Startup Circuit and Low-Power Reference Source

Abstract

The present application discloses a startup circuit and a low-power reference source. The startup circuit is connected to the reference circuit; the startup circuit includes: a coupled boost module connected to a first node for coupling and boosting the voltage of the first node; a startup control module connected to the first node for adjusting the voltage of the first node according to the bandgap reference voltage of the reference circuit; a current limiting module connected to the coupled boost module for adjusting the output current of the coupled boost module according to the bandgap reference voltage of the reference circuit; a conversion module for adjusting the voltage of a second node according to the voltage of the first node; wherein, the current limiting module is further used for adjusting the output current of the coupled boost module according to the voltage of the second node. According to the embodiments of the present application, rapid startup of the startup circuit and shutdown and exit after startup completion can be achieved, the stability of the startup circuit is improved, and the power consumption of the startup circuit is reduced.

Description

Technical Field

[0001] This application belongs to the technical field of electronic circuits, and particularly relates to a startup circuit and a low-power reference source. Background Art

[0002] Bandgap references are usually used to provide stable reference voltages / currents. To enable the reference circuit of the bandgap reference to maintain a steady-state operating point, a startup circuit is usually provided within the bandgap reference. The startup circuit can provide an excitation voltage / current for the reference circuit when the power supply is powered on, so that the reference circuit can quickly enter the steady-state operating point and avoid the reference circuit entering the degeneracy point. When the reference circuit enters the normal operating state, the startup circuit will gradually turn off and exit.

[0003] Currently, the startup circuits in related technologies are usually composed of MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) or other types of transistors. The startup circuit can control the conduction state of the MOSFET according to the bandgap reference voltage or bias signal output by the reference circuit. However, when the reference circuit enters the normal operating state, the voltage difference between the bandgap reference voltage or bias signal received by the startup circuit and the power supply signal is relatively large, so that the MOSFET remains in the conduction state due to the gate-source voltage difference reaching the conduction threshold. The current flowing through the MOSFET in the conduction state is relatively large, which will cause the power consumption of the startup circuit in the normal operating state of the reference circuit to increase. Moreover, in a high-temperature environment, the conduction threshold of the MOSFET will further decrease, resulting in a further increase in the power consumption of the startup circuit. Summary of the Invention

[0004] Embodiments of this application provide a startup circuit and a low-power reference source, which can solve the technical problem of large power consumption of the startup circuit when the reference circuit is operating normally in related technologies.

[0005] In a first aspect, an embodiment of this application provides a startup circuit, which is connected to a reference circuit; the startup circuit includes:

[0006] A coupling boost module, connected to a first node, for coupling and boosting the voltage of the first node; wherein, the first node is used to provide an excitation voltage for a startup switch, and the startup switch is used to provide a startup current for the reference circuit when conducting;

[0007] A startup control module, connected to the first node, for adjusting the voltage of the first node according to the bandgap reference voltage of the reference circuit;

[0008] A current limiting module, connected to the coupling boost module, for adjusting the output current of the coupling boost module according to the bandgap reference voltage of the reference circuit;

[0009] A conversion module is connected between the first node and the second node and is configured to adjust the voltage of the second node according to the voltage of the first node. Among them, a current limiting module is connected to the second node, and the current limiting module is further configured to adjust the output current of the coupled boost module according to the voltage of the second node.

[0010] In some embodiments, the startup control module includes:

[0011] A first transistor is connected between the first node and the ground terminal, and the gate of the first transistor is connected to the reference circuit. The bandgap reference voltage of the reference circuit is used to adjust the conduction state of the first transistor.

[0012] In some embodiments, the coupled boost module includes:

[0013] A current source is connected between the first node and the power supply terminal, and the control terminal of the current source is connected to the current limiting module;

[0014] A coupling unit is connected between the first node and the power supply terminal and is configured to couple and boost the voltage of the first node when the power supply voltage is provided at the power supply terminal.

[0015] In some embodiments, the coupling unit includes a first capacitor, and the current source includes:

[0016] A second transistor is connected between the first node and the power supply terminal;

[0017] A third transistor is connected between the current limiting module and the power supply terminal, the gate of the third transistor is connected to the gate of the second transistor, and the gate of the third transistor is further connected to the current limiting module.

[0018] In some embodiments, the current limiting module includes:

[0019] A fourth transistor is connected between the coupled boost module and the third node, and the gate of the fourth transistor is connected to the reference circuit. The bandgap reference voltage of the reference circuit is used to adjust the conduction state of the fourth transistor;

[0020] A fifth transistor is connected between the third node and the ground terminal, and the gate of the fifth transistor is connected to the second node. The voltage of the second node is used to adjust the conduction state of the fifth transistor.

