terminal of the second constant current source module 330 and the collector terminal of the first transistor Q1.
  • the above-mentioned second constant current source module 330 includes a third resistor R3, a third transistor Q3, and a controllable precision voltage regulator source U1.
  • the second end of the control module 320 is connected to the first end of the third resistor R3, the second end of the third resistor R3 is connected to the emitter terminal of the third transistor Q3, and the base terminal of the third transistor Q3
  • the base terminal of the above-mentioned second transistor Q2 is connected to the collector terminal of the above-mentioned first transistor Q1
  • the collector terminal of the above-mentioned third transistor Q3 is connected to the base terminal of the above-mentioned first transistor Q1 and the above-mentioned controllable terminal.
  • the cathode terminal of the precision voltage regulator source U1 is connected to the emitter terminal of the first transistor Q1 and the first terminal of the above-mentioned first resistor R1, and the The anode terminal is connected to the second terminal of the first resistor R1 and the sampling voltage output terminal Vout.
  • the first constant current source module 310 When the resistance values of the second resistor R2 and the third resistor R3 are equal, and the models of the second transistor Q2 and the third transistor Q3 are the same, the first constant current source module 310
  • the current output by the fifth terminal 315 of the above-mentioned second constant current source module 330 is the same as the current output by the fifth terminal 335 of the second constant current source module 330 .
  • the bias voltage sub-module 420 includes a fourth resistor R4 and a first capacitor C1 connected in parallel.
  • the positive pole of the power supply 220 is connected to the first end of the fourth resistor R4 and the first end of the first capacitor C1; the second end of the fourth resistor R4 and the second end of the first capacitor C1 are connected to the first three The base terminal of the transistor Q1, the collector terminal of the third transistor Q3, and the cathode terminal of the controllable precision voltage-stabilizing source U1.
  • the fourth resistor R4 provides a bias voltage for the base of the first transistor Q1, and the first capacitor C1 is the base of the first transistor Q1 when the first constant current source module 310 is turned on Provides a forward bias voltage.
  • the above-mentioned control module 320 includes: a first switch transistor Q4 , a second switch transistor Q5 , a fifth resistor R5 , a sixth resistor R6 , and a second capacitor C2 .
  • the positive pole of the power supply 220 is connected to the first end of the first switch tube Q4, the first end of the fifth resistor R5 and the first end of the second capacitor C2, and the second end of the first switch tube Q4 is connected to the first end of the first switch tube Q4.
  • the first end of the three resistors R3, the third end of the first switch tube Q4 are connected to the second end of the fifth resistor R5, the second end of the second capacitor C2 and the first end of the sixth resistor R6, the above The second end of the sixth resistor R6 is connected to the first end of the second switch tube Q5, the second end of the second switch tube Q5 is connected to the negative electrode of the power supply 220 and the second end of the to-be-sampling resistor Rcc, the second The third end of the switch tube Q5 is connected to the above-mentioned micro-control unit MCU (not shown in FIG. 4 ).
  • the micro control unit MCU When the micro control unit MCU outputs the first voltage to the third terminal of the second switch transistor Q5, the first switch transistor Q4 and the second switch transistor Q5 are turned on, and the control module 320 is in a connected state.
  • the micro-control unit MCU When the micro-control unit MCU outputs the second voltage or no voltage to the third terminal of the second switch tube Q5, the first switch tube Q4 and the second switch tube Q5 are turned off, and the control module 320 is in an off state .
  • the first voltage is greater than or equal to the turn-on voltage of the second switch transistor Q5, and the second voltage is less than the turn-on voltage of the second switch tube Q5.
  • the first switch transistor Q4 includes any one of a relay, a transistor, and a metal oxide semiconductor field effect MOS transistor
  • the second switch transistor Q5 includes any one of a relay, a transistor, and a MOS transistor.
  • the first switch transistor Q4 is a PMOS transistor
  • the second switch transistor Q5 is an NMOS transistor.
  • the above-mentioned power supply is connected in parallel with the third capacitor C3, and the third capacitor C3 filters the power supply.
  • the first constant current source module 310 is a constant current source module that takes the emitter current of the first transistor Q1 as the output current. When the first transistor Q1 is in an amplifying state, the current at the emitter of the first transistor Q1 is: The output current of the first constant current source module.
  • the second resistor R2 and the second transistor Q2 form the load sub-module 410 of the collector of the first transistor Q1, and provide the collector voltage for the collector of the first transistor Q1; the fourth resistor R4 and the first capacitor C1
  • the bias voltage sub-module forming the base of the first triode Q1 provides the base bias voltage for the base of the first triode Q1.
  • the reference electrode of the controllable precision voltage stabilizing source U1 in the second constant current source module 330 is connected to the emitter terminal of the first transistor Q1 to provide a stable voltage U1 to the emitter terminal of the first transistor Q1;
  • the cathode terminal of the voltage regulator source U1 is connected to the base electrode of the first transistor Q1, so that the voltage of the reference terminal in the controllable precision voltage regulator source U1 controls the voltage of the base terminal of the first transistor Q1 through negative feedback, so that the The first transistor Q1 works in an amplified state, and when the base current of the first transistor Q1 is much smaller than the collector current of the first transistor Q1, the current at the collector terminal of the first transistor Q1 is equal to the first transistor Q1.
