CN216390503U - Current-limiting sampling circuit and electrical equipment - Google Patents
Current-limiting sampling circuit and electrical equipment Download PDFInfo
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- CN216390503U CN216390503U CN202122449731.2U CN202122449731U CN216390503U CN 216390503 U CN216390503 U CN 216390503U CN 202122449731 U CN202122449731 U CN 202122449731U CN 216390503 U CN216390503 U CN 216390503U
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Abstract
The application discloses current-limiting sampling circuit and electrical equipment, current-limiting sampling circuit, including the control unit, first resistance branch road, the second resistance branch road, the third resistance branch road, first switch branch road and second switch branch road, first switch branch road, the second resistance branch road, variable resistance branch road is constituteed with the third resistance branch road to the second switch branch road, first switch branch road is configured to switch on or break off according to the first control signal of control unit output, with the resistance that changes the second resistance branch road and insert variable resistance branch road, the second switch branch road is configured to switch on or break off according to the second control signal of control unit output, with the resistance that changes the third resistance branch road and insert variable resistance branch road. By the above method, the accuracy of the arrangement of the current limiting points can be improved.
Description
Technical Field
The application relates to the technical field of electronic circuits, in particular to a current-limiting sampling circuit and electrical equipment.
Background
Along with the diversification of the requirements of people on the types of household electrical appliances, the functions of the household electrical appliances are more and more abundant, so that the design requirements on the circuit boards in the household electrical appliances are higher and higher. In order to reduce the cost, each appliance brand supplier usually selects a circuit board to drive different loads, and different loads usually need to be configured with different current limiting points, which are referred to as current limiting points for short. The circuit for configuring and sampling the current-limiting point is a current-limiting sampling circuit. At present, a MOS transistor is often disposed in a common current-limiting sampling circuit.
However, the MOS transistor has an on-resistance, which varies with temperature, and thus affects the current-limiting point, resulting in a low accuracy of the current-limiting point.
SUMMERY OF THE UTILITY MODEL
The embodiment of the application aims to provide a current-limiting sampling circuit and electrical equipment, and the configuration precision of a current-limiting point can be improved.
To achieve the above object, in a first aspect, the present application provides a current-limiting sampling circuit, including:
the circuit comprises a control unit, a first resistance branch circuit, a second resistance branch circuit, a third resistance branch circuit, a first switch branch circuit and a second switch branch circuit;
the first end of the first switch branch, the first end of the first resistance branch, the first end of the second resistance branch and the first end of the second switch branch are all connected with the first end of a driving power supply, the second end of the first switch branch is connected with the second end of the second resistance branch, and the third end of the first switch branch is connected with the control unit;
the third end of the second resistance branch is respectively connected with the second end of the driving power supply, the second end of the second switch branch and the first end of the third resistance branch;
the third end of the second switch branch circuit is connected with the second end of the third resistance branch circuit, and the fourth end of the second switch branch circuit is connected with the control unit;
the second end of the first resistance branch is connected with the third end of the third resistance branch;
the first switch branch, the second resistance branch, the second switch branch and the third resistance branch form a variable resistance branch, the first switch branch is configured to be switched on or switched off according to a first control signal output by the control unit to change the resistance of the second resistance branch switched in the variable resistance branch, and the second switch branch is configured to be switched on or switched off according to a second control signal output by the control unit to change the resistance of the third resistance branch switched in the variable resistance branch.
In an alternative mode, the first resistance branch comprises a first resistance;
the first end of the first resistor is connected with the first end of the driving power supply, and the second end of the first resistor is connected with the third end of the third resistor branch.
In an optional mode, the second resistance branch comprises a second resistance and a third resistance;
the first end of the second resistor is connected with the second end of the first switch branch circuit, the second end of the second resistor is connected with the first end of the third resistor branch circuit, the second end of the second switch branch circuit and the first end of the third resistor, and the second end of the third resistor is connected with the first end of the driving power supply.
