Voltage detection circuit, voltage monitoring circuit, power supply and control circuit thereof

Abstract

The invention discloses a voltage detection circuit, a voltage monitoring circuit, a power supply and a control circuit thereof, which are used for detecting voltage between a sampling positive end and a sampling negative end, and comprise a first voltage-current conversion circuit, a second voltage-current conversion circuit, a third voltage-current conversion circuit and a fourth voltage-current conversion circuit, a first current flowing through the output end of the voltage detection circuit is generated, and the first voltage is the voltage output by the output end of the voltage detection circuit; and the second voltage-current conversion circuit is connected with the sampling negative end, the reference ground and the output end of the voltage detection circuit, and generates a second current flowing through the output end of the voltage detection circuit according to the voltage of the sampling negative end. The sampling positive end and the sampling negative end do not need to be connected with two input ends of a differential operational amplifier respectively, the influence of the bandwidth of the operational amplifier on the detection speed is small, and the bias voltage of the operational amplifier is easy to control; reference voltage does not need to be generated on the sampling negative end, and the circuit is simple; the to-be-detected voltage information can be accurately obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a voltage detection circuit, a voltage monitoring circuit, a power supply and a control circuit thereof. Background Art

[0002] like Figure 1 As shown, when the distance between the power supply and the load is far, the transmission line resistance R between the power supply and the load WIRE The voltage divider effect will cause the load voltage V LOAD Less than the actual output voltage V OUT , especially in high current applications, the transmission line resistance R WIRE The voltage drop caused is large. Among them, the power supply includes a power stage circuit and a control circuit. The power stage circuit outputs an output voltage V OUT In order to accurately control the load voltage and / or monitor the load voltage, the control circuit needs to have a load voltage V LOAD A voltage detection circuit is used for detection.

[0003] A first voltage detection circuit 100 of the prior art, such as Figure 2a As shown, using differential op amp U1, the load voltage V LOAD , that is, sampling positive terminal voltage V OSP And sample the negative terminal voltage V OSN The voltage difference is converted into a single-ended voltage signal with reference to the reference ground GND, and then the single-ended voltage signal is divided by a voltage divider circuit composed of two series resistors to obtain a sampling signal V 采 The control circuit of the power supply uses the error amplifier U2 to compare the reference voltage Vref and the sampling signal V 采 The error is amplified, and the actual output voltage of the power supply is controlled according to the signal Vc output by the error amplifier U2, thereby controlling the load voltage. 采 The load voltage information can be accurately obtained. Therefore, the voltage detection circuit 100 can also be applied to a voltage monitoring circuit. The voltage monitoring unit 50 in the voltage monitoring circuit generates a voltage signal according to the sampling signal V 采 Output monitoring signal. However, the voltage detection circuit 100 has the following disadvantages: the bandwidth of the differential operational amplifier U1 completely affects the detection speed of the voltage between the sampling positive terminal and the sampling negative terminal; the difference in bias voltage of the differential operational amplifier U1 under different common mode voltages will affect the detection accuracy of the voltage between the sampling positive terminal and the sampling negative terminal.

[0004] A second voltage detection circuit 200 of the prior art, such as Figure 2b As shown, the reference voltage generated by the voltage source U4 needs to be transferred to the sampling negative terminal voltage V OSN Then, the error amplifier U2 is used to sample the negative terminal voltage VOSN The voltage obtained after superimposing the reference voltage is equal to the sampling positive terminal voltage V OSP The error is amplified, and the control circuit of the power supply controls the actual output voltage of the power supply according to the signal Vc output by the error amplifier U2. However, the voltage detection circuit 200 has the following disadvantages: the reference voltage needs to be set before sampling the negative terminal voltage V OSN The circuit is relatively complicated; the signal output by the error amplifier U2 can only represent the voltage information between the sampling positive terminal and the sampling negative terminal, but the voltage information between the sampling positive terminal and the sampling negative terminal cannot be accurately obtained according to the signal output by the error amplifier U2, so the voltage between the sampling positive terminal and the sampling negative terminal cannot be monitored. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a voltage detection circuit, a voltage monitoring circuit, a power supply and a control circuit thereof, so as to solve the technical problems existing in the prior art that the bandwidth of the differential operational amplifier completely affects the detection speed of the voltage between the sampling positive terminal and the sampling negative terminal, and the difference in the bias voltage of the differential operational amplifier under different common mode voltages will affect the detection accuracy of the voltage between the sampling positive terminal and the sampling negative terminal; or, a reference voltage signal is generated on the sampling negative terminal voltage, the circuit is relatively complicated, and the voltage information between the sampling positive terminal and the sampling negative terminal cannot be accurately obtained.