  • Transistor Q1 emits extreme current.
  • the BE junction of the third resistor R3 and the third transistor Q3 in the second constant current source module 330 is connected in parallel with the second resistor R2 and the BE junction of the second transistor Q2 in the load sub-module 410, and the BE junction represents the base of the triode The part from pole B to emitter E.
  • the BE junction voltage drops of Q2 and Q3 are the same, and the voltages across the second resistor R2 and the third resistor R3 are the same. If the resistances of R2 and R3 If the value is the same, the current at the emitter of Q2 is the same as the current at the emitter of Q3.
  • the current at the collector terminal of the third transistor Q3 is equal to the current at the collector terminal of the first transistor, because the current at the collector terminal of the first transistor Q1 is equal to the current at the emitter terminal of the first transistor Q1, so at R2
  • the resistance value of R3 is the same and the models of Q2 and Q3 are the same, the current output by the fifth terminal 315 of the first constant current source module 310 is the same as the current output by the fifth terminal 335 of the second constant current source module 330 .
  • the control module 320 is composed of a PMOS transistor Q4, a fifth resistor R5, a second capacitor C2, a sixth resistor R6 and an NMOS transistor Q5.
  • PMOS tubes are used to control the opening and closing of the circuit in the circuit.
  • the maximum voltage that the microcontroller MCU can output is 3.3V.
  • the on-off of the NMOS transistor Q5 is controlled by the micro-control unit MCU, so as to control the on-off of the Q4.
  • a constant current source sampling circuit Compared with the existing constant current source sampling circuit, a constant current source sampling circuit provided by the embodiment of the present application includes a constant current source circuit, a resistor to be sampled, a micro control unit MCU, a power supply and a sampling voltage output terminal, wherein the micro The control unit MCU determines the constant current value output by the constant current source circuit by detecting the initial resistance value of the resistance to be sampled, and the voltage at the output terminal of the sampling voltage is the product of the constant current value and the sampling resistance value, so that the resistances to be sampled in different resistance value intervals correspond to Different constant current values and sampling voltages meet the requirements of the sampling range and sampling accuracy of the MCU, which improves the sampling efficiency of the constant current source sampling circuit.
  • an embodiment of the present application further provides a constant current source sampling method.
  • the method is applied to the constant current source sampling circuit shown in FIG. 1 , FIG. 2 , FIG. 3 or FIG. 4 .
  • the method may include: :
  • the micro-control unit measures the initial resistance value of the resistor to be sampled, and determines the target resistance value range in which the initial resistance value falls.
  • the micro-control unit determines a target constant current value corresponding to the target resistance value interval according to the corresponding relationship between the resistance value interval set and the constant current value set.
  • the set of resistance value intervals includes a first resistance value interval and a second resistance value interval
  • the set of constant current values includes a first constant current value and a second constant current value
  • the first resistance value interval corresponds to the first constant current value
  • the second resistance value interval corresponds to the second constant current value
  • the micro-control unit controls the second end of the constant current source circuit to output a constant current corresponding to the target constant current value, so as to measure the final resistance value of the resistor to be sampled.
  • the resistance interval set includes a first resistance value interval and a second resistance value interval
  • the constant current value set includes a first constant current value and a second constant current value
  • the first resistance value interval and the first constant current value When the second resistance value interval corresponds to the second constant current value.
  • the micro-control unit controls the second end of the constant current source circuit to output a constant current corresponding to the target constant current value to measure the final resistance value of the resistor to be sampled, specifically: when the target resistance value interval is the first In a resistance value interval, the micro-control unit controls the second end of the constant current source circuit to output a constant current corresponding to the first constant current value to measure the final resistance value of the resistor to be sampled. When the target resistance value interval is the second resistance value interval, the micro-control unit controls the second end of the constant current source circuit to output a constant current corresponding to the second constant current value to measure the final resistance value of the resistor to be sampled.

