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CN-122018617-A - Current source circuit

CN122018617ACN 122018617 ACN122018617 ACN 122018617ACN-122018617-A

Abstract

The invention discloses a constant current source circuit which comprises an operational amplifier unit, a driving control unit, N power circuits, wherein the in-phase input end of the operational amplifier unit is the input end of the current source circuit, the inverting input end of the operational amplifier unit is used for inputting a feedback signal representing the output current of the current source circuit, the output end of the operational amplifier unit is used for outputting a first voltage signal, the driving control unit is connected with the output end of the operational amplifier unit and used for generating a bus voltage under the control of the first voltage signal and generating a pull-down control function through a pull-down function output port of the operational amplifier unit, the input end of each power circuit is connected with the bus voltage, the control end of each power circuit is connected with the pull-down function output port of the driving control unit, the output end of each power circuit is connected with the first output end of the current source circuit and used for generating an output current through the bus voltage under the effect of the pull-down control function, the output sampling unit is connected with the second output end of the current source circuit and used for acquiring the feedback signal, and the 2 nd to N power circuits respectively comprise a current equalizing circuit. The invention can avoid damage caused by parameter difference of each power circuit.

Inventors

  • HUANG SEN

Assignees

  • 广州金升阳科技有限公司

Dates

Publication Date
20260512
Application Date
20260126

Claims (10)

  1. 1. A current source circuit for providing a regulated current to a load connected between a first output terminal and a second output terminal thereof, said current source circuit having an input for a controllable voltage from a digital signal to an analog signal, said current source circuit comprising: The non-inverting input end of the operational amplifier unit is an input end of the current source circuit, the inverting input end of the operational amplifier unit inputs a feedback signal representing the output current of the current source circuit, and the output end of the operational amplifier unit outputs a first voltage signal; The driving control unit is connected with the output end of the operational amplifier unit and is used for generating bus voltage under the control of the first voltage signal and generating a pull-down control function through a pull-down function output port of the bus voltage; N power circuits, N is a natural number greater than or equal to 2, the input end of each power circuit is connected with the bus voltage, the control end is connected with the pull-down function output port of the drive control unit, the output end is connected with the first output end of the current source circuit, and the power circuits are used for generating an output current through the bus voltage under the action of the pull-down control function; the output sampling unit is connected with the second output end of the current source circuit and is used for acquiring the feedback signal; The 2 nd to the N th power circuits respectively comprise a current equalizing circuit, each current equalizing circuit is used for obtaining a voltage signal representing the output current of the first power circuit and a voltage signal representing the output current of the corresponding power circuit, comparing the voltage signal and the voltage signal to generate an error control signal, and dynamically adjusting the output current of the corresponding power circuit to enable the output current of the corresponding power circuit to be consistent with the output current of the first power circuit.
  2. 2. The current source circuit of claim 1, wherein the operational amplifier unit comprises an operational amplifier U1, the non-inverting input terminal of the operational amplifier U1 is the non-inverting input terminal of the operational amplifier unit, the inverting input terminal of the operational amplifier unit is the inverting input terminal of the operational amplifier unit, and the output terminal of the operational amplifier unit is the output terminal of the operational amplifier unit.
  3. 3. The current source circuit of claim 2, wherein the inverting input terminal and the output terminal of the operational amplifier U1 are connected in parallel with a two-terminal network comprising a resistor and a capacitor connected in series, and at least one two-terminal network comprising a resistor, a capacitor and a relay connected in series.
  4. 4. The current source circuit of claim 1, wherein the driving control unit comprises a resistor R15, a resistor R4, a resistor R5, a resistor R6 and a switch tube Q3, one end of the resistor R15 is connected with the output end of the operational amplifier unit, one end of the resistor R4 is connected with a power supply voltage, the other end of the resistor R15, the other end of the resistor R4, one end of the resistor R5 and the control end of the switch tube Q3 are connected together, one end of the resistor R6 outputs the bus voltage, the other end of the resistor R6 is connected with one end of the switch tube Q3 to form a pull-down function output port of the driving control unit, and the other end of the switch tube Q3 and the other end of the resistor R5 are connected together and then used for grounding.
  5. 5. The current source circuit according to claim 4, wherein the switching tube Q3 is a MOS tube, the drain electrode of the switching tube Q3 is one end of the switching tube Q3, the source electrode of the switching tube Q3 is the other end of the switching tube Q3, and the gate electrode of the switching tube Q3 is the control end of the switching tube Q3, or the switching tube Q3 is a triode, the collector electrode of the triode is one end of the switching tube Q3, the emitter electrode of the triode is the other end of the switching tube Q3, and the base electrode of the triode is the control end of the switching tube Q3.
  6. 6. The current source circuit of claim 1, wherein each power circuit comprises a first resistor, a second resistor and a first switch, one end of the first resistor is connected with the bus voltage, the other end of the first resistor is connected with one end of the first switch, one end of the second resistor is connected with a pull-down function output port of the drive control unit, the other end of the second resistor is connected with a control end of the first switch, the other end of the first switch is a first output end of the current source circuit, the current at the other end of each first switch is controlled by the current at the control end of the first switch, the current change amount at the other end of each first switch is beta times the current change amount at the control end of the first switch, and beta is larger than 1.
  7. 7. The current source circuit of claim 6, wherein the first switch is a triode, the emitter of the triode is one end of the first switch, the collector is the other end of the first switch, and the base is the control end of the first switch, or the first switch is a MOS transistor, the source of the MOS transistor is one end of the first switch, the drain is the other end of the first switch, and the grid is the control end of the first switch.
  8. 8. The current source circuit of claim 6, wherein each current equalizing circuit comprises a third resistor, a fourth resistor, a fifth resistor and a first operational amplifier, wherein one end of the third resistor is connected with one end of a first switching tube in the corresponding power circuit, the other end of the third resistor is connected with an inverting input end of the first operational amplifier, one end of the fourth resistor is connected with one end of the first switching tube in the first power circuit, the other end of the fourth resistor is connected with a non-inverting input end of the first operational amplifier, an output end of the first operational amplifier is connected with one end of the fifth resistor, and the other end of the fifth resistor is connected with a control end of the first switching tube in the corresponding power circuit.
  9. 9. The current source circuit according to claim 6, wherein the first resistors of the power circuits have the same resistance.
  10. 10. The current source circuit according to claim 1, wherein the output sampling unit comprises a sampling resistor R14, and one end of the sampling resistor R14 is simultaneously connected with the second output end of the current source circuit and the inverting input end of the operational amplifier unit, and the other end of the sampling resistor R is used for grounding.

