Current judgment circuit

Abstract

A current judgment circuit is used to judge the state of a current passing through a coil of a motor, and includes a high-side circuit, a low-side circuit, and a processing unit. The high-side circuit is used to output a first judgment signal according to a first voltage difference between two ends of a first body diode of a high-side transistor and the voltage level of a first control signal. The low-side circuit is used to output a second judgment signal according to a second voltage difference between two ends of a second body diode of a low-side transistor and the voltage level of a second control signal. The processing unit is used to receive the first judgment signal and the second judgment signal, and judge the state of the current according to the voltage level of the first judgment signal and the voltage level of the second judgment signal. Through the design of the high-side circuit and the low-side circuit, the current judgment circuit does not need to measure the voltage value of the node, thereby avoiding problems caused by measuring voltage values higher than the system high voltage or lower than the system low voltage.

Description

Technical Field

[0001] The present disclosure relates to a current judgment circuit, and particularly to a current judgment circuit for judging the state of a coil current. Background Art

[0002] Taking one group of high-side transistors and low-side transistors in a driving circuit of a three-phase motor as an example, generally, the high-side transistors and the low-side transistors conduct alternately to change the flowing direction of the coil current, thereby driving the motor. When the motor is driven, there is a period (hereinafter referred to as the Dead Zone) during which both the high-side transistors and the low-side transistors are in the off state. It should be noted that the flowing direction of the coil current in the Dead Zone can best reflect the immediate state of the operating motor. Also, the voltage value of a node commonly coupled by the high-side transistors, the low-side transistors, and the motor coil changes according to the flowing direction of the coil current in the Dead Zone. Accordingly, conventionally, by comparing the voltage value of this node with the system high voltage or the system low voltage, the flowing direction of the coil current in the Dead Zone can be judged to obtain the immediate state information of the operating motor.

[0003] However, the above judgment result is easily affected by system noise, and since it is necessary to measure a voltage value higher than the system high voltage (or lower than the system low voltage), an auxiliary circuit (or other special methods) is often required, which leads to an increase in cost. In addition, when the voltage value of this node is between the system high voltage and the system low voltage, the flowing direction of the coil current often cannot be judged. Summary of the Invention

[0004] In view of this, the present disclosure provides a current judgment circuit. The current judgment circuit is used to judge the state of a current passing through a coil of a motor, and includes a high-side transistor, a low-side transistor, a high-side circuit, a low-side circuit, and a processing unit. The high-side transistor is coupled to the coil and is used to selectively conduct or turn off according to the voltage level of a first control signal, and includes a first body diode. The low-side transistor is coupled to the coil and is used to selectively conduct or turn off according to the voltage level of a second control signal, and includes a second body diode. The high-side circuit is coupled to the high-side transistor and is used to output a first judgment signal according to a first voltage difference between two ends of the first body diode and the voltage level of the first control signal. The low-side circuit is coupled to the low-side transistor and is used to output a second judgment signal according to a second voltage difference between two ends of the second body diode and the voltage level of the second control signal. The processing unit is used to output the first control signal and the second control signal, receive the first judgment signal and the second judgment signal, and judge the state of the current according to the voltage level of the first judgment signal and the voltage level of the second judgment signal.

[0005] In another embodiment, when the first judgment signal is at a low voltage level and the second judgment signal is at a low voltage level, the processing unit determines that the current is zero.

[0006] In another embodiment, when the first judgment signal is at a high voltage level and the second judgment signal is at a low voltage level, the processing unit determines that the current flows out of the coil and then passes through the first body diode.

[0007] In another embodiment, when the first judgment signal is at a low voltage level and the second judgment signal is at a high voltage level, the processing unit determines that the current passes through the second body diode and then flows into the coil.

[0008] In another embodiment, when the first judgment signal is at a high voltage level and the second judgment signal is at a high voltage level, the processing unit determines that the state of the current is undetermined.

[0009] In another embodiment, the high-side circuit includes a first comparator, coupled to the first body diode, and configured to output a first status signal according to the first voltage difference across the two ends of the first body diode.

