Passive hysteresis current source circuit

Abstract

A passive hysteresis current source circuit includes an upper arm switch, a lower arm switch, an inductor, and a controller. The lower arm switch is connected in series with the upper arm switch at a common contact to form the input side. The upper arm switch receives the input voltage, and the lower arm switch is connected to ground. The inductor has a first terminal and a second terminal. The first terminal is connected to the common contact, and the second terminal outputs the output current flowing through the inductor. The controller receives a current-voltage signal corresponding to the output current and a reference voltage signal, and compares the current-voltage signal with the reference voltage signal. If the reference voltage signal is greater than the current-voltage signal, the controller turns on the upper arm switch and turns off the lower arm switch; if the reference voltage signal is less than the current-voltage signal, the controller turns off the upper arm switch and turns on the lower arm switch to provide a constant output current.

Description

Technical Field

[0001] This invention relates to a current source circuit, and more particularly to a passive hysteresis current source circuit. Background Technology

[0002] Buck topologies are commonly used for constant voltage power supplies, but their application in constant current power supplies is rarely discussed.

[0003] However, as Figure 1 As shown, this is a circuit diagram of a traditional current source circuit. Figure 1 As shown, it illustrates a current source circuit with a single switch, which utilizes switch Q. A A constant current output is achieved through a feedback circuit. However, in traditional single-switch current source circuits, due to the switching Q... A The operation is in the ohmic region between full on and full off, thus resulting in unavoidable power loss, which is why it has the drawback of low efficiency.

[0004] Therefore, when using a traditional current source circuit as a current power supply, it requires pulse width modulation (PWM) control technology. This not only necessitates a custom controller design, increasing design complexity and cost, but also limits its performance to specific applications, such as those with a fixed output voltage, making it unsuitable for applications with variable output voltages. Furthermore, PWM control cannot be applied to devices with grounded outputs, such as current loads, significantly restricting its application areas. Moreover, when using a traditional current source circuit as a current load, an external hysteresis circuit is typically required, further increasing design complexity and cost.

[0005] Therefore, how to design a passive hysteresis current source circuit to solve the problems and technical bottlenecks of the existing technology is an important research topic for the inventors of this case. Summary of the Invention

[0006] The purpose of this invention is to provide a passive hysteresis current source circuit. The passive hysteresis current source circuit includes an upper arm switch, a lower arm switch, an inductor, and a controller. The lower arm switch is connected in series with the upper arm switch at a common contact to form the input side. The upper arm switch receives the input voltage, and the lower arm switch is connected to ground. The inductor has a first terminal and a second terminal. The first terminal is connected to the common contact, and the second terminal outputs the output current flowing through the inductor. The controller receives a current-voltage signal corresponding to the output current and a reference voltage signal, and compares the current-voltage signal with the reference voltage signal. If the reference voltage signal is greater than the current-voltage signal, the controller turns on the upper arm switch and turns off the lower arm switch; if the reference voltage signal is less than the current-voltage signal, the controller turns off the upper arm switch and turns on the lower arm switch to provide a constant output current.

[0007] In one embodiment, the upper arm switch has a first terminal, a second terminal, and a control terminal. The lower arm switch also has a first terminal, a second terminal, and a control terminal. The first terminal of the lower arm switch is connected to the second terminal of the upper arm switch at a common contact point, wherein the first terminal of the upper arm switch receives an input voltage, and the second terminal of the lower arm switch is connected to a ground terminal. The second terminal of the inductor and the load terminal form the output side of the current power supply.

[0008] In one embodiment, the upper arm switch has a first terminal, a second terminal, and a control terminal. The lower arm switch also has a first terminal, a second terminal, and a control terminal. The first terminal of the lower arm switch is connected to the second terminal of the upper arm switch at a common contact point, wherein the first terminal of the upper arm switch receives an input voltage, and the second terminal of the lower arm switch is connected to a ground terminal. The second terminal of the inductor and the ground terminal form the output side of a current load.

