Adaptive current-limiting power switch circuit

Abstract

The invention discloses a power switch circuit capable of adaptively limiting current. The adaptive current limiting power switch circuit comprises a current sensing resistor, a power switch, a charge pump and an adaptive current limiting circuit. The first end of the current sensing resistor is coupled to an input voltage. The first end of the power switch is connected with the second end of the current sensing resistor. The second end of the power switch is connected with the first end of the output capacitor. The second end of the output capacitor is grounded. The output end of the charge pump is connected with the control end of the power switch. The adaptive current limiting circuit determines whether to control the operation of the power switch to limit the current flowing through the power switch according to the input voltage, the voltage of the second end of the current sensing resistor and the voltage of the first end of the output capacitor.

Description

Technical Field

[0001] The invention relates to a switching power supply circuit, in particular to an adaptive current limiting power supply switching circuit. Background Art

[0002] With the development and progress of science and technology, electronic devices are increasingly widely used in homes and offices, becoming an indispensable tool in people's daily lives. The traditional current limiting circuit of the power switch sets a fixed current limit value. When the input current of the power switch of the electronic device reaches this fixed current limit value, the traditional current limiting circuit locks the input current of the power switch at this fixed current limit value. At this time, if the load continues to draw a large amount of power through the power switch, the output voltage of the power switch will continue to decrease. When the output voltage of the power switch drops below the threshold value, such as 0V, the matrix current generated by the mutual collision and ionization of hot carriers inside the power switch will continue to increase to the maximum value. When the matrix current increases to cause the parasitic component of the power switch to turn on, for example, when the base-emitter voltage of the parasitic component reaches about 0.7V, the power switch, especially the low-voltage NMOS transistor, will burn out. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an adaptive current limiting power switch circuit in view of the shortcomings of the prior art. The adaptive current limiting power switch circuit comprises a current sensing resistor, a power switch, a charging pump and an adaptive current limiting circuit. The first end of the current sensing resistor is coupled to an input voltage. The first end of the power switch is connected to the second end of the current sensing resistor. The second end of the power switch is connected to the first end of an output capacitor. The second end of the output capacitor is grounded. The voltage of the first end of the output capacitor is used as the output voltage of the adaptive current limiting power switch circuit. The charging pump is connected to the control end of the power switch. The charging pump is configured to supply power to the control end of the power switch. The adaptive current limiting circuit is coupled to the input voltage. The adaptive current limiting circuit is connected to the first end of the output capacitor, the second end of the current sensing resistor and the control end of the power switch. The adaptive current limiting circuit determines whether to output a current limiting signal to the control end of the power switch according to the input voltage, the voltage of the second end of the current sensing resistor and the voltage of the first end of the output capacitor. The power switch operates according to the current limiting signal to limit the current flowing through the power switch.

[0004] In an embodiment, the adaptive current limiting power switch circuit further comprises an oscillating circuit. The oscillating circuit is connected to the charging pump. The oscillating circuit is configured to output an oscillating signal to the charging pump. The charging pump determines to supply power to the control end of the power switch according to the frequency of the oscillating signal.

[0005] In an embodiment, the adaptive current limiting circuit includes a current limiting adjustment circuit and a current limiting control circuit. The current limiting adjustment circuit is coupled to the input voltage and connected to the first end of the output capacitor. The current limiting adjustment circuit is configured to detect the input voltage and the voltage of the first end of the output capacitor to output a current adjustment signal. The current limiting control circuit is connected to the output end of the current limiting adjustment circuit, the second end of the current sensing resistor, and the control end of the power switch. The current limiting control circuit is configured to output a current limiting control signal to the control end of the power switch based on the voltage of the current adjustment signal and the voltage of the second end of the current sensing resistor.

[0006] In an embodiment, the current limiting adjustment circuit includes a first operational amplifier, a comparator, a first current mirror circuit, a switching component and a second current mirror circuit. The first input terminal of the first operational amplifier is connected to a voltage source. The voltage source is coupled to the input voltage. The second input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier and the first end of the first resistor. The first input terminal of the comparator is coupled to a limiting voltage. The second input terminal of the comparator and the second end of the first resistor are connected to the first end of the output capacitor. The input terminal of the first current mirror circuit is connected to the output terminal of the first operational amplifier. The first end of the switching component is connected to the output terminal of the first current mirror circuit. The control end of the switching component is connected to the output terminal of the comparator. The input terminal of the second current mirror circuit is connected to the second end of the switching component. The output terminal of the second current mirror circuit is connected to the input terminal of the current limiting control circuit.