In an optional manner, the third resistive branch includes a fourth resistor and a fifth resistor;
the first end of the fourth resistor is connected with the third end of the second resistor branch and the second end of the second switch branch, the second end of the fourth resistor is connected with the first end of the fifth resistor and the second end of the driving power supply, and the second end of the fifth resistor is connected with the third end of the second switch branch.
In an optional manner, the first switching branch includes a first switching unit and a second switching unit;
the first end of the first switch unit is connected with the control unit, the second end of the first switch unit is connected with the first end of the second switch unit, the third end of the first switch unit is grounded, the second end of the second switch unit is connected with the second end of the second resistance branch, and the third end of the second switch unit is connected with the first end of the driving power supply;
the first switching unit is configured to be turned on or off according to the first control signal;
the second switching unit is configured to be turned on according to the turning-on of the first switching unit and to be turned off according to the turning-off of the first switching unit.
In an alternative mode, the first switching unit includes a first switching tube;
the first end of the first switch tube is connected with the control unit, the second end of the first switch tube is grounded, and the third end of the first switch tube is connected with the second switch unit.
In an optional mode, the second switch unit includes a second switch tube, a sixth resistor and a seventh resistor;
the first end of the sixth resistor is connected with the second end of the first switch unit, the second end of the sixth resistor is connected with the first end of the seventh resistor and the first end of the second switch tube, the second end of the seventh resistor is connected with the second end of the second switch tube and the first end of the driving power supply, and the third end of the second switch tube is connected with the second end of the second resistor branch.
In an optional manner, the second switching branch includes a third switching unit and a fourth switching unit;
the first end of the third switching unit is connected with the control unit, the second end of the third switching unit is grounded, the third end of the third switching unit is connected with the first end of the fourth switching unit, the second end of the fourth switching unit is connected with the third end of the second resistance branch and the second end of the driving power supply, the third end of the fourth switching unit is connected with the second end of the third resistance branch, and the fourth end of the fourth switching unit is connected with the first end of the driving power supply;
the third switching unit is configured to be turned on or off according to the second control signal;
the fourth switching unit is configured to be turned on according to the turning-on of the third switching unit and to be turned off according to the turning-off of the third switching unit.
In an alternative mode, the third switching unit includes a third switching tube;
the first end of the third switching tube is connected with the control unit, the second end of the third switching tube is grounded, and the third end of the third switching tube is connected with the first end of the fourth switching unit.
In an optional mode, the fourth switching unit comprises a fourth switching tube, an eighth resistor and a ninth resistor;
the first end of the eighth resistor is connected with the third end of the third switch unit, the second end of the eighth resistor is connected with the first end of the ninth resistor and the first end of the fourth switch tube, the second end of the ninth resistor is connected with the first end of the driving power supply, the second end of the fourth switch tube is connected with the third end of the second resistor branch, and the third end of the fourth switch tube is connected with the second end of the third resistor branch.
In a second aspect, the present application provides an electrical device, which includes a driving chip and the current-limiting sampling circuit as described above, where the driving chip is configured to provide a driving power supply for the current-limiting sampling circuit.
The beneficial effects of the embodiment of the application are that: the application provides a current-limiting sampling circuit, including the control unit, first resistance branch road, second resistance branch road, third resistance branch road, first switch branch road and second switch branch road. The first switch branch circuit, the second resistance branch circuit, the second switch branch circuit and the third resistance branch circuit form a variable resistance branch circuit, the first switch branch circuit is configured to be switched on or switched off according to a first control signal output by the control unit so as to change the resistance of the second resistance branch circuit connected to the variable resistance branch circuit, and the second switch branch circuit is configured to be switched on or switched off according to a second control signal output by the control unit so as to change the resistance of the third resistance branch circuit connected to the variable resistance branch circuit. Therefore, because the influence of the temperature on the conduction internal resistance of the two switch branches is basically the same, the influence of the temperature on the conduction internal resistance can be reduced by matching the two switch branches and the two resistance branches, and the configuration precision of the current limiting point can be improved.
Drawings
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.