[0010] In another embodiment, the high-side circuit further includes a first logic gate, which is coupled to the first comparator and the high-side transistor, and is configured to output the first judgment signal according to the voltage level of the first status signal and the voltage level of the first control signal.

[0011] In another embodiment, the low-side circuit includes a second comparator, coupled to the second body diode, and configured to output a second status signal according to the second voltage difference across the two ends of the second body diode.

[0012] In another embodiment, the low-side circuit further includes a second logic gate and a third logic gate. The second logic gate is coupled to the low-side transistor and is configured to switch the voltage level of the second control signal. The third logic gate is coupled to the second comparator and the second logic gate, and is configured to output the second judgment signal according to the voltage level of the second status signal and the voltage level of the second control signal switched by the second logic gate.

[0013] In another embodiment, the high-side transistor further includes a first terminal, a second terminal, and a first control terminal. The two ends of the first body diode are coupled to the first terminal and the second terminal. The first terminal is used to receive a system high voltage, the second terminal is coupled to the coil, and the first control terminal is used to receive the first control signal. The low-side transistor further includes a third terminal, a fourth terminal, and a second control terminal. The two ends of the second body diode are coupled to the third terminal and the fourth terminal. The third terminal is coupled to the coil, the fourth terminal is used to receive a system low voltage, and the second control terminal is used to receive the second control signal.

[0014] Through the design of the high-side circuit and the low-side circuit, the current judgment circuit of the present disclosure can determine the state of the current in the coil in the stagnant region according to the first voltage difference across the first body diode parasitic on the high-side transistor and the second voltage difference across the second body diode parasitic on the low-side transistor. Since the voltage value of the node does not need to be measured, the current judgment circuit can avoid problems caused by measuring voltage values higher than the system high voltage or lower than the system low voltage. In addition, the processing unit can also obtain the phase information of the current and adjust the phase relationship between the current and the back electromotive force of the motor, so that the motor can operate at the optimal speed value. Description of the Drawings

[0015] Figure 1 FIG. is a schematic diagram of a current judgment circuit according to some embodiments of the present disclosure;

[0016] Figure 2 FIG. is a schematic diagram of the current judgment circuit in operation according to some embodiments of the present disclosure;

[0017] Figure 3 FIG. is a schematic diagram of the current judgment circuit in operation according to some embodiments of the present disclosure;

[0018] Figure 4 FIG. is a schematic diagram of the current judgment circuit in operation according to some embodiments of the present disclosure;

[0019] Figure 5 FIG. is a schematic diagram of the current judgment circuit in operation according to some embodiments of the present disclosure.

[0020] Symbol Description

[0021] 10: Coil

[0022] 100: Current judgment circuit

[0023] 102: High-side transistor

[0024] 104: Low-side transistor [[ID=4D]]

[0025] 106: High-side circuit

[0026] 108: Low-side circuit

[0027] 110: Processing unit

[0028] 120: Controller

[0029] 121: First body diode

[0030] 141: Second body diode

[0031] 161: First comparator

[0032] 162: First logic gate

[0033] 181: Second comparator

[0034] 182: Second logic gate

[0035] 183: Third logic gate

[0036] CS1: First control signal

[0037] CS2: Second control signal

[0038] SS1: First status signal

[0039] SS2: Second status signal

[0040] DS1: First judgment signal

[0041] DS2: Second judgment signal

[0042] Vcc: System high voltage

[0043] Vss: System low voltage

[0044] I1, I2, I3, I4: Current

[0045] N: Node Detailed implementation manners

[0046] The following are detailed descriptions with reference to the accompanying drawings by way of examples. However, the specific examples described are only used to explain the present case and do not limit the present case. The description of the structure and operation does not limit the execution order. Any structure formed by recombining components and having equivalent functions is within the scope covered by the present disclosure.

[0047] The terms used throughout the specification and claims, unless otherwise specifically noted, generally have their ordinary meanings as used in this field, in the content disclosed herein, and in the specific context.

[0048] Regarding the "first", "second", etc. used herein, they do not particularly refer to the order or sequence, nor are they used to limit the present disclosure. They are merely used to distinguish components or operations described with the same technical terms.