[0006] The technical solution of the present invention is, in a first aspect, to provide a voltage detection circuit for detecting the voltage between a sampling positive terminal and a sampling negative terminal, the voltage detection circuit comprising:

[0007] a first voltage-to-current conversion circuit, connected to the sampling positive terminal and the output terminal of the voltage detection circuit, and generating a first current flowing through the output terminal of the voltage detection circuit according to the sampling positive terminal voltage and a first voltage, wherein the first voltage is the voltage output by the output terminal of the voltage detection circuit;

[0008] The second voltage-to-current conversion circuit is connected to the sampling negative terminal, the reference ground and the output terminal of the voltage detection circuit, and generates a second current flowing through the output terminal of the voltage detection circuit according to the sampling negative terminal voltage.

[0009] Optionally, the first current flows to the output end of the voltage detection circuit, and the second current flows out of the output end of the voltage detection circuit;

[0010] Alternatively, the first current flows out of the output end of the voltage detection circuit, and the second current flows toward the output end of the voltage detection circuit.

[0011] Optionally, the magnitude of the second current is proportional to the magnitude of the sampled negative terminal voltage.

[0012] Optionally, the magnitude of the first current is proportional to the difference between the sampled positive terminal voltage and the first voltage.

[0013] Optionally, a proportionality coefficient between the magnitude of the first current and the difference between the sampled positive terminal voltage and the first voltage is equal to a proportionality coefficient between the magnitude of the second current and the magnitude of the sampled negative terminal voltage.

[0014] Optionally, at the same moment, the ratio of the magnitude of the first current to the difference between the sampled positive terminal voltage and the first voltage is equal to the ratio of the magnitude of the second current to the magnitude of the sampled negative terminal voltage.

[0015] Optionally, the magnitude of the first current is equal to the magnitude of the second current.

[0016] Optionally, the voltage detection circuit further includes:

[0017] A current source is connected to the output end of the voltage detection circuit to generate a third current flowing to or out of the output end of the voltage detection circuit.

[0018] Optionally, the magnitude of the third current is adjustable.

[0019] Optionally, according to Kirchhoff's law, a relationship between the first voltage and the difference between the sampling positive terminal voltage and the sampling negative terminal voltage can be obtained.

[0020] Optionally, the second voltage-current conversion circuit includes:

[0021] a first transistor, a first end of which is connected to the output end of the voltage detection circuit;

[0022] a third resistor network, a first end of which is connected to the second end of the first transistor, and a second end of which is connected to the reference ground;

[0023] The first operational amplifier has a first input terminal receiving the sampling negative terminal voltage, a second input terminal connected to the first terminal of the third resistor network, and an output terminal connected to the control terminal of the first transistor.

[0024] Optionally, the first voltage-current conversion circuit includes:

[0025] The first resistor network has a first end receiving the sampling positive terminal voltage and a second end connected to the output end of the voltage detection circuit.

[0026] Optionally,

[0027] Wherein, V1 represents the first voltage, V OSP Represents the sampled positive terminal voltage, V OSNrepresents the sampled negative terminal voltage, R1 represents the resistance value of the first resistor network, and R3 represents the resistance value of the third resistor network.

[0028] Optionally, the first voltage-current conversion circuit further includes:

[0029] The second resistor network has a first end connected to the output end of the voltage detection circuit and a second end connected to the reference ground.

[0030] Optionally,

[0031] Wherein, V1 represents the first voltage, R1 represents the resistance value of the first resistor network, R2 represents the resistance value of the second resistor network, R3 represents the resistance value of the third resistor network, V OSP Represents the sampled positive terminal voltage, V OSN Represents the sampled negative terminal voltage.

[0032] Optionally, the resistance value of the first resistance network is equal to the resistance value of the third resistance network.

[0033] Optionally, the voltage detection circuit further includes a current source, and the current source includes:

[0034] a second transistor, a first end of which is connected to the output end of the voltage detection circuit;

[0035] a fourth resistor network, a first end of which is connected to the second end of the second transistor, and a second end of which is connected to the reference ground;

[0036] The second operational amplifier has a first input terminal receiving a second voltage, a second input terminal connected to the first terminal of the fourth resistor network, and an output terminal connected to the control terminal of the second transistor.