[0021] In some embodiments, the conversion module includes:

[0022] A first inverter and a second inverter, the first inverter is connected between the first node and the second inverter, and the second inverter is connected between the first inverter and the second node;

[0023] A second capacitor is connected between the power supply terminal and the second node.

[0024] In some embodiments, the startup circuit further includes:

[0025] An indication signal module, connected to the second node, for generating an indication signal according to the voltage of the second node.

[0026] In some embodiments, the startup circuit further includes a voltage dividing module, and the voltage dividing module is disposed in at least one of the following:

[0027] Between the current limiting module and the coupled boost module;

[0028] Between the startup control module and the ground terminal;

[0029] Between the coupled boost module and the power supply terminal;

[0030] Between the conversion module and the power supply terminal; and,

[0031] Between the conversion module and the ground terminal.

[0032] In some embodiments, the voltage dividing module includes a voltage dividing MOSFET, and the gate and the drain of the voltage dividing MOSFET are connected.

[0033] In a second aspect, an embodiment of the present application provides a low-power reference source, including a reference circuit and the startup circuit of the first aspect.

[0034] Compared with the prior art, the startup circuit and the low-power reference source provided by the embodiments of the present application can couple and boost the voltage of the first node when powering on by setting a coupled boost module. When the voltage of the first node is pulled up, an excitation voltage can be provided for the reference circuit to start the reference circuit. The bandgap reference voltage output by the reference circuit during startup gradually increases, and the startup control module can pull down the voltage of the first node according to the gradually increasing bandgap reference voltage, so that when the bandgap reference voltage is stable, the voltage of the first node is pulled down to a level where it cannot provide excitation for the reference circuit, realizing the shutdown and exit of the startup circuit. The bandgap reference voltage output by the reference circuit and the voltage of the second node generated based on the voltage of the first node can both adjust the current limiting effect of the current limiting module. When the bandgap reference voltage is low, the current limiting effect of the current limiting module is small, and the coupled boost module can quickly boost the voltage of the first node to achieve a quick startup of the startup circuit; when the bandgap reference voltage gradually increases, the current limiting effect of the current limiting module also gradually increases, thereby reducing the self-power consumption of the startup circuit. After the startup circuit completes startup, the voltage of the second node that changes with the voltage of the first node can also increase the current limiting effect of the current limiting module, reduce the self-power consumption of the startup circuit, and ensure that the startup circuit can be completely shut down and exited to prevent the startup circuit from affecting the normal operation of the reference circuit. Description of the Drawings

[0035] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings required for use in the embodiments of the present application. Obviously, the accompanying drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0036] Figure 1 is a schematic circuit diagram of a startup circuit provided by an embodiment of the present application;

[0037] Figure 2 is a schematic circuit diagram of a startup circuit provided by another embodiment of the present application;

[0038] Figure 3 is a schematic circuit diagram of a startup circuit provided by another embodiment of the present application;

[0039] Figure 4 is a schematic circuit diagram of a startup circuit provided by yet another embodiment of the present application;

[0040] Figure 5 is a schematic circuit diagram of a startup circuit provided by yet another embodiment of the present application;

[0041] Figure 6 is a schematic circuit diagram of a startup circuit provided by yet another embodiment of the present application.

[0042] In the accompanying drawings:

[0043] 10. Coupling boost module; 11. Current source; 12. Coupling unit; 20. Startup control module; 30. Current limiting module; 40. Conversion module; 2. Reference circuit; VBG. Bandgap reference voltage; 41. First inverter; 42. Second inverter; 50. Indication signal module; 60. Voltage dividing module; N1. First node; N2. Second node; N3. Third node; C1. First capacitor; C2. Second capacitor; MO. Startup switch; M1. First transistor; M2. Second transistor; M3. Third transistor; M4. Fourth transistor; M5. Fifth transistor. Detailed implementation manners

[0044] The following will describe in detail the features and exemplary embodiments of various aspects of the present application. To make the purpose, technical solutions and advantages of the present application clearer and more understandable, the following further describes the present application in detail in combination with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than limiting the present application. For those skilled in the art, the present application can be implemented without some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application.

[0045] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0046] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The embodiments will be described in detail below with reference to the drawings.

[0047] A bandgap reference is usually used to provide a stable reference voltage / current. In order to enable the reference circuit of the bandgap reference to maintain at a steady-state operating point, a startup circuit is usually provided in the bandgap reference. The startup circuit can provide an excitation voltage / current for the reference circuit when the power is turned on, so that the reference circuit can quickly enter the steady-state operating point and avoid the reference circuit from entering the degeneracy point. When the reference circuit enters the normal operating state, the startup circuit will gradually turn off and exit.