Fig. 1 is a schematic circuit diagram of a current-limiting sampling circuit in the related art;
fig. 2 is a schematic structural diagram of a current-limiting sampling circuit according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a current-limiting sampling circuit according to another embodiment of the present disclosure;
fig. 4 is a schematic circuit structure diagram of a current-limiting sampling circuit according to an embodiment of the present disclosure.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, fig. 1 is a circuit structure diagram of a current-limiting sampling circuit in the related art. As shown in FIG. 1, the circuit can realize the configuration of two different sampling resistors by controlling the on or off of the MOS transistor Q10 so as to configure two different current-limiting points. Specifically, when the MOS transistor Q10 is turned on, the resistor R10 is connected in parallel with the resistor R11, and a first current limiting value can be obtained by calculating a ratio between a voltage between the port V + and the port V-and a resistance after the resistor R10 is connected in parallel with the resistor R11. When the MOS transistor Q10 is turned off, a second current limit value can be obtained by calculating the ratio between the voltage at the port V + and the port V-and the resistor R10.
In the process of implementing the present application, the inventors of the present application found that: since the MOS transistor Q10 has on-resistance, the on-resistance varies with temperature. When the on-resistance is not negligible with respect to the resistance of the resistor R11 and the resistance of the resistor R10, the sampling resistance is deviated, and the accuracy of the arrangement of the current-limiting point is low. On the other hand, if the MOS transistor Q10 with smaller on-resistance is selected, the cost is higher, and the size of the device is increased.
Based on this, the application provides a current-limiting sampling circuit. In the circuit, the variable resistance branch circuit is arranged and comprises two switch branch circuits and two resistance branch circuits, and because the influence of the temperature on the conduction internal resistance of the two switch branch circuits is basically the same, the influence of the temperature on the conduction internal resistance can be reduced by matching the two switch branch circuits and the two resistance branch circuits, so that the configuration precision of the current limiting point can be improved.
As shown in fig. 2, the current-limiting sampling circuit includes a first resistive branch 10, a second resistive branch 20, a third resistive branch 30, a first switching branch 40, a second switching branch 50, and a control unit 60. The first end of the first switch branch 40, the first end of the first resistance branch 10, the first end of the second resistance branch 20, and the first end of the second switch branch 50 are all connected to the first end of the driving power VIN, the second end of the first switch branch 40 is connected to the second end of the second resistance branch 20, the third end of the first switch branch 40 is connected to the control unit 60, the third end of the second resistance branch 20 is connected to the second end of the driving power VIN, the second end of the second switch branch 50, and the first end of the third resistance branch 30, the third end of the second switch branch 50 is connected to the second end of the third resistance branch 30, the fourth end of the second switch branch 50 is connected to the control unit 60, and the second end of the first resistance branch 10 is connected to the third end of the third resistance branch 30. The driving power source VIN may be a voltage source outputting a constant voltage.
The first switching branch 40, the second resistive branch 20, the second switching branch 50 and the third resistive branch 30 form a variable resistive branch. The first switching branch 40 is configured to be turned on or off according to a first control signal output by the control unit 60 to change the resistance of the second resistive branch 20 accessing the variable resistive branch, and the second switching branch 50 is configured to be turned on or off according to a second control signal output by the control unit 60 to change the resistance of the third resistive branch 30 accessing the variable resistive branch.
Specifically, the first switching branch 40 and the second switching branch 50 are both controlled by the control unit 60. The first control signal output by the control unit 60 controls the first switching branch 40 to be switched on or off to change the resistance of the second resistive branch 20 accessing the variable resistive branch. That is, when the first switching branch 40 is turned on, the resistance of the second resistive branch 20 accessing the variable resistive branch is different from the resistance of the second resistive branch 20 accessing the variable resistive branch when the first switching branch 40 is turned off. Likewise, the second control signal outputted by the control unit 60 controls the second switching branch 50 to be turned on or off to change the resistance of the third resistive branch 30 accessing the variable resistive branch. Therefore, since the resistance of the second resistance branch 20 or the third resistance branch 30 accessing the variable resistance branch can be changed, the resistances of the variable resistance branches with different sizes can be obtained, and the driving power source VIN is not changed, so that a plurality of current limiting points can be obtained. Meanwhile, when the temperature changes, the influence on the first switching branch 40 and the second switching branch 50 is nearly the same, that is, the change of the resistance of the second resistance branch 20 or the third resistance branch 30 accessing the variable resistance branch can be considered to be the same, so that the influence of the temperature on the precision of the current limiting point (i.e. the current limiting point) can be reduced, and the configuration precision of the current limiting point can be improved.
