Current detection circuit for half-bridge driver and half-bridge driving device
By combining the current sampling and detection module and the mirror module, the output voltage is used to control the mirror current, which solves the problem that the current is difficult to detect directly in the half-bridge driver and realizes accurate current detection without the need for a high-precision sampling resistor.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN SHUMA ELECTRONICS TECH
- Filing Date
- 2023-05-17
- Publication Date
- 2026-06-05
AI Technical Summary
In existing technologies, the current to be measured in a half-bridge driver is difficult to detect directly, and a high-precision sampling resistor is required for accurate detection, making on-chip integration difficult.
By combining a current sampling and detection module and a mirror module, the target current is obtained by controlling the mirror module to mirror the current by acquiring the output voltage of the half-bridge driver, eliminating the need for a high-precision sampling resistor and achieving accurate current detection.
It enables accurate detection of the current in the half-bridge driver, reduces detection requirements, and simplifies the current detection process.
Smart Images
Figure CN116609568B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of current detection technology, and in particular to a current detection circuit and a half-bridge driving device for a half-bridge driver. Background Technology
[0002] A half-bridge driver includes an upper transistor QH and a lower transistor QL connected in series, and drivers DH and DL for driving the upper transistor QH and the lower transistor QL, respectively. Drivers DH and DL drive the upper and lower transistors under the instruction of drive signals VC1 and VC2, respectively. Figure 1 As shown, the drain of the upper transistor QH is used to receive the reference voltage VCC, the source of the lower transistor QL is connected to ground, and the source of the upper transistor QH and the drain of the lower transistor QL are connected together to serve as the output terminal of the half-bridge driver, thereby driving the external load.
[0003] The current to be measured exists in the conductive circuit of the half-bridge driver and is difficult to detect directly. Therefore, a sampling resistor is usually set between the source of the lower transistor QL and the ground terminal so that the end of the sampling resistor connected to the source of the upper transistor DH generates a current sampling voltage that can be used to characterize the current to be measured. However, in order to achieve accurate detection of the current to be measured, the sampling resistor is required to have high precision, the detection requirements are high, and it is difficult to integrate on-chip. Summary of the Invention
[0004] This application relates to a current detection circuit and a half-bridge driving device for a half-bridge driver with low detection requirements, which can achieve accurate detection of the half-bridge driver current without the need to set a high-precision sampling resistor.
[0005] A current detection circuit for a half-bridge driver includes:
[0006] A current sampling and detection module is connected to the output terminal of the half-bridge driver;
[0007] The mirror module is connected to the current sampling and detection module;
[0008] The current sampling and detection module is used for:
[0009] The output voltage of the half-bridge driver is acquired, and the mirror module is controlled to mirror the target current according to the output voltage. The current value of the target current corresponds one-to-one with the current value of the current to be measured by the half-bridge driver.
[0010] The target current is then mirrored and output.
[0011] In one embodiment, the output voltage includes a first voltage output when the lower transistor of the half-bridge driver is turned on; the target current includes a first current.
[0012] The current sampling and detection module includes a first sampling and detection unit, which is connected to the output terminal of the half-bridge driver;
[0013] The mirror module includes a transistor Q1, the gate of which is used to receive a first on-state voltage, the drain of which is connected to the first sampling and detection unit, and the source of which is connected to ground.
[0014] The first sampling and detection unit is used for:
[0015] The first voltage is acquired, and the drain voltage of the transistor Q1 is controlled to be maintained at the first target voltage according to the first voltage, so that the transistor Q1 mirrors the first current, wherein the first target voltage corresponds one-to-one with the first current;
[0016] The first current is mirrored and output.
[0017] In one embodiment, the first sampling and detection unit includes a first switch and a first current source I. A Second current source I B The components include a first compensation current source Io1, a first operational amplifier, transistors Q2, Q3, and Q4, wherein the first operational amplifier includes transistors Q5 and Q6.