[0048] Currently, the startup circuit in the related art is usually composed of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or other types of transistors. The startup circuit can control the on-state of the MOSFET according to the bandgap reference voltage or bias signal output by the reference circuit. However, when the reference circuit enters the normal operating state, the voltage difference between the bandgap reference voltage or bias signal received by the startup circuit and the power supply signal is relatively large, so that the MOSFET remains in the on-state due to the gate-source voltage difference reaching the on-threshold. The current flowing through the MOSFET in the on-state is relatively large, which will cause the power consumption of the startup circuit in the normal operating state of the reference circuit to increase. Moreover, in a high-temperature environment, the on-threshold of the MOSFET will be further reduced, resulting in a further increase in the power consumption of the startup circuit.

[0049] In order to solve the above technical problems, the embodiments of this application provide a startup circuit and a low-power reference source. First, the startup circuit provided by the embodiments of this application will be introduced below.

[0050] Figure 1The schematic structural diagram of the startup circuit provided by an embodiment of the present application is shown. The startup circuit can be connected to the reference circuit 2. The startup circuit includes a coupled boost module 10, a startup control module 20, a current limiting module 30, and a conversion module 40.

[0051] The coupled boost module 10 is connected to the first node N1. The coupled boost module 10 can couple and boost the voltage of the first node N1 to raise the voltage of the first node N1. The voltage of the first node N1 can be used as the excitation voltage of the startup switch M0. When the excitation voltage reaches the conduction threshold of the startup switch M0, the startup switch M0 conducts, and provides a startup current for the reference circuit 2 when conducting. Raising the voltage of the first node N1 is equivalent to injecting a startup current into the reference circuit 2 to achieve the startup of the reference circuit 2.

[0052] The above-mentioned coupled boost module 10 coupling and boosting the voltage of the first node N1 can be that when the startup circuit is powered on, the coupled boost module 10 couples and boosts the voltage of the first node N1 according to the power supply voltage after power-on.

[0053] The startup control module 20 is connected to the first node N1. The startup control module 20 can be connected to the reference circuit 2 and receive the bandgap reference voltage VBG provided by the reference circuit 2. When the reference circuit 2 is not in the working state, the bandgap reference voltage VBG is relatively low; and during the process that the voltage of the first node N1 gradually increases as the excitation voltage of the startup switch M0, the startup switch M0 gradually conducts, and the bandgap reference voltage VBG provided by the reference circuit 2 during startup also gradually increases.

[0054] During the increasing process of the bandgap reference voltage VBG, the startup control module 20 can adjust the voltage of the first node N1 according to the gradually increasing bandgap reference voltage VBG. For example, the startup control module 20 can pull down the voltage of the first node N1 in response to the gradually increasing bandgap reference voltage VBG. When the bandgap reference voltage VBG provided by the reference circuit 2 reaches the stable state, the startup control module 20 can pull down the voltage of the first node N1 to be lower than the conduction voltage of the startup switch M0, so that the startup switch M0 changes from the conducting state to the off state, which is equivalent to the startup circuit stopping injecting the startup current into the reference circuit 2, that is, the startup circuit closes and exits. Correspondingly, in order to adapt to the startup switch M0 being off when the voltage of the first node N1 is a low-level signal, the startup switch M0 can be selected as an N-type transistor.

[0055] The current limiting module 30 can be connected to the coupled boost module 10. The current limiting module 30 can also be connected to the reference circuit 2 and receive the bandgap reference voltage VBG provided by the reference circuit 2. The current limiting module 30 can adjust the output current of the coupled boost module 10 according to the bandgap reference voltage VBG provided by the reference circuit 2.

[0056] When the reference circuit 2 is not in the working state, the bandgap reference voltage VBG is relatively low. At this time, the current limiting module 30 has a relatively small current limiting effect on the output current of the coupled boost module 10. The coupled boost module 10 can quickly boost the voltage of the first node N1 through a relatively large output current, thereby improving the startup speed of the startup circuit.

[0057] During the process of the gradually increasing bandgap reference voltage VBG provided by the reference circuit 2, the current limiting effect of the current limiting module 30 on the output current of the coupled boost module 10 also gradually increases. That is, during the process of the gradually increasing bandgap reference voltage VBG provided by the reference circuit 2, the current limiting module 30 can play a current limiting role to limit the output current of the coupled boost module 10. When the output current of the coupled boost module 10 is limited, it is equivalent to reducing the operating power consumption of the startup circuit by restricting the current magnitude.

[0058] When the bandgap reference voltage VBG output by the reference circuit 2 is small, the current limiting effect of the current limiting module 30 is small. At this time, the coupled boost module 10 can quickly raise the voltage of the first node N1 through a relatively large output current, improving the startup speed of the startup circuit. When the reference circuit 2 outputs a stable bandgap reference voltage VBG, the current limiting module 30 can limit the output current of the coupled boost module 10 to reduce the power consumption of the startup circuit.