In an embodiment, please refer to fig. 2 and fig. 3, the first switching branch 40 includes a first switching unit 41 and a second switching unit 42. A first end of the first switch unit 41 is connected to the control unit 60, a second end of the first switch unit 41 is connected to a first end of the second switch unit 42, a third end of the first switch unit 41 is grounded GND, a second end of the second switch unit 42 is connected to a second end of the second resistive branch 20, and a third end of the second switch unit 42 is connected to a first end of the driving power VIN, a first end of the first resistive branch 10, and a first end of the second resistive branch 20.
The first switching unit 41 is configured to be turned on or off according to a first control signal. The second switching unit 42 is configured to be turned on according to the turn-on of the first switching unit 41 and to be turned off according to the turn-off of the first switching unit 41.
Specifically, the first switching unit 41 is turned on or off according to the first control signal output by the control unit 60. The second switching unit 42 is turned on according to the turning-on of the first switching unit 41 and turned off according to the turning-off of the first switching unit 41. For example, in one embodiment, when the first switch unit 41 is turned on, the second switch unit 42 is turned on, and when the first switch unit 41 is turned off, the second switch unit 42 is turned off, so that the resistance of the second resistance branch 20 accessing the variable resistance branch can be changed.
In an embodiment, referring to fig. 4 in combination with fig. 3, the first switch unit 41 includes a first switch tube Q1. A first end of the first switch tube Q1 is connected to the control unit 60 through the interface S1, a second end of the first switch tube Q1 is grounded to GND, and a third end of the first switch tube Q1 is connected to the second switch unit 42. In this embodiment, the first switch Q1 is an NPN transistor.
In one embodiment, the second switch unit 42 includes a second switch transistor Q2, a sixth resistor R6, and a seventh resistor R7. A first end of the sixth resistor R6 is connected to the second end of the first switch unit 41, a second end of the sixth resistor R6 is connected to a first end of the seventh resistor R7 and a first end of the second switch tube Q2, a second end of the seventh resistor R7 is connected to a second end of the second switch tube Q2 and the interface V1, and a third end of the second switch tube Q2 is connected to a second end of the second resistor branch 20. The interface V1 is connected to a first end of the driving power VIN, the interface V2 is connected to a second end of the driving power VIN, the current I1 is a current flowing through the first resistor R1, and the interface VOUT is used for outputting a voltage. In this embodiment, the second switching transistor Q2 is taken as PMOS as an example. The sixth resistor R6 and the seventh resistor R7 are used for dividing voltage to provide a conducting voltage for the second switch Q2, and the sixth resistor R6 can also be used for limiting current to limit current at the first end of the second switch Q2.
In this embodiment, the first control signal output by the control unit 60 is transmitted to the first switch tube Q1 through the interface S1. If the control unit 60 controls the first switch Q1 to be turned on, the first terminal of the second switch Q2 is grounded, and since the second terminal of the second switch Q2 is connected to the driving power VIN through the interface V1, the second switch Q2 is turned on. Conversely, if the control unit 60 controls the first switching tube Q1 to be turned off, the second switching tube Q2 is also turned off.
It should be noted that, in the embodiment of the present application, any switching tube may be a switching device such as a triode, an MOS tube, or an IGBT switching tube, and each switching tube may be the same or different. Specifically, the first switching tube Q1 is taken as an example.
If the first switch tube Q1 is a triode, the base of the triode is the first end of the first switch tube Q1, the emitter of the triode is the second end of the first switch tube Q1, and the collector of the triode is the third end of the first switch tube Q1.
