Control Circuit of Buck Power Supply Circuit

Abstract

An embodiment of the present application provides a control circuit for a Buck power supply circuit. The control circuit includes a current detection module and a control module. The current detection module is connected between the output terminal of the Buck power supply circuit to be controlled and the control module, and the control module is connected to a boost resistor deployed in the Buck power supply circuit. The current detection module is configured to detect the output current of the Buck power supply circuit and send a control signal to the control module according to the output current. The control module is configured to control whether the boost resistor is connected to the Buck power supply circuit according to the control signal. Through the present application, the problem of low efficiency of the Buck power supply circuit is solved, and the effect of improving the efficiency of the Buck power supply circuit is achieved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of Buck power circuits, and more particularly, to a control circuit for a Buck power circuit. Background Art

[0002] In a typical server, Rboot (boost resistor) and Cboot (boost capacitor) are passive components for the server to boost the Vcc (access circuit voltage) of the BuckConverter (buck converter). When the output current at the backend of the Lout (output inductor) in the circuit is too large, it may cause the VDS (Voltage Drain to Source Vds, drain-source voltage) of the upper-arm MOSFET (metal-oxide-semiconductor field-effect transistor) to be too large, which is likely to cause the burnout of the MOSFET. In the prior art, generally, increasing Rboot is used to slow down the turn-on time of the upper-arm MOSFET, thereby reducing VDS to avoid the burnout of the MOSFET. However, in practical applications, the increase of Rboot not only increases the switching loss of the H_MOS (i.e., the upper-arm metal-oxide-semiconductor field-effect transistor), but also increases the conduction loss of the resistance of the circuit itself, resulting in a reduction in the efficiency of the circuit.

[0003] In view of the problem of low efficiency of the Buck power circuit in the related art, no effective solution has been proposed yet. Summary of the Invention

[0004] The embodiments of the present application provide a control circuit for a Buck power circuit to at least solve the problem of low efficiency of the Buck power circuit in the related art.

[0005] According to an embodiment of the present application, a control circuit for a Buck power circuit is provided, including: a current detection module and a control module, wherein,

[0006] The current detection module is connected between the output end of the Buck power circuit to be controlled and the control module, and the control module is connected to the boost resistor deployed in the Buck power circuit;

[0007] The current detection module is configured to detect the output current of the Buck power circuit; and send a control signal to the control module according to the output current;

[0008] The control module is configured to control whether the boost resistor is connected to the Buck power circuit according to the control signal.

[0009] In an exemplary embodiment, the current detection module is configured to:

[0010] Compare the output current with a current threshold;

[0011] When the output current is greater than the current threshold, a first control signal is sent to the control module, where the first control signal is used to indicate connecting the boost resistor to the Buck power supply circuit;

[0012] When the output current is less than or equal to the current threshold, a second control signal is sent to the control module, where the second control signal is used to indicate short - circuiting the boost resistor from the Buck power supply circuit, and the control signal includes the first control signal and the second control signal.

[0013] In an exemplary embodiment, the current detection module includes: a comparator, a first resistor circuit, and a second resistor circuit, where,

[0014] The output terminal of the comparator is connected to the control module. The first resistor circuit is connected between the negative input terminal of the comparator and the voltage output terminal of the output inductor in the Buck power supply circuit. The second resistor circuit is connected between the positive input terminal of the comparator and the voltage output terminal of the output inductor in the Buck power supply circuit;

[0015] The comparator is configured to send a low - level signal to the control module when the voltage at the positive input terminal of the comparator is less than the voltage at the negative input terminal of the comparator, where the first control signal includes the low - level signal; and send a high - level signal to the control module when the voltage at the positive input terminal of the comparator is greater than or equal to the voltage at the negative input terminal of the comparator, where the second control signal includes the high - level signal;

[0016] The first resistor circuit is used to control the voltage at the negative input terminal of the comparator to a preset voltage threshold;

[0017] The second resistor circuit is used to convert the current fluctuation in the Buck power supply circuit into a voltage drop across the second resistor circuit.

[0018] In an exemplary embodiment, the first resistor circuit includes: a first resistor and a second resistor, where,

[0019] The first resistor is connected between the negative input terminal of the comparator and the voltage output terminal of the output inductor in the Buck power supply circuit. One end of the second resistor is connected to the negative input terminal of the comparator, and the other end of the second resistor is grounded.