[0009] In one embodiment, the output current may be changed accordingly in response to an adjustment of the reference voltage signal.

[0010] In one embodiment, the controller provides an upper arm switch control signal to control the upper arm switch and a lower arm switch control signal to control the lower arm switch.

[0011] In one embodiment, the upper arm switch control signal and the lower arm switch control signal are square wave signals to fully turn on or completely turn off the upper arm switch and the lower arm switch.

[0012] In one embodiment, the upper arm switch control signal and the lower arm switch control signal are complementary signals.

[0013] In one embodiment, the controller includes a comparator. The comparator has a first input, a second input, and an output. The first input receives a reference voltage signal, and the second input receives a current-voltage signal. After comparing the reference voltage signal and the current-voltage signal, the comparator outputs an upper arm switch control signal and a lower arm switch control signal through its output.

[0014] In one embodiment, the comparator is an operational amplifier.

[0015] In one embodiment, the comparator further includes an inverting unit. The inverting unit is connected to the output of the comparator, receives the upper arm switch control signal, and inverts the level of the upper arm switch control signal to change it into the lower arm switch control signal.

[0016] In one embodiment, the output current increases when the reference voltage signal is greater than the current voltage signal, and decreases when the reference voltage signal is less than the current voltage signal.

[0017] In one embodiment, the inductive element provides hysteretic on and off of the upper arm switch and the lower arm switch.

[0018] In one embodiment, a load is connected to the output side, and the load is connected between the output side and the ground terminal.

[0019] In one embodiment, the output side is directly connected to the ground terminal.

[0020] Therefore, the passive hysteresis current source circuit provided by this invention has the following features and advantages: 1. It achieves the effect of passive hysteresis by using simple passive components and two switches; 2. The passive hysteresis current source circuit of this invention can be used as a current power supply and a current load; 3. The controller has a simple circuit structure, mainly relying on comparators and basic logic circuits; 4. Hysteresis control adjusts the switching state immediately according to the current, which is suitable for applications with rapidly changing output current; 5. The energy storage function of the inductor and the stable characteristics of hysteresis control ensure a constant output current; 6. This invention adopts square wave control (rather than pulse width modulation control), so there is no need to use additional means or methods to detect the output voltage information, which simplifies the control architecture and reduces the cost of the circuit; 7. The passive hysteresis current source circuit operates in the ohmic region to reduce power loss and improve efficiency.

[0021] To gain a deeper understanding of the techniques, means, and effects employed by this invention to achieve its intended purpose, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this invention can be understood in a thorough and specific manner from these drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit this invention. Attached Figure Description

[0022] Figure 1 The circuit diagram is for a traditional current source circuit.

[0023] Figure 2A This is a circuit diagram of a first embodiment of the passive hysteresis current source circuit of the present invention;

[0024] Figure 2B for Figure 2A A circuit diagram showing the connection of a passive hysteresis current source circuit to the load.

[0025] Figure 3 This is a circuit diagram of a second embodiment of the passive hysteresis current source circuit of the present invention;

[0026] Figure 4 This is a circuit diagram of the controller for the passive hysteresis current source circuit of the present invention.

[0027] Figure 5 The diagram shows the reference voltage signal, current voltage signal, upper arm switch control signal, output current, and input current of the passive hysteresis current source circuit of this invention.

[0028] Explanation of icon numbers

[0029] 100, 200, 300: Passive hysteresis current source circuit

[0030] 10: Controller

[0031] 11: Comparator

[0032] 12: Inverting unit

[0033] Q H Upper arm switch

[0034] Q L Lower arm switch

[0035] L: Inductor element

[0036] R: Load

[0037] IN: Input side

[0038] OUT: Output side

[0039] I OUT Output current

[0040] I IN Input current

[0041] V IN Input voltage

[0042] N C Common contact point

[0043] GND: Ground terminal

[0044] V IOUT Current and voltage signals

[0045] V REF Reference voltage signal

[0046] S QH Upper arm switch control signal

[0047] S QL Lower arm switch control signal

[0048] t1, t2, t3: Time

[0049] Q A :switch Detailed Implementation

[0050] The technical content and detailed description of the present invention are explained below in conjunction with the accompanying drawings.