[0059] The conversion module 40 is connected between the first node N1 and the second node N2. The conversion module 40 can adjust the voltage of the second node N2 according to the voltage of the first node N1. The second node N2 is connected to the current limiting module 30, and the current limiting module 30 can adjust the output current of the coupled boost module 10 according to the voltage of the second node N2.

[0060] The conversion module 40 can obtain the voltage of the first node N1 and adjust the voltage of the second node N2 according to the voltage of the first node N1. For example, the conversion module 40 can raise the voltage of the second node N2 when the voltage of the first node N1 increases and reduce the voltage of the second node N2 when the voltage of the first node N1 decreases; or, reduce the voltage of the second node N2 when the voltage of the first node N1 increases and increase the voltage of the second node N2 when the voltage of the first node N1 decreases.

[0061] The current limiting module 30 can obtain the voltage of the second node N2 and adjust the output current of the coupled boost module 10 according to the voltage of the second node N2. That is, based on adjusting the degree of the current limiting effect according to the bandgap reference voltage VBG of the reference circuit 2, the current limiting module 30 can also adjust the degree of the current limiting effect according to the voltage of the second node N2.

[0062] It should be noted that the above current limiting module 30 adjusts the current limiting intensity of the output current of the coupled boost module 10 according to the voltage of the second node N2, and can be analyzed based on the voltage of the first node N1. For example, during the process of the increase of the bandgap reference voltage VBG provided by the reference circuit 2, the voltage of the first node N1 gradually decreases. At this time, the current limiting module 30 should respond to the voltage of the second node N2 and gradually increase the current limiting intensity of the output current of the coupled boost module 10. If the voltage of the second node N2 decreases as the voltage of the first node N1 decreases, the current limiting module 30 can gradually enhance the current limiting effect during the process of the decrease of the voltage of the second node N2; if the voltage of the second node N2 increases as the voltage of the first node N1 decreases, the current limiting module 30 can gradually enhance the current limiting effect during the process of the increase of the voltage of the second node N2.

[0063] During the process of the increase of the bandgap reference voltage VBG, the voltage of the first node N1 gradually decreases. The increased bandgap reference voltage VBG can drive the current limiting module 30 to enhance the current limiting effect on the coupled boost module 10. The conversion module 40 can adjust the voltage of the second node N2 through the decreased first voltage, and use the voltage of the second node N2 to drive the current limiting module 30 to enhance the current limiting effect on the coupled boost module 10. That is, both the bandgap reference voltage VBG and the voltage of the second node N2 can strengthen the current limiting function of the current limiting module 30, so as to ensure that the current limiting module 30 can limit the loop current to reduce the power consumption of the startup circuit, and can also ensure that the startup circuit can be turned off and exited after startup, preventing the startup circuit from affecting the normal operation of the reference circuit 2.

[0064] In this embodiment, by setting the coupling boost module 10, the voltage of the first node N1 can be coupled and boosted when power is applied. When the voltage of the first node N1 is pulled up, it can provide an excitation voltage for the reference circuit 2 to start the reference circuit 2. The bandgap reference voltage VBG output by the reference circuit 2 during startup gradually increases. The startup control module 20 can pull down the voltage of the first node N1 according to the gradually increasing bandgap reference voltage VBG, so that when the bandgap reference voltage VBG is stable, the voltage of the first node N1 is pulled down to a level where it cannot provide excitation for the reference circuit 2, achieving the shutdown and exit of the startup circuit. Both the bandgap reference voltage VBG output by the reference circuit 2 and the voltage of the second node N2 generated based on the voltage of the first node N1 can adjust the current limiting effect of the current limiting module 30. When the bandgap reference voltage VBG is low, the current limiting effect of the current limiting module 30 is small, and the coupling boost module 10 can quickly boost the voltage of the first node N1 to achieve the quick startup of the startup circuit; when the bandgap reference voltage VBG gradually increases, the current limiting effect of the current limiting module 30 also gradually increases, thereby reducing the self-power consumption of the startup circuit. After the startup circuit completes startup, the voltage of the second node N2 that changes with the voltage of the first node N1 can also increase the current limiting effect of the current limiting module 30, reduce the self-power consumption of the startup circuit, and ensure that the startup circuit can be completely shut down and exited to prevent the startup circuit from affecting the normal operation of the reference circuit 2.

[0065] Please refer to Figure 2 , in some embodiments, the above startup control module 20 may include a first transistor M1. The first transistor may be connected between the first node N1 and the ground terminal. The gate of the first transistor M1 may be connected to the reference circuit 2, and the bandgap reference voltage VBG provided by the reference circuit 2 can adjust the conduction state of the first transistor M1.

[0066] When the startup circuit is not powered on, the voltage of the first node N1 is lower than the conduction threshold voltage of the startup switch M0. At this time, the reference circuit 2 is not working, and the bandgap reference voltage VBG provided by the reference circuit 2 is low.