[0020] In an exemplary embodiment, the resistance values of the first resistor and the second resistor are both determined according to the expected output current of the Buck power supply circuit.

[0021] In an exemplary embodiment, the second resistor circuit includes: a third resistor, wherein,

[0022] the third resistor is connected between the positive input terminal of the comparator and the voltage output terminal of the output inductor in the Buck power supply circuit.

[0023] In an exemplary embodiment, the preset voltage threshold is the desired output voltage of the Buck power supply circuit.

[0024] In an exemplary embodiment, the control module includes: a control switch, wherein the control switch has a first switch port, a second switch port, and a control port,

[0025] the first switch port is connected to one end of the boost resistor, the second switch port is connected to the other end of the boost resistor, and the control port is connected to the current detection module;

[0026] the current detection module is configured to send a control signal to the control port according to the output current;

[0027] the control module is configured to control whether the first switch port and the second switch port are conducting according to the control signal.

[0028] In an exemplary embodiment, the control switch includes a MOS transistor, and the control terminal is the gate of the MOS transistor.

[0029] In an exemplary embodiment, the current detection module is configured to:

[0030] send a low-level signal to the control port when the output current is greater than the desired output current;

[0031] send a high-level signal to the control port when the output current is less than or equal to the desired output current.

[0032] Through this application, a Buck power supply circuit is connected to a control circuit including a current detection module and a control module. The current detection module is connected between the output terminal of the Buck power supply circuit to be controlled and the control module, and is used to detect the output current of the Buck power supply circuit and send a control signal to the control module according to the output current. The control module is connected to a boost resistor deployed in the Buck power supply circuit, and controls whether the boost resistor is connected to the Buck power supply circuit according to the control signal, so as to flexibly control the connection of the boost resistor in the Buck power supply circuit according to the output current in the circuit, without adjusting the resistance value of the boost resistor, reducing the influence of the boost resistor on the switching loss of the upper-arm MOSFET, and also reducing the conduction loss of the resistance of the circuit itself. Therefore, the problem of low efficiency of the Buck power supply circuit can be solved, and the effect of improving the efficiency of the Buck power supply circuit can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of a control circuit of a Buck power supply circuit according to an embodiment of the present application Figure 1 ;

[0034] Figure 2 is a schematic diagram of a Buck power supply circuit according to an optional embodiment of the present application;

[0035] Figure 3 is a schematic structural diagram of a control circuit of a Buck power supply circuit according to an optional embodiment of the present application Figure 2 ;

[0036] Figure 4 is a schematic structural diagram of a control circuit of a Buck power supply circuit according to an embodiment of the present application Figure 3 ;

[0037] Figure 5 is a schematic structural diagram of a control circuit of a Buck power supply circuit according to an embodiment of the present application Figure 4 ;

[0038] Figure 6 is a schematic structural diagram of a control circuit of a Buck power supply circuit according to an embodiment of the present application Figure 5 ;

[0039] Figure 7 is a schematic structural diagram of a control circuit of a Buck power supply circuit according to an embodiment of the present application Figure 6 ;

[0040] Figure 8 is a schematic diagram of the VDS waveform of the upper-arm MOS transistor according to an embodiment of the present application;

[0041] Figure 9It is a schematic diagram of a control circuit of a Buck power supply circuit according to an optional embodiment of the present application. Specific embodiments

[0042] In the following, embodiments of the present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0043] It should be noted that the terms "first", "second", etc. in the specification, claims and above-mentioned drawings of the present application are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence.

[0044] In this embodiment, a control circuit of a Buck power supply circuit is provided. Figure 1 It is a structural schematic of a control circuit of a Buck power supply circuit according to an embodiment of the present application. Figure 1 , as Figure 1 shown, the control circuit includes: a current detection module 102 and a control module 104. Among them, the current detection module 102 is connected between the output end of the Buck power supply circuit 106 to be controlled and the control module 104, and the control module 104 is connected to a boost resistor 108 deployed in the Buck power supply circuit 106; the current detection module 102 is used to detect the output current of the Buck power supply circuit 106; and send a control signal to the control module 104 according to the output current; the control module 104 is used to control whether the boost resistor 108 is connected to the Buck power supply circuit 106 according to the control signal.