If the first switch transistor Q1 is an MOS transistor, the gate of the MOS transistor is the first end of the first switch transistor Q1, the source of the MOS transistor is the second end of the first switch transistor Q1, and the drain of the MOS transistor is the third end of the first switch transistor Q1.
If the first switch tube Q1 is an IGBT switch tube, the gate of the IGBT switch tube is the first end of the first switch tube Q1, the emitter of the IGBT switch tube is the second end of the first switch tube Q1, and the collector of the IGBT switch tube is the third end of the first switch tube Q1.
In an embodiment, referring to fig. 3 again, the second switching branch 50 includes a third switching unit 51 and a fourth switching unit 52. The first end of the third switching unit 51 is connected to the control unit 60, the second end of the third switching unit 51 is grounded GND, the third end of the third switching unit 51 is connected to the first end of the fourth switching unit 52, the second end of the fourth switching unit 52 is connected to the third end of the second resistive branch 20 and the second end of the driving power supply VIN, the third end of the fourth switching unit 52 is connected to the second end of the third resistive branch 30, and the fourth end of the fourth switching unit 52 is connected to the first end of the driving power supply VIN.
The third switching unit 51 is configured to be turned on or off according to the second control signal, and the fourth switching unit 52 is configured to be turned on according to the turn-on of the third switching unit 51 and turned off according to the turn-off of the third switching unit 51.
Specifically, the third switching unit 51 is turned on or off according to the second control signal output by the control unit 60. The fourth switching unit 52 is turned on according to the turning-on of the third switching unit 51 and turned off according to the turning-off of the third switching unit 51. For example, in one embodiment, the third switching unit 51 is turned on, and the fourth switching unit 52 is turned on; and the third switching unit 51 is turned off, the fourth switching unit 52 is turned off. Thus, the resistance of the third resistive branch 30 into the variable resistive branch may be varied.
In an embodiment, referring to fig. 4 in combination with fig. 3, the third switching unit 51 includes a third switching tube Q3. A first end of the third switching tube Q3 is connected to the control unit 60 through the interface S2, a second end of the third switching tube Q3 is grounded GND, and a third end of the third switching tube Q3 is connected to a first end of the fourth switching unit 52. In this embodiment, the third switching transistor Q3 is an NPN transistor.
In one embodiment, the fourth switching unit 52 includes a fourth switching transistor Q4, an eighth resistor R8, and a ninth resistor R9. A first end of the eighth resistor R8 is connected to a third end of the third switching unit 51, a second end of the eighth resistor R8 is connected to a first end of the ninth resistor R9 and a first end of the fourth switching tube Q4, a second end of the ninth resistor R9 is connected to the first end of the driving power VIN, a second end of the fourth switching tube Q4 is connected to a third end of the second resistor branch 20, and a third end of the fourth switching tube Q4 is connected to a second end of the third resistor branch 30. In this embodiment, the fourth switching transistor Q4 is taken as PMOS as an example. The eighth resistor R8 and the ninth resistor R9 are used for dividing voltage to provide a conducting voltage for the fourth switching transistor Q4, and the eighth resistor R8 can also be used for limiting current to limit current at the first end of the fourth switching transistor Q4.
In this embodiment, the second control signal output by the control unit 60 is transmitted to the third switching tube Q3 through the interface S2. If the control unit 60 controls the third switching transistor Q3 to be turned on, the first terminal of the fourth switching transistor Q4 is grounded, and since the second terminal of the fourth switching transistor Q4 is connected to the driving power VIN through the interface V2, the fourth switching transistor Q4 is turned on. On the contrary, if the control unit 60 controls the third switching tube Q3 to be turned off, the fourth switching tube Q4 is also turned off.
In an embodiment, referring to fig. 4 with continued reference to fig. 3, the first resistance branch 10 includes a first resistor R1. A first end of the first resistor R1 is connected to the interface V1, the first end of the first switch branch 40, the first end of the second switch branch 50, and the first end of the second resistor branch 20, and a second end of the first resistor R1 is connected to the third end of the third resistor branch 30. The interface V1 is connected to a first end of the driving power VIN, the interface V2 is connected to a second end of the driving power VIN, the current I1 is a current flowing through the first resistor R1, and the interface VOUT is used for outputting a voltage.