[0049] In addition, regarding the "coupled" or "connected" used herein, it can refer to two or more components being in direct physical or electrical contact with each other, or being in indirect physical or electrical contact with each other, and can also refer to two or more components operating or acting on each other.

[0050] Please refer to Figure 1, one embodiment of the present disclosure relates to a current determination circuit 100. The current determination circuit 100 is used to determine the state of a current (such as the current I2 in Figure 3 or the current I3 in Figure 4 ) passing through a coil 10 of a motor (not shown in the figure), and includes a high-side transistor 102, a low-side transistor 104, a high-side circuit 106, a low-side circuit 108, and a processing unit 110.

[0051] In this embodiment, the motor is a three-phase motor. It can be understood that the motor includes three coils (one of which is the coil 10 as shown in Figure 1 ). However, for simplicity of description, the other two coils and the two current determination circuits corresponding to these coils are omitted in Figure 1 .

[0052] Structurally, the processing unit 110 is coupled to the high-side transistor 102 and the low-side transistor 104, and is used to output a first control signal CS1 and a second control signal CS2 to the high-side transistor 102 and the low-side transistor 104 respectively to control the high-side transistor 102 and the low-side transistor 104. Specifically, the processing unit 110 includes a controller 120, and the controller 120 is used to generate the first control signal CS1 and the second control signal CS2.

[0053] The high-side transistor 102 is used to selectively conduct or turn off according to the voltage level of the first control signal CS1, and the low-side transistor 104 is used to selectively conduct or turn off according to the voltage level of the second control signal CS2. As shown in Figure 1 , the high-side transistor 102, the low-side transistor 104, and the coil 10 of the motor are commonly coupled to a node N.

[0054] Specifically, the high-side transistor 102 includes a first end, a second end, a first control end, and a first body diode 121 parasitic between the first end and the second end. Among them, the first end is used to receive a system high voltage Vcc, the second end is coupled to the node N, the first control end is used to receive a first control signal CS1, the cathode end of the first body diode 121 is coupled to the first end, and the anode end of the first body diode 121 is coupled to the second end (or node N). The low-side transistor 104 includes a third end, a fourth end, a second control end, and a second body diode 141 parasitic between the third end and the fourth end. Among them, the third end is coupled to the node N, the fourth end is used to receive a system low voltage Vss, the second control end is used to receive a second control signal CS2, the cathode end of the second body diode 141 is coupled to the third end (or node N), and the anode end of the second body diode 141 is coupled to the fourth end. In other words, the second end of the high-side transistor 102 and the third end of the low-side transistor 104 are coupled to the coil 10 of the motor.

[0055] In this embodiment, the high-side transistor 102 is a P-type metal oxide semiconductor, and the low-side transistor 104 is an N-type metal oxide semiconductor. However, the disclosure is not limited thereto. In some embodiments, the high-side transistor 102 can be implemented with an N-type metal oxide semiconductor, and the low-side transistor 104 can be implemented with a P-type metal oxide semiconductor. Or, in other some embodiments, the high-side transistor 102 and the low-side transistor 104 can also be implemented with bipolar transistors.

[0056] The high-side circuit 106 and the low-side circuit 108 are respectively coupled to the high-side transistor 102 and the low-side transistor 104. Among them, the high-side circuit 106 is used to output a first judgment signal DS1 according to a first voltage difference VD1 between the two ends of the first body diode 121 and the voltage level of the first control signal CS1 (corresponding to the conduction state of the high-side transistor 102), and the low-side circuit 108 is used to output a second judgment signal DS2 according to a second voltage difference VD2 between the two ends of the second body diode 141 and the voltage level of the second control signal CS2 (corresponding to the conduction state of the low-side transistor 104).