[0045] Through the above structure, the Buck power supply circuit is connected to a control circuit including a current detection module and a control module. The current detection module is connected between the output end of the Buck power supply circuit to be controlled and the control module, and is used to detect the output current of the Buck power supply circuit and send a control signal to the control module according to the output current. The control module is connected to a boost resistor deployed in the Buck power supply circuit and controls whether the boost resistor is connected to the Buck power supply circuit according to the control signal, so as to flexibly control the connection of the boost resistor in the Buck power supply circuit according to the output current in the circuit, without the need to adjust the resistance value of the boost resistor, reducing the influence of the boost resistor on the switching loss of the upper-arm MOSFET and also reducing the conduction loss of the resistance of the circuit itself. Therefore, the problem of low efficiency of the Buck power supply circuit can be solved, and the effect of improving the efficiency of the Buck power supply circuit can be achieved.

[0046] Optionally, in this embodiment, there are many applications of Buck power supplies on the server, such as: Mother Board, GPU Board (graphics processing unit board), etc.

[0047] In an alternative embodiment, an example of a Buck power supply circuit is provided. Figure 2 It is a schematic diagram of a Buck power supply circuit according to an alternative embodiment of the present application, as Figure 2 shown. In the Buck power supply circuit, the BuckController (step-down controller) provides Vcc (access circuit voltage), and is connected to the HDRV (high-side metal-oxide-semiconductor field-effect transistor driver) at the HS terminal and the LDRV (low-side metal-oxide-semiconductor field-effect transistor driver) at the LS terminal. The H_MOS and L_MOS respectively need to be driven by the HDRV and LDRV to turn on. Since the negative terminal of the HDRV is connected to Vsw (switching voltage), which is a 12V voltage source, the HDRV requires a higher cross-voltage than 12V to drive the high-side MOSFET to turn on. The Vcc (access circuit voltage) passes through the Rboot (boost resistor) and Cboot (boost capacitor) to charge the Vcc + Vsw = 5V + 12V = 17V as an RC charge. When the accumulated voltage reaches 17V, it is provided to the HDRV to drive the H_MOS to turn on.

[0048] Optionally, in this embodiment, the above boost resistor can be, but is not limited to, one or more resistors, which can be, but are not limited to, used to suppress the VDS of the H_MOS in the Buck power supply circuit, or used together with the boost capacitor in the Buck power supply circuit as an RC (Resistor-Capacitance circuit) charging circuit to accumulate voltage and provide it to the HDRV (high-side metal-oxide-semiconductor field-effect transistor driver) to drive the H_MOS.

[0049] Optionally, in this embodiment, in the Buck power supply circuit, the output current of the Buck power supply circuit can be, but is not limited to, detected by adding a current detection module, and then the access of the boost resistor in the Buck power supply circuit can be controlled by the control module according to the output current of the Buck power supply circuit detected by the current detection module.

[0050] Optionally, in this embodiment, based on the principle that the current and voltage drop in the Buck power supply circuit are proportional, the voltage difference between the input voltage and the output voltage of the Buck power supply circuit can be detected by the current detection module, and the magnitude relationship between the output current of the Buck power supply circuit and the threshold value of the originally expected output current value of the Buck power supply circuit can be detected, so as to determine whether the control signal sent to the control module indicates the access or disconnection of the boost resistor in the Buck power supply circuit.

[0051] Optionally, in this embodiment, the above control signal may, but is not limited to, be a signal for indicating whether to connect the boost resistor to the Buck power supply circuit determined by comparing the output current of the Buck power supply circuit with a threshold value that is predetermined to indicate the originally desired output current value of the Buck power supply circuit. It may, but is not limited to, be an electrical signal for controlling the connection of the boost resistor in the circuit according to the output current of the Buck power supply circuit. For example, when the output current of the Buck power supply circuit is greater than the threshold value of the originally desired output current value of the Buck power supply circuit, the control signal is used to indicate connecting the boost resistor to the Buck power supply circuit to protect the H_MOS. Or, when the actual output current of the Buck power supply circuit is less than the threshold value of the originally desired output current value of the Buck power supply circuit, the control signal is used to indicate short - circuiting the boost resistor from the Buck power supply circuit to improve the working efficiency of the circuit.

[0052] In an exemplary embodiment, the current detection module is configured to: compare the output current with a current threshold; in the case where the output current is greater than the current threshold, send a first control signal to the control module, where the first control signal is used to indicate connecting the boost resistor to the Buck power supply circuit; in the case where the output current is less than or equal to the current threshold, send a second control signal to the control module, where the second control signal is used to indicate short - circuiting the boost resistor from the Buck power supply circuit, and the control signal includes the first control signal and the second control signal.