[0007] In an embodiment, the current limiting control circuit comprises a third current mirror circuit, a second operational amplifier and a current limiting switch. The input end of the third current mirror circuit is connected to the output end of the second current mirror circuit and the output end of the current source. The input end of the current source is coupled to the input voltage. The first input end of the second operational amplifier is connected to the output end of the third current mirror circuit. The second input end of the second operational amplifier is connected to the second end of the current sensing resistor. The control end of the current limiting switch is connected to the output end of the second operational amplifier. The first end of the current limiting switch is connected to the control end of the power switch. The second end of the current limiting switch is grounded.

[0008] In an embodiment, the first current mirror circuit comprises a first transistor and a second transistor. The first end of the first transistor is coupled to the input voltage. The second end of the first transistor is connected to the output end of the first operational amplifier and the control end of the first transistor. The first end of the second transistor is coupled to the input voltage. The control end of the second transistor is connected to the control end of the first transistor. The second end of the second transistor is connected to the first end of the switching component.

[0009] In an embodiment, the second current mirror circuit comprises a third transistor and a fourth transistor. A first end of the third transistor is connected to a second end of the switching component and a control end of the third transistor. A second end of the third transistor is grounded. A first end of the fourth transistor is connected to an output end of the current source. A control end of the fourth transistor is connected to a control end of the third transistor. A second end of the fourth transistor is grounded.

[0010] In an embodiment, the third current mirror circuit includes a fifth transistor and a sixth transistor. The first end of the fifth transistor is connected to the first end of the fourth transistor and the output end of the current source. The second end of the fifth transistor is grounded. The control end of the sixth transistor is connected to the control end and the first end of the fifth transistor. The first end of the sixth transistor is connected to the first input end of the second operational amplifier. The second end of the sixth transistor is grounded.

[0011] In an embodiment, the current limiting control circuit further comprises a second resistor, a first end of the second resistor is coupled to the input voltage, and a second end of the second resistor is connected to the first end of the sixth transistor and the first input end of the second operational amplifier.

[0012] In an embodiment, the adaptive current limiting circuit includes a plurality of current limiting adjustment circuits and a current limiting control circuit. Each of the current limiting adjustment circuits is coupled to the input voltage and connected to the first end of the output capacitor. Each of the current limiting adjustment circuits is configured to detect the input voltage and the voltage of the first end of the output capacitor to output a current regulation signal. The current limiting control circuit is connected to the output end of each of the current limiting adjustment circuits, the second end of the current sensing resistor, and the control end of the power switch. The current limiting control circuit is configured to output a plurality of current limiting control signals to the control end of the power switch in a multi-stage current limiting operation according to the difference between the plurality of current regulation signals output by the plurality of current limiting adjustment circuits and the voltage of the second end of the current sensing resistor, so as to reduce the current flowing through the power switch multiple times.

[0013] In an embodiment, each of the current limiting adjustment circuits includes a first operational amplifier, a comparator, a first current mirror circuit, a switching component, and a second current mirror circuit. The first input terminal of the first operational amplifier is connected to a voltage source. The voltage source is coupled to the input voltage. The second input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier and the first end of the first resistor. The first input terminal of the comparator is coupled to a limiting voltage. The second input terminal of the comparator and the second end of the first resistor are connected to the first end of the output capacitor. The input terminal of the first current mirror circuit is connected to the output terminal of the first operational amplifier. The first end of the switching component is connected to the output terminal of the first current mirror circuit. The control end of the switching component is connected to the output terminal of the comparator. The input terminal of the second current mirror circuit is connected to the second end of the switching component. The output terminal of the second current mirror circuit is connected to the input terminal of the current limiting control circuit.

[0014] As described above, the present invention provides an adaptive current limiting power switch circuit. In the adaptive current limiting power switch circuit of the present invention, the adaptive current limiting circuit flexibly determines the current limiting value for limiting the current flowing through the power switch according to the input voltage and output voltage of the power switch, rather than using a fixed current limiting value, so that the power switch can be effectively prevented from burning under any circumstances, especially in the case of high input voltage and low output voltage, and when the output short circuit occurs at high input voltage.

[0015] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and description and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. 4 is a circuit diagram of a power switch circuit with adaptive current limiting according to a first embodiment of the present invention.

[0017] Figure 2 FIG. 4 is a circuit diagram of a power switch circuit with adaptive current limiting according to a second embodiment of the present invention.

[0018] Figure 3 FIG. 4 is a circuit diagram of an adaptive current limiting circuit for performing a single-stage current limiting operation included in an adaptive current limiting power switch circuit according to a third embodiment of the present invention.