[0037] Optionally, the magnitude of the second voltage is adjustable.

[0038] Optionally, a ratio of the resistance values ​​of the first resistance network to the fourth resistance network is adjustable.

[0039] Optionally, all or part of the voltage detection circuit is integrated into one chip, and the reference ground of the voltage detection circuit serves as the reference ground of the chip.

[0040] In a second aspect, the present invention further provides a voltage monitoring circuit, the voltage monitoring circuit comprising an analog-to-digital conversion circuit and the voltage detection circuit, wherein:

[0041] The analog-to-digital conversion circuit receives the first voltage output by the voltage detection circuit, and outputs a conversion signal according to the first voltage;

[0042] The voltage monitoring circuit outputs a voltage monitoring signal according to the conversion signal.

[0043] In a third aspect, the present invention further provides a control circuit for a power supply, the control circuit comprising an error amplifier and the voltage detection circuit, wherein:

[0044] The first input terminal of the error amplifier receives a reference voltage, the second input terminal receives a first voltage output by the voltage detection circuit, and the output terminal outputs a compensation signal;

[0045] The control circuit outputs a control signal according to the compensation signal.

[0046] Optionally, the voltage detection circuit is used to detect the voltage between two ends of a load of the power supply.

[0047] In a fourth aspect, the present invention further provides a power supply, the power supply comprising a power stage circuit and the control circuit;

[0048] The control signal output by the control circuit is used to control the power tube in the power stage circuit.

[0049] Optionally, the power supply includes a switching power supply, and the control signal is used to control the on and off of the power tube.

[0050] Compared with the prior art, the circuit structure of the present invention has the following advantages: it is not necessary to connect the sampling positive terminal and the sampling negative terminal to the two input terminals of a differential operational amplifier respectively, most voltage signals do not pass through the differential operational amplifier, the response of the first voltage is less affected by the bandwidth of the operational amplifier, so the bandwidth of the operational amplifier has little effect on the detection speed of the voltage between the sampling positive terminal and the sampling negative terminal; the input common mode voltage of the operational amplifier changes very little, and the bias voltage is easy to control; the reference voltage can be established on the reference of the chip, and there is no need to set the sampling negative terminal voltage V OSN A reference voltage is generated on the sampling terminal, and the circuit structure is simple; the voltage information between the sampling positive terminal and the sampling negative terminal can be accurately obtained, thereby enabling the voltage between the sampling positive terminal and the sampling negative terminal to be monitored. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is the connection diagram of power supply and load;

[0052] Figure 2a It is a circuit structure schematic diagram of a first voltage detection circuit in the prior art;

[0053] Figure 2b A schematic diagram of the circuit structure of a second voltage detection circuit in the prior art;

[0054] Figure 3is a circuit block diagram of a voltage detection circuit according to an embodiment of the present invention;

[0055] Figure 4 Based on Figure 3 A schematic diagram of the circuit structure of a first embodiment of a voltage detection circuit;

[0056] Figure 5 Based on Figure 3 A schematic diagram of the circuit structure of a second embodiment of a voltage detection circuit. DETAILED DESCRIPTION

[0057] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitution, modification, equivalent method and scheme made within the spirit and scope of the present invention.

[0058] In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without these detailed descriptions.

[0059] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the accompanying drawings are all simplified and not in exact proportion, and are only used for the purpose of conveniently and clearly assisting in explaining the embodiments of the present invention.