[0053] Optionally, in this embodiment, the above current threshold may, but is not limited to, be the originally desired output current value of the Buck power supply circuit, and it may, but is not limited to, be used to compare with the actual output current of the Buck power supply circuit to determine the connection or disconnection of the boost resistor in the Buck power supply circuit.

[0054] Optionally, in this embodiment, it may, but is not limited to, detect the actual output current of the Buck power supply circuit through a current detection module. In the case where the output current is greater than the originally desired output current value of the Buck power supply circuit, send a first control signal for connecting the boost resistor to the Buck power supply circuit to the control module. In the case where the output current is less than or equal to the originally desired output current value of the Buck power supply circuit, send a second control signal to the control module to short - circuit the boost resistor from the Buck power supply circuit, and determine the connection mode of the boost resistor adapted to the current circuit according to the obtained actual output current of the circuit, which ensures reducing and improving the VDS surge in the case of large current and also improves the working efficiency of the circuit in the case of small current.

[0055] Optionally, in this embodiment, an element with a resistance value much smaller than the boost resistor can be connected to the circuit to short-circuit the boost resistor from the Buck power supply circuit. For example, an element with a resistance value much smaller than the boost resistor is connected in parallel with the boost resistor to the circuit to short-circuit the boost resistor from the Buck power supply circuit.

[0056] In an exemplary embodiment, an example of a control circuit for a Buck power supply circuit is provided. Figure 3 It is a structural schematic diagram of a control circuit for a Buck power supply circuit according to an optional embodiment of the present application Figure 2 , as Figure 3 shown, the current detection module 102 includes: a comparator 302, a first resistor circuit 304, and a second resistor circuit 306. Among them, the output end of the comparator 302 is connected to the control module 104. The first resistor circuit 304 is connected between the negative input end of the comparator 302 and the voltage output end of the output inductor 308 in the Buck power supply circuit 106. The second resistor circuit 306 is connected between the positive input end of the comparator 302 and the voltage output end of the output inductor 308 in the Buck power supply circuit 106. The comparator 302 is configured to send a low-level signal to the control module 104 when the voltage at the positive input end of the comparator 302 is less than the voltage at the negative input end of the comparator 302, where the first control signal includes the low-level signal. When the voltage at the positive input end of the comparator 302 is greater than or equal to the voltage at the negative input end of the comparator 302, a high-level signal is sent to the control module 104, where the second control signal includes the high-level signal. The first resistor circuit 304 is used to control the voltage at the negative input end of the comparator to a preset voltage threshold. The second resistor circuit 306 is used to convert the current fluctuation in the Buck power supply circuit 106 into a voltage drop across the second resistor circuit 306.

[0057] Optionally, in this embodiment, the above comparator can, but is not limited to, compare the input voltage at its positive input end and the input voltage at its negative input end to compare the actual output current in the Buck power supply circuit with the current threshold. For example, when the output current is greater than the desired current threshold, the input voltage at the positive input end of the comparator will be less than the input voltage at its negative input end, and the output end of the comparator will enter the saturation state due to extremely high gain, that is, a low-level signal for indicating that the boost resistor is connected to the Buck power supply circuit is sent. Or, when the output current is less than the desired current threshold, the input voltage at the positive input end of the comparator will be greater than the input voltage at its negative input end, the differential mode signal of the comparator is positive, and after non-inverting amplification, the power supply voltage of the comparator is output, and a high-level signal for indicating that the boost resistor is short-circuited from the Buck power supply circuit is sent.

[0058] Optionally, in this embodiment, the above first resistance circuit is used to control the voltage at the negative input terminal of the comparator to be the desired output voltage obtained according to the desired output current of the Buck power supply circuit, so that the comparator can compare the desired output voltage at the negative input terminal with the actual output voltage of the Buck power supply circuit at the positive input terminal to determine the control signal sent to the control module.