[0051] Please see Figure 2A , Figure 2B as well as Figure 3These are circuit diagrams of the first and second embodiments of the passive hysteresis current source circuit of the present invention, respectively. Specifically, the first embodiment ( Figure 2A and Figure 2B This is a passive hysteresis current source circuit used as a current power supply (also known as a current source), meaning it can stably output a fixed current regardless of changes in load impedance. Figure 2B for Figure 2A The circuit diagram further connects the passive hysteresis current source circuit to the powered load. Second embodiment ( Figure 3 This is a passive hysteresis current source circuit used as a current sink, meaning it can stably absorb a fixed current regardless of changes in the drive power supply voltage. Compared to... Figure 2A and Figure 2B The application of the current power supply shown is as follows: Figure 3 The current load shown is directly grounded on the output side.

[0052] like Figure 2A , Figure 2B and / or Figure 3 As shown, the passive hysteresis current source circuits 100, 200, and 300 include an upper arm switch Q. H Lower arm switch Q L The inductor L and controller 10. The upper arm switch Q... H Also known as a high-side switch, high-edge switch, or lower arm switch. L Also known as a low-side switch, lower arm switch, or simply a low-side switch. L Series connection of upper arm switch Q H At common junction N C This forms the input side IN of the passive hysteresis current source circuits 100, 200, and 300. The upper arm switch Q is located on the input side IN. H Receive input voltage V IN And the lower arm switch Q L Connect to ground (GND). In this embodiment, the input voltage V... IN It can be a DC voltage.

[0053] Inductor L has a first terminal and a second terminal. The first terminal is connected to the common contact N. C The second terminal outputs the output current I flowing through the inductor L. OUT .

[0054] The passive hysteresis current source circuits 100, 200, and 300 are controlled by controller 10. Specifically, controller 10 receives the corresponding output current I. OUT Current and voltage signals V IOUTWith reference voltage signal V REF In other words, the current and voltage signal V IOUT The voltage magnitude corresponds to the output current I. OUT Magnitude of current: Current-voltage signal V IOUT The higher the voltage, the greater the output current I. OUT The larger the current, the greater the voltage signal V; conversely, the smaller the current, the greater the voltage signal V. IOUT The smaller the voltage, the smaller the output current I. OUT The smaller the current, the better. Therefore, controller 10 determines the current based on the current-voltage signal V. IOUT The voltage magnitude allows us to obtain the output current I. OUT The magnitude of the current. Furthermore, the controller 10 further compares the current and voltage signals V. IOUT With reference voltage signal V REF .

[0055] To further explain, based on the reference voltage signal V REF Greater than the current voltage signal V IOUT Controller 10 turns on upper arm switch Q H And turn off the lower arm switch Q L And based on the reference voltage signal V REF Less than the current-voltage signal V IOUT Controller 10 shuts off upper arm switch Q H And the lower arm switch Q is turned on. L To provide a constant output current I OUT .

[0056] like Figure 2A , Figure 2B and / or Figure 3 As shown, upper arm switch Q H It has a first terminal, a second terminal, and a control terminal. Lower arm switch Q L It has a first terminal, a second terminal, and a control terminal. Lower arm switch Q L The first end is connected to the upper arm switch Q H The second end is at the common junction N C The upper arm switch Q H The first terminal receives the input voltage V IN And the lower arm switch Q L The second end is connected to the ground terminal GND.

[0057] right Figure 2A and Figure 2B For a current power supply, the first terminal of the inductor L is connected to the common terminal N. C The second end of the inductor L and the load end form the output side OUT of the current power supply. The load end refers to the terminal used to connect the load. Compared to Figure 2A , Figure 2BIt also shows a load R connected between the output side OUT and the ground terminal GND.