[0060] Figure 3 The circuit block diagram of the voltage detection circuit 300 of the embodiment of the present invention is shown. The voltage detection circuit 300 is used to detect the voltage between the sampling positive terminal and the sampling negative terminal. In some embodiments, it includes a first voltage-to-current conversion circuit 31 and a second voltage-to-current conversion circuit 32. The first voltage-to-current conversion circuit 31 is connected to the sampling positive terminal and the output terminal of the voltage detection circuit, and converts the sampling positive terminal voltage V OSP and the first voltage V1, generating a first current flowing through the output end of the voltage detection circuit, wherein the first voltage V1 is the voltage output by the output end of the voltage detection circuit; the second voltage-to-current conversion circuit 32 is connected to the sampling negative end, the reference ground GND and the output end of the voltage detection circuit, and according to the sampling negative end voltage V OSN , generating a second current flowing through the output end of the voltage detection circuit. In one embodiment, the first current can be set to flow to the output end of the voltage detection circuit, and the second current can flow out of the output end of the voltage detection circuit. In another embodiment, the first current can also be set to flow out of the output end of the voltage detection circuit, and the second current can flow to the output end of the voltage detection circuit. Specifically, the magnitude of the second current is related to the magnitude of the sampled negative terminal voltage, and the magnitude of the first current is related to the sampled positive terminal voltage V OSPFurther, in one embodiment, the magnitude of the second current can be set to be related to the sampling negative terminal voltage V OSN In one embodiment, the magnitude of the first current can be set to be proportional to the sampling positive terminal voltage V OSP Furthermore, in one embodiment, the magnitude of the second current can be set to be proportional to the difference between the negative terminal voltage V OSN The magnitude of the first current is proportional to the sampled positive terminal voltage V OSP Proportional to the difference of the first voltage V1, and the proportional coefficient is equal; in another embodiment, it can also be set that at the same time, the ratio between the magnitude of the first current and the difference between the sampling positive terminal voltage and the first voltage is equal to the ratio between the magnitude of the second current and the magnitude of the sampling negative terminal voltage; according to Kirchhoff's current law, it can be known that the magnitude of the first current is equal to the magnitude of the second current, and then the relationship between the first voltage and the difference between the sampling positive terminal voltage and the sampling negative terminal voltage can be obtained, and the voltage between the sampling positive terminal and the sampling negative terminal can be accurately obtained according to the magnitude of the first voltage. In some other embodiments, the voltage detection circuit 300 also includes a current source 33, and the current source 33 is connected to the output end of the voltage detection circuit to generate a third current flowing to or out of the output end of the voltage detection circuit. Similarly, according to Kirchhoff's current law, the relationship between the first voltage and the difference between the sampling positive terminal voltage and the sampling negative terminal voltage can be obtained. Under the premise of knowing the magnitude and direction of the third current, the voltage between the sampling positive terminal and the sampling negative terminal can be accurately obtained according to the magnitude of the first voltage. Further, in one embodiment, the magnitude of the third current is adjustable.

[0061] Please continue to refer to Figure 3, and an application example of the voltage detection circuit 300 of the embodiment of the present invention is also given. On the one hand, the voltage detection circuit 300 can be applied in a voltage monitoring circuit. In one embodiment, the voltage monitoring circuit includes a voltage detection circuit 300 and a voltage monitoring unit 50. The voltage monitoring unit 50 outputs a voltage monitoring signal according to the first voltage V1 output by the voltage detection circuit 300, wherein the voltage monitoring signal can be an indication signal indicating whether the voltage between the sampling positive terminal and the sampling negative terminal meets the requirements, or a signal for displaying the voltage between the sampling positive terminal and the sampling negative terminal. This application does not limit this. For example, the voltage monitoring unit 50 includes an analog-to-digital conversion circuit U3, the analog-to-digital conversion circuit U3 receives the first voltage V1, and outputs a conversion signal according to the first voltage V1. The voltage monitoring unit 50 outputs a voltage monitoring signal according to the conversion signal, wherein the analog-to-digital conversion circuit U3 can directly receive the first voltage V1, or can receive a signal after processing the first voltage V1; the conversion signal can be directly output as the voltage monitoring signal, or can be output as the voltage monitoring signal after processing the conversion signal. This application does not limit this. On the other hand, the voltage detection circuit 300 can also be used in a control circuit of a power supply. In one embodiment, the power supply includes a power stage circuit and a control circuit. The control circuit includes a voltage detection circuit 300 and a control unit 40. The voltage detection circuit 300 is used to detect the voltage between the two ends of the load of the power supply. The control unit 40 includes an error amplifier U2. The first input end of the error amplifier U2 receives a reference voltage Vref, the second input end receives a first voltage V1 output by the voltage detection circuit 300, and the output end outputs a compensation signal Vc. The control unit 40 outputs a control signal according to the compensation signal Vc. The control signal is used to control the power tube in the power stage circuit of the power supply. The compensation signal Vc can be output as the control signal, or the signal obtained by processing the compensation signal can be output as the control signal. This application does not limit this. It can be understood that in another embodiment, the control circuit can also include a voltage monitoring unit 50 to realize monitoring the voltage between the two ends of the load while controlling the power tube in the power stage circuit of the power supply. Among them, the power supply can be a linear power supply, and the control signal is used to control the current flowing through the power tube in the power stage circuit; it can also be a switching power supply, and the control signal is used to control the conduction and shutdown of the power tube in the power stage circuit.