[0018] The first terminal of the first switch is connected to the output terminal of the half-bridge driver; the first current source I A The positive terminal, the second current source I B The positive terminal of transistor I, the source of transistor Q3, and the source of transistor Q4 are all connected together to receive the power supply voltage VDD; the first current source I A The negative terminal of transistor Q1, the drain and gate of transistor Q5, and the gate of transistor Q6 are all connected together; the source of transistor Q5 is connected to the source of transistor Q2 and to the drain of transistor Q1; the second current source I B The negative terminal of transistor Q3, the drain of transistor Q6, and the gate of transistor Q2 are all connected together; the source of transistor Q6 is connected to the second terminal of the first switch; the gate and drain of transistor Q3, the gate of transistor Q4, the drain of transistor Q2, and the positive terminal of the first compensation current source Io1 are all connected together; the first compensation current source Io1 is connected to the ground terminal; the current of the first compensation current source Io1 is equal to the current flowing through transistor Q6; the first current source Io1 A and the second current source I B The currents are equal; the transistor Q4 is used to mirror the output of the current flowing through the transistor Q3.
[0019] In one embodiment, the current value of the first current is in a first preset ratio to the current value of the current to be measured.
[0020] In one embodiment, the gate of transistor Q1 is connected to the gate of the lower transistor of the half-bridge driver, and is used to jointly receive the gate turn-on voltage output by driver DL as the first turn-on voltage; the width-to-length ratio of transistor Q1 is the same as the width-to-length ratio of the lower transistor of the half-bridge driver, which is the first preset ratio.
[0021] In one embodiment, the output voltage includes a second voltage output when the upper transistor of the half-bridge driver is turned on; the target current includes a second current.
[0022] The current sampling and detection module includes a second sampling and detection unit, which is connected to the output terminal of the half-bridge driver;
[0023] The mirror module includes a transistor M1, the gate of which is used to receive a second conduction voltage, the drain of which is connected to the drain of the upper transistor and is used to receive a reference voltage VCC, and the source of which is connected to the second sampling and detection unit.
[0024] The second sampling and detection unit is used for:
[0025] The second voltage is acquired, and the source voltage of the transistor M1 is controlled to be maintained at the second target voltage according to the second voltage, so that the transistor M1 mirrors the second current, wherein the second target voltage corresponds one-to-one with the second current;
[0026] The second current is mirrored and output.
[0027] In one embodiment, the second sampling and detection unit includes a second switch and a third current source I. C Second compensation current source Io2, fourth current source I D The second operational amplifier includes transistors M2, M3, and M4, wherein the second operational amplifier includes transistors M5 and M6.
[0028] The first terminal of the second switch is connected to the output terminal of the half-bridge driver; the negative terminals of the third current source, the fourth current source, the source of transistor M3, and the source of transistor M4 are respectively connected to ground; the positive terminal of the third current source, the drain and gate of transistor M5, and the gate of transistor M6 are connected together; the source of transistor M5 is connected to the second terminal of the second switch; the fourth current source I... DThe positive terminal of transistor M1, the drain of transistor M6, and the gate of transistor M2 are all connected together; the source of transistor M6 and the source of transistor M2 are all connected together and connected to the source of transistor M1; the gate and drain of transistor M3, the gate of transistor M4, the drain of transistor M2, and the negative terminal of the second compensation current source Io2 are all connected together; the positive terminal of the second compensation current source Io2 is used to receive the reference voltage VCC; the current of the second compensation current source Io2 is equal to the current flowing through transistor M5; the third current source I... C and the fourth current source I D The currents are equal; the transistor M4 is used to mirror the output current flowing through the transistor M3.
[0029] In one embodiment, the current value of the second current is in a second preset ratio to the current value of the current to be measured.
[0030] In one embodiment, the gate of transistor M1 is connected to the gate of the upper transistor of the half-bridge driver, and is used to jointly receive the gate turn-on voltage output by driver DH as the second turn-on voltage; the width-to-length ratio of transistor M1 is in the second preset ratio to the width-to-length ratio of the upper transistor of the half-bridge driver.
[0031] A half-bridge drive device, comprising:
[0032] Half-bridge driver;
[0033] And the current detection circuit of the half-bridge driver described in any of the above embodiments.