[0058] right Figure 3 For a current load circuit, the first terminal of the inductor L is connected to the common junction N. C The second end of the inductor L and the grounding terminal GND form the output side OUT of the current load, that is, the output side OUT is directly connected to the grounding terminal GND.

[0059] Incidentally, controller 10 provides upper arm switch control signal S QH Control upper arm switch Q H Provides lower arm switch control signal S QL Control lower arm switch Q L The upper arm switch control signal S QH With lower arm switch control signal S QL The signals are complementary in level, i.e., the upper arm switch control signal S. QH When the signal is high, the lower arm switch control signal S QL A low level indicates an active signal; conversely, an active signal indicates an active signal. The upper arm switch control signal S is active. QH When the signal is low, the lower arm switch control signal S QL It is a high level.

[0060] like Figure 2A , Figure 2B and / or Figure 3 As shown, the passive hysteresis current source circuits 100, 200, and 300 of this invention are essentially buck converters. However, unlike existing power converters that control switching elements using pulse-width modulation (PWM), this invention uses a triangular or sawtooth wave as a carrier wave, comparing it with a reference wave to generate a control signal for controlling the switching elements. In this invention, the upper arm switch control signal S provided by the controller 10... QH With lower arm switch control signal S QL The signal is a square wave, meaning this invention uses linear control of a square wave signal to fully turn on or off the upper arm switch control signal S. QH With lower arm switch control signal S QL To ensure the upper arm switch Q H With lower arm switch Q L It can be fully turned on or completely turned off, which is normal and correct operation. Incidentally, since pulse width modulation control requires information about the output voltage to function, this invention uses linear control of a square wave signal (rather than pulse width modulation control), which eliminates the need for additional means or methods to detect the output voltage information, thus simplifying the control architecture and reducing the cost of the circuit.

[0061] Please see Figure 4 The diagram shown is a circuit diagram of the controller of the passive hysteresis current source circuit of the present invention. The controller 10 includes a comparator 11 and an inverting unit 12. The comparator 11 has a first input terminal, a second input terminal, and an output terminal. In this embodiment, the first input terminal receives a reference voltage signal V. REF The second input terminal receives the current and voltage signals V. IOUT However, this is not intended to limit the invention. Comparator 11 compares the reference voltage signal V. REF With current and voltage signal V IOUT Then, the upper arm switch control signal S is output through the output terminal. QH With lower arm switch control signal S QL .

[0062] In this embodiment, comparator 11 is an operational amplifier, with its first input being a non-inverting input and its second input being an inverting input. Therefore, the non-inverting input receives the reference voltage signal V. REF The inverting input receives the current and voltage signals V. IOUT The reference voltage signal V is compared via an operational amplifier. REF With current and voltage signal V IOUT Then, the upper arm switch control signal S is output through the output terminal. QH Furthermore, the inverting unit 12 is connected to the output of the comparator 11 to receive the upper arm switch control signal S. QH And the upper arm switch control signal S QH The level is reversed and changed into the lower arm switch control signal S. QL That is, when the upper arm switch control signal S QH If the signal is high, then after passing through the inverting unit 12, the lower arm switch control signal S... QL When the upper arm switch control signal S is low; conversely, when it is high. QH If the signal is low, then after passing through the inverting unit 12, the lower arm switch control signal S... QL The output is high. However, the description of comparator 11 and inverting unit 12 above is only one embodiment; therefore, the output of comparator 11 can also be used as the lower arm switch control signal S. QL After passing through the inverting unit 12, the upper arm switch control signal S is generated. QH .