[0019] Figure 4 It is a waveform diagram of signals when the adaptive current limiting power switch circuit according to the third embodiment of the present invention performs a single-stage current limiting operation.

[0020] Figure 5 FIG. 4 is a circuit diagram of an adaptive current limiting circuit for performing a multi-stage current limiting operation included in an adaptive current limiting power switch circuit according to a fourth embodiment of the present invention.

[0021] Figure 6 A circuit diagram of a current limiting adjustment circuit in an adaptive current limiting circuit for performing a multi-stage current limiting operation included in an adaptive current limiting power switch circuit according to a fourth embodiment of the present invention.

[0022] Figure 7 It is a waveform diagram of signals when the adaptive current limiting power switch circuit according to the fourth embodiment of the present invention performs a multi-stage current limiting operation. DETAILED DESCRIPTION

[0023] The following is an explanation of the embodiments of the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual dimensions. It is stated in advance. The following embodiments will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention. In addition, the term "or" used herein may include any one or more combinations of the associated listed items depending on the actual situation.

[0024] See also Figure 1 , which is a circuit diagram of an adaptive current limiting power switch circuit according to a first embodiment of the present invention.

[0025] The power switch circuit with adaptive current limiting according to the first embodiment of the present invention comprises a current sensing resistor Rs, a power switch SWP, a charge pump CHP and an adaptive current limiting circuit ACL.

[0026] The first end of the current sensing resistor Rs is coupled to an input voltage VIN. The first end of the power switch SWP is connected to the second end of the current sensing resistor Rs. The second end of the power switch SWP is connected to the first end of an output capacitor Cout. The second end of the output capacitor Cout is grounded. The first end of the output capacitor Cout or the second end of the power switch SWP can be used as the output end of the switching power supply circuit of the present invention. The output end of the switching power supply circuit of the present invention is connected to a load. The voltage of the first end of the output capacitor Cout or the voltage of the second end of the power switch SWP is used as the output voltage VOUT of the switching power supply circuit of the present invention.

[0027] The charge pump CHP is connected to the control terminal NGA of the power switch SWP. The charge pump CHP is configured to supply power to the control terminal NGA of the power switch SWP. The charge pump CHP is configured to supply power to the control terminal NGA of the power switch SWP.

[0028] If necessary, the power switch circuit of the present invention may further include an oscillating circuit OSC. The oscillating circuit OSC is connected to the charge pump CHP. The oscillating circuit OSC can output an oscillating signal CLK to the charge pump CHP. The charge pump CHP determines the power supply to the control terminal NGA of the power switch SWP according to the frequency of an oscillating signal CLK received from the oscillating circuit OSC.

[0029] It is worth noting that the adaptive current limiting circuit ACL of the switching power supply circuit of the present invention is coupled to the input voltage VIN and connected to the first end of the output capacitor Cout or the second end of the power switch SWP, the second end of the current sensing resistor Rs and the control end NGA of the power switch SWP.

[0030] The adaptive current limiting circuit ACL of the switching power supply circuit of the present invention is based on the input voltage VIN, the voltage at the second end of the current sensing resistor Rs (ie, Figure 1 The control terminal NGA of the power switch SWP is determined by a sensing voltage VCS as shown in FIG. 1 and a voltage at a first terminal of the output capacitor Cout or a voltage at a second terminal of the power switch SWP (i.e., an output voltage VOUT of the switching power supply circuit) to determine whether to output a current limiting signal to a control terminal NGA of the power switch SWP. The power switch SWP operates according to the current limiting signal to limit the input current IIN1 or IIN2 flowing through the power switch SWP.

[0031] As a result, the adaptive current limiting circuit ACL of the switching power supply circuit of the present invention limits the substrate current IBULK1 or IBULK2 generated by the mutual collision and ionization of hot carriers inside the power switch SWP to not exceed the current limit value, so as to prevent the power switch SWP from burning due to overcurrent. At the same time, the output current IOUT supplied from the switching power supply circuit of the present invention to the load is limited.

[0032] See also Figure 2 , which is a circuit diagram of an adaptive current limiting power switch circuit of the second embodiment of the present invention. The similarities between the second embodiment of the present invention and the first embodiment are not repeated here.

[0033] The adaptive current limiting circuit ACL of the power switch circuit according to the second embodiment of the present invention comprises a current limiting adjustment circuit ACLD and a current limiting control circuit ACLT.