[0034] The current detection circuit of the above-mentioned half-bridge driver acquires the output voltage of the half-bridge driver through the current sampling detection module, then obtains the target current by mirroring it with the mirror module, and finally outputs the mirrored current of the mirror module. This method acquires and mirrors the target current according to the output voltage of the half-bridge driver and outputs it without the need to use a high-precision resistor to convert the current to the sampling voltage, and has low detection requirements. Attached Figure Description
[0035] Figure 1 This is a circuit diagram of a half-bridge driver according to one embodiment;
[0036] Figure 2 This is a current detection circuit for a half-bridge driver according to an embodiment of this application;
[0037] Figure 3 This is a current detection circuit for a half-bridge driver according to another embodiment of this application;
[0038] Figure 4 This is a circuit diagram of the first sampling and detection unit according to an embodiment of this application;
[0039] Figure 5 This is a current detection circuit for a half-bridge driver according to another embodiment of this application;
[0040] Figure 6 This is a current detection circuit for a half-bridge driver according to another embodiment of this application;
[0041] Figure 7 This is a circuit diagram of the second sampling and detection unit according to an embodiment of this application;
[0042] Figure 8 This is a current detection circuit for a half-bridge driver according to another embodiment of this application;
[0043] Figure 9 This is a current detection circuit for a half-bridge driver according to another embodiment of this application. Implementation
[0044] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.
[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0046] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly. The connection can be a direct connection or an indirect connection.
[0047] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.
[0048] Figure 2 Here is a block diagram of the current detection circuit of a half-bridge driver according to one embodiment, as follows: Figure 2As shown, the current detection circuit of the half-bridge driver includes a current sampling and detection module 101 and a mirror module 102; the mirror module 102 is connected to the current sampling and detection module 101; the current sampling and detection module 101 is used to: collect the output voltage of the half-bridge driver, and control the mirror module 102 to generate a target current according to the output voltage, wherein the current value of the target current corresponds one-to-one with the current value of the current to be measured in the half-bridge driver; and mirror and output the target current.
[0049] In this half-bridge driver, only one of the upper and lower transistors is turned on. When either the upper or lower transistor is on, the half-bridge driver can output a non-zero output voltage. Specifically, when the upper transistor of the half-bridge driver is on, the reference voltage VCC charges the external load through the upper transistor, and the output voltage at the output terminal of the half-bridge driver is not zero. When the lower transistor of the half-bridge driver is on, the external load discharges to ground through the lower transistor, and the output voltage at the output terminal of the half-bridge driver is also not zero.
[0050] The current sampling and detection module 101, in response to the output voltage, controls the mirror module 102 to generate a target current. The target current corresponds one-to-one with the output voltage. Based on the acquired output voltage, the current sampling and detection module 101 controls the mirror module 102 to mirror the corresponding target current. Since the output voltage corresponds one-to-one with the current to be measured in the half-bridge driver, the target current also corresponds one-to-one with the current to be measured, and can be used to characterize the current to be measured in the half-bridge driver. Based on the mapping relationship between the target current and the current to be measured, after obtaining the target current, the magnitude of the current to be measured in the half-bridge driver can be further determined based on this mapping relationship.
[0051] After the mirror module 102 mirrors the target current, in order to output the target current, the current sampling and detection module 101 can be used to mirror and output the target current, thus realizing the detection of the on-chip current.
[0052] The current detection circuit of the above-mentioned half-bridge driver acquires the output voltage of the half-bridge driver through the current sampling detection module 101, then obtains the target current by mirroring it with the mirror module 102, and finally outputs the mirrored current of the mirror module 102. This method acquires and mirrors the target current according to the output voltage of the half-bridge driver and outputs it without the need to use a high-precision resistor to convert the current to the sampling voltage, and the detection requirements are low.
[0053] In one embodiment, such as Figure 3As shown, the output voltage includes a first voltage output when the lower transistor of the half-bridge driver is turned on; the target current includes a first current; the current sampling and detection module 101 includes a first sampling and detection unit 1011, which is connected to the output terminal of the half-bridge driver; the mirror module 102 includes a transistor Q1, the gate of transistor Q1 is used to receive a first on-state voltage U1, the drain of transistor Q1 is connected to the first sampling and detection unit 1011, and the source of transistor Q1 is connected to ground; the first sampling and detection unit 1011 is used to: acquire the first voltage, and control the drain voltage of transistor Q1 to maintain the first target voltage according to the first voltage, so that transistor Q1 mirrors the first current, wherein the first target voltage and the first current correspond one-to-one; mirror the first current and output it.