[0062] Figure 4 The circuit structure diagram of the first embodiment of the voltage detection circuit 300 of the present invention is shown, including a first voltage-current conversion circuit 31 and a second voltage-current conversion circuit 32. Specifically, in one embodiment, the first voltage-current conversion circuit 31 includes a first resistor network R1, and a first end of the first resistor network R1 is connected to the sampling positive end to receive the sampling positive end voltage VOSP , and the second end is connected to the output end of the voltage detection circuit. The second voltage-current conversion circuit 32 includes a first transistor M1, a third resistor network R3, and a first operational amplifier U5, wherein the first end of the first transistor M1 is connected to the output end of the voltage detection circuit; the first end of the third resistor network R3 is connected to the second end of the first transistor, and the second end is connected to the reference ground GND; the first input end of the first operational amplifier U5 is connected to the sampling positive end to receive the sampling negative end voltage V OSN , the second input terminal is connected to the first terminal of the third resistor network R3, and the output terminal is connected to the control terminal of the first transistor M1. In the present application, R1 represents the first resistor network, and R1 also represents the resistance value of the first resistor network, and so on. In this embodiment, the first voltage-current conversion circuit 31 generates a first current flowing to the output terminal of the voltage detection circuit, which is equal to i11=(V OSP -V1) / R1, the second voltage-current conversion circuit 32 generates a second current i2=V flowing out of the output end of the voltage detection circuit OSN / R3, according to Kirchhoff's current law, we know that i11=i2, that is (V OSP -V1) / R1=V OSN / R3, from which we can conclude:

[0063]

[0064] Wherein, V1 represents the first voltage, V OSP Represents the sampling positive terminal voltage, V OSN represents the sampling negative terminal voltage, R1 represents the resistance value of the first resistor network, and R3 represents the resistance value of the third resistor network. In another embodiment, the first voltage-current conversion circuit 31 further includes a second resistor network R2, a first end of the second resistor network R2 is connected to the output end of the voltage detection circuit, and a second end is connected to the reference ground GND. In this embodiment, the first voltage-current conversion circuit 31 generates a first current flowing to the output end of the voltage detection circuit, which is equal to i11-i12=(V OSP -V1) / R1-V1 / R3, according to Kirchhoff's current law, i11-i12=i2, that is (V OSP -V1) / R1-V1 / R3=V OSN / R3, from which we can conclude:

[0065]

[0066] It can be seen from formula (1) and formula (2) that in the above embodiment, the magnitude of the first voltage V1 can represent the sampling positive terminal voltage V OSP The negative terminal voltage V OSN The difference.

[0067] Furthermore, in some other embodiments, the resistance value R1 of the first resistor network may be set equal to the resistance value R3 of the third resistor network. Substituting R1=R3 into formula (1), we can obtain:

[0068] V1=V OSP -V OSN (3)

[0069] It can be seen from formula (3) that in this embodiment, the voltage between the sampling positive terminal and the sampling negative terminal can be accurately obtained according to the magnitude of the first voltage V1.

[0070] Substituting R1=R3 into formula (2), we can obtain:

[0071]

[0072] As can be seen from formula (4), in this embodiment, when the resistance value R1 of the first resistor network and the resistance value R2 of the second resistor network are known, or the ratio between the two is known, the voltage between the sampling positive terminal and the sampling negative terminal can be accurately obtained according to the magnitude of the first voltage V1.

[0073] It can be understood that in other embodiments, the resistance value R1 of the first resistor network and the resistance value R3 of the third resistor network can also be set as variable resistors. It is only necessary to ensure that the resistance value R1 of the first resistor network is equal to the resistance value R3 of the third resistor network at the same time, so as to ensure that formula (3) and formula (4) are valid. The voltage between the sampling positive terminal and the sampling negative terminal can be accurately obtained according to the size of the first voltage V1.

[0074] It can be understood that in the present embodiment, the first voltage-current conversion circuit 31 generates a first current flowing to the output end of the voltage detection circuit, and the second voltage-current conversion circuit 32 generates a second current flowing out of the output end of the voltage detection circuit. In other embodiments, the directions of the first current and the second current can be changed by adding a current mirror or using other types of voltage-current conversion circuits, so that the first current flows out from the output end of the voltage detection circuit and the second current flows to the output end of the voltage detection circuit, thereby producing the same technical effect as the present embodiment.