[0063] As mentioned above, the upper arm switch control signal S provided by controller 10 QH With lower arm switch control signal S QL Control the upper arm switch Q respectively H With lower arm switch Q LThe complete on / off states of the passive hysteresis current source circuits 100, 200, and 300 ensure that they provide a constant output current I. OUT Therefore, when the reference voltage signal V REF Greater than the current voltage signal V IOUT At that time, the upper arm switch Q H The lower arm switch Q is on. L When the circuit is turned off, the current flowing through the inductor L increases, therefore the output current I... OUT Increase. Conversely, when the reference voltage signal V... REF Less than the current-voltage signal V IOUT At that time, the upper arm switch Q H Off and lower arm switch Q L When the circuit is turned on, the current flowing through the inductor L decreases, therefore the output current I... OUT reduce.

[0064] Therefore, once the set reference voltage signal V REF Fixed, the controller 10 will adjust according to the reference voltage signal V REF With current and voltage signal V IOUT The comparison results control the upper arm switch Q. H With lower arm switch Q L One circuit is fully on, and the other is fully off, thereby adjusting the output current I. OUT Increase or decrease, thereby achieving a constant output current I OUT .

[0065] It is worth mentioning that Figure 2A and Figure 2B The passive hysteresis current source circuits 100 and 200 shown (which are current power supplies) are intended to output a variable output current I. OUT Then, the reference voltage signal V can be adjusted. REF The magnitude of the output current I, in turn, affects the magnitude of the output current I. OUT The output current I is correspondingly changed to a constant value. OUT For example, if the passive hysteresis current source circuit 100 wants to provide a larger constant output current I... OUT Then the reference voltage signal V can be increased. REF And according to the aforementioned reference voltage signal V REF With current and voltage signal V IOUT The comparison results control the upper arm switch Q. H With lower arm switch Q L One circuit is fully on, and the other is fully off, thereby adjusting the output current I. OUT To achieve a constant output current I OUT .

[0066] also, Figure 3The passive hysteresis current source circuit 300 shown (which is a current load) is intended to absorb (deload) a changing output current I. OUT Then, the reference voltage signal V can be adjusted. REF The magnitude of the output current I, in turn, affects the magnitude of the output current I. OUT The output current I is correspondingly changed to a constant value. OUT For example, if the passive hysteresis current source circuit 200 wants to provide a larger constant output current I... OUT Then the reference voltage signal V can be increased. REF And according to the aforementioned reference voltage signal V REF With current and voltage signal V IOUT The comparison results control the upper arm switch Q. H With lower arm switch Q L One circuit is fully on, and the other is fully off, thereby adjusting the output current I. OUT To achieve a constant output current I OUT .

[0067] Please see Figure 5 As shown, it is a schematic waveform diagram of the reference voltage signal, current voltage signal, upper arm switch control signal, output current, and input current of the passive hysteresis current source circuit of the present invention. Figure 5 As shown, the first column illustrates the reference voltage signal V. REF With current and voltage signal V IOUT The waveform diagram; the second column shows the upper arm switch control signal S. QH The waveform diagram; the third column shows the output current I. OUT The waveform diagram; the fourth column shows the input current I. IN The waveform diagram. Referring to the previous explanation, during time t1 to time t2, assume the reference voltage signal V... REF When set to 2.70 volts (but not limited thereto), the comparator 11 of the controller 10 will compare the reference voltage signal V. REF With current and voltage signal V IOUT If the reference voltage signal V REF Greater than the current voltage signal V IOUT At that time, the upper arm switch Q H The lower arm switch Q is on. L When the circuit is turned off, the current flowing through inductor L increases (because inductor L is charging), thus increasing the output current I. OUT Increase; conversely, if the reference voltage signal V REF Less than the current-voltage signal V IOUT At that time, the upper arm switch Q H Off and lower arm switch Q L When the circuit is turned on, the current flowing through the inductor L decreases (because the inductor L discharges), hence the output current I...OUT Reduced. Therefore, the upper arm switch Q... H With lower arm switch Q L Alternating on and off states create periodic switching, achieving a constant output current I. OUT That is, ensure the output current I OUT The current fluctuates around the target current value without deviating from the hysteresis range (i.e., the hysteresis range limits the amplitude of the current fluctuation), which in this embodiment is approximately 30 amperes.