[0059] Optionally, in this embodiment, the current fluctuation in the Buck power supply circuit can be converted into the voltage drop across the second resistance circuit, for example, but not limited to: given the resistance value in the second resistance circuit, the input voltage of the second resistance circuit, and the output current of the second resistance circuit, the voltage consumed by the second resistance circuit is calculated through the output current of the second resistance circuit (voltage drop = resistance value in the second resistance circuit * output current of the second resistance circuit). Based on the input voltage and the generated voltage drop of the second resistance circuit, the output voltage of the second resistance circuit can be calculated (output voltage of the second resistance circuit = input voltage of the second resistance circuit - voltage drop generated by the second resistance circuit). Thus, it can be known that the voltage drop across the second resistance circuit can be controlled by designing, for example, but not limited to, the resistance value of the second resistance circuit. Based on the voltage drop across the second resistance circuit, it can be determined whether the output current in the Buck power supply circuit is the desired output current of the pre-determined Buck power supply circuit, thereby determining the current fluctuation in the Buck power supply circuit.

[0060] Optionally, in this embodiment, the preset voltage threshold can be, for example, but not limited to, the desired output voltage of the Buck power supply circuit.

[0061] In an alternative embodiment, a calculation method for the desired output voltage of the Buck power supply circuit, i.e., the voltage threshold, is provided. Taking Vcom (input voltage of the third resistor) = 5.1V, Iout (output current) = 10A, Vout (output voltage) = 5V, and Rshunt (third resistor) = 10mohm as an example:

[0062] According to the voltage difference across Rshunt due to the output current, the voltage across the circuit is calculated as: (Iout * Rshunt) = (10A * 100mohm) = 100mV; under normal circumstances, the input voltage Vcom of the third resistor is 5.1V, and the desired output voltage of the third resistor, i.e., the voltage threshold, is Vout = (5.1V - 100mV) = 5V.

[0063] In an exemplary embodiment, an example of a control circuit for a Buck power supply circuit is provided. Figure 4 It is a structural schematic of a control circuit for a Buck power supply circuit according to an embodiment of the present application Figure 3 asFigure 4 As shown, the first resistor circuit 304 includes: a first resistor 402 and a second resistor 404. Among them, the first resistor 402 is connected between the negative input terminal of the comparator 302 and the voltage output terminal of the output inductor 308 in the Buck power supply circuit 106. One end of the second resistor 404 is connected to the negative input terminal of the comparator 302, and the other end of the second resistor 404 is grounded.

[0064] In an exemplary embodiment, the resistance values of the first resistor and the second resistor are both determined according to the desired output current of the Buck power supply circuit.

[0065] In an alternative embodiment, a calculation method for the resistance values of the first resistor and the second resistor is provided. Taking the desired output current within 10A, the desired output voltage of 5V, the input voltage of 5.1V, and Vref (desired output voltage) = Vcom (input voltage) * [R2 / (R1 + R2)] as an example: According to the formula Vref = 5.1V * (R2 / (R1 + R2)) = 5V, the resistance value of the first resistor R1 = 10 ohm and the resistance value of the second resistor R2 = 500 ohm are obtained.

[0066] In an exemplary embodiment, an example of the structure of the control circuit of the Buck power supply circuit is provided. Figure 5 It is a schematic diagram of the structure of the control circuit of a Buck power supply circuit according to an embodiment of the present application Figure 4 As Figure 5 shown, the second resistor circuit 306 includes: a third resistor 502. Among them, the third resistor 502 is connected between the positive input terminal of the comparator 302 and the voltage output terminal of the output inductor 308 in the Buck power supply circuit 106.

[0067] Optionally, in this embodiment, the current fluctuation in the Buck power supply circuit can be, but is not limited to, converted into a voltage drop across the second resistor circuit through the third resistor.

[0068] In an alternative embodiment, a calculation method for the voltage drop across the second resistor circuit is provided. Taking the third resistor of 10 mohm, the input voltage of 5.1V, and the output current of 10A as an example, the voltage drop = the third resistor * the output current = (10A * 100 mohm) = 100 mV, and the output voltage = the input voltage - the voltage drop = (5.1V - 100 mV) = 5V.

[0069] In a Buck power supply circuit, since the current is proportional to the voltage drop across the third resistor, it is possible to, but not limited to, determine the voltage difference (voltage drop) between the input voltage and the output voltage of the third resistor in the circuit by determining the resistance value of the third resistor. Thus, when the voltage drop across the third resistor exceeds the expected output voltage of the circuit, a boost resistor is connected to the circuit to delay the turn-on speed of the H_MOS.

[0070] In an exemplary embodiment, the preset voltage threshold is the expected output voltage of the Buck circuit power supply.