In one embodiment, the second resistor branch 20 includes a second resistor R2 and a third resistor R3. A first end of the second resistor R2 is connected to the second end of the first switching branch 40, a second end of the second resistor R2 is connected to the first end of the third resistor branch 30, the second end of the second switching branch 50, and the first end of the third resistor R3, and a second end of the third resistor R3 is connected to the interface V1, the first end of the first resistor branch 10, and the first end of the second switching branch 50.
In one embodiment, the third resistive branch 50 includes a fourth resistor R4 and a fifth resistor R5. A first end of the fourth resistor R4 is connected to the third end of the second resistor branch 20 and the second end of the second switch branch 50, a second end of the fourth resistor R4 is connected to the first end of the fifth resistor R5 and the interface V2, and a second end of the fifth resistor R5 is connected to the third end of the second switch branch 50.
In practical applications, if the control unit 60 controls the first switching transistor Q1 to be turned off by the first control signal and controls the third switching transistor Q3 to be turned off by the second control signal, the second switching transistor Q2 and the fourth switching transistor Q4 are also turned off. In this case, a circuit in which the third resistor R3 and the fourth resistor R4 are connected in series is connected in parallel to the first resistor R1. Combining the voltage across the third resistor R3 as the voltage Vref output by the driving power supply, the current I1 is:
wherein r isR1Is the resistance value, R, of the first resistor R1R3Is the resistance value, R, of the third resistor R3R4Is the resistance value of the fourth resistor R4.
In this embodiment, the sum of the resistance of the third resistor R3 and the resistance of the fourth resistor R4 is configured to be much larger than the resistance of the first resistor R1, so that the current flowing through the third resistor R3 and the fourth resistor R4 is negligible. At this time, the current I1 is the output current outputted by the current-limiting sampling circuit, i.e. the first current-limiting point. Meanwhile, because the current flowing through the third resistor R3 and the fourth resistor R4 can be ignored, the requirements on the parameters such as the accuracy or the temperature drift coefficient of the third resistor R3 and the fourth resistor R4 can be reduced, that is, the third resistor R3 and the fourth resistor R4 with lower prices can be selected, which is beneficial to reducing the cost.
If the control unit 60 controls the first switch transistor Q1 to be turned on by the first control signal and controls the third switch transistor Q3 to be turned on by the second control signal, the second switch transistor Q2 and the fourth switch transistor Q4 are also turned on. In this case, the circuit formed by the second resistor R2 connected in parallel with the third resistor R3 is connected in series with the circuit formed by the fourth resistor R4 connected in parallel with the fifth resistor R5, and the circuit formed in series is connected in parallel with the first resistor R1.
Let the on-state internal resistance of the second switching tube Q2 be rQ2The on-state internal resistance of the fourth switching tube Q4 is denoted as rQ4Is provided with req1Is the on internal resistance r of the second switch tube Q2Q2A total resistance, R, connected in series with the second resistor R2 and then in parallel with the third resistor R3eq2Is the on internal resistance r of the fourth switching tube Q4Q4The total resistance is connected with the fifth resistor R5 in series and then connected with the fourth resistor R4 in parallel. The voltage across the third resistor R3 is combined to be the voltage Vref output by the driving power supply. The available current I1 is:
in this embodiment, the total resistance r can be configuredeq1And total resistance req2Is much larger than the resistance of the first resistor R1, so that the current flowing through the second resistor branch 20, the second switch Q2, the third resistor branch 30 and the fourth switch Q4 is negligible. At this time, the current I1 is the output current of the current-limiting sampling circuit. And due to the total resistance r in equation (2)eq1And total resistance req2Unlike the resistance values of the third resistor R3 and the fourth resistor R4 in formula (1), the current obtained by formula (1) and formula (2) is different. Thus, in this embodiment, a second choke point may be obtained.