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Abstract

一种恒流源采样电路、方法，该恒流源采样电路包括：恒流源电路（210）、待采样电阻（230）、微控制单元（MCU）、电源（220）以及采样电压输出端（Vout），恒流源电路（210）的第一端（211）与电源（220）的正极相连，待采样电阻（230）的第一端（231）与恒流源电路（210）的第二端（212）以及采样电压输出端（Vout）相连，电源（220）的负极连接待采样电阻（230）的第二端（232）和恒流源电路（210）的第三端（213），恒流源电路（210）的第四端（214）连接微控制单元（MCU）；采样电压输出端（Vout）连接至微控制单元（MCU）。微控制单元（MCU）通过检测待采样电阻（230）的初始电阻值确定恒流源电路（210）输出的恒定电流值，以使不同电阻值区间的待采样电阻（230）对应不同的恒定电流值，采样电压满足微控制单元（MCU）采样量程和采样精度的要求，提高了恒流源采样电路的采样效率。

Description

恒流源采样电路和方法 技术领域
本申请涉及电子技术领域，具体涉及一种恒流源采样电路和方法。
背景技术
恒流源电路是输出电流保持恒定的电流源电路。恒流源采样电路是通过固定的恒流源将待测电阻的电阻值转换成电压值，再通过单片机采集电压信号并将电压信号转换成数字信号。
在恒流源采样电路的实际应用场景中，单片机模拟数字转换器采样量程的基准电压一般为2.5V，而待测电阻的电阻值变化范围大。现有的恒流源采样电路，当待测电阻的电阻值较小时，输出的电压信号弱且易受干扰，无法满足单片机的采样精度要求；当待测电阻的电阻值较大时，输出的电压信号超出了单片机的量程限制，现有的恒流源采样电路无法保证采样精度以及采样量程，采样效率低。
发明内容
为解决上述恒流源采样电路中出现的问题，本申请提供了一种恒流源采样电路和方法，可以使恒流源采样电路通过控制模块切换恒流源电流值，实现满足单片机量程以及精度的要求，提高了采样效率。
本申请实施例第一方面，提供了一种恒流源采样电路，应用于电阻采样，其特征在于，所述恒流源采样电路包括：恒流源电路、待采样电阻、微控制单元、电源以及采样电压输出端；
所述恒流源电路的第一端与所述电源的正极相连；所述恒流源电路的第二端与所述待采样电阻的第一端以及所述采样电压输出端相连；所述待采样电阻的第二端与所述电源的负极以及所述恒流源电路的第三端连接；所述微控制单元一端与所述采样电压输出端连接，另一端与所述恒流源电路的第四端连接。
在一个实施例中，所述恒流源电路包括：第一恒流源模块、第二恒流源模块和控制模块；
所述电源的正极连接所述第一恒流源模块的第一端和所述控制模块的第一端；所述控制模块的第二端连接所述第二恒流源模块的第一端；所述控制模块的第三端连接所述电源的负极以及所述待采样电阻的第二端；所述控制模块的第四端连接所述微控制单元；所述第二恒流源模块的第二端、所述第二恒流源模块的第三端以及所述第二恒流源模块的第四端分别与对应的所述第一恒流源模块的第二端、所述第一恒流源模块的第三端以及所述第一恒流源模块的第四端连接；所述第一恒流源模块的第五端与所述第二恒流源模块的第五端以及所述采样电压输出端连接；
在一个实施例中，所述第一恒流源模块包括负载子模块、恒流源子模块以及偏置电压子模块；
所述电源的正极连接所述负载子模块的第一端和所述偏置电压子模块的第一端；所述负载子模块的第二端和所述第二恒流源模块的第二端连接所述恒流源子模块的第一端；所述偏置电压子模块的第二端连接所述恒流源子模块的第二端和所述第二恒流源模块的第三端；所述恒流源子模块的第三端连接所述第二恒流源模块的第四端；所述恒流源子模块的第四端连接所述第二恒流源模块的第五端和所述采样电压输出端。
在一个实施例中，所述恒流源子模块包括：第一三极管、第一电阻；
所述负载子模块的第二端和所述第二恒流源模块的第二端连接所述第一三极管的集电极端；所述偏置电压子模块的第二端和所述第二恒流源模块的第三端连接所述第一三极管的基极端；所述第一三极管的发射极端连接所述第一电阻的第一端和所述第二恒流源模块的第四端；所述第一电阻的第二端连接所述第二恒流源模块的第五端和所述采样电压输出端；
所述偏置电压子模块为所述第一三极管的基极提供偏置电压；所述负载子模块为所述第一三极管的负载电阻；
所述第一恒流源模块用于控制所述第一三极管处于放大状态，以使所述第一三极管的发射极端输出的电流为所述第一恒流源模块第五端输出的电流。
在一个实施例中，所述负载子模块包括第二电阻和第二三极管；
所述电源的正极连接所述第二电阻的第一端；所述第二电阻的第二端连接所述第二三极管的发射极端；所述第二三极管的集电极端悬空；所述第二三极 管的基极端和所述第二恒流源模块的第二端连接所述第一三极管的集电极端；
所述第二恒流源模块包括第三电阻、第三三极管和可控精密稳压源；
所述控制模块的第二端连接所述第三电阻的第一端；所述第三电阻的第二端连接所述第三三极管的发射极端；所述第三三极管的基极端连接所述第二三极管的基极端和所述第一三极管的集电极端；所述第三三极管的集电极端连接所述第一三极管的基极端和所述可控精密稳压源的阴极端；所述可控精密稳压源的参考极端连接第一三极管的发射极端和所述第一电阻的第一端；所述可控精密稳压源的阳极端连接所述第一电阻的第二端和所述采样电压输出端。