[0054] It is understandable that when the half-bridge driver is driven by the lower transistor, the current to be measured by the half-bridge driver can be characterized by the first current, and the current to be measured can be measured by the first sampling and detection unit 1011 and transistor Q1.
[0055] In this transistor, transistor Q1 can be an N-type MOS transistor. The sources of transistor Q1 and the lower transistor QL are both grounded. When the width-to-length ratio and gate voltage of transistor Q1 are constant, the current flowing through transistor Q1 can be adjusted by adjusting the drain voltage. Therefore, the first target voltage and the first current correspond one-to-one. Since the first target voltage and the first voltage also correspond one-to-one, the first current also corresponds one-to-one with the first voltage. Thus, the first sampling and detection unit 1011 controls the drain voltage of transistor Q1 to maintain the first target voltage based on the first voltage, thereby obtaining the first current corresponding to the current to be measured.
[0056] In this embodiment, by setting transistor Q1 and controlling the drain voltage of transistor Q1 to maintain the first target voltage based on the first voltage, the first current is obtained. The method is simple and effective.
[0057] In one embodiment, such as Figure 4 As shown, the first sampling and detection unit 1011 includes a first switch 1031 and a first current source I. A Second current source I BThe system comprises a first compensation current source Io1, a first operational amplifier 1011a, transistors Q2, Q3, and Q4, wherein the first operational amplifier 1011a includes transistors Q5 and Q6; the first terminal of a first switch 1031 is connected to the output terminal of a half-bridge driver; the positive terminals of the first current source, the second current source, the source of transistor Q3, and the source of transistor Q4 are connected together to receive the power supply voltage VDD; the negative terminal of the first current source, the drain and gate of transistor Q5, and the gate of transistor Q6 are connected together; and a crystal... The source of transistor Q5 is connected to the source of transistor Q2 and to the drain of transistor Q1; the negative terminal of the second current source, the drain of transistor Q6, and the gate of transistor Q2 are connected together; the source of transistor Q6 is connected to the second terminal of the first switch 1031; the gate and drain of transistor Q3, the gate of transistor Q4, the drain of transistor Q2, and the positive terminal of the first compensation current source Io1 are connected together; the current of the first compensation current source Io1 is equal to the current flowing through transistor Q6; transistor Q4 is used to mirror the output current flowing through transistor Q3.
[0058] The first switch 1031 can be used to turn on the conductive path between the half-bridge driver and the first operational amplifier 1011a, so that the first operational amplifier 1011a can acquire the first voltage; transistors Q3 and Q4 can be P-type MOS transistors, and transistors Q2, Q5 and Q6 can be N-type MOS transistors. It is understandable that, firstly, the source of transistor Q6 serves as the positive input terminal vp of the first operational amplifier 1011a, and the source of transistor Q5 serves as the negative input terminal vn of the first operational amplifier 1011a. Transistor Q6 conducts under the action of the first voltage, thereby driving transistor Q2. After transistor Q2 conducts, the current flowing through transistor Q2 is adjusted by the compensation of the first compensation current source Io1, that is, the source voltage of transistor Q2 fed back to the source of transistor Q5 is adjusted. Finally, the source voltage of transistor Q2, that is, the drain voltage of transistor Q1, is adjusted by the driving process of transistor Q5. In this way, the drain voltage of transistor Q1 can be adjusted to reach the first target voltage by using the negative feedback of the first operational amplifier 1011a, thereby obtaining the desired first current. This is simple and effective.
[0059] Furthermore, let the first current source I... A The current is I a Second current source I B The current is I b The current flowing through transistor Q1 is the first current, denoted by I1; the current flowing through transistor Q2 is I2; the current flowing through transistor Q3 is I3; the current flowing through transistor Q4 is I4; and the current from the first compensation current source Io1 is I5. Since I5 = I... b, I3=I2+I5, then I2=I3-I5=I3-I b Therefore, I1 = I a +I2=I a +I3-I b And because I a =I b Therefore, we can obtain I1=I3; I4 mirrors the current I3 of transistor Q3, so I4=I3=I1, thus achieving the mirror output of the first current.