[0075] Figure 5The circuit structure diagram of the second embodiment of the voltage detection circuit 300 of the present invention is shown. The circuit structure of the voltage detection circuit of this embodiment is basically the same as that of the first embodiment, and will not be repeated here. The difference is that the voltage detection circuit 300 of this embodiment also includes a current source 33, and the current source 33 is connected to the output end of the voltage detection circuit to generate a third current i3 flowing to or out of the output end of the voltage detection circuit. The following takes the first voltage-current conversion circuit 31 including the second resistor network R2, and the third current i3 flowing out of the output end of the voltage detection circuit as an example to introduce this embodiment. According to Kirchhoff's current law, it can be known that i11-i12=i2+i3, and then it can be obtained:

[0076]

[0077] It can be seen from formula (5) that in this embodiment, the magnitude of the first voltage V1 can represent the sampling positive terminal voltage V OSP The negative terminal voltage V OSN The difference.

[0078] Furthermore, the resistance value R1 of the first resistor network can be set equal to the resistance value R3 of the third resistor network. Substituting R1=R3 into the above formula (5), we can obtain Thus, when the resistance value R1 of the first resistor network, the resistance value R2 of the second resistor network and the magnitude of the third current i3 are known, the voltage between the sampling positive terminal and the sampling negative terminal can be accurately obtained according to the magnitude of the first voltage V1.

[0079] Specifically, in one embodiment, the current source 33 includes a second transistor M2, a fourth resistor network R4, and a second operational amplifier U6, wherein the first end of the second transistor M2 is connected to the output end of the voltage detection circuit; the first end of the fourth resistor network R4 is connected to the second end of the second transistor M2, and the second end is connected to the reference ground GND; the first input end of the second operational amplifier U6 receives the second voltage V2, the second input end is connected to the first end of the fourth resistor network R4, and the output end is connected to the control end of the second transistor M2. In this embodiment, the third current i3 = V2 / R4. Combined with the above analysis, it can be seen that in this embodiment, the magnitude of the first voltage V1 can represent the sampling positive terminal voltage V OSP The negative terminal voltage V OSN Further, when the resistance value R1 of the first resistor network is set equal to the resistance value R3 of the third resistor network, for example, when the resistance value R1 of the first resistor network, the resistance value R2 of the second resistor network, and the resistance value R4 of the fourth resistor network are known (or the ratio between the three is known), and the magnitude of the second voltage V2 is known, the voltage between the sampling positive terminal and the sampling negative terminal can be accurately obtained according to the magnitude of the first voltage V1.

[0080] Please continue to refer to Figure 5 When the voltage detection circuit 300 is applied to the control circuit of the power supply, the voltage detection circuit 300 can be used to detect the voltage between the two ends of the load of the power supply. The error amplifier U2 in the control circuit will stabilize the first voltage V1 at a voltage value corresponding to the reference voltage Vref. Substituting V1=Vref into formula (5) yields:

[0081]

[0082] It can be seen from formula (6) that in this embodiment, the reference voltage Vref can be kept constant, that is, the input of the error amplifier U2 can be kept stable, and the magnitude of the third current i3 can be adjusted. The size of the third current is adjusted by adjusting the resistance value R1 of the first resistor network. The magnitude of the size.

[0083] Furthermore, in one embodiment, the resistance value R1 of the first resistor network may be set equal to the resistance value R3 of the third resistor network. Substituting R1=R3 into formula (6), we can obtain:

[0084]

[0085] Among them, V LOAD represents the load voltage, that is, the voltage between the two ends of the load. According to formula (7), combined with the above analysis of formula (6), it can be seen that this embodiment can adjust V by adjusting the size of the third current i3 while maintaining the stability of the input of the error amplifier U2. OSP -V OSN The size of the third current i3 is adjusted to adjust the load voltage V LOAD size.

[0086] Furthermore, in one embodiment, the current source 33 includes a second transistor M2, a fourth resistor network R4 and a second operational amplifier U6. The second transistor M2 is connected in a manner as described above and will not be described again. In this embodiment, the third current i3=V2 / R4. Substituting it into formula (7) yields:

[0087]

[0088] It can be seen from formula (8) that in this embodiment, the load voltage V can be adjusted by adjusting the magnitude of the second voltage V2 while keeping the reference voltage Vref unchanged, that is, while keeping the input of the error amplifier U2 stable. LOADThe load voltage V can be adjusted by adjusting the size of the second voltage V2 by adjusting the ratio of the resistance values ​​of the first resistance network to the fourth resistance network. LOAD The magnitude of the size.