在一个实施例中，当所述第二电阻和所述第三电阻的电阻值相等，且所述第二三极管和所述第三三极管的型号相同时，所述第一恒流源模块的第五端输出的电流与所述第二恒流源模块的第五端输出的电流相同。
在一个实施例中，所述偏置电压子模块包括并联的第四电阻和第一电容；
所述电源的正极连接所述第四电阻的第一端和所述第一电容的第一端；所述第四电阻的第二端和所述第一电容的第二端连接所述第一三极管的基极端、所述第三三极管的集电极端和所述可控精密稳压源的阴极端；
所述第四电阻为所述第一三极管的基极提供偏置电压；所述第一电容在所述电路导通时，为所述第一三极管的基极提供正偏电压。
在一个实施例中，所述控制模块包括：第一开关管、第二开关管、第五电阻、第六电阻和第二电容；
所述电源的正极连接所述第一开关管的第一端、所述第五电阻的第一端和所述第二电容的第一端；所述第一开关管的第二端连接所述第二恒流源模块的第一端；所述第一开关管的第三端连接所述第五电阻的第二端、所述第二电容的第二端和所述第六电阻的第一端；所述第六电阻的第二端连接所述第二开关管的第一端；所述第二开关管的第二端连接所述电源的负极和所述待采样电阻的第二端；所述第二开关管的第三端连接所述微控制单元；
当所述微控制单元向所述第二开关管的第三端输出第一电压时，所述第一开关管和所述第二开关管导通，所述控制模块为连通状态；当所述微控制单元向所述第二开关管的第三端输出第二电压或不输出电压时，所述第一开关管和所述第二开关管截止，所述控制模块为断开状态。
在一个实施例中，所述第一开关管包括继电器、三极管、金属氧化物半导体场效应MOS管中的任一个，所述第二开关管包括继电器、三极管、MOS管中的任一个。
本申请实施例第二方面，提供了一种恒流源采样方法，应用于上述恒流源采样电路，该方法可包括：
当所述恒流源电路的第二端输出初始恒定电流值时，所述微控制单元测量所述待采样电阻的初始电阻值，确定所述初始电阻值落入的目标电阻值区间；
所述微控制单元根据电阻值区间集合与恒定电流值集合的对应关系确定与所述目标电阻值区间对应的目标恒定电流值；
所述微控制单元控制所述恒流源电路的第二端输出与所述目标恒定电流值对应的恒定电流，以测量所述待采样电阻的最终电阻值。
在一个实施例中，所述电阻值区间集合包括第一阻值区间和第二阻值区间，所述恒定电流值集合包括第一恒定电流值和第二恒定电流值；所述第一阻值区间与所述第一恒定电流值对应，所述第二阻值区间与所述第二恒定电流值对应。
在一个实施例中，所述微控制单元控制所述恒流源电路的第二端输出与所述目标恒定电流值对应的恒定电流，以测量所述待采样电阻的最终电阻值，包括：当所述目标电阻值区间为所述第一阻值区间时，所述微控制单元控制所述恒流源电路的第二端输出与所述第一恒定电流值对应的恒定电流，以测量所述待采样电阻的最终电阻值；当所述目标电阻值区间为所述第二阻值区间时，所述微控制单元控制所述恒流源电路的第二端输出与所述第二恒定电流值对应的恒定电流，以测量所述待采样电阻的最终电阻值。
实施本申请实施例，针对变化范围大的待采样电阻，微控制单元通过检测待采样电阻的初始电阻值确定恒流源电路输出的恒定电流值，采样电压输出端的电压为恒定电流值和采样电阻值的乘积，以使不同电阻值区间的待采样电阻对应不同的恒定电流值，采样电压满足微控制单元采样量程和采样精度的要求，提高了恒流源采样电路的采样效率。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施例，对于本领域普通技术人员而言，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例中一种恒流源采样电路的结构示意图；
图2为本申请实施例中一种恒流源采样电路的具体结构示意图；
图3为本申请实施例中另一种恒流源采样电路的具体结构示意图；
图4为本申请实施例中又一种恒流源采样电路的具体结构示意图；
图5为本申请实施例中一种恒流源采样方法的流程示意图。
具体实施方式
为了使本技术领域的人员更好地理解本申请方案，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，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，都属于本申请保护的范围。
本申请的说明书和权利要求书及上述附图中的术语“第一”、“第二”等是用于区别不同对象，而不是用于描述特定顺序。此外，术语“包括”和“具有”以及它们任何变形，意图在于覆盖不排他的包含。例如包含了一系列步骤或单元的过程、系统、产品或设备没有限定于已列出的步骤或单元，而是可选地还包括没有列出的步骤或单元，或可选地还包括对于这些过程、产品或设备固有的其他步骤或单元。
在本文中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。
请参阅图1，图1为本申请实施例提供的一种恒流源采样电路的结构示意图。
本申请提供一种恒流源采样电路，包括恒流源电路210、电源220，待采样电阻230、采样电压输出端(图1以Vout表示)、微控制单元(microcontroller unit，MCU)。