[0034] The current limiting adjustment circuit ACLD is coupled to the input voltage VIN and connected to the first end of the output capacitor Cout or the second end of the power switch SWP. The current limiting control circuit ACLT is connected to the output end of the current limiting adjustment circuit ACLD, the second end of the current sensing resistor Rs and the control end NGA of the power switch SWP.

[0035] The current limiting adjustment circuit ACLD of the adaptive current limiting circuit ACL detects the input voltage VIN and the voltage of the first end of the output capacitor Cout or the voltage of the second end of the power switch SWP (i.e., the output voltage VOUT of the switching power circuit) to output a current regulation signal to the current limiting control circuit ACLT.

[0036] The current limiting control circuit ACLT of the adaptive current limiting circuit ACL outputs a current limiting control signal to the control terminal NGA of the power switch SWP according to the difference between a sensing voltage VCS at the second end of the current sensing resistor Rs and a reference voltage VR generated by a current adjustment signal received from the current limiting control circuit ACLT, and multiplies the difference by a gain, so as to control the operation of the power switch SWP to prevent the power switch SWP from being burned due to excessive body current IBULK1 or IBULK2 generated by internal hot carriers colliding and ionizing each other. At the same time, the output current IOUT supplied from the switching power supply circuit of the present invention to the load is limited.

[0037] See also Figure 3 and Figure 4 ,in Figure 3 is a circuit diagram of an adaptive current limiting circuit for performing a single-stage current limiting operation included in an adaptive current limiting power switch circuit according to a third embodiment of the present invention, Figure 4 It is a waveform diagram of signals when the adaptive current limiting power switch circuit according to the third embodiment of the present invention performs a single-stage current limiting operation.

[0038] The adaptive current limiting circuit of the power switch circuit of the present invention, for example Figure 1 or Figure 2 The adaptive current limiting circuit ACL shown in FIG. Figure 3 The adaptive current limiting circuit ACL11 is shown.

[0039] like Figure 3 As shown, the adaptive current limiting circuit ACL11 may include: Figure 3 The current limiting adjustment circuit ACLD1 and the current limiting control circuit ACLT1 are shown. Figure 2 The current limiting adjustment circuit ACLD shown in FIG. Figure 3 The current limiting adjustment circuit ACLD1 shown in FIG. Figure 2 The current limiting control circuit ACLT shown in FIG. Figure 3 The current limiting control circuit ACLT1 is shown.

[0040] like Figure 3As shown, the current limiting adjustment circuit ACLD1 includes a first operational amplifier OPA1, a comparator COM, a first current mirror circuit MR1, a switching element SW, a second current mirror circuit MR2 and a first resistor R1. The current limiting control circuit ACLT1 includes a current source AS, a third current mirror circuit MR3, a second operational amplifier OPA2 and a current limiting switch TLM.

[0041] The first input terminal of the first operational amplifier OPA1, for example, the non-inverting input terminal, is connected to a voltage source PW. The voltage source PW is coupled to the input voltage VIN. The voltage source PW provides a power supply voltage so that there is a voltage difference between the first input terminal of the first operational amplifier OPA1 and the input voltage VIN.

[0042] A second input terminal of the first operational amplifier OPA1, for example, an inverting input terminal, is connected to an output terminal of the first operational amplifier OPA1 and a first terminal of the first resistor R1.

[0043] The first input terminal of the comparator COM, for example, the non-inverting input terminal, is coupled to a limiting voltage VB. The second input terminal of the comparator COM, for example, the non-inverting input terminal, is connected to the second end of the first resistor R1. The second input terminal of the comparator COM, for example, the non-inverting input terminal, is coupled to the output voltage VOUT of the switching power supply circuit. In other words, the second input terminal of the comparator COM, for example, the non-inverting input terminal, is connected to the second end of the first resistor R1. Figure 1 or Figure 2 The first end of the output capacitor Cout or the second end of the power switch SWP (ie, the output end of the switching power supply circuit of the present invention) is shown.

[0044] The first current mirror circuit MR1 may include a first transistor T1 and a second transistor T2 .

[0045] The first end of the first transistor T1 and the first end of the second transistor T2 are coupled to the input voltage VIN. The second end of the first transistor T1 (i.e., the input end of the first current mirror circuit MR1) is connected to the output end of the first operational amplifier OPA1 and the control end of the first transistor T1. The control end of the second transistor T2 is connected to the control end of the first transistor T1. The second end of the second transistor T2 (i.e., the output end of the first current mirror circuit MR1) is connected to the first end of the switching component SW. The control end of the switching component SW is connected to the output end of the comparator COM.