[0089] It is easy to understand that in some other embodiments, reference Figure 5 , the first voltage-to-current conversion circuit 31 may be configured not to include the second resistor network, and the third current i3 may be configured to flow to the output end of the voltage detection circuit. Based on the contents of this application, those skilled in the art can easily obtain the first voltage V1 and the sampling positive terminal voltage V in these embodiments. OSP , sample the negative terminal voltage V OSN The relationship is not repeated here.

[0090] At least part of the voltage detection circuit, voltage monitoring circuit and power supply control circuit of the above embodiments can be integrated into one chip, which can have obvious cost advantages, wherein the reference ground of the voltage detection circuit can be used as the reference ground of the chip.

[0091] In addition, it should be noted that the first resistor network, the second resistor network, the third resistor network and the fourth resistor network described in the present application may include only a single resistor, or may include a resistor network composed of multiple components.

[0092] In summary, relative to Figure 2a The first prior art shown, the voltage detection circuit 300 of the embodiment of the present application, does not need to connect the sampling positive terminal and the sampling negative terminal to the two input terminals of a differential operational amplifier respectively, most of the voltage signals do not pass through the first operational amplifier U5, and the response of the first voltage is less affected by the bandwidth of the first operational amplifier, so the bandwidth of the first operational amplifier has little effect on the detection speed of the voltage between the sampling positive terminal and the sampling negative terminal; in addition, the first operational amplifier U5 only receives the sampling negative terminal voltage, and does not need to receive the sampling positive terminal voltage, the input common mode voltage changes very little, and the bias voltage is easier to control. Figure 2b The second prior art shown, the voltage detection circuit 300 of the embodiment of the present application, can accurately obtain the voltage information between the sampling positive terminal and the sampling negative terminal according to the first voltage, so as to realize the monitoring of the voltage between the sampling positive terminal and the sampling negative terminal; the control circuit of the power supply of the embodiment of the present application, the reference voltage Vref can be established on the reference ground of the chip, and there is no need to generate a reference voltage on the sampling negative terminal voltage, and the circuit structure is simpler. In addition, the voltage detection circuit 300 including the current source 33 in the embodiment of the present application, when applied to the control circuit of the power supply, can adjust the load voltage V by adjusting the parameters of the current source 33 under the premise of keeping the input of the error amplifier U2 stable. LOADsize.

[0093] The above-described implementation methods do not constitute a limitation on the protection scope of the technical solution. Any modification, equivalent replacement and improvement made within the spirit and principle of the above-described implementation methods shall be included in the protection scope of the technical solution.

Claims

1. A voltage detection circuit for detecting the voltage between a sampling positive terminal and a sampling negative terminal, characterized in that: include: a first voltage-to-current conversion circuit, connected to the sampling positive terminal and the output terminal of the voltage detection circuit, and generating a first current flowing through the output terminal of the voltage detection circuit according to the sampling positive terminal voltage and a first voltage, wherein the first voltage is the voltage output by the output terminal of the voltage detection circuit; The second voltage-current conversion circuit is connected to the sampling negative terminal, the reference ground and the output terminal of the voltage detection circuit, and generates a second current flowing through the output terminal of the voltage detection circuit according to the sampling negative terminal voltage.

2. The voltage detection circuit according to claim 1, characterized in that: The first current flows to the output end of the voltage detection circuit, and the second current flows out of the output end of the voltage detection circuit; Alternatively, the first current flows out of the output end of the voltage detection circuit, and the second current flows toward the output end of the voltage detection circuit.

3. The voltage detection circuit according to claim 1, characterized in that: The magnitude of the second current is proportional to the magnitude of the sampled negative terminal voltage.

4. The voltage detection circuit according to claim 3, characterized in that: The magnitude of the first current is proportional to the difference between the sampling positive terminal voltage and the first voltage.

5. The voltage detection circuit according to claim 4, characterized in that: The proportionality coefficient between the magnitude of the first current and the difference between the sampling positive terminal voltage and the first voltage is equal to the proportionality coefficient between the magnitude of the second current and the magnitude of the sampling negative terminal voltage.

6. The voltage detection circuit according to claim 1, characterized in that: At the same time, the ratio of the magnitude of the first current to the difference between the sampled positive terminal voltage and the first voltage is equal to the ratio of the magnitude of the second current to the magnitude of the sampled negative terminal voltage.