[0068] Furthermore, to accommodate the larger output current I from the passive hysteresis current source circuits 100 and 200 (which are current power supplies), OUT When required, or in response to a larger output current I being drawn from the passive hysteresis current source circuit 300 (which is a current load circuit). OUT When required, at time t2, the reference voltage signal V... REF When adjusted to a larger 3.00 volt, controller 10 will continuously output a high-level upper arm switch control signal S. QH To control the upper arm switch Q H The circuit remains continuously on, thus causing the output current I to... OUT Gradually increase. At this time, the current and voltage signals V IOUT The output current I will also increase accordingly until it reaches a constant value. OUT In this embodiment, the current is approximately 60 amperes. The operation of the controller 10 during the process can be found in the preceding description and will not be repeated here.

[0069] Similarly, if the passive hysteresis current source circuits 100 and 200 (which are current power supplies) output a relatively small output current I... OUT When needed, or in response to a small output current I being drawn from the passive hysteresis current source circuit 300 (which is a current load circuit). OUT When required, at time t3, the reference voltage signal V... REF When adjusted back to a smaller 2.70 volts, controller 10 will continuously output a low-level upper arm switch control signal S. QH To control the upper arm switch Q H The continuous shutdown causes the output current I to be reduced. OUT Gradually decrease. At this time, the current and voltage signals V IOUT The output current I will also decrease accordingly until it reaches a constant value. OUT In this embodiment, the current is approximately 30 amperes. The operation of the controller 10 during the process can be found in the preceding description and will not be repeated here.

[0070] However, the constant current of 30 amps or 60 amps mentioned above is not intended to limit the present invention. It can be adjusted and set according to the desired output current of the passive hysteresis current source circuit 100, 200 (as a current power supply) or the desired current to be drawn from the passive hysteresis current source circuit 300 (as a current load) (i.e., the dynamic current needs to be constant) to achieve a constant output current I. OUT The purpose.

[0071] Incidentally, due to the limitations of the switching elements, complete turn-on and turn-off cannot be achieved at high speeds (e.g., microseconds, nanoseconds). Therefore, to ensure the upper arm switch Q... H With lower arm switch Q L Being able to operate under normal on and off conditions (rather than operating in the ohmic region between full on and full off), this invention, through the transient response capability of the inductor element L to current, can provide a suitable solution for the upper arm switch Q. H With lower arm switch Q L It provides hysteresis-based on / off switching and can reduce power loss to improve efficiency.

[0072] Incidentally, when the passive hysteresis current source circuit 200 is used as a current power supply, it can be used in conjunction with a diode (not shown in the figure). This diode is positioned between the output side OUT of the passive hysteresis current source circuit 200 and the ground terminal GND, i.e., between the inductor L and the ground terminal GND, to enable the current power supply to provide a stable output current I. OUT Applications.

[0073] In summary, the passive hysteresis current source circuit provided by this invention has the following features and advantages:

[0074] 1. By using simple passive components and two switches, the effect of passive hysteresis can be achieved.

[0075] 2. The passive hysteresis current source circuit of the present invention can be used as a current power supply and a current load.

[0076] 3. The controller has a simple circuit structure, mainly relying on comparators and basic logic circuits.

[0077] 4. Hysteresis control adjusts the switching state immediately according to the current current, which is suitable for applications where the output current changes rapidly.

[0078] 5. The energy storage function of the inductor and the stability characteristics of hysteresis control ensure a constant output current.

[0079] 6. This invention uses linear control of square wave signals (rather than pulse width modulation control), so there is no need to use additional means or methods to detect output voltage information, which simplifies the control architecture and cost of the circuit.

[0080] 7. The passive hysteresis current source circuit operates in the ohmic region to reduce power loss and improve efficiency.