Description

Current source circuit Technical Field The invention relates to the field of circuit design, in particular to a current source circuit. Background A programmable current source circuit is a circuit capable of supplying a stable current to a load, whose output current cannot be changed with a change in the load, and which can supply different magnitudes of output current for different input voltages. Fig. 1 is a schematic diagram of a conventional current source circuit, please refer to fig. 1, the circuit is a programmable current source circuit, and the circuit can realize outputting different currents Io by adjusting an input voltage Ui, and the main working principle is that when a controllable voltage Ui is input at a non-inverting input end of an operational amplifier U1, the output of the operational amplifier U1 can start a power tube Q1, so that an output current Io is realized, and the output current Io is sampled through a resistor R2 and fed back to an inverting input end of the operational amplifier U1, so that a deep negative feedback effect is realized, and balance is achieved. When the input voltage Ui is regulated, a voltage difference is generated between the input voltage Ui and the feedback voltage input by the reverse input end of the operational amplifier, the output end of the operational amplifier also generates voltage change, the output state of a switching tube is regulated through the changed voltage, the output current is regulated, the feedback voltage on a sampling resistor is changed, the input voltage Ui and the feedback voltage are continuously compared, the input voltage Ui and the feedback voltage are gradually made to approach, dynamic balance is finally achieved, and the output current is controllable. The circuit has simple structure, can realize the effect of controllable current output, but has the following defects: 1. The output current capability is poor, and the output current is generated completely by depending on the power tube Q1; 2. The loop speed is fixed, because the magnitude of the input voltage directly influences the output speed, and when different loads such as different capacitances or inductances are encountered, overshoot or oscillation of the output current can be caused; 3. the starting current of the power tube Q1 is provided by the operational amplifier U1, and the starting current is small, so that the starting speed of the power tube Q1 can be influenced; 4. the output load is connected with the high voltage end, and the interference ratio of the supplied power is large. For a high-power constant current source circuit, in order to output larger current, a parallel power tube mode is often adopted to improve the output current, and because individual parameter differences exist between the same power tubes, the power tubes can be damaged due to the differences. Disclosure of Invention Accordingly, the present invention is directed to a current source circuit that at least partially solves the drawbacks of the prior art. In order to solve the technical problems, the technical scheme of the embodiment of the current source circuit provided by the invention is as follows: A current source circuit for providing a stabilizing current to a load connected between a first output terminal and a second output terminal thereof, the input terminal of the current source circuit being a controllable voltage from a digital signal to an analog signal, wherein the current source circuit comprises: The non-inverting input end of the operational amplifier unit is an input end of the current source circuit, the inverting input end of the operational amplifier unit inputs a feedback signal representing the output current of the current source circuit, and the output end of the operational amplifier unit outputs a first voltage signal; The driving control unit is connected with the output end of the operational amplifier unit and is used for generating bus voltage under the control of the first voltage signal and generating a pull-down control function through a pull-down function output port of the bus voltage; N power circuits, N is a natural number greater than or equal to 2, the input end of each power circuit is connected with the bus voltage, the control end is connected with the pull-down function output port of the drive control unit, the output end is connected with the first output end of the current source circuit, and the power circuits are used for generating an output current through the bus voltage under the action of the pull-down control function; the output sampling unit is connected with the second output end of the current source circuit and is used for acquiring the feedback signal; The 2 nd to the N th power circuits respectively comprise a current equalizing circuit, each current equalizing circuit is used for obtaining a voltage signal representing the output current of the first power circuit and a voltage signal representing the output cu