7. The voltage detection circuit according to claim 1, characterized in that: The magnitude of the first current is equal to the magnitude of the second current.

8. The voltage detection circuit according to claim 1, characterized in that: The voltage detection circuit also includes: A current source is connected to the output end of the voltage detection circuit to generate a third current flowing to or out of the output end of the voltage detection circuit.

9. The voltage detection circuit according to claim 8, characterized in that: The magnitude of the third current is adjustable.

10. The voltage detection circuit according to claim 1 or 8, characterized in that: According to Kirchhoff's law, the relationship between the first voltage and the difference between the sampling positive terminal voltage and the sampling negative terminal voltage can be obtained.

11. The voltage detection circuit according to claim 1, characterized in that: The second voltage-current conversion circuit comprises: a first transistor, a first end of which is connected to the output end of the voltage detection circuit; a third resistor network, a first end of which is connected to the second end of the first transistor, and a second end of which is connected to the reference ground; The first operational amplifier has a first input terminal receiving the sampling negative terminal voltage, a second input terminal connected to the first terminal of the third resistor network tube, and an output terminal connected to the control terminal of the first transistor.

12. The voltage detection circuit according to claim 11, characterized in that: The first voltage-current conversion circuit comprises: The first resistor network has a first end receiving the sampling positive terminal voltage and a second end connected to the output end of the voltage detection circuit.

13. The voltage detection circuit according to claim 12, characterized in that: Wherein, V1 represents the first voltage, V OSP Represents the sampled positive terminal voltage, V OSN represents the sampled negative terminal voltage, R1 represents the resistance value of the first resistor network, and R3 represents the resistance value of the third resistor network.

14. The voltage detection circuit according to claim 12, characterized in that: The first voltage-current conversion circuit further includes: The second resistor network has a first end connected to the output end of the voltage detection circuit and a second end connected to the reference ground.

15. The voltage detection circuit according to claim 14, characterized in that: Wherein, V1 represents the first voltage, R1 represents the resistance value of the first resistor network, R2 represents the resistance value of the second resistor network, R3 represents the resistance value of the third resistor network, V OSP Represents the sampled positive terminal voltage, V OSN Represents the sampled negative terminal voltage.

16. The voltage detection circuit according to claim 12 or 14, characterized in that: The resistance value of the first resistor network is equal to the resistance value of the third resistor network.

17. The voltage detection circuit according to claim 12 or 14, characterized in that: The voltage detection circuit further includes a current source, and the current source includes: a second transistor, a first end of which is connected to the output end of the voltage detection circuit; a fourth resistor network, a first end of which is connected to the second end of the second transistor, and a second end of which is connected to the reference ground; The second operational amplifier has a first input terminal receiving a second voltage, a second input terminal connected to the first terminal of the fourth resistor network, and an output terminal connected to the control terminal of the second transistor.

18. The voltage detection circuit according to claim 17, characterized in that: The magnitude of the second voltage is adjustable.

19. The voltage detection circuit according to claim 17, characterized in that: The ratio of the resistance values ​​of the first resistance network to the fourth resistance network is adjustable.

20. The voltage detection circuit according to claim 1, characterized in that: All or part of the voltage detection circuit is integrated into one chip, and the reference ground of the voltage detection circuit serves as the reference ground of the chip.

21. A voltage monitoring circuit, characterized in that: comprising an analog-to-digital conversion circuit, and a voltage detection circuit as claimed in any one of claims 1 to 20, wherein: The analog-to-digital conversion circuit receives the first voltage output by the voltage detection circuit, and outputs a conversion signal according to the first voltage; The voltage monitoring circuit outputs a voltage monitoring signal according to the conversion signal.

22. A control circuit for a power supply, characterized in that: comprising an error amplifier, and a voltage detection circuit as claimed in any one of claims 1 to 20, wherein: The first input terminal of the error amplifier receives a reference voltage, the second input terminal receives a first voltage output by the voltage detection circuit, and the output terminal outputs a compensation signal; The control circuit outputs a control signal according to the compensation signal.

23. The control circuit according to claim 22, characterized in that: The voltage detection circuit is used to detect the voltage between the two ends of the load of the power supply.

24. A power supply, characterized in that: comprising a power stage circuit and a control circuit as claimed in any one of claims 22 to 23; The control signal output by the control circuit is used to control the power tube in the power stage circuit.

25. The power supply according to claim 24, characterized in that The power supply comprises a switching power supply, The control signal is used to control the on and off of the power tube.

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