[0057] Specifically, the high-side circuit 106 includes a first comparator 161 and a first logic gate 162. A positive input terminal and a negative input terminal of the first comparator 161 are respectively coupled to the anode terminal and the cathode terminal of the first body diode 121, and are configured to output a first status signal SS1 according to a first voltage difference VD1 between two ends (i.e., the anode terminal and the cathode terminal) of the first body diode 121. In this embodiment, the first voltage difference VD1 changes according to whether there is a forward current flowing through the first body diode 121. For example, when there is a forward current flowing through the first body diode 121, the first voltage difference VD1 (e.g., 0.7 volts) between two ends of the first body diode 121 is greater than 0 volts (i.e., is a positive value), resulting in the voltage level of the positive input terminal of the first comparator 161 being higher than the voltage level of the negative input terminal of the first comparator 161, and further causing the first comparator 161 to output the first status signal SS1 with a high voltage level. Conversely, when there is no forward current flowing through the first body diode 121, the first voltage difference VD1 between two ends of the first body diode 121 is not greater than 0 volts (i.e., is not a positive value), resulting in the voltage level of the positive input terminal of the first comparator 161 being lower than the voltage level of the negative input terminal of the first comparator 161, and further causing the first comparator 161 to output the first status signal SS1 with a low voltage level.

[0058] Two input terminals of the first logic gate 162 are respectively coupled to the output terminal of the first comparator 161 and the first control terminal of the high-side transistor 102, and are configured to output a first determination signal DS1 with a high voltage level or a low voltage level according to the voltage level of the first status signal SS1 and the voltage level of the first control signal CS1. For example, when at least one of the first status signal SS1 and the first control signal CS1 is at a low voltage level, the first logic gate 162 outputs the first determination signal DS1 with a low voltage level. When the first status signal SS1 and the first control signal CS1 are both at a high voltage level, the first logic gate 162 outputs the first determination signal DS1 with a high voltage level. In this embodiment, the first logic gate 162 is an AND gate.

[0059] The low-side circuit 108 includes a second comparator 181, a second logic gate 182, and a third logic gate 182. A positive input terminal and a negative input terminal of the second comparator 181 are respectively coupled to the anode terminal and the cathode terminal of the second body diode 141. Similar to the description of the foregoing first comparator 161, the second voltage difference VD2 changes according to whether there is a forward current flowing through the second body diode 141. In this way, the second comparator 181 can be configured to determine whether to output a second status signal SS2 with a high voltage level or a low voltage level according to whether the second voltage difference VD2 between two ends of the second body diode 141 is a positive value.

[0060] The second logic gate 182 is coupled to the second control terminal of the low-side transistor 104 and is configured to switch the voltage level of the second control signal CS2. For example, when the processing unit 110 outputs the second control signal CS2 with a low voltage level, the second logic gate 182 can switch the second control signal CS2 from the low voltage level to the high voltage level, and vice versa. In this embodiment, the second logic gate 182 is a NOT gate.

[0061] The two input terminals of the third logic gate 182 are respectively coupled to the output terminal of the second comparator 181 and the output terminal of the second logic gate 182. Similar to the description of the foregoing first logic gate 162, the third logic gate 182 is configured to output a second determination signal DS2 with a high voltage level or a low voltage level according to the voltage level of the second status signal SS2 and the voltage level of the second control signal CS2. In this embodiment, the third logic gate 182 is an AND gate.

[0062] In addition, the output terminal of the first logic gate 162 and the output terminal of the third logic gate 182 are coupled to the processing unit 110. In this way, the processing unit 110 can be configured to receive the first determination signal DS1 and the second determination signal DS2, and determine the state of the current in the coil 10 according to the voltage level of the first determination signal DS1 and the voltage level of the second determination signal DS2.

[0063] To better understand the present case, the operation of the current determination circuit 100 will be described in conjunction with the accompanying drawings in the following paragraphs.

[0064] When the motor is operating, the processing unit 110 of the current determination circuit 100 will control the voltage levels of the first control signal CS1 and the second control signal CS2 through the controller 120 to alternately turn on the high-side transistor 102 and the low-side transistor 104.