[0046] The second current mirror circuit MR2 includes a third transistor T3 and a fourth transistor T4 .

[0047] The first end of the third transistor T3 (i.e., the input end of the second current mirror circuit MR2) is connected to the second end of the switching component SW and the control end of the third transistor T3. The second end of the third transistor T3 is grounded. The first end of the fourth transistor T4 is connected to the output end of the current source AS. The input end of the current source AS is coupled to the input voltage VIN. The control end of the fourth transistor T4 is connected to the control end of the third transistor T3. The second end of the fourth transistor T4 is grounded.

[0048] The third current mirror circuit MR3 includes a fifth transistor T5 and a sixth transistor T6 .

[0049] The first end of the fifth transistor T5 of the third current mirror circuit MR3 (i.e., the input end of the third current mirror circuit MR3) is connected to the first end of the fourth transistor T4 of the second current mirror circuit MR2 (i.e., the output end of the second current mirror circuit MR2) and the output end of the current source AS. The second end of the fifth transistor T5 of the third current mirror circuit MR3 is grounded. The control end of the sixth transistor T6 is connected to the first end and the control end of the fifth transistor T5. The first end of the sixth transistor T6 is connected to the first input end, for example, the non-inverting input end, of the second operational amplifier OPA2. The second end of the sixth transistor T6 is grounded.

[0050] If necessary, the current limiting control circuit ACLT1 of the adaptive current limiting circuit ACL11 of the power switch circuit of the present invention may further include a second resistor R2. The first end of the second resistor R2 is coupled to the input voltage VIN. The second end of the second resistor R2 is connected to the first end of the sixth transistor T6 and the first input end of the second operational amplifier OPA2, such as the non-inverting input end. The second input end of the second operational amplifier OPA2, such as the inverting input end, is connected to the first end of the sixth transistor T6 and the first input end of the second operational amplifier OPA2, such as the non-inverting input end. Figure 1 or Figure 2 The second end of the current sensing resistor Rs is shown. According to the input voltage VIN, the output voltage VOUT, the resistance values ​​of the first resistor R1 and the second resistor R2, and the size ratio of the first current mirror circuit MR1, the second current mirror circuit MR2 and the third current mirror circuit MR3, the output current IOUT of the power switch circuit of the present invention can be determined. According to the input voltage VIN, the output voltage VOUT, the resistance values ​​of the first resistor R1 and the second resistor R2, and the size ratio of the first current mirror circuit MR1, the second current mirror circuit MR2 and the third current mirror circuit MR3, and the current source AS, the output current IOUT of the power switch circuit of the present invention can be determined.

[0051] The control end of the current limiting switch TLM is connected to the output end of the second operational amplifier OPA2. The first end of the current limiting switch TLM is connected to Figure 1 or Figure 2 The control terminal NGA of the power switch SWP is shown as shown. The second terminal of the current limiting switch TLM is grounded.

[0052] When the load is unloaded or lightly loaded, the load only needs to obtain less power from the output voltage VOUT and the output current IOUT of the power switch circuit of the present invention. In this case, the current limiting control circuit ACLT1 may not perform the current limiting operation to limit the amount of the output current IOUT supplied to the load. At this time, in the power switch circuit of the present invention, the switching element SW of the current limiting adjustment circuit ACLD1 may be in the OFF state.

[0053] It is worth noting that when the load is heavy or overloaded, the load needs to obtain more power from the output voltage VOUT and the output current IOUT of the power switch circuit of the present invention, such as Figure 4 The output voltage VOUT of the switching power supply circuit shown in FIG. 1 is reduced. At this time, when the output voltage VOUT of the switching power supply circuit is as shown in FIG. Figure 4 When the voltage VIN of the first terminal of the power switch SWP decreases, the voltage difference between the input voltage VIN received by the first terminal of the power switch SWP and the voltage of the second terminal of the power switch SWP (i.e., the output voltage VOUT of the switching power supply circuit) increases, resulting in an increase in the substrate current IBULK1 flowing through the power switch SWP. In this case, in the power switch circuit of the present invention, the switching element SW of the current limiting adjustment circuit ACLD1 is switched to the ON state. At this time, the current limiting control circuit ACLT1 performs the current limiting operation.