[0060] In one embodiment, continue to refer to Figure 4 As shown, the first switch 1031 may have two contact points at its first end and one movable contact at its second end. The first contact point is connected to the output terminal of the half-bridge driver, and the second contact point is connected to ground. When the movable contact point contacts the first contact point, the conductive path between the first operational amplifier 1011a and the half-bridge driver is open; when the movable contact point contacts the second contact point, the conductive path between the first operational amplifier 1011a and the half-bridge driver is closed. The first switch 1031 may be an overvoltage protection switch. Under default conditions, the movable contact point is in contact with the first contact point. When the lower transistor is on, the voltage received by the first switch 1031 is within a safe range, and the movable contact point remains in contact with the first contact point. When the upper transistor is on, the voltage received by the first switch 1031 exceeds the safe threshold, and the movable contact point switches to contact the second contact point to disconnect from the half-bridge driver. Thus, the first switch 1031 only opens the conductive path between the first operational amplifier 1011a and the half-bridge driver when the lower transistor is on.
[0061] In one embodiment, the current value of the first current is in a first preset ratio to the current value of the current to be measured.
[0062] It is understood that after obtaining the first current, in order to facilitate subsequent measurement of the first current by external devices to obtain the value of the current to be measured, the current value of the first current can be in a first preset ratio with the current value of the current to be measured, so as to meet the measurement requirements of the external devices. In one embodiment, the current value of the first current can be equal to one-thousandth of the current value of the current to be measured.
[0063] In one embodiment, such as Figure 5 As shown, the gate of transistor Q1 is connected to the gate of the lower transistor of the half-bridge driver, and is used to jointly receive the gate turn-on voltage output by driver DL as the first turn-on voltage; the width-to-length ratio of transistor Q1 is in a first preset ratio to the width-to-length ratio of the lower transistor of the half-bridge driver.
[0064] It is understood that the gate of transistor Q1 is connected to the lower transistor of the half-bridge driver via a common gate. Therefore, the first preset ratio between the first current flowing through transistor Q1 and the measured current flowing through the lower transistor of the half-bridge driver can be determined by the ratio between the width-to-length ratio of transistor Q1 and the width-to-length ratio of the lower transistor. By setting the width-to-length ratio of transistor Q1 to the width-to-length ratio of the lower transistor of the half-bridge driver to be in the first preset ratio, the current flowing through transistor Q1 and the measured current flowing through the lower transistor of the half-bridge driver can be controlled to be in the first preset ratio.
[0065] In one embodiment, such as Figure 6 As shown, the output voltage includes the second voltage output when the upper transistor of the half-bridge driver is turned on; the target current includes the second current; the current sampling and detection module 101 includes a second sampling and detection unit 1012, which is connected to the output terminal of the half-bridge driver; the mirror module 102 includes a transistor M1, the gate of which is used to receive the second turn-on voltage, the drain of which is connected to the drain of the upper transistor and is used to receive the reference voltage VCC, and the source of which is connected to the second sampling and detection unit 1012; the second sampling and detection unit 1012 is used to: acquire the second voltage, and control the source voltage of the transistor M1 to maintain the second target voltage according to the second voltage, so that the transistor M1 mirrors the second current, wherein the second target voltage and the second current correspond one-to-one; mirror the second current and output it.
[0066] It is understandable that when the half-bridge driver is driven by the upper transistor, the current to be measured by the half-bridge driver can be characterized by the second current, and the current to be measured can be measured by the second sampling and detection unit 1012 and transistor M1.
[0067] It can be understood that the drains of both transistor M1 and the upper transistor QH receive the reference voltage VCC. Given that the width-to-length ratio and gate voltage of transistor M1 are constant, the current flowing through transistor M1 can be adjusted by adjusting the source voltage. Therefore, the second target voltage and the second current correspond one-to-one. Since the second target voltage and the second voltage also correspond one-to-one, the second current also corresponds one-to-one with the second voltage. Thus, the second sampling and detection unit controls the source voltage of transistor M1 to maintain the second target voltage based on the second voltage, thereby obtaining the second current corresponding to the current to be measured.
[0068] In this embodiment, by setting transistor M1 and controlling the source voltage of transistor M1 to maintain the second target voltage based on the second voltage, the second current is obtained. The method is simple and effective.