[0065] In this embodiment (i.e., the high-side transistor 102 is a P-type metal oxide semiconductor and the low-side transistor 104 is an N-type metal oxide semiconductor), please refer to Figure 2 , first, the processing unit 110 respectively outputs the first control signal CS1 with a low voltage level and the second control signal CS2 with a low voltage level to turn on the high-side transistor 102 and turn off the low-side transistor 104. In this way, the current I1 can flow out from the system high voltage Vcc, sequentially pass through the high-side transistor 102 and the node N, and flow into the coil 10 to drive the motor. The processing unit 110 determines that the current determination circuit 100 does not enter the dead zone according to the first control signal CS1 with a low voltage level and the second control signal CS2 with a low voltage level.

[0066] The processing unit 110 then changes the first control signal CS1 from a low voltage level to a high voltage level to switch the high-side transistor 102 from an on state to an off state. Please refer to Figure 3 , Figure 4 , the high-side transistor 102 and the low-side transistor 104 are both in an off state (i.e., the current judgment circuit 100 enters the dead zone). At the moment when the high-side transistor 102 is switched from an on state to an off state (meanwhile, the low-side transistor 104 remains off), there is still a transient current (such as the current I2 shown in Figure 3 or the current I3 shown in Figure 4 ). As the high-side transistor 102 is completely turned off, the transient current will flow forward through the first body diode 121 or flow forward through the second body diode 141, causing the first voltage difference VD1 or the second voltage difference VD2 to change. For example, when both the high-side transistor 102 and the low-side transistor 104 are in an off state, if there is a current I2 (sequentially passing through the second body diode 141 and the node N and flowing into the coil 10) as shown in Figure 3 , it means that the second voltage difference VD2 becomes positive. On the contrary, if there is a current I3 (flowing out of the coil 10 and sequentially passing through the node N and the first body diode 121) as shown in Figure 4 , it means that the first voltage difference VD1 becomes positive. It can be understood that the first voltage difference VD1 shown in Figure 3 (because there is no current flowing forward through the first body diode 121 in Figure 3 ) and the second voltage difference VD2 shown in Figure 4 (because there is no current flowing forward through the second body diode 141 in Figure 4 ) will not become positive.

[0067] Please refer to again Figure 3, since the first voltage difference VD1 is not positive (because the current I2 does not flow forward through the first body diode 121), the first comparator 161 outputs a first status signal SS1 with a low voltage level according to the non-positive first voltage difference VD1. The first logic gate 162 outputs a first judgment signal DS1 with a low voltage level (e.g., logic 0) according to the first status signal SS1 with a low voltage level and the first control signal CS1 with a high voltage level. Since the second voltage difference VD2 is positive (because the current I2 flows out from the system low voltage Vss and sequentially passes through the second body diode 141 and the node N) and the second control signal CS2 is switched from a low voltage level to a high voltage level via the second logic gate 182, the second comparator 181 outputs a second status signal SS2 with a high voltage level according to the positive second voltage difference VD2. The third logic gate 183 outputs a second judgment signal DS2 with a high voltage level (e.g., logic 1) according to the second status signal SS2 with a high voltage level and the second control signal CS2 with a high voltage level. The processing unit 110 determines that the current judgment circuit 100 enters the hysteresis region according to the first control signal CS1 with a high voltage level and the second control signal CS2 with a low voltage level, and determines that the current I2 flows into the coil 10 after sequentially passing through the second body diode 141 and the node N according to the first judgment signal DS1 with a low voltage level and the second judgment signal DS2 with a high voltage level.

[0068] Please refer to again Figure 4 , since the first voltage difference VD1 is positive (because the current I3 sequentially passes through the node N and the first body diode 121 and flows into the system high voltage Vcc), the first comparator 161 outputs a first status signal SS1 with a high voltage level according to the positive first voltage difference VD1. The first logic gate 162 outputs a first judgment signal DS1 with a high voltage level (e.g., logic 1) according to the first status signal SS1 with a high voltage level and the first control signal CS1 with a high voltage level. Since the second voltage difference VD2 is not positive (because the current I3 does not flow forward through the second body diode 141) and the second control signal CS2 is switched from a low voltage level to a high voltage level via the second logic gate 182, the second comparator 181 outputs a first status signal SS1 with a low voltage level according to the non-positive second voltage difference VD2. The third logic gate 183 outputs a second judgment signal DS2 with a low voltage level (e.g., logic 0) according to the second status signal SS2 with a low voltage level and the second control signal CS2 with a high voltage level. The processing unit 110 determines that the current judgment circuit 100 enters the hysteresis region according to the first control signal CS1 with a high voltage level and the second control signal CS2 with a low voltage level, and determines that the current I3 flows out of the coil 10 and sequentially passes through the node N and the first body diode 121 according to the first judgment signal DS1 with a high voltage level and the second judgment signal DS2 with a low voltage level.