[0067] The first transistor M1 may be an N-type transistor, for example, it may be an N-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or other transistors that conduct in response to a high-level signal. When the bandgap reference voltage VBG is low, the first transistor M1 is in a cut-off state, and the first node N1 is disconnected from the ground terminal.

[0068] When the first node N1 is disconnected from the ground terminal, the first node N1 can be regarded as a high-impedance state with respect to the ground. When the startup circuit is powered on, the coupling boost module 10 can couple and boost the voltage of the first node N1, causing the voltage of the first node N1 to gradually rise.

[0069] Since the voltage of the first node N1 can be used as the excitation voltage of the reference circuit 2, after the voltage of the first node N1 rises to the conduction threshold voltage of the startup switch M0, the startup switch M0 conducts, injecting a startup current into the reference circuit 2. At this time, the reference circuit 2 starts to operate, and during the operation of the reference circuit 2, the bandgap reference voltage VBG output by the reference circuit 2 gradually increases.

[0070] Taking the first transistor M1 as an N-type transistor as an example, as the bandgap reference voltage VBG gradually increases, the conduction amplitude of the first transistor M1 gradually increases, causing the current flowing through the first transistor M1 to also gradually increase. Since the first transistor M1 is connected between the ground terminal and the first node N1, the gradually conducting first transistor M1 can pull down the potential of the first node N1. That is, as the bandgap reference voltage VBG increases, the first transistor M1 can pull down the potential of the first node N1, causing the potential of the first node N1 to drop below the conduction threshold voltage of the startup switch M0. At this time, the startup switch M0 disconnects, which is equivalent to the startup circuit stopping and exiting the startup process.

[0071] Please continue to refer to Figure 2 , in some embodiments, the above-mentioned coupling boost module 10 may include a current source 11 and a coupling unit 12.

[0072] The current source 11 may be connected between the first node N1 and the power supply terminal VCC, and the control terminal of the current source 11 may be connected to the current limiting module 30.

[0073] The coupling unit 12 may be connected between the first node N1 and the power supply terminal VCC. When the startup circuit is powered on, the power supply terminal VCC can provide a power supply voltage, and the coupling unit 12 can couple and boost the voltage of the first node N1.

[0074] One end of the coupling unit 12 is connected to the power supply terminal VCC, and the other end is connected to the first node N1. When the startup circuit is powered on, the voltage of the power supply terminal VCC is pulled up to the power supply voltage. Due to the characteristic that the voltage across the two ends of the coupling unit 12 cannot change suddenly, it will correspondingly pull up the potential of the first node N1, causing the voltage of the first node N1 to be coupled and boosted.

[0075] After the voltage of the first node N1 rises, the reference circuit 2 gradually starts to operate as it receives the increased voltage of the first node N1 as an excitation, causing the bandgap reference voltage VBG to gradually increase. The current limiting module 30 can limit the current of the current source 11 based on the gradually increasing bandgap reference voltage VBG. When the control terminal of the current source 11 decreases the current, it also limits the loop current between the power supply terminal VCC and the first node N1, thereby reducing the self-power consumption of the startup circuit by decreasing the loop current. Through the current source 11 and the coupling unit 12, the coupling boost module 10 can achieve DC coupling and AC coupling of the first node N1.

[0076] In some embodiments, the above-mentioned coupling unit 12 may include a first capacitor C1, and the current source 11 may include a second transistor M2 and a third transistor M3.

[0077] Both ends of the first capacitor C1 are respectively connected to the power supply terminal VCC and the first node N1. When the startup circuit is powered on, the voltage of the power supply terminal VCC is pulled up to the power supply voltage, and the first capacitor C1 can couple and lift the potential of the first node N_1 to achieve the coupling boost of the first node N1.

[0078] The second transistor M2 can be connected between the first node N1 and the power supply terminal VCC, and the third transistor M3 can be connected between the current limiting module 30 and the power supply terminal VCC. The gate of the second transistor M2 is connected to the gate of the third transistor M3, and the gate of the third transistor M3 can also be connected to the current limiting module 30.

[0079] The above-mentioned second transistor M2 and third transistor M3 can form a current mirror, that is, a mirror constant current source. The current in the loop where the current limiting module 30 is located is the input current, and the current in the loop where the first node N1 is located is the output current. Since the input-output current transfer ratio of the current mirror is equal to 1, the current limiting module 30 can correspondingly limit the current in the loop where the first node N1 is located by limiting the current in its loop.