[0069] In one embodiment, such as Figure 7 As shown, the second sampling and detection unit 1012 includes a second switch 1032 and a third current source I. C Fourth current source I DThe system comprises a second compensation current source Io2, a second operational amplifier 1011b, transistors M2, M3, and M4, wherein the second operational amplifier 1011b includes transistors M5 and M6; the first terminal of the second switch 1032 is connected to the output terminal of the half-bridge driver; the negative terminals of the third and fourth current sources, the source terminals of transistors M3 and M4 are respectively connected to ground; the positive terminal of the third current source, the drain and gate terminals of transistor M5, and the gate terminal of transistor M6 are connected together; the source terminal of transistor M5 is connected to the second terminal of the second switch 1032; the fourth current source Io2... D The positive terminal of transistor M1, the drain of transistor M6, and the gate of transistor M2 are connected together; the source of transistor M6 and the source of transistor M2 are connected together and connected to the source of transistor M1; the gate and drain of transistor M3, the gate of transistor M4, the drain of transistor M2, and the negative terminal of the second compensation current source Io2 are connected together; the positive terminal of the second compensation current source Io2 is used to receive the reference voltage VCC; the current of the second compensation current source Io2 is equal to the current flowing through transistor M5; the third current source I... C and the fourth current source I D The currents are equal; transistor M4 is used to mirror the output current flowing through transistor M3.
[0070] The second switch 1032 can be used to turn on the conductive path between the half-bridge driver and the second operational amplifier 1011b, so that the second operational amplifier 1011b can acquire the second voltage; transistors M3 and M4 can be N-type MOS transistors, and transistors M2, M5 and M6 can be P-type MOS transistors. It can be understood that, firstly, the source of transistor M6 serves as the negative input terminal vn of the second operational amplifier 1011b, and the source of transistor M5 serves as the positive input terminal vp of the second operational amplifier 1011b. Transistor M5 conducts under the action of the second voltage, thereby driving transistor M6, which in turn drives transistor M2. After transistor M2 conducts, the current flowing through transistor M2 is adjusted by the compensation of the second compensation current source Io2, that is, the source voltage of transistor M2 fed back to the source of transistor M5 is adjusted. Finally, the source voltage of transistor M2, that is, the drain voltage of transistor M1, is adjusted by the driving process of transistor M5. In this way, the drain voltage of transistor M1 can be adjusted to reach the second target voltage by using the negative feedback of the second operational amplifier 1011b, thereby obtaining the desired second current. This is simple and effective.
[0071] Furthermore, let the third current source I be... C The current is I c Fourth current source I D The current is I dThe current flowing through transistor M1 is the second current, denoted as I6; the current flowing through transistor M2 is I7; the current flowing through transistor M3 is I8; the current flowing through transistor M4 is I9; and the current flowing through the second compensation current source Io2 is I... 10 ; Due to I 10 =I c I8 = I7 + I 10 =I7+I c Then I7 = I8 - I c Therefore, I6 = I d +I7= I d +I8-I c And because I c =I d Therefore, we can obtain I6=I8; I9 mirrors the current I8 of transistor M3, so I9=I8=I6, thus achieving the mirror output of the second current.
[0072] In one embodiment, continue to refer to Figure 7 As shown, the first end of the second switch 1032 may have two contact points, and the second end may have one movable contact. The first contact point is connected to the output terminal of the half-bridge driver, and the second contact point is used to receive the reference voltage VCC. When the movable contact point contacts the first contact point, the conductive path between the second operational amplifier 1011b and the half-bridge driver is open; when the movable contact point contacts the second contact point, the conductive path between the second operational amplifier 1011b and the half-bridge driver is closed. The second switch 1032 can be an overvoltage protection switch. Under default conditions, the movable contact point is in contact with the first contact point. When the upper transistor is on, the voltage received by the second switch 1032 is within a safe range, and the movable contact point remains in contact with the first contact point. When the upper transistor is off, the voltage received by the second switch 1032 exceeds the voltage safety threshold, and the movable contact point switches to contact the second contact point to disconnect from the half-bridge driver. In this way, the second switch 1032 can only open the conductive path between the second operational amplifier 1011b and the half-bridge driver when the lower transistor is on.