其中，上述恒流源电路210的第一端211与上述电源220的正极相连，上述恒流源电路210的第二端212与上述待采样电阻230的第一端231以及上述采样电压输出端Vout相连，上述待采样电阻230的第二端232与上述电源220的负极以及上述恒流源电路210的第三端213连接，上述微控制单元MCU的一端与上述采样电压的输出端Vout连接，微控制单元MCU的另一端与上述恒流源电路210的第四端214连接。
在一个实施方式中，上述待采样电阻230为连接确认功能(connection confirm function，CC)电阻Rcc，该恒流源电路210应用于电动汽车传导充电系统，电动汽车传导充电系统的连接确认功能是通过充电枪连接不同阻值的电阻Rcc来实现车辆接口连接状态以及充电桩充电电缆容量的判断。
上述微控制单元MCU，用于在上述恒流源电路210的第二端212输出初始恒定电流值的情况下，测量待采样电阻230的初始电阻值，确定初始电阻值落入的目标电阻值区间，并根据电阻值区间集合与恒定电流值集合的对应关系确定与上述目标电阻值区间对应的目标恒定电流值，以及控制上述恒流源电路210的第二端212重新输出与上述目标恒定电流值对应的恒定电流，以测量上述待采样电阻230的最终电阻值。
可选的，上述恒流源电路210包括多个并联的恒流源模块，每个恒流源模块由该恒流源模块对应的控制模块控制是否工作，每个恒流源模块的控制模块由上述微控制单元MCU控制，当上述任一恒流源模块工作时，处于工作状态的恒流源模块输出一个恒定电流，恒流源电路210输出的电流为处于工作状态的多个恒流源模块输出电流之和。
通过上述连接方式，微控制单元MCU通过检测待采样电阻230的初始电阻值确定恒流源电路的恒定电流值，采样电压输出端Vout的电压为恒定电流值和待采样电阻230的电阻值的乘积，以使不同电阻值区间的待采样电阻230对应不同的恒定电流值，使得采样电压满足微控制单元MCU采样量程和采样精度的要求，提高了恒流源采样电路的采样效率。
在一个实施方式中，上述电阻值区间集合包括第一阻值区间和第二阻值区间，上述恒定电流值集合包括第一恒定电流值和第二恒定电流值，上述第一阻值区间与上述第一恒定电流值对应，上述第二阻值区间与上述第二恒定电流值对应。
在上述目标电阻值区间为上述第一阻值区间的情况下，上述微控制单元MCU控制上述恒流源电路210的第二端212输出与上述第一恒定电流值对应的恒定电流，以测量上述待采样电阻230的最终电阻值。
在上述目标电阻值区间为上述第二阻值区间的情况下，上述微控制单元MCU控制上述恒流源电路210的第二端212输出与上述第二恒定电流值对应的恒定电流，以测量上述待采样电阻230的最终电阻值。
在一个实施方式中，如图2所示，图2所示的恒流源电路210包括第一恒流源模块310、第二恒流源模块330和控制模块320。
电源220的正极连接上述第一恒流源模块310的第一端311和上述控制模块320的第一端321，上述控制模块320的第二端322连接上述第二恒流源模块330的第一端331，上述控制模块320的第三端323连接电源220的负极以及待采样电阻230的第二端232，上述控制模块320的第四端324连接上述微控制单元MCU，上述第二恒流源模块330的第二端332、第三端333以及第四端334分别对应连接上述第一恒流源模块310的第二端312、第三端313以及第四端314，上述第一恒流源模块310的第五端315与上述第二恒流源模块330的第五端335以及采样电压输出端Vout连接。
上述控制模块320用于控制上述第二恒流源模块330是否工作。
具体的，在一个实施例中，上述微控制单元MCU控制上述控制模块320为连通状态，以使上述第一恒流源模块310的第五端315输出与上述第二恒定电流值对应的恒定电流，上述第二恒流源模块330的第五端335输出与第三恒定电流值对应的恒定电流，上述第一恒定电流值等于上述第二恒定电流值与上述第三恒定电流值之和。
在另一个实施例中，上述微控制单元MCU控制上述控制模块320为断开状态，以使上述第一恒流源模块310的第五端315输出与上述第二恒定电流值对应的恒定电流，由于控制模块320为断开状态时，第二恒流源模块330为开 路状态，此时第二恒流源模块330无电流输出。
可选的，如图2所示，上述恒流源电路210还可以包括第一控制模块，第一控制模块位于第一恒流源模块310和电源220之间，第一控制模块用于控制第一恒流源模块310的开断状态。当微控制单元MCU控制第一控制模块为连通状态且控制模块320为断开状态时，恒流源电路210第二端212输出第二恒定电流值对应的恒定电流；当微控制单元MCU控制第一控制模块为连通状态且控制模块320为连通状态时，恒流源电路210第二端212输出第一恒定电流值对应的恒定电流。
在一个实施例中，如图3所示，第一恒流源模块310包括负载子模块410、恒流源子模块430以及偏置电压子模块420。
电源220的正极连接上述负载子模块410的第一端411和上述偏置电压子模块420的第一端421。第二恒流源模块330的第二端332连接恒流源子模块430的第一端431。偏置电压子模块420的第二端422连接恒流源子模块430的第二端432以及第二恒流源模块330的第三端333，恒流源子模块430的第三端433连接第二恒流源模块330的第四端334，恒流源子模块430的第四端434连接第二恒流源模块330的第五端335和采样电压输出端Vout。