[0071] Optionally, in this embodiment, the preset voltage threshold can be, but not limited to, used to indicate the value of the negative input terminal of the comparator in the current detection module, and can be, but not limited to, controlling the voltage of the negative input terminal of the comparator to the preset voltage threshold through the first resistor circuit.

[0072] In an exemplary embodiment, an example of the structure of a control circuit of a Buck power supply circuit is provided. Figure 6 It is a schematic diagram of the structure of a control circuit of a Buck power supply circuit according to an embodiment of the present application Figure 5 , as Figure 6 shown, the control module 104 includes: a control switch 602, where the control switch 602 has a first switch port, a second switch port, and a control port. The first switch port is connected to one end of the boost resistor 108, the second switch port is connected to the other end of the boost resistor 108, and the control port is connected to the current detection module 102; the current detection module 102 is configured to send a control signal to the control port according to the output current; the control module 104 is configured to control whether the first switch port and the second switch port are conducting according to the control signal.

[0073] Optionally, in this embodiment, the above control switch can be, but not limited to, a circuit element that can short-circuit the boost resistor from the Buck power supply circuit. For example, the first switch port and the second switch port can be, but not limited to, the source or drain of a MOS transistor, and the control port can be, but not limited to, the gate of a MOS transistor.

[0074] Optionally, in this embodiment, it is possible but not limited to obtain, through a control port, a control signal sent by a current detection module for indicating whether a boost resistor is connected, and control whether the boost resistor is turned on using a first switch port and a second switch port according to the indication of the control signal. For example, taking the control switch as a MOS transistor, the first switch port is the source of the MOS transistor and the second switch port is the drain of the MOS transistor, and the control port is the gate of the MOS transistor as an example, receive the control signal sent by the current detection module through the gate of the MOS transistor. When the control signal indicates to turn on the boost resistor, control the source or the drain of the MOS transistor to be disconnected, so as to turn on the boost resistor in the Buck power supply circuit. Or, when the control signal indicates to short-circuit the boost resistor, control the source or the drain of the MOS transistor to be respectively connected to both ends of the boost resistor, so as to short-circuit the boost resistor in the Buck power supply circuit.

[0075] In an exemplary embodiment, an example of the structure of a control circuit of a Buck power supply circuit is provided. Figure 7 It is a schematic diagram of the structure of a control circuit of a Buck power supply circuit according to an embodiment of the present application Figure 6 , as Figure 7 shown, the control switch 602 includes a MOS transistor 702, and the control terminal is the gate of the MOS transistor 702.

[0076] Optionally, in this embodiment, the control terminal of the control switch is the gate of the MOS transistor, and the first switch port and the second switch port of the control switch can be but are not limited to the source or the drain of the MOS transistor. For example, when the source of the MOS transistor is the first switch port of the control switch, the drain of the MOS transistor is the second switch port of the control switch. Or, when the source of the MOS transistor is the second switch port of the control switch, the drain of the MOS transistor is the first switch port of the control switch.

[0077] In an exemplary embodiment, the current detection module is configured to: send a low-level signal to the control port when the output current is greater than the desired output current; send a high-level signal to the control port when the output current is less than or equal to the desired output current.

[0078] Optionally, in this embodiment, Figure 8 It is a schematic diagram of the VDS waveform of the upper-arm MOS transistor according to an embodiment of the present application, as Figure 8As shown, when the output current of the Buck power supply circuit is greater than the expected design, i.e., Vout (the voltage at the positive input terminal of the comparator) is less than Vref (the voltage at the negative input terminal of the comparator), the output of the comparator enters the saturation state with an extremely high gain and outputs Vout = 0V. At this time, the VDS voltage of the boost resistor is 23.8V, and the VDS voltage of short - circuiting the boost resistor is 30.2V. Therefore, the control switch is selected to conduct the boost resistor, so that the boost resistor is connected to the circuit as an RC charging circuit, achieving the purpose of reducing the VDS surge and protecting the H_MOS.

[0079] When the output current of the Buck power supply circuit is less than the expected design and Vout is greater than Vref, the differential - mode signal of the comparator is positive and is amplified non - inverting, so the output Vout = + 12V (the power supply voltage of the comparator). At this time, M1 is turned on (i.e., short - circuiting the boost resistor from the Buck power supply circuit). Since the resistance of M1 is approximately 0 ohm, which is much smaller than the resistance of the boost resistor, the short - circuit of the boost resistor is achieved, reducing the conduction interval, decreasing the area of the power - consumption interval, reducing the wattage consumed by the H_MOS, and improving the working efficiency of the circuit.