[0073] In one embodiment, the current value of the second current is in a second preset ratio to the current value of the current to be measured.
[0074] It is understood that after obtaining the second current, in order to facilitate subsequent measurement of the second current by external devices to obtain the value of the current to be measured, the current value of the second current can be in a second preset ratio to the current value of the current to be measured, so as to meet the measurement requirements of the external devices. In one embodiment, the current value of the second current can be equal to one-thousandth of the current to be measured.
[0075] In one embodiment, such as Figure 8As shown, the gate of transistor M1 is connected to the gate of the upper transistor of the half-bridge driver, and is used to jointly receive the gate turn-on voltage output by driver DH as the second turn-on voltage; the width-to-length ratio of transistor M1 is in a second preset ratio to the width-to-length ratio of the upper transistor of the half-bridge driver.
[0076] It is understood that the gate of transistor M1 is connected to the gate of the upper transistor of the half-bridge driver. Therefore, the first preset ratio of the second current flowing through transistor M1 to the measured current flowing through the upper transistor of the half-bridge driver can be determined by the ratio of the width-to-length ratio of transistor M1 to the width-to-length ratio of the upper transistor. By setting the width-to-length ratio of transistor M1 to the width-to-length ratio of the upper transistor of the half-bridge driver to be in a second preset ratio, the current flowing through transistor M1 and the measured current flowing through the upper transistor of the half-bridge driver can be controlled to be in a second preset ratio.
[0077] Another embodiment of the present invention also provides a current detection circuit for a half-bridge driver, such as... Figure 9 As shown. The current detection circuit includes a current sampling and detection module 101 and a mirror module 102. The current sampling and detection module 101 includes a first sampling and detection unit 1011 and a second sampling and detection unit 1012. The mirror module 102 includes transistor Q1 and transistor M1. The first sampling and detection unit 1011 includes a first switch 1031 and a first current source I. A Second current source I B The system comprises a first compensation current source Io1, a first operational amplifier 1011a, transistors Q2, Q3, and Q4, wherein the first operational amplifier 1011a includes transistors Q5 and Q6; the second sampling and detection unit 1012 includes a second switch 1032 and a third current source Io1. C Fourth current source I D The components include a second compensation current source Io2, a second operational amplifier 1011b, transistors M2, M3, and M4, wherein the second operational amplifier 1011b includes transistors M5 and M6; the specific connection relationships and operating principles of each component can be found above. Figure 4 and Figure 7 Examples are not described in detail here.
[0078] This invention also provides a half-bridge drive device, including a half-bridge driver and a current detection circuit for the half-bridge driver in any of the above embodiments.
[0079] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural changes made based on the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.
Claims
1. A current detection circuit for a half-bridge driver, characterized in that, include: A current sampling and detection module is connected to the output terminal of the half-bridge driver; The mirror module is connected to the current sampling and detection module; The current sampling and detection module is used for: The output voltage of the half-bridge driver is acquired, and the mirror module is controlled to mirror the target current according to the output voltage. The current value of the target current corresponds one-to-one with the current value of the current to be measured by the half-bridge driver. Mirror and output the target current; The output voltage includes a first voltage output when the lower transistor of the half-bridge driver is turned on; the target current includes a first current. The current sampling and detection module includes a first sampling and detection unit, which is connected to the output terminal of the half-bridge driver; The mirror module includes a transistor Q1, the gate of which is used to receive a first on-state voltage, the drain of which is connected to the first sampling and detection unit, and the source of which is connected to ground. The first sampling and detection unit is used for: The first voltage is acquired, and the drain voltage of the transistor Q1 is controlled to be maintained at the first target voltage according to the first voltage, so that the transistor Q1 mirrors the first current, wherein the first target voltage corresponds one-to-one with the first current; Mirror the first current and output it; The first sampling and detection unit includes a first switch and a first current source I. A Second current source I B The components include a first compensation current source Io1, a first operational amplifier, transistors Q2, Q3, and Q4, wherein the first operational amplifier includes transistors Q5 and Q6. The first terminal of the first switch is connected to the output terminal of the half-bridge driver; the first current source I A The positive terminal, the second current source I B The positive terminal of transistor I, the source of transistor Q3, and the source of transistor Q4 are all connected together to receive the power supply voltage VDD; the first current source I A The negative terminal of transistor Q1, the drain and gate of transistor Q5, and the gate of transistor Q6 are all connected together; the source of transistor Q5 is connected to the source of transistor Q2 and to the drain of transistor Q1; the second current source I B The negative terminal of transistor Q3, the drain of transistor Q6, and the gate of transistor Q2 are all connected together; the source of transistor Q6 is connected to the second terminal of the first switch; the gate and drain of transistor Q3, the gate of transistor Q4, the drain of transistor Q2, and the positive terminal of the first compensation current source Io1 are all connected together; the first compensation current source Io1 is connected to the ground terminal; the current of the first compensation current source Io1 is equal to the current flowing through transistor Q6; the first current source Io1 A and the second current source I B The currents are equal; the transistor Q4 is used to mirror the output of the current flowing through the transistor Q3.
