Current limiting circuits capable of adjusting current limiting value

1. A current limiting circuit, comprising:

a first voltage terminal;

a second voltage terminal;

a first transistor comprising an input terminal and an output terminal of the first transistor that are connected in series on a path formed by the first voltage terminal and the second voltage terminal;

a current limiting module electrically connected to a control terminal of the first transistor;

a boost unit, wherein a first terminal of the boost unit is electrically connected to the first voltage terminal, and a second terminal of the boost unit is electrically connected to the input terminal of the first transistor;

a variable voltage unit, wherein a first terminal of the variable voltage unit is electrically connected to the first voltage terminal;

a first comparison unit, wherein a first terminal of the first comparison unit is electrically connected to a second terminal of the variable voltage unit, a second terminal of the first comparison unit is electrically connected to the input terminal of the first transistor, and

a constant current unit, wherein a third terminal of the first comparison unit is electrically connected to a first terminal of the constant current unit, and a second terminal of the constant current unit is electrically connected to the control terminal of the first transistor;

wherein the current limiting module is configured to output a control signal to the control terminal of the first transistor for controlling a state of the first transistor so that a current limiting value of the current limiting circuit is adjustable,

wherein the boost unit is configured to cause a voltage at the second terminal of the boost unit to be higher than a voltage at the first terminal of the boost unit, the variable voltage unit is configured to output a variable voltage, the first comparison unit is configured to output a constant-current-unit control signal at the third terminal of the first comparison unit based on a voltage at the first terminal of the first comparison unit and a voltage at the second terminal of the first comparison unit, and the constant current unit is controlled by the constant-current-unit control signal to output a constant current.

2. The current limiting circuit of claim 1 , wherein the boost unit comprises an inductor, a second transistor, and a diode, and

wherein, a first terminal of the inductor is electrically connected to the first voltage terminal, a second terminal of the inductor and a first terminal of the second transistor are electrically connected to a first terminal of the diode, a second terminal of the diode is electrically connected to the input terminal of the first transistor, and a second terminal of the second transistor is electrically connected to a ground terminal.

3. The current limiting circuit of claim 2 , wherein the current limiting value of the current limiting circuit is obtained according to a formula:

I =( V 1− V 2)/ R , and

wherein I represents the current limiting value of the current limiting circuit, V1 represents a voltage value set by the variable voltage unit, V2 represents a voltage drop value of the diode, and R represents an impedance value of the inductor.

4. The current limiting circuit of claim 1 , wherein the variable voltage unit comprises a variable voltage source,

wherein a first terminal of the variable voltage source is electrically connected to the first voltage terminal, and a second terminal of the variable voltage source is electrically connected to the first terminal of the first comparison unit.

5. The current limiting circuit of claim 1 , wherein the first comparison unit comprises a first comparator, and

wherein a first terminal of the first comparator is electrically connected to the second terminal of the variable voltage unit, a second terminal of the first comparator is electrically connected to the input terminal of the first transistor, and a third terminal of the first comparator is electrically connected to the first terminal of the constant current unit.

6. The current limiting circuit of claim 1 , wherein the constant current unit comprises a constant current source, and

wherein a first terminal of the constant current source is electrically connected to the third terminal of the first comparison unit, a second terminal of the constant current source is electrically connected to the control terminal of the first transistor, and a third terminal of the constant current source is electrically connected to a ground terminal.

7. The current limiting circuit of claim 1 , further comprising a timing unit and a second comparison unit,

wherein the timing unit is electrically connected to a first terminal of the second comparison unit, a second terminal of the second comparison unit is electrically connected to the second voltage terminal, a third terminal of the second comparison unit receives a constant voltage signal, and a fourth terminal of the second comparison unit is electrically connected to the control terminal of the first transistor,

wherein the timing unit is configured to output a comparison-unit control signal at intervals with a preset time,

wherein the second comparison unit is controlled by the comparison-unit control signal to output a first-transistor control signal of the first transistor at the fourth terminal of the second comparison unit to the control terminal of the first transistor based on a voltage at the second terminal of the second comparison unit and a voltage at the third terminal of the second comparison unit.

8. The current limiting circuit of claim 7 , wherein the timing unit comprises a timer, wherein the timer is electrically connected to the first terminal of the second comparison unit.

9. The current limiting circuit of claim 7 , wherein the second comparison unit comprises a second comparator,

wherein a first terminal of the second comparator is electrically connected to the timing unit, a second terminal of the second comparator is electrically connected to the second voltage terminal, a third terminal of the second comparator receives the constant voltage signal, and a fourth terminal of the second comparator is electrically connected to the control terminal of the first transistor.

10. The current limiting circuit of claim 7 , wherein a voltage value of the constant voltage signal is in a range between 0.85 times a voltage value of the first voltage terminal and 0.9 times the voltage value of the first voltage terminal.