[0080] In an alternative embodiment, a control circuit for a Buck power supply circuit is provided. Figure 9 is a schematic diagram of a control circuit for a Buck power supply circuit according to an alternative embodiment of the present application, as Figure 9 shown. In the Buck power supply circuit, the Buck Controller (step - down controller) provides Vcc (the voltage connected to the circuit), and is connected to HDRV (high - side metal - oxide - semiconductor field - effect transistor driver) at the HS terminal and LDRV (low - side metal - oxide - semiconductor field - effect transistor driver) at the LS terminal. The H_MOS and L_MOS respectively need to be driven by HDRV and LDRV to be turned on. Since the negative terminal of HDRV is connected to Vsw (switching voltage), which is a 12V voltage source, HDRV requires a higher cross - voltage than 12V to drive the high - side MOSFET to turn on. Vcc (the voltage connected to the circuit) passes through Rboot (boost resistor) and Cboot (boost capacitor) for RC charging, Vcc + Vsw = 5V+12V = 17V. When the accumulated voltage reaches 17V, it is provided to HDRV to drive the H_MOS to turn on.

[0081] In the control circuit of the Buck power supply circuit, taking Vin (the power supply voltage of the comparator) = 12V, Rshunt (the third resistor) = 10mohm, Vcom (the input voltage of the third resistor) = 5.1V, and Iout (current threshold) = 10A as an example:

[0082] According to the expected output current of the Buck power supply circuit, i.e., the current threshold, calculate the voltage difference across the third resistor of the output current (i.e., the voltage difference across the circuit) (Iout * Rshunt) = (10A * 100mohm) = 100mV; since the input voltage of the third resistor Vcom = 5.1V, the output voltage of the third resistor should be Vout = (5.1V - 100mV) = 5V; because the higher the current in the circuit, the greater the voltage drop, which causes Vout to become smaller, so by adding a first resistor circuit in the circuit to ensure that Vcom - Vout (the voltage difference across the third resistor) is within a reasonable range, the normal operation of the backend load is achieved. Since the expected output current of the Buck power supply circuit is within 10A, according to Vref (the voltage at the negative input terminal of the comparator) = Vcom * [R2 / (R1 + R2)], calculate Vref = 5.1V * (R2 / (R1 + R2)) = 5V, and find that R1 (the first resistor) = 10ohm, R2 (the second resistor) = 500ohm. Therefore, when the first resistor in the current detection module is set to 10ohm, the second resistor is set to 500ohm, the third resistor is set to 100mohm, and the input voltage is 5.1V, the current threshold of the Buck power supply circuit can be determined to be 10A, and the voltage threshold is 5V.

[0083] When the current is higher, the voltage drop generated is too large, and the voltage difference received by the detection circuit device Comparators (comparator) exceeds the pre-designed voltage difference across the third resistor. By turning off M1 (control switch) of the control module and using Rboot to delay the turn-on speed of H_MOS, VDS is reduced to avoid the burnout of H_MOS caused by overshoot due to too fast turn-on of H_MOS.

[0084] When the current is smaller, the voltage drop generated is smaller, and the voltage difference received by the detection circuit device Comparators is lower than the pre-designed voltage difference across the third resistor. Use M1 to short-circuit Rboot, and increase the turn-on speed of H_MOS through the low impedance of M1. Since the current is small at this time and there is no problem of VDS overshoot in the circuit, and the turn-on speed of VDS becomes faster, the cross-over area between VDS and Iout is reduced, the loss of H_MOS is reduced, and the working efficiency of the circuit is improved. At the same time, since the impedance of M1 is smaller than that of Rboot, the resistance power consumption loss in the circuit is further saved.

[0085] Through the description of the above embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by means of software plus a necessary general hardware platform. Of course, it can also be implemented by hardware, but in many cases, the former is a better implementation method. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions for causing a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in various embodiments of the present application.

[0086] The specific examples in this embodiment can refer to the examples described in the above embodiments and the exemplary embodiments, and will not be repeated here.