[0054] In the current limiting operation, the current limiting control circuit ACLT1 controls the power switch SWP to operate to reduce the current flowing through the power switch SWP. Figure 1 and Figure 4 The input current IIN1 shown, for example Figure 4 As shown in the figure, when the output voltage VOUT of the switching power supply circuit decreases to less than a limiting voltage VB, the input current IIN1 flowing through the power switch SWP is reduced from the initial current value ICL to the current limiting value ISC. As a result, while limiting the output current IOUT supplied to the load, the body current IBULK1 flowing through the power switch SWP is limited to not exceed the current limiting value IBC, thereby preventing the power switch SWP from burning due to the parasitic components being turned on due to excessive body current IBULK1.

[0055] See also Figures 5 to 7 ,in Figure 5 FIG. 4 is a circuit diagram of an adaptive current limiting circuit for performing a multi-stage current limiting operation included in an adaptive current limiting power switch circuit according to a fourth embodiment of the present invention. Figure 6 FIG. 4 is a circuit diagram of a current limiting adjustment circuit in an adaptive current limiting circuit for performing a multi-stage current limiting operation included in an adaptive current limiting power switch circuit according to a fourth embodiment of the present invention. Figure 7It is a waveform diagram of signals when the adaptive current limiting power switch circuit according to the fourth embodiment of the present invention performs a multi-stage current limiting operation.

[0056] The fourth embodiment of the present invention differs from the third embodiment in that the adaptive current limiting circuit ACL11 of the switching power supply circuit of the third embodiment of the present invention is as follows: Figure 3 The figure only includes a single current limiting adjustment circuit ACLD1, while the adaptive current limiting circuit ACL12 of the switching power supply circuit of the fourth embodiment of the present invention is as shown in FIG. Figure 5 The shown embodiment includes a plurality of current limiting adjustment circuits ACLD1 to ACLDn.

[0057] The configuration and operation of the circuit components in each of the multiple current limiting adjustment circuits ACLD1 to ACLD are the same as those described above. Figure 3 The current limiting adjustment circuit ACLD1 is not described here.

[0058] In the switching power supply circuit of the third embodiment of the present invention, Figure 3 The single current limiting adjustment circuit ACLD1 shown in the figure adjusts the input current IIN1 of the power switch SWP to Figure 4 As shown, the initial current value ICL is reduced to the current limit value ISC at one time.

[0059] However, in the switching power supply circuit of the fourth embodiment of the present invention, as Figure 3 When performing a multi-stage current limiting operation, the multiple current limiting adjustment circuits ACLD1 to ACLDn adjust the input current IIN2 of the power switch SWP as shown in FIG. Figure 7 As shown, the current is reduced from the initial current value ICL to the current limit value ISC in multiple steps. As a result, while limiting the output current IOUT supplied to the load, the base current IBULK2 flowing through the control terminal of the power switch SWP is limited to not exceed the current limit value IBC, thereby preventing the power switch SWP from burning due to the parasitic components being turned on due to excessive base current IBULK2.

[0060] The circuit components in each of the plurality of current limiting adjustment circuits ACLD1 to ACLD of the adaptive current limiting circuit ACL of the switching power supply circuit according to the fourth embodiment of the present invention are configured as follows: Figure 6 As shown, it is similar to Figure 3 The current limiting regulation circuit ACLD1 shown is the same.

[0061] The plurality of current limiting adjustment circuits ACLD1 to ACLD are connected to the output end of the current source AS of the current limiting control circuit ACLT1 and the first end of the fifth transistor T5 of the third current mirror circuit MR3 through a common node NCM.

[0062] In summary, the present invention provides an adaptive current limiting power switch circuit. In the adaptive current limiting power switch circuit of the present invention, the adaptive current limiting circuit flexibly determines the current limiting value for limiting the current flowing through the power switch according to the input voltage and output voltage of the power switch, rather than using a fixed current limiting value, so that the power switch can be effectively prevented from burning under any circumstances, especially in the case of high input voltage and low output voltage, and when the output short circuit occurs at high input voltage.

[0063] The contents disclosed above are only preferred feasible embodiments of the present invention, and are not intended to limit the claims of the present invention. Therefore, all equivalent technical changes made using the description and drawings of the present invention are included in the claims of the present invention.

Claims

1. A power switch circuit with adaptive current limiting, characterized in that: The adaptive current limiting power switch circuit comprises: A current sensing resistor, wherein a first end of the current sensing resistor is coupled to an input voltage; A power switch, wherein a first end of the power switch is connected to a second end of the current sensing resistor, a second end of the power switch is connected to a first end of an output capacitor, a second end of the output capacitor is grounded, and a voltage at the first end of the output capacitor serves as an output voltage of the adaptive current limiting power switch circuit; a charging pump connected to the control end of the power switch and configured to supply power to the control end of the power switch; as well as an adaptive current limiting circuit, coupled to the input voltage, connected to a first end of the output capacitor, a second end of the current sensing resistor, and a control end of the power switch; The adaptive current limiting circuit determines whether to output a current limiting signal to the control end of the power switch based on the input voltage, the voltage at the second end of the current sensing resistor and the voltage at the first end of the output capacitor. The power switch operates based on the current limiting signal to limit the current flowing through the power switch.