11. The current limiting circuit of claim 1 , further comprising a first capacitor, a second capacitor, a third capacitor, and a resistor,

wherein a first terminal of the first capacitor is electrically connected to the first voltage terminal, a first terminal of the second capacitor is electrically connected to the input terminal of the first transistor, a first terminal of the third capacitor and a first terminal of the resistor are electrically connected to the second voltage terminal, and a second terminal of the first capacitor, a second terminal of the second capacitor, a second terminal of the third capacitor, and a second terminal of the resistor are electrically connected to a ground terminal.

12. A current limiting circuit, comprising:

a first voltage terminal;

a second voltage terminal;

a first transistor comprising an input terminal and an output terminal of the first transistor that are connected in series on a path formed by the first voltage terminal and the second voltage terminal;

a current limiting module electrically connected to a control terminal of the first transistor;

a boost unit, wherein a first terminal of the boost unit is electrically connected to the first voltage terminal, and a second terminal of the boost unit is electrically connected to the input terminal of the first transistor;

a variable voltage unit, wherein a first terminal of the variable voltage unit is electrically connected to the first voltage terminal;

a first comparison unit, wherein a first terminal of the first comparison unit is electrically connected to a second terminal of the variable voltage unit, a second terminal of the first comparison unit is electrically connected to the input terminal of the first transistor, and

a constant current unit, wherein a third terminal of the first comparison unit is electrically connected to a first terminal of the constant current unit, and a second terminal of the constant current unit is electrically connected to the control terminal of the first transistor;

a first capacitor, electrically connected between a first terminal to the first voltage terminal and a ground terminal;

a second capacitor, electrically connected between the input terminal of the first transistor and the ground terminal;

a third capacitor, electrically connected between the second voltage terminal and the ground terminal; and

a resistor, electrically connected between the second voltage terminal and the ground terminal;

wherein the current limiting module is configured to output a control signal to the control terminal of the first transistor for controlling a state of the first transistor so that a current limiting value of the current limiting circuit is adjustable, and

wherein the boost unit is configured to cause a voltage at the second terminal of the boost unit to be higher than a voltage at the first terminal of the boost unit, the variable voltage unit is configured to output a variable voltage, the first comparison unit is configured to output a constant-current-unit control signal at the third terminal of the first comparison unit based on a voltage at the first terminal of the first comparison unit and a voltage at the second terminal of the first comparison unit, and the constant current unit is controlled by the constant-current-unit control signal to output a constant current.

13. The current limiting circuit of claim 12 , wherein the boost unit comprises an inductor, a second transistor, and a diode, and

wherein, a first terminal of the inductor is electrically connected to the first voltage terminal, a second terminal of the inductor and a first terminal of the second transistor are electrically connected to a first terminal of the diode, a second terminal of the diode is electrically connected to the input terminal of the first transistor, and a second terminal of the second transistor is electrically connected to the ground terminal.

14. The current limiting circuit of claim 13 , wherein the current limiting value of the current limiting circuit is obtained according to a formula:

I =( V 1− V 2)/ R , and

wherein I represents the current limiting value of the current limiting circuit, V1 represents a voltage value set by the variable voltage unit, V2 represents a voltage drop value of the diode, and R represents an impedance value of the inductor.

15. The current limiting circuit of claim 12 , wherein the variable voltage unit comprises a variable voltage source,

wherein a first terminal of the variable voltage source is electrically connected to the first voltage terminal, and a second terminal of the variable voltage source is electrically connected to the first terminal of the first comparison unit.

16. The current limiting circuit of claim 12 , wherein the first comparison unit comprises a first comparator, and

wherein a first terminal of the first comparator is electrically connected to the second terminal of the variable voltage unit, a second terminal of the first comparator is electrically connected to the input terminal of the first transistor, and a third terminal of the first comparator is electrically connected to the first terminal of the constant current unit.

17. The current limiting circuit of claim 12 , wherein the constant current unit comprises a constant current source, and

wherein a first terminal of the constant current source is electrically connected to the third terminal of the first comparison unit, a second terminal of the constant current source is electrically connected to the control terminal of the first transistor, and a third terminal of the constant current source is electrically connected to the ground terminal.

18. The current limiting circuit of claim 12 , further comprising a timing unit and a second comparison unit,

wherein the timing unit is electrically connected to a first terminal of the second comparison unit, a second terminal of the second comparison unit is electrically connected to the second voltage terminal, a third terminal of the second comparison unit receives a constant voltage signal, and a fourth terminal of the second comparison unit is electrically connected to the control terminal of the first transistor,

wherein the timing unit is configured to output a comparison-unit control signal at intervals with a preset time,

wherein the second comparison unit is controlled by the comparison-unit control signal to output a first-transistor control signal of the first transistor at the fourth terminal of the second comparison unit to the control terminal of the first transistor based on a voltage at the second terminal of the second comparison unit and a voltage at the third terminal of the second comparison unit.

19. The current limiting circuit of claim 18 , wherein the timing unit comprises a timer electrically connected to the first terminal of the second comparison unit, and the second comparison unit comprises a second comparator, wherein a first terminal of the second comparator is electrically connected to the timing unit, a second terminal of the second comparator is electrically connected to the second voltage terminal, a third terminal of the second comparator receives the constant voltage signal, and a fourth terminal of the second comparator is electrically connected to the control terminal of the first transistor.