[0080] When the current limiting module 30 limits the current in the loop where the first node N1 is located, since the current between the power supply terminal VCC and the first node N1 gradually decreases, the ability of the power supply voltage to pull up the potential of the first node N1 weakens, which will cause the potential of the first node N1 to gradually decrease. Moreover, during the process of the gradual increase of the bandgap reference voltage VBG, the gradually turned-on first transistor M1 will increase the ability of the ground terminal to pull down the potential of the first node N1.

[0081] When the pull-up ability weakens and the pull-down ability strengthens, the potential of the first node N1 will gradually decrease. That is, the current limiting module 30 responds to the increase of the bandgap reference voltage VBG to enhance the current limiting effect and can pull down the potential of the first node N1; the first transistor M1 of the startup control module 20 gradually conducts in response to the bandgap reference voltage VBG and can also pull down the potential of the first node N1.

[0082] Please refer to Figure 3 , in some embodiments, the current limiting module 30 may include a fourth transistor M4 and a fifth transistor M5. The fourth transistor M4 is connected between the coupled boost module 10 and the third node N3, and the gate of the fourth transistor M4 is connected to the reference circuit 2. The fifth transistor M5 is connected between the third node N3 and the ground terminal, and the gate of the fifth transistor M5 is connected to the second node N2.

[0083] The bandgap reference voltage VBG output by the reference circuit 2 can adjust the conduction state of the fourth transistor M4. When the bandgap reference voltage VBG gradually increases, the fourth transistor M4 operates in the saturation region, and the current flowing through the fourth transistor M4 is negatively correlated with the gate-source voltage difference. Since the gate voltage is the bandgap reference voltage VBG and the source voltage is the voltage of the third node N3, when the bandgap reference voltage VBG gradually increases, the gate-source voltage difference of the fourth transistor M4 gradually increases, resulting in a gradual decrease in the source-drain current of the fourth transistor M4, thereby realizing the current limiting effect in response to the change of the bandgap reference voltage VBG.

[0084] The voltage of the second node N2 can control the conduction state of the fifth transistor M5. When the voltage of the second node N2 decreases as the voltage of the first node N1 decreases, the gate voltage of the fifth transistor M5 gradually decreases. At this time, the fifth transistor M5 operates in the saturation region and can reduce the source-drain current in response to the gradually decreasing gate voltage to achieve the current limiting effect.

[0085] The above-mentioned fourth transistor M4 and fifth transistor M5 can both be P-type transistors, for example, they can be P-channel MOSFETs. The gate of the fourth transistor M4 receives the bandgap reference voltage VBG. When the bandgap reference voltage VBG gradually increases, the source-drain current of the fourth transistor M4 gradually decreases. The gate of the fifth transistor M5 is connected to the second node N2 through an inverter. When the voltage of the second node N2 gradually decreases, the inverter can jump the output low-level signal to a high-level signal when the voltage of the second node N2 drops below the jump threshold, causing the fifth transistor M5 to change from the conduction state to the cut-off state to achieve further current limiting. That is, at this time, the fifth transistor M5 switches between the cut-off state and the conduction state.

[0086] In another example, the above-mentioned fifth transistor M5 can also be an N-type transistor. At this time, the second node N2 can be directly connected to the gate of the fifth transistor M5. When the voltage of the second node N2 gradually decreases, the gate voltage of the fifth transistor M5 gradually decreases, and the source-drain current also gradually decreases.

[0087] It can be understood that the voltage of the second node N2 can also be set to increase as the voltage of the first node N1 decreases. The type of the fifth transistor M5 and the corresponding additional devices can be adaptively adjusted based on the above embodiments.

[0088] Please refer to Figure 4 , in some embodiments, the above-mentioned conversion module 40 may include a first inverter 41, a second inverter 42, and a second capacitor C2.

[0089] The first inverter 41 can be connected between the first node N1 and the second inverter 42, and the second inverter 42 is connected between the first inverter 41 and the second node N2.

[0090] The second capacitor C2 can be connected between the power supply terminal VCC and the second node N2.

[0091] When the startup circuit is powered on, the voltage of the power supply terminal VCC is pulled up to the power supply voltage. At this time, the second capacitor C2 can pull up the second node N2 to a high-level signal through coupling and boosting.

[0092] Taking the above embodiment where the fifth transistor M5 is a P-type transistor and the fifth transistor M5 is connected to the second node N2 through an inverter as an example, the high-level signal of the second node N2 becomes a low-level signal after passing through the inverter, driving the fifth transistor M5 to remain in the on state, that is, the fifth transistor M5 does not play a current-limiting role at this time. Similarly, the bandgap reference voltage VBG has not risen at this time and can drive the fourth transistor M4 to remain in the on state, that is, the fourth transistor M4 does not play a current-limiting role at this time. The coupling boost module 10 can quickly pull up the potential of the first node N1.