2. The power switch circuit with adaptive current limiting according to claim 1, characterized in that: The adaptive current limiting power switch circuit further comprises: The oscillating circuit is connected to the charging pump and configured to output an oscillating signal to the charging pump. The charging pump determines to supply power to the control end of the power switch according to the frequency of the oscillating signal.

3. The power switch circuit with adaptive current limiting according to claim 1, characterized in that: The adaptive current limiting circuit comprises: A current limiting adjustment circuit, coupled to the input voltage and connected to the first end of the output capacitor, configured to detect the input voltage and the voltage of the first end of the output capacitor to output a current adjustment signal; as well as The current limiting control circuit is connected to the output end of the current limiting adjustment circuit, the second end of the current sensing resistor and the control end of the power switch, and is configured to output a current limiting control signal to the control end of the power switch according to the voltage of the current regulation signal and the voltage of the second end of the current sensing resistor.

4. The power switch circuit with adaptive current limiting according to claim 3, characterized in that: The current limiting adjustment circuit comprises: A first operational amplifier, wherein a first input terminal of the first operational amplifier is connected to a voltage source, the voltage source is coupled to the input voltage, and a second input terminal of the first operational amplifier is connected to an output terminal of the first operational amplifier and a first terminal of a first resistor; A comparator, wherein a first input terminal of the comparator is coupled to a limiting voltage, and a second input terminal of the comparator and a second terminal of the first resistor are connected to a first terminal of the output capacitor; A first current mirror circuit, wherein an input end of the first current mirror circuit is connected to an output end of the first operational amplifier; a switching component, wherein a first end of the switching component is connected to an output end of the first current mirror circuit, and a control end of the switching component is connected to an output end of the comparator; as well as A second current mirror circuit, wherein an input end of the second current mirror circuit is connected to the second end of the switching component, and an output end of the second current mirror circuit is connected to the input end of the current limiting control circuit.

5. The power switch circuit with adaptive current limiting according to claim 4, characterized in that: The current limiting control circuit comprises: a third current mirror circuit, wherein an input end of the third current mirror circuit is connected to an output end of the second current mirror circuit and an output end of a current source, and an input end of the current source is coupled to the input voltage; a second operational amplifier, wherein a first input terminal of the second operational amplifier is connected to an output terminal of the third current mirror circuit, and a second input terminal of the second operational amplifier is connected to a second terminal of the current sensing resistor; as well as A current limiting switch, wherein a control end of the current limiting switch is connected to the output end of the second operational amplifier, a first end of the current limiting switch is connected to the control end of the power switch, and a second end of the current limiting switch is grounded.

6. The power switch circuit with adaptive current limiting according to claim 5, characterized in that: The first current mirror circuit comprises: a first transistor, wherein a first terminal of the first transistor is coupled to the input voltage, and a second terminal of the first transistor is connected to an output terminal of the first operational amplifier and a control terminal of the first transistor; as well as A second transistor, wherein a first terminal of the second transistor is coupled to the input voltage, a control terminal of the second transistor is connected to the control terminal of the first transistor, and a second terminal of the second transistor is connected to the first terminal of the switching component.

7. The power switch circuit with adaptive current limiting according to claim 6, characterized in that: The second current mirror circuit comprises: a third transistor, a first terminal of the third transistor being connected to the second terminal of the switching component and the control terminal of the third transistor, and a second terminal of the third transistor being grounded; and A fourth transistor, wherein a first end of the fourth transistor is connected to the output end of the current source, a control end of the fourth transistor is connected to the control end of the third transistor, and a second end of the fourth transistor is grounded.

8. The power switch circuit with adaptive current limiting according to claim 7, characterized in that: The third current mirror circuit comprises: a fifth transistor, a first terminal of the fifth transistor being connected to the first terminal of the fourth transistor and the output terminal of the current source, and a second terminal of the fifth transistor being grounded; and A sixth transistor, wherein the control end of the sixth transistor is connected to the control end and the first end of the fifth transistor, the first end of the sixth transistor is connected to the first input end of the second operational amplifier, and the second end of the sixth transistor is grounded.