[0081] The above description is merely a detailed description and accompanying drawings of preferred embodiments of the present invention. However, the features of the present invention are not limited thereto and are not intended to limit the present invention. The entire scope of the present invention should be determined by the following claims. All embodiments that conform to the spirit of the claims of the present invention and similar variations thereof should be included in the scope of the present invention. Any variations or modifications that can be easily conceived by those skilled in the art within the field of the present invention can be covered by the following claims.

Claims

1. A passive hysteresis current source circuit, comprising: Upper arm switch; The lower arm switch is connected in series with the upper arm switch to form an input side through a common contact point, wherein the upper arm switch receives the input voltage and the lower arm switch is connected to the ground terminal; An inductor has a first terminal and a second terminal, the first terminal being connected to the common contact point, and the second terminal outputting the output current flowing through the inductor. as well as The controller receives a current-voltage signal corresponding to the output current and a reference voltage signal, and compares the current-voltage signal with the reference voltage signal. When the reference voltage signal is greater than the current voltage signal, the controller turns on the upper arm switch and turns off the lower arm switch; when the reference voltage signal is less than the current voltage signal, the controller turns off the upper arm switch and turns on the lower arm switch to provide a constant output current.

2. The passive hysteresis current source circuit according to claim 1, wherein... The upper arm switch has a first end, a second end, and a control end; The lower arm switch has a first terminal, a second terminal, and a control terminal. The first terminal of the lower arm switch is connected to the second terminal of the upper arm switch at the common contact point. The first terminal of the upper arm switch receives the input voltage, and the second terminal of the lower arm switch is connected to the ground terminal. The second end of the inductor and the load end form the output side of the current power supply.

3. The passive hysteresis current source circuit according to claim 1, wherein... The upper arm switch has a first end, a second end, and a control end; The lower arm switch has a first terminal, a second terminal, and a control terminal. The first terminal of the lower arm switch is connected to the second terminal of the upper arm switch at the common contact point. The first terminal of the upper arm switch receives the input voltage, and the second terminal of the lower arm switch is connected to the ground terminal. The second end of the inductor and the ground end form the output side of the current load.

4. The passive hysteresis current source circuit according to claim 1, wherein the output current can be changed accordingly in response to the adjustment of the reference voltage signal.

5. The passive hysteresis current source circuit according to claim 1, wherein the controller provides an upper arm switch control signal to control the upper arm switch and provides a lower arm switch control signal to control the lower arm switch.

6. The passive hysteresis current source circuit according to claim 5, wherein the upper arm switch control signal and the lower arm switch control signal are square wave signals to fully turn on or completely turn off the upper arm switch and the lower arm switch.

7. The passive hysteresis current source circuit according to claim 5, wherein the upper arm switch control signal and the lower arm switch control signal are level complementary signals.

8. The passive hysteresis current source circuit according to claim 5, wherein the controller comprises: A comparator has a first input terminal, a second input terminal, and an output terminal; The first input terminal receives the reference voltage signal, and the second input terminal receives the current and voltage signals; The comparator compares the reference voltage signal with the current voltage signal, and then outputs the upper arm switch control signal and the lower arm switch control signal through the output terminal.

9. The passive hysteresis current source circuit according to claim 8, wherein the comparator is an operational amplifier.

10. The passive hysteresis current source circuit according to claim 8, wherein the comparator further comprises: The inverting unit is connected to the output terminal of the comparator, receives the upper arm switch control signal, and inverts the level of the upper arm switch control signal to change it into the lower arm switch control signal.

11. The passive hysteresis current source circuit according to claim 1, wherein the output current increases when the reference voltage signal is greater than the current voltage signal; and the output current decreases when the reference voltage signal is less than the current voltage signal.

12. The passive hysteresis current source circuit according to claim 1, wherein the inductor provides hysteretic on and off of the upper arm switch and the lower arm switch.

13. The passive hysteresis current source circuit according to claim 2, wherein the output side is connected to The load is connected between the output side and the ground.

14. The passive hysteresis current source circuit according to claim 3, wherein the output side is directly connected to the ground terminal.

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