[0093] During the process of gradually pulling up the voltage of the first node N1, the voltage of the first node N1 can be converted into the voltage of the second node N2 through the first inverter 41 and the second inverter 42. The interference spike signals in the voltage of the first node N1 can be filtered through the process of two inverse conversions. When the voltage of the first node N1 is a high-level signal, the voltage of the second node N2 after two inverse conversions is also a high-level signal.

[0094] When the start control module 20 increases the pull-down ability and the current limiting module 30 reduces the pull-up ability through current limiting, the potential of the first node N1 is pulled down, and the voltage of the second node N2 after two inversions also becomes a low-level signal. This low-level signal becomes a high-level signal after passing through an inverter, driving the fifth transistor M5 to cut off to further enhance the current limiting effect of the current limiting module 30.

[0095] Please refer to Figure 5 , in some embodiments, the above start-up circuit may further include an indication signal module 50.

[0096] The indication signal module 50 may be connected to the second node N2 and generate an indication signal according to the voltage of the second node N2.

[0097] When the start-up circuit is powered on, the second capacitor C2 can couple the voltage of the second node N2 into a high-level signal, and as the voltage of the first node N1 increases, the voltage of the second node N2 will also remain a high-level signal.

[0098] After the start-up circuit successfully starts the reference circuit 2, the bandgap reference voltage VBG output by the reference circuit 2 gradually increases, causing the voltage of the first node N1 to gradually decrease, and correspondingly the voltage of the second node N2 will also switch from a high-level signal to a low-level signal. When the voltage of the second node N2 is a low-level signal, it can drive the fifth transistor M5 to cut off. At this time, the start-up circuit completes the start of the reference circuit 2 and closes and exits.

[0099] Since the voltage of the second node N2 only becomes a low-level signal when the start-up circuit closes and exits, the indication signal module 50 can generate an indication signal when the voltage of the second node N2 is a low-level signal to indicate that the start-up circuit has completed starting and closed and exited.

[0100] As an optional implementation manner, the above indication signal module 50 may be an inverter. Since the voltage of the second node N2 only becomes a low-level signal after the start-up circuit completes starting, the indication signal module 50 can invert this low-level signal as the indication signal.

[0101] Please refer to Figure 6 , in some embodiments, the above start-up circuit may further include a voltage dividing module 60. The voltage dividing module 60 may be composed of at least one voltage dividing unit, and the voltage dividing unit may be disposed at least at one of the following positions:

[0102] Between the current limiting module 30 and the coupling boost module 10;

[0103] Between the start control module 20 and the ground terminal;

[0104] Between the coupling boost module 10 and the power supply terminal VCC;

[0105] between the conversion module 40 and the power supply terminal VCC; and,

[0106] between the conversion module 40 and the ground terminal.

[0107] The voltage dividing unit is arranged between the current limiting module 30 and the coupled boost module 10, and can supply the power supply voltage to the current limiting module 30 after step-down. When the current limiting module 30 includes the fourth transistor M4, the voltage dividing unit can supply the power supply voltage to the source of the fourth transistor M4 after step-down, so as to avoid too high source voltage of the fourth transistor M4. That is, by arranging the voltage dividing unit, when the reference circuit 2 outputs a stable bandgap reference voltage VBG, the bandgap reference voltage VBG as the gate voltage of the fourth transistor M4 can make the source-drain current of the fourth transistor M4 as small as possible or make the fourth transistor M4 cut off.

[0108] The voltage dividing unit is arranged between the start control module 20 and the ground terminal, and can boost the lower-end voltage of the start control module 20. When the start control module 20 includes the first transistor M1, the source voltage of the first transistor M1 can be boosted, and the gate-source voltage difference of the first transistor M1 can be reduced. When the reference circuit 2 outputs a stable bandgap reference voltage VBG, the bandgap reference voltage VBG as the gate voltage of the first transistor M1 can make the source-drain current of the first transistor M1 as small as possible or make the first transistor M1 cut off.

[0109] The voltage dividing unit is arranged between the coupled boost module 10 and the power supply terminal VCC. When the coupled boost module 10 includes the second transistor M2, the voltage dividing unit can be arranged between the source of the second transistor M2 and the power supply terminal VCC. By means of the voltage dividing unit, the source voltage of the second transistor M2 can be reduced, so that the source-drain current of the second transistor M2 can be as small as possible under the current limiting effect of the current limiting module 30 or the second transistor M2 can be cut off.