9. The power switch circuit with adaptive current limiting according to claim 8, characterized in that: The current limiting control circuit further comprises: A second resistor, wherein a first end of the second resistor is coupled to the input voltage, and a second end of the second resistor is connected to the first end of the sixth transistor and the first input end of the second operational amplifier.

10. The power switch circuit with adaptive current limiting according to claim 1, characterized in that: The adaptive current limiting circuit comprises: A plurality of current limiting adjustment circuits, each of which is coupled to the input voltage and connected to the first end of the output capacitor, and is configured to detect the input voltage and the voltage of the first end of the output capacitor to output a current adjustment signal; as well as The current limiting control circuit is connected to the output end of each of the current limiting adjustment circuits, the second end of the current sensing resistor and the control end of the power switch, and is configured to output multiple current limiting control signals to the control end of the power switch in a multi-stage current limiting operation according to the difference between the multiple current adjustment signals output by the multiple current limiting adjustment circuits and the voltage of the second end of the current sensing resistor, so as to reduce the current flowing through the power switch multiple times.

11. The power switch circuit with adaptive current limiting according to claim 10, characterized in that: Each of the current limiting adjustment circuits comprises: A first operational amplifier, wherein a first input terminal of the first operational amplifier is connected to a voltage source, the voltage source is coupled to the input voltage, and a second input terminal of the first operational amplifier is connected to an output terminal of the first operational amplifier and a first terminal of a first resistor; A comparator, wherein a first input terminal of the comparator is coupled to a limiting voltage, and a second input terminal of the comparator and a second terminal of the first resistor are connected to a first terminal of the output capacitor; A first current mirror circuit, wherein an input end of the first current mirror circuit is connected to an output end of the first operational amplifier; a switching component, wherein a first end of the switching component is connected to an output end of the first current mirror circuit, and a control end of the switching component is connected to an output end of the comparator; as well as A second current mirror circuit, wherein an input end of the second current mirror circuit is connected to the second end of the switching component, and an output end of the second current mirror circuit is connected to the input end of the current limiting control circuit.

12. The power switch circuit with adaptive current limiting according to claim 11, characterized in that: The current limiting control circuit comprises: a third current mirror circuit, wherein an input end of the third current mirror circuit is connected to an output end of the second current mirror circuit and an output end of a current source, and an input end of the current source is coupled to the input voltage; a second operational amplifier, wherein a first input terminal of the second operational amplifier is connected to an output terminal of the third current mirror circuit, and a second input terminal of the second operational amplifier is connected to a second terminal of the current sensing resistor; as well as A current limiting switch, wherein a control end of the current limiting switch is connected to the output end of the second operational amplifier, a first end of the current limiting switch is connected to the control end of the power switch, and a second end of the current limiting switch is grounded.

13. The power switch circuit with adaptive current limiting according to claim 12, characterized in that: The first current mirror circuit comprises: a first transistor, wherein a first terminal of the first transistor is coupled to the input voltage, and a second terminal of the first transistor is connected to an output terminal of the first operational amplifier and a control terminal of the first transistor; as well as A second transistor, wherein a first terminal of the second transistor is coupled to the input voltage, a control terminal of the second transistor is connected to the control terminal of the first transistor, and a second terminal of the second transistor is connected to the first terminal of the switching component.

14. The power switch circuit with adaptive current limiting according to claim 13, characterized in that: The second current mirror circuit comprises: a third transistor, a first terminal of the third transistor being connected to the second terminal of the switching component and the control terminal of the third transistor, and a second terminal of the third transistor being grounded; and A fourth transistor, wherein a first end of the fourth transistor is connected to the output end of the current source, a control end of the fourth transistor is connected to the control end of the third transistor, and a second end of the fourth transistor is grounded.

15. The power switch circuit with adaptive current limiting according to claim 14, characterized in that: The third current mirror circuit comprises: a fifth transistor, a first terminal of the fifth transistor being connected to the first terminal of the fourth transistor, and a second terminal of the fifth transistor being grounded; and A sixth transistor, wherein the control end of the sixth transistor is connected to the first end of the fourth transistor and the control end of the fifth transistor, the first end of the sixth transistor is connected to the first input end of the second operational amplifier, and the second end of the sixth transistor is grounded.

16. The power switch circuit with adaptive current limiting according to claim 15, characterized in that: The current limiting control circuit further comprises: A second resistor, wherein a first end of the second resistor is coupled to the input voltage, and a second end of the second resistor is connected to the first end of the sixth transistor and the first input end of the second operational amplifier.

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