Meanwhile, as the current flowing through the second resistance branch 20, the second switch tube Q2, the third resistance branch 30 and the fourth switch tube Q4 is negligible, the parameter requirements on the second switch tube Q2 and the fourth switch tube Q4 can be reduced, i.e., the second switch tube Q2 and the fourth switch tube Q4 with lower prices can be selected, which is beneficial to reducing the cost.
Furthermore, the first circuit formed by the second resistance branch 20 and the second switch tube Q2 and the second circuit formed by the third resistance branch 30 and the fourth switch tube Q4 are designed symmetrically, so that the influence of temperature on the current precision of the current limiting point can be reduced. That is, even if the second switch tube Q2 and the fourth switch tube Q4 are affected by temperature changes, the current precision of the current-limiting point is less affected, which is beneficial to improving the current precision of the current-limiting point.
For example, in one embodiment, the resistances of the second switch transistor Q2 and the fourth switch transistor Q4 increase due to the temperature increase. Since the first circuit and the second circuit are connected in series, the current of the first circuit is equal to the current of the second circuit, that is, the ratio of the voltage to the resistance of the first circuit is equal to the ratio of the voltage to the resistance of the second circuit. In other words, a first ratio K1 of the resistance of the first circuit to the resistance of the second circuit is equal to a second ratio K2 of the voltage of the first circuit to the voltage of the second circuit. In practical applications, the parameters of each element in the first circuit and the parameters of each element in the second circuit can be set to be equal or closer. Therefore, if the resistances of the second switch transistor Q2 and the fourth switch transistor Q4 are both increased, that is, the resistances of the first circuit and the second circuit are both increased and the variation widths of the resistances of the first circuit and the second circuit can be considered to be substantially consistent approximately, the first ratio K1 is not changed, and then the second ratio K2 is not changed. On the premise that the voltage of the first circuit is kept as the voltage Vref output by the driving power supply and the second ratio K2 is not changed, the voltage of the second circuit is also not changed. Since the voltage across the first resistor R1 is the voltage of the first circuit plus the voltage of the second circuit, the voltage across the first resistor R1 remains unchanged, and the current I1 remains unchanged.
The embodiment of the application also provides electric equipment which comprises a driving chip and the current-limiting sampling circuit in any one of the embodiments. The driving chip is used for providing a driving power supply for the current-limiting sampling circuit.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; within the context of the present application, where technical features in the above embodiments or in different embodiments can also be combined, the steps can be implemented in any order and there are many other variations of the different aspects of the present application as described above, which are not provided in detail for the sake of brevity; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.
Claims (11)
1. A current-limiting sampling circuit, comprising:
the circuit comprises a control unit, a first resistance branch circuit, a second resistance branch circuit, a third resistance branch circuit, a first switch branch circuit and a second switch branch circuit;
the first end of the first switch branch, the first end of the first resistance branch, the first end of the second resistance branch and the first end of the second switch branch are all connected with the first end of a driving power supply, the second end of the first switch branch is connected with the second end of the second resistance branch, and the third end of the first switch branch is connected with the control unit;
the third end of the second resistance branch is respectively connected with the second end of the driving power supply, the second end of the second switch branch and the first end of the third resistance branch;
the third end of the second switch branch circuit is connected with the second end of the third resistance branch circuit, and the fourth end of the second switch branch circuit is connected with the control unit;
the second end of the first resistance branch is connected with the third end of the third resistance branch;
the first switch branch, the second resistance branch, the second switch branch and the third resistance branch form a variable resistance branch, the first switch branch is configured to be switched on or switched off according to a first control signal output by the control unit to change the resistance of the second resistance branch switched in the variable resistance branch, and the second switch branch is configured to be switched on or switched off according to a second control signal output by the control unit to change the resistance of the third resistance branch switched in the variable resistance branch.
2. The current-limited sampling circuit of claim 1,
the first resistance branch comprises a first resistance;
the first end of the first resistor is connected with the first end of the driving power supply, and the second end of the first resistor is connected with the third end of the third resistor branch.