2. The current detection circuit of the half-bridge driver according to claim 1, characterized in that, The current value of the first current is in a first preset ratio to the current value of the current to be measured.
3. The current detection circuit of the half-bridge driver according to claim 2, characterized in that, The gate of transistor Q1 is connected to the gate of the lower transistor of the half-bridge driver, and is used to jointly receive the gate turn-on voltage output by driver DL as the first turn-on voltage; the width-to-length ratio of transistor Q1 is in the first preset ratio to the width-to-length ratio of the lower transistor of the half-bridge driver.
4. The current detection circuit of the half-bridge driver according to claim 1, characterized in that, The output voltage includes a second voltage output when the upper transistor of the half-bridge driver is turned on; the target current includes a second current. The current sampling and detection module includes a second sampling and detection unit, which is connected to the output terminal of the half-bridge driver; The mirror module includes a transistor M1, the gate of which is used to receive a second conduction voltage, the drain of which is connected to the drain of the upper transistor and is used to receive a reference voltage VCC, and the source of which is connected to the second sampling and detection unit. The second sampling and detection unit is used for: The second voltage is acquired, and the source voltage of the transistor M1 is controlled to be maintained at the second target voltage according to the second voltage, so that the transistor M1 mirrors the second current, wherein the second target voltage corresponds one-to-one with the second current; The second current is mirrored and output.
5. The current detection circuit of the half-bridge driver according to claim 4, characterized in that, The second sampling and detection unit includes a second switch and a third current source I. C Fourth current source I D The system includes a second compensation current source Io2, a second operational amplifier, transistors M2, M3, and M4, wherein the second operational amplifier includes transistors M5 and M6. The first terminal of the second switch is connected to the output terminal of the half-bridge driver; the negative terminals of the third current source, the fourth current source, the source of transistor M3, and the source of transistor M4 are respectively connected to ground; the positive terminal of the third current source, the drain and gate of transistor M5, and the gate of transistor M6 are connected together; the source of transistor M5 is connected to the second terminal of the second switch; the fourth current source I... D The positive terminal of transistor M1, the drain of transistor M6, and the gate of transistor M2 are all connected together; the source of transistor M6 and the source of transistor M2 are all connected together and connected to the source of transistor M1; the gate and drain of transistor M3, the gate of transistor M4, the drain of transistor M2, and the negative terminal of the second compensation current source Io2 are all connected together; the positive terminal of the second compensation current source Io2 is used to receive the reference voltage VCC; the current of the second compensation current source Io2 is equal to the current flowing through transistor M5; the third current source I... C and the fourth current source I D The currents are equal; the transistor M4 is used to mirror the output current flowing through the transistor M3.
6. The current detection circuit of the half-bridge driver according to claim 4, characterized in that, The current value of the second current is in a second preset ratio to the current value of the current to be measured.
7. The current detection circuit of the half-bridge driver according to claim 6, characterized in that, The gate of transistor M1 is connected to the gate of the upper transistor of the half-bridge driver, and is used to jointly receive the gate turn-on voltage output by driver DH as the second turn-on voltage; the width-to-length ratio of transistor M1 is in the second preset ratio to the width-to-length ratio of the upper transistor of the half-bridge driver.
8. A half-bridge drive device, characterized in that, include: Half-bridge driver; And the current detection circuit of the half-bridge driver according to any one of claims 1 to 7.