[0110] The voltage dividing unit can also be disposed between the conversion module 40 and the power supply terminal VCC and between the conversion module 40 and the ground terminal. The first inverter 41 and the second inverter 42 in the conversion module 40 can be composed of two transistors of different types. For example, the first inverter 41 can include a P-type transistor and an N-type transistor. The P-type transistor is connected between the power supply terminal VCC and the second node N2, and the N-type transistor is connected between the ground terminal and the second node N2. The gates of the P-type transistor and the N-type transistor are connected to the first node N1. The voltage dividing unit can also be disposed between the conversion module 40 and the power supply terminal VCC, which is equivalent to the P-type transistor being connected to the power supply terminal VCC through the voltage dividing unit; the voltage dividing unit can also be disposed between the conversion module 40 and the ground terminal, which is equivalent to the N-type transistor being connected to the ground terminal through the voltage dividing unit. By setting a suitable voltage dividing unit, the source voltages of the P-type transistor and the N-type transistor can be adjusted so that the voltage change range of the first node N1 can drive the P-type transistor and the N-type transistor to switch between conduction states.

[0111] In some embodiments, the above voltage dividing module 60 may include a voltage dividing MOSFET. The gate and the drain of the voltage dividing MOSFET are connected.

[0112] Connecting the gate and the drain of the MOSFET can serve as a voltage drop diode. The voltage dividing MOSFET disposed at the corresponding position can achieve a voltage reduction effect so that the source voltages of each transistor can meet the requirements.

[0113] As an optional implementation manner, the above voltage dividing MOSFET can be an N-channel MOSFET or a P-channel MOSFET. The voltage dividing module 60 can include a single voltage dividing MOSFET or can be composed of multiple voltage dividing MOSFETs connected in series. As Figure 6 shown, the voltage dividing module 60 disposed between the current limiting module 30 and the coupled boost module 10 can be composed of a P-channel MOSFET and two N-channel MOSFETs connected in series.

[0114] In an optional implementation manner, after software simulation verification based on Figure 6 the shown circuit topology schematic diagram, the static power consumption of the startup circuit at room temperature can reach below 1 nA, and the power consumption under the high temperature and high voltage FF (Fast N Fast P) process corner (worst case) does not exceed 10 nA, and the power consumption performance is excellent.

[0115] The embodiment of the present application also provides a low-power reference source, which can include a reference circuit and the startup circuit provided by the embodiment of the present application. The reference circuit is connected to the startup circuit.

[0116] The functional blocks shown in the above-described structural block diagrams can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a functional card, and so on. When implemented in software, the elements of the present application are programs or code segments for performing the required tasks. The program or code segment can be stored in a machine-readable medium or transmitted via a data signal carried in a carrier wave over a transmission medium or a communication link. A "machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memories, erasable ROMs (EROMs), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, and so on. The code segment can be downloaded via a computer network such as the Internet, an intranet, and so on.

[0117] It should be noted that in this article, the terms "comprising", "including" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such a process, method, article or device.

[0118] In this article, specific examples are used to elaborate on the principles and implementation manners of the present application. The description of the above examples is only used to help understand the method of the present application and its core idea. The above is only the preferred implementation manner of the present application. It should be noted that due to the limited nature of literal expression and objectively infinite specific structures, for those of ordinary skill in the art, without departing from the principle of the present application, several improvements, refinements or changes can be made, or the above technical features can be combined in an appropriate manner; these improvements, refinements, changes or combinations, or directly applying the concept and technical solution of the present application to other occasions without improvement, should all be regarded as the protection scope of the present application.

Claims

1. A starting circuit, characterized in that: The startup circuit is connected to the reference circuit; the startup circuit includes: a coupling boost module connected to a first node, configured to couple and boost the voltage of the first node; wherein the first node is configured to provide an excitation voltage for a startup switch, and the startup switch is configured to provide a startup current for the reference circuit when turned on; a startup control module, connected to the first node, and configured to adjust the voltage of the first node according to the bandgap reference voltage of the reference circuit; a current limiting module, connected to the coupling boost module, and configured to adjust an output current of the coupling boost module according to a bandgap reference voltage of the reference circuit; A conversion module is connected between the first node and the second node, and is used to adjust the voltage of the second node according to the voltage of the first node; wherein the current limiting module is connected to the second node, and the current limiting module is also used to adjust the output current of the coupled boost module according to the voltage of the second node.

2. The starting circuit according to claim 1, characterized in that: The startup control module includes: A first transistor is connected between the first node and a ground terminal, and a gate of the first transistor is connected to the reference circuit; a bandgap reference voltage of the reference circuit is used to adjust the conduction state of the first transistor.

3. The starting circuit according to claim 1, wherein: The coupling boost module includes: a current source connected between the first node and a power supply terminal, wherein a control terminal of the current source is connected to the current limiting module; The coupling unit is connected between the first node and the power supply end, and is used to couple and boost the voltage of the first node when the power supply end provides a power voltage.

4. The starting circuit according to claim 3, characterized in that: The coupling unit includes a first capacitor, and the current source includes: a second transistor connected between the first node and the power supply terminal; A third transistor is connected between the current limiting module and the power supply end, a gate of the third transistor is connected to the gate of the second transistor, and the