[0069] The processing unit 110 then changes the second control signal CS2 from a low voltage level to a high voltage level to switch the low-side transistor 104 from an off state to an on state. Please refer to Figure 5 , the high-side transistor 102 is in an off state, and the low-side transistor 104 is in an on state. In this way, the current I4 can flow out of the coil 10, sequentially pass through the node N and the low-side transistor 104, and flow into the system low voltage Vss to drive the motor. The processing unit 110 determines that the current determination circuit 100 does not enter the dead zone based on the first control signal CS1 at a high voltage level and the second control signal CS2 at a high voltage level.

[0070] It should be noted that when the current determination circuit 100 enters the dead zone (the first control signal CS1 is at a high voltage level and the second control signal CS2 is at a low voltage level), the first voltage difference VD1 and the second voltage difference VD2 may not be positive because the magnitudes of the current I2 or the current I3 are exactly zero. In this way, since the first voltage difference VD1 is not positive and the first control signal CS1 is at a high voltage level, the first logic gate 162 outputs a first determination signal DS1 at a low voltage level (e.g., logic 0) based on the first state signal SS1 at a low voltage level and the first control signal CS1 at a high voltage level. And since the second voltage difference VD2 is not positive and the second control signal CS2 switches from a low voltage level to a high voltage level via the second logic gate 182, the third logic gate 183 outputs a second determination signal DS2 at a low voltage level (e.g., logic 0) based on the second state signal SS2 at a low voltage level and the second control signal CS2 at a high voltage level. The processing unit 110 determines that the current determination circuit 100 enters the dead zone based on the first control signal CS1 at a high voltage level and the second control signal CS2 at a low voltage level, and determines that the magnitudes of the current I2 or the current I3 are zero (i.e., no current passes through the coil 10) based on the first determination signal DS1 at a low voltage level and the second determination signal DS2 at a low voltage level.

[0071] In addition, when the current determination circuit 100 enters the dead zone (the first control signal CS1 is at a high voltage level and the second control signal CS2 is at a low voltage level), the first comparator 161 and the second comparator 181 may also output a first status signal SS1 at a high voltage level and a second status signal SS2 at a high voltage level respectively due to circuit failures. In this way, the first logic gate 162 outputs a first determination signal DS1 at a high voltage level (e.g., logic 1) based on the first status signal SS1 at a high voltage level and the first control signal CS1 at a high voltage level. And since the second control signal CS2 switches from a low voltage level to a high voltage level via the second logic gate 182, the third logic gate 183 outputs a second determination signal DS2 at a high voltage level (e.g., logic 1) based on the second status signal SS2 at a high voltage level and the second control signal CS2 at a high voltage level. The processing unit 110 determines that the current determination circuit 100 enters the dead zone based on the first control signal CS1 at a high voltage level and the second control signal CS2 at a low voltage level, and determines that the state of the current passing through the coil 10 is undetermined based on the first determination signal DS1 at a high voltage level and the second determination signal DS2 at a high voltage level. Since the state of the current passing through the coil 10 is undetermined, the processing unit 110 determines that the current determination circuit 100 has a fault and stops the operation of the current determination circuit 100.