在一个实施例中，如图4所示，本申请提供的又一种恒流源采样电路，其中，上述恒流源子模块430包括：第一三极管Q1、第一电阻R1。
上述负载子模块410的第二端和上述第二恒流源模块330的第二端连接上述第一三极管Q1的集电极端，上述偏置电压子模块420的第二端和上述第二恒流源模块330的第三端连接上述第一三极管Q1的基极端，上述第一三极管Q1的发射极端连接上述第一电阻R1的第一端和上述第二恒流源模块330的第四端，上述第一电阻R1的第二端连接上述第二恒流源模块330的第五端和上述采样电压输出端Vout。
上述偏置电压子模块420为上述第一三极管Q1的基极提供偏置电压，上述负载子模块410为上述第一三极管Q1的负载电阻。
上述第一恒流源模块310用于控制上述第一三极管Q1处于放大状态，以使上述第一三极管Q1的发射极端输出的电流为上述第一恒流源模块310第五端输出的电流。
在一个实施例中，如图4所示，上述负载子模块410包括第二电阻R2和第二三极管Q2。
上述电源220的正极连接上述第二电阻R2的第一端，上述第二电阻R2的第二端连接上述第二三极管Q2的发射极端，上述第二三极管Q2的集电极端悬空，上述第二三极管Q2的基极端连接上述第二恒流源模块330的第二端和上述第一三极管Q1的集电极端。
上述第二恒流源模块330包括第三电阻R3、第三三极管Q3、可控精密稳压源U1。
上述控制模块320的第二端连接上述第三电阻R3的第一端，上述第三电阻R3的第二端连接上述第三三极管Q3的发射极端，上述第三三极管Q3的基极端连接上述第二三极管Q2的基极端和上述第一三极管Q1的集电极端，上述第三三极管Q3的集电极端连接上述第一三极管Q1的基极端和上述可控精密稳压源U1的阴极端，上述可控精密稳压源U1的参考极端连接第一三极管Q1的发射极端和上述第一电阻R1的第一端，上述可控精密稳压源U1的阳极端连接上述第一电阻R1的第二端和上述采样电压输出端Vout。
可选的，当上述第二电阻R2和上述第三电阻R3的电阻值相等，且上述第二三极管Q2和上述第三三极管Q3的型号相同时，上述第一恒流源模块310的第五端315输出的电流与上述第二恒流源模块330的第五端335输出的电流相同。
可选的，如图4所示，上述偏置电压子模块420包括并联的第四电阻R4和第一电容C1。上述电源220的正极连接上述第四电阻R4的第一端和上述第一电容C1的第一端；上述第四电阻R4的第二端和上述第一电容C1的第二端连接上述第一三极管Q1的基极端、上述第三三极管Q3的集电极端和上述可控精密稳压源U1的阴极端。上述第四电阻R4为上述第一三极管Q1的基极提供偏置电压，上述第一电容C1在上述第一恒流源模块310导通时，为上述第一三极管Q1的基极提供正偏电压。
在一个实施例中，如图4所示，上述控制模块320包括：第一开关管Q4、第二开关管Q5、第五电阻R5、第六电阻R6、第二电容C2。
上述电源220的正极连接上述第一开关管Q4的第一端、上述第五电阻R5的第一端和上述第二电容C2的第一端，上述第一开关管Q4的第二端连接 上述第三电阻R3的第一端，上述第一开关管Q4的第三端连接上述第五电阻R5的第二端、上述第二电容C2的第二端和上述第六电阻R6的第一端，上述第六电阻R6的第二端连接上述第二开关管Q5的第一端，上述第二开关管Q5的第二端连接上述电源220的负极和上述待采样电阻Rcc的第二端，上述第二开关管Q5的第三端连接上述微控制单元MCU(图4未示出)。
当上述微控制单元MCU向上述第二开关管Q5的第三端输出第一电压时，上述第一开关管Q4和上述第二开关管Q5导通，上述控制模块320为连通状态。当上述微控制单元MCU向上述第二开关管Q5的第三端输出第二电压或不输出电压时，上述第一开关管Q4和上述第二开关管Q5截止，上述控制模块320为断开状态。其中，第一电压大于或等于第二开关管Q5的导通电压，第二电压小于第二开关管Q5的导通电压。
可选的，上述第一开关管Q4包括继电器、三极管、金属氧化物半导体场效应MOS管中的任一个，上述第二开关管Q5包括继电器、三极管、MOS管中的任一个。在一种实施例中，如图4所示，上述第一开关管Q4为PMOS管，上述第二开关管Q5为NMOS管。
在一个实施例中，如图4所示，上述电源与第三电容C3并联，第三电容C3为电源进行滤波。
结合图2至图4，下面对本申请提供的恒流源采样电路的工作原理进行说明。
第一恒流源模块310为以第一三极管Q1发射极电流为输出电流的恒流源模块，当第一三极管Q1处于放大状态时，第一三极管Q1发射极端的电流为第一恒流源模块的输出电流。第二电阻R2和第二三极管Q2组成第一三极管Q1集电极的负载子模块410，为第一三极管Q1的集电极提供集电极电压；第四电阻R4和第一电容C1组成第一三极管Q1基极的偏置电压子模块，为第一三极管Q1基极提供基极的偏置电压。第二恒流源模块330中的可控精密稳压源U1的参考极连接至第一三极管Q1的发射极端，给第一三极管Q1的发射极端提供一个稳定电压U1；可控精密稳压源U1的阴极端连接至第一三极管Q1的基极，以使可控精密稳压源U1中参考极端的电压通过负反馈控制第一三极管Q1基极端的电压，从而使第一三极管Q1工作在放大状态，在第一三极管Q1基极电流远小于 第一三极管Q1集电极电流的情况下，第一三极管Q1集电极端的电流等于第一三极管Q1发射极端的电流。