3. The current-limited sampling circuit of claim 1,
the second resistance branch comprises a second resistance and a third resistance;
the first end of the second resistor is connected with the second end of the first switch branch circuit, the second end of the second resistor is connected with the first end of the third resistor branch circuit, the second end of the second switch branch circuit and the first end of the third resistor, and the second end of the third resistor is connected with the first end of the driving power supply.
4. The current-limited sampling circuit of claim 1,
the third resistance branch comprises a fourth resistor and a fifth resistor;
the first end of the fourth resistor is connected with the third end of the second resistor branch and the second end of the second switch branch, the second end of the fourth resistor is connected with the first end of the fifth resistor and the second end of the driving power supply, and the second end of the fifth resistor is connected with the third end of the second switch branch.
5. The current-limited sampling circuit of claim 1,
the first switch branch comprises a first switch unit and a second switch unit;
the first end of the first switch unit is connected with the control unit, the second end of the first switch unit is connected with the first end of the second switch unit, the third end of the first switch unit is grounded, the second end of the second switch unit is connected with the second end of the second resistance branch, and the third end of the second switch unit is connected with the first end of the driving power supply;
the first switching unit is configured to be turned on or off according to the first control signal;
the second switching unit is configured to be turned on according to the turning-on of the first switching unit and to be turned off according to the turning-off of the first switching unit.
6. The current-limited sampling circuit of claim 5,
the first switch unit comprises a first switch tube;
the first end of the first switch tube is connected with the control unit, the second end of the first switch tube is grounded, and the third end of the first switch tube is connected with the second switch unit.
7. The current-limited sampling circuit of claim 5,
the second switch unit comprises a second switch tube, a sixth resistor and a seventh resistor;
the first end of the sixth resistor is connected with the second end of the first switch unit, the second end of the sixth resistor is connected with the first end of the seventh resistor and the first end of the second switch tube, the second end of the seventh resistor is connected with the second end of the second switch tube and the first end of the driving power supply, and the third end of the second switch tube is connected with the second end of the second resistor branch.
8. The current-limited sampling circuit of claim 1,
the second switching branch comprises a third switching unit and a fourth switching unit;
the first end of the third switching unit is connected with the control unit, the second end of the third switching unit is grounded, the third end of the third switching unit is connected with the first end of the fourth switching unit, the second end of the fourth switching unit is connected with the third end of the second resistance branch and the second end of the driving power supply, the third end of the fourth switching unit is connected with the second end of the third resistance branch, and the fourth end of the fourth switching unit is connected with the first end of the driving power supply;
the third switching unit is configured to be turned on or off according to the second control signal;
the fourth switching unit is configured to be turned on according to the turning-on of the third switching unit and to be turned off according to the turning-off of the third switching unit.
9. The current-limited sampling circuit of claim 8,
the third switching unit comprises a third switching tube;
the first end of the third switching tube is connected with the control unit, the second end of the third switching tube is grounded, and the third end of the third switching tube is connected with the first end of the fourth switching unit.
10. The current-limited sampling circuit of claim 8,
the fourth switching unit comprises a fourth switching tube, an eighth resistor and a ninth resistor;
the first end of the eighth resistor is connected with the third end of the third switch unit, the second end of the eighth resistor is connected with the first end of the ninth resistor and the first end of the fourth switch tube, the second end of the ninth resistor is connected with the first end of the driving power supply, the second end of the fourth switch tube is connected with the third end of the second resistor branch, and the third end of the fourth switch tube is connected with the second end of the third resistor branch.
11. An electrical device, comprising a driver chip and a current-limiting sampling circuit according to any one of claims 1 to 10;
the driving chip is used for providing the driving power supply for the current-limiting sampling circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122449731.2U CN216390503U (en) | 2021-10-11 | 2021-10-11 | Current-limiting sampling circuit and electrical equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122449731.2U CN216390503U (en) | 2021-10-11 | 2021-10-11 | Current-limiting sampling circuit and electrical equipment |
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| Publication Number | Publication Date |
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| CN216390503U true CN216390503U (en) | 2022-04-26 |
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| CN202122449731.2U Active CN216390503U (en) | 2021-10-11 | 2021-10-11 | Current-limiting sampling circuit and electrical equipment |
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