[0072] Based on the above several situations, a truth table can be compiled. In other words, the processing unit 110 can determine the state of the current in the coil 10 in the dead zone according to this truth table. Among them, the truth table is as follows:

[0073] DS1 DS2 Status of the current flowing through the coil 0 0 The current is zero 0 1 The current flows into the coil 1 0 The current flows out of the coil 1 1 The current status is undetermined

[0074] Through the designs of the high-side circuit 106 and the low-side circuit 108, the current determination circuit 100 of the present disclosure can determine the state of the current in the coil 10 in the dead zone according to the first voltage difference VD1 across the two ends of the first body diode 121 parasitic on the high-side transistor 102 and the second voltage difference VD2 across the two ends of the second body diode 141 parasitic on the low-side transistor 104. Since it is not necessary to measure the voltage value of the node N, the current determination circuit 100 can avoid problems caused by measuring voltage values higher than the system high voltage Vcc or lower than the system low voltage Vss. In addition, the processing unit 110 can also obtain the phase information of the current and adjust the phase relationship between the current and the back electromotive force of the motor, so that the motor can operate at the optimal speed value.

[0075] Although the present disclosure has been disclosed as above in embodiments, it is not intended to limit the present disclosure. Those of ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the scope defined by the appended claims.

Claims

1. A current judgment circuit for judging the state of a current passing through a coil of a motor, characterized in that, Comprising: A high-side transistor, coupled to the coil, for selectively conducting or turning off according to the voltage level of a first control signal, and including a first body diode, wherein a first control terminal of the high-side transistor receives the first control signal; A low-side transistor, coupled to the coil, for selectively conducting or turning off according to the voltage level of a second control signal, and including a second body diode, wherein a second control terminal of the low-side transistor receives the second control signal; A high-side circuit, coupled to the high-side transistor, for receiving the first control signal, and for outputting a first determination signal according to a first voltage difference between two ends of the first body diode and the voltage level of the first control signal; A low-side circuit, coupled to the low-side transistor, for receiving the second control signal, and for outputting a second determination signal according to a second voltage difference between two ends of the second body diode and the voltage level of the second control signal; and A processing unit, for outputting the first control signal and the second control signal, receiving the first determination signal and the second determination signal, and judging the state of the current according to the voltage level of the first determination signal and the voltage level of the second determination signal.

2. The current judgment circuit according to claim 1, wherein When the first determination signal is at a low voltage level and the second determination signal is at a low voltage level, the processing unit judges that the current is zero.

3. The current judgment circuit according to claim 1, wherein When the first determination signal is at a high voltage level and the second determination signal is at a low voltage level, the processing unit judges that the current flows out of the coil and then passes through the first body diode.

4. The current judgment circuit according to claim 1, wherein When the first determination signal is at a low voltage level and the second determination signal is at a high voltage level, the processing unit judges that the current passes through the second body diode and then flows into the coil.

5. The current judgment circuit according to claim 1, wherein When the first determination signal is at a high voltage level and the second determination signal is at a high voltage level, the processing unit judges that the state of the current is undetermined.

6. The current judgment circuit according to claim 1, wherein The high-side circuit includes a first comparator, coupled to the first body diode, and for outputting a first state signal according to the first voltage difference between two ends of the first body diode.

7. The current judgment circuit according to claim 6, wherein The high-side circuit further includes a first logic gate, the first logic gate is coupled to the first comparator and the high-side transistor, and for outputting the first determination signal according to the voltage level of the first state signal and the voltage level of the first control signal.

8. The current judgment circuit according to claim 1, wherein The low-side circuit includes a second comparator, coupled to the second body diode, and for outputting a second state signal according to the second voltage difference between two ends of the second body diode.

9. The current judgment circuit according to claim 8, wherein The low-side circuit further includes a second logic gate and a third logic gate, the second logic gate is coupled to the low-side transistor, and for switching the voltage level of the second control signal, the third logic gate is coupled to the second comparator and the second logic gate, and for outputting the second determination signal according to the voltage level of the second state signal and the voltage level of the second control signal switched via the second logic gate.

10. The current determination circuit according to claim 1, wherein: The high-side transistor further includes a first end and a second end. Both ends of the first body diode are coupled to the first end and the second end. The first end is used to receive a system high voltage, and the second end is coupled to the coil; The low-side transistor further includes a third end and a fourth end. Both ends of the second body diode are coupled to the third end and the fourth end. The third end is coupled to the coil, and the fourth end is used to receive a system low voltage.

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