第二恒流源模块330中第三电阻R3、第三三极管Q3的BE结与负载子模块410中的第二电阻R2、第二三极管Q2的BE结并联，BE结表示三极管基极B至发射极E的部分。在第二三极管Q2和第二三极管Q3型号相同的情况下，Q2和Q3的BE结压降相同，第二电阻R2和第三电阻R3两端的电压相同，若R2和R3的电阻值相同，则Q2发射极端的电流与Q3发射极端的电流相同。在Q2集电极端悬空的情况下，Q2相当于一个二极管，Q2基极端的电流等于Q2发射极端的电流，且等于第一三极管Q1集电极端的电流。在第三三极管Q3基极电流远小于第三三极管Q3集电极电流时，第三三极管Q3集电极端的电流与第三三极管Q3发射极端的电流相同，此时，第三三极管Q3集电极端的电流等于第一三极管集电极端的电流，因为第一三极管Q1集电极端的电流等于第一三极管Q1发射极端的电流，因此在R2和R3阻值相同且Q2和Q3型号相同的情况下，第一恒流源模块310第五端315输出的电流与第二恒流源模块330第五端335输出的电流相同。
控制模块320，如图4所示，由PMOS管Q4、第五电阻R5、第二电容C2、第六电阻R6和NMOS管Q5组成，在本申请提供的恒流源采样电路中，由于需要控制的电路两端都有电压，因此在电路中用PMOS管控制电路的开断。微控制单元MCU能输出的电压值最高为3.3V，当Q4源极S端的电压大于3.3V时，无法直接通过微控制单元MCU输出的电压控制Q4栅极G端的电压大于S端以使Q4断开，因此在本申请提供的恒流源采样电路中，通过微控制单元MCU控制NMOS管Q5的开断，以控制Q4的开断。
相比起现有的恒流源采样电路，本申请实施例提供的一种恒流源采样电路，包括恒流源电路、待采样电阻、微控制单元MCU、电源以及采样电压输出端，其中微控制单元MCU通过检测待采样电阻的初始电阻值确定恒流源电路输出的恒定电流值，采样电压输出端的电压为恒定电流值和采样电阻值的乘积，以使不同电阻值区间的待采样电阻对应不同的恒定电流值，采样电压满足微控制单元MCU采样量程和采样精度的要求，提高了恒流源采样电路的采样效率。
如图5所示，本申请实施例还提供了一种恒流源采样方法，该方法应用于 如图1、图2、图3或图4所示的恒流源采样电路，该方法可包括：
501、当恒流源电路的第二端输出初始恒定电流值时，微控制单元测量待采样电阻的初始电阻值，确定初始电阻值落入的目标电阻值区间。
502、微控制单元根据电阻值区间集合与恒定电流值集合的对应关系确定与目标电阻值区间对应的目标恒定电流值。
可选的，电阻值区间集合包括第一阻值区间和第二阻值区间，恒定电流值集合包括第一恒定电流值和第二恒定电流值，第一阻值区间与第一恒定电流值对应，第二阻值区间与第二恒定电流值对应。
503、微控制单元控制恒流源电路的第二端输出与目标恒定电流值对应的恒定电流，以测量待采样电阻的最终电阻值。
在一种实施方式中，电阻区间集合包括第一阻值区间和第二阻值区间，恒定电流值集合包括第一恒定电流值和第二恒定电流值，第一阻值区间与第一恒定电流值对应，第二阻值区间与第二恒定电流值对应时。
在一种实施方式中，微控制单元控制恒流源电路的第二端输出与目标恒定电流值对应的恒定电流，以测量待采样电阻的最终电阻值，具体为：当目标电阻值区间为第一阻值区间时，微控制单元控制恒流源电路的第二端输出与第一恒定电流值对应的恒定电流，以测量待采样电阻的最终电阻值。当目标电阻值区间为第二阻值区间时，微控制单元控制恒流源电路的第二端输出与第二恒定电流值对应的恒定电流，以测量待采样电阻的最终电阻值。
以上对本申请实施例进行了详细介绍，本文中应用了具体的个例对本申请的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本申请的核心思想；同时，对于本领域的一般技术人员，依据本申请的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本申请的限制。

Claims (10)

  1. 一种恒流源采样电路，应用于电阻采样，其特征在于，所述恒流源采样电路包括：恒流源电路、待采样电阻、微控制单元、电源以及采样电压输出端；
    所述恒流源电路的第一端与所述电源的正极相连；所述恒流源电路的第二端与所述待采样电阻的第一端以及所述采样电压输出端相连；所述待采样电阻的第二端与所述电源的负极以及所述恒流源电路的第三端连接；所述微控制单元一端与所述采样电压输出端连接，另一端与所述恒流源电路的第四端连接。
  2. 根据权利要求1所述的恒流源采样电路，其特征在于，所述恒流源电路包括：第一恒流源模块、第二恒流源模块和控制模块；
    所述电源的正极连接所述第一恒流源模块的第一端和所述控制模块的第一端；所述控制模块的第二端连接所述第二恒流源模块的第一端；所述控制模块的第三端连接所述电源的负极以及所述待采样电阻的第二端；所述控制模块的第四端连接所述微控制单元；所述第二恒流源模块的第二端、第三端以第四端分别与对应的所述第一恒流源模块的第二端、第三端以及所述第四端连接；所述第一恒流源模块的第五端与所述第二恒流源模块的第五端以及所述采样电压输出端连接。
  3. 根据权利要求2所述的恒流源采样电路，其特征在于，所述第一恒流源模块包括负载子模块、恒流源子模块以及偏置电压子模块；