[0087] Obviously, those skilled in the art should understand that the above-mentioned modules or steps of the present application can be implemented by a general computing device. They can be concentrated on a single computing device or distributed on a network composed of multiple computing devices. They can be implemented by program codes executable by the computing device. Thus, they can be stored in a storage device and executed by the computing device. And in some cases, the steps shown or described can be executed in a different order than here, or they can be separately made into individual integrated circuit modules, or multiple modules or steps among them can be made into a single integrated circuit module to implement. In this way, the present application is not limited to any specific combination of hardware and software.

[0088] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the principle of the present application shall be included in the protection scope of the present application.

Claims

1. A control circuit for a Buck power supply circuit, characterized in that, Comprising: A current detection module and a control module, wherein, The current detection module is connected between the output end of the Buck power supply circuit to be controlled and the control module, and the control module is connected to a boost resistor deployed in the Buck power supply circuit, and the boost resistor is used to suppress the drain-source voltage of the upper-arm metal-oxide-semiconductor field-effect transistor in the Buck power supply circuit; The current detection module is used to detect the output current of the Buck power supply circuit; and send a control signal to the control module according to the output current; The control module is used to control whether the boost resistor is connected to the Buck power supply circuit according to the control signal; Wherein, the current detection module is further used to: compare the output current with a current threshold; in the case where the output current is greater than the current threshold, send a first control signal to the control module, wherein the first control signal is used to indicate connecting the boost resistor to the Buck power supply circuit; in the case where the output current is less than or equal to the current threshold, send a second control signal to the control module, wherein the second control signal is used to indicate short-circuiting the boost resistor from the Buck power supply circuit, and the control signal includes the first control signal and the second control signal.

2. The control circuit of the Buck power supply circuit according to claim 1, wherein The current detection module includes: a comparator, a first resistor circuit and a second resistor circuit, wherein, The output end of the comparator is connected to the control module, the first resistor circuit is connected between the negative input end of the comparator and the voltage output end of the output inductor in the Buck power supply circuit, and the second resistor circuit is connected between the positive input end of the comparator and the voltage output end of the output inductor in the Buck power supply circuit; The comparator is used to send a low-level signal to the control module in the case where the voltage at the positive input end of the comparator is less than the voltage at the negative input end of the comparator, wherein the first control signal includes the low-level signal; in the case where the voltage at the positive input end of the comparator is greater than or equal to the voltage at the negative input end of the comparator, send a high-level signal to the control module, wherein the second control signal includes the high-level signal; The first resistor circuit is used to control the voltage at the negative input end of the comparator to be a preset voltage threshold; The second resistor circuit is used to convert the current fluctuation in the Buck power supply circuit into a voltage drop across the second resistor circuit.

3. The control circuit of the Buck power supply circuit according to claim 2, characterized in that, The first resistor circuit includes: a first resistor and a second resistor, wherein, The first resistor is connected between the negative input end of the comparator and the voltage output end of the output inductor in the Buck power supply circuit, one end of the second resistor is connected to the negative input end of the comparator, and the other end of the second resistor is grounded.

4. The control circuit of the Buck power supply circuit according to claim 3, characterized in that, The resistance values of the first resistor and the second resistor are both determined according to the expected output current of the Buck power supply circuit.

5. The control circuit of the Buck power supply circuit according to claim 2, characterized in that, The second resistor circuit includes: a third resistor, wherein, The third resistor is connected between the positive input terminal of the comparator and the voltage output terminal of the output inductor in the Buck power supply circuit.

6. The control circuit of the Buck power supply circuit according to claim 2, wherein The preset voltage threshold is the desired output voltage of the Buck power supply circuit.

7. The control circuit of the Buck power supply circuit according to claim 1, characterized in that, The control module includes: a control switch, wherein the control switch has a first switch port, a second switch port and a control port. The first switch port is connected to one end of the boost resistor, the second switch port is connected to the other end of the boost resistor, and the control port is connected to the current detection module. The current detection module is configured to send a control signal to the control port according to the output current. The control module is configured to control whether the first switch port and the second switch port are turned on according to the control signal.

8. The control circuit of the Buck power supply circuit according to claim 7, wherein The control switch includes a MOS transistor, and the control terminal is the gate of the MOS transistor.

9. The control circuit of the Buck power supply circuit according to claim 8, characterized in that, The current detection module is configured to: send a low-level signal to the control port when the output current is greater than the desired output current; send a high-level signal to the control port when the output current is less than or equal to the desired output current.

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