    所述电源的正极连接所述负载子模块的第一端和所述偏置电压子模块的第一端；所述负载子模块的第二端和所述第二恒流源模块的第二端连接所述恒流源子模块的第一端；所述偏置电压子模块的第二端连接所述恒流源子模块的第二端和所述第二恒流源模块的第三端；所述恒流源子模块的第三端连接所述第二恒流源模块的第四端；所述恒流源子模块的第四端连接所述第二恒流源模块的第五端和所述采样电压输出端。
  4. 根据权利要求3所述的恒流源采样电路，其特征在于，所述恒流源子 模块包括：第一三极管、第一电阻；
    所述负载子模块的第二端和所述第二恒流源模块的第二端连接所述第一三极管的集电极端；所述偏置电压子模块的第二端和所述第二恒流源模块的第三端连接所述第一三极管的基极端；所述第一三极管的发射极端连接所述第一电阻的第一端和所述第二恒流源模块的第四端；所述第一电阻的第二端连接所述第二恒流源模块的第五端和所述采样电压输出端；
    所述偏置电压子模块为所述第一三极管的基极提供偏置电压；所述负载子模块为所述第一三极管的负载电阻；
    所述第一恒流源模块控制所述第一三极管处于放大状态，以使所述第一三极管的发射极端输出的电流为所述第一恒流源模块第五端输出的电流。
  5. 根据权利要求4所述的恒流源采样电路，其特征在于，所述负载子模块包括第二电阻和第二三极管；
    所述电源的正极连接所述第二电阻的第一端；所述第二电阻的第二端连接所述第二三极管的发射极端；所述第二三极管的集电极端悬空；所述第二三极管的基极端和所述第二恒流源模块的第二端连接所述第一三极管的集电极端；
    所述第二恒流源模块包括第三电阻、第三三极管和可控精密稳压源；
    所述控制模块的第二端连接所述第三电阻的第一端；所述第三电阻的第二端连接所述第三三极管的发射极端；所述第三三极管的基极端连接所述第二三极管的基极端和所述第一三极管的集电极端；所述第三三极管的集电极端连接所述第一三极管的基极端、所述偏置电压子模块的第二端和所述可控精密稳压源的阴极端；所述可控精密稳压源的参考极端连接第一三极管的发射极端和所述第一电阻的第一端；所述可控精密稳压源的阳极端连接所述第一电阻的第二端和所述采样电压输出端。
  6. 根据权利要求5所述的恒流源采样电路，其特征在于，所述偏置电压子模块包括并联的第四电阻和第一电容；
    所述电源的正极连接所述第四电阻的第一端和所述第一电容的第一端；所述第四电阻的第二端和所述第一电容的第二端连接所述第一三极管的基极 端、所述第三三极管的集电极端和所述可控精密稳压源的阴极端；
    所述第四电阻为所述第一三极管的基极提供偏置电压；所述第一电容在所述电路导通时，为所述第一三极管的基极提供正偏电压。
  7. 根据权利要求2-6中任一所述的恒流源采样电路，其特征在于，所述控制模块包括：第一开关管、第二开关管、第五电阻、第六电阻、第二电容；
    所述电源的正极连接所述第一开关管的第一端、所述第五电阻的第一端和所述第二电容的第一端；所述第一开关管的第二端连接所述第二恒流源模块的第一端；所述第一开关管的第三端连接所述第五电阻的第二端、所述第二电容的第二端和所述第六电阻的第一端；所述第六电阻的第二端连接所述第二开关管的第一端；所述第二开关管的第二端连接所述电源的负极和所述待采样电阻的第二端；所述第二开关管的第三端连接所述微控制单元；
    当所述微控制单元向所述第二开关管的第三端输出第一电压时，所述第一开关管和所述第二开关管导通，所述控制模块为连通状态；当所述微控制单元向所述第二开关管的第三端输出第二电压或不输出电压时，所述第一开关管和所述第二开关管截止，所述控制模块为断开状态。
  8. 一种恒流源采样方法，应用于权利要求1所述的恒流源采样电路，其特征在于，所述方法包括：
    当所述恒流源电路的第二端输出初始恒定电流值时，所述微控制单元测量所述待采样电阻的初始电阻值，确定所述初始电阻值落入的目标电阻值区间；
    所述微控制单元根据电阻值区间集合与恒定电流值集合的对应关系确定与所述目标电阻值区间对应的目标恒定电流值；
    所述微控制单元控制所述恒流源电路的第二端输出与所述目标恒定电流值对应的恒定电流，以测量所述待采样电阻的最终电阻值。
  9. 根据权利要求8所述的恒流源采样方法，其特征在于，所述电阻值区间集合包括第一阻值区间和第二阻值区间，所述恒定电流值集合包括第一恒定电流值和第二恒定电流值；所述第一阻值区间与所述第一恒定电流值对应，所 述第二阻值区间与所述第二恒定电流值对应。
  10. 根据权利要求9所述的恒流源采样方法，其特征在于，所述微控制单元控制所述恒流源电路的第二端输出与所述目标恒定电流值对应的恒定电流，以测量所述待采样电阻的最终电阻值，包括：
    当所述目标电阻值区间为所述第一阻值区间时，所述微控制单元控制所述恒流源电路的第二端输出与所述第一恒定电流值对应的恒定电流，以测量所述待采样电阻的最终电阻值；
    当所述目标电阻值区间为所述第二阻值区间时，所述微控制单元控制所述恒流源电路的第二端输出与所述第二恒定电流值对应的恒定电流，以测量所述待采样电阻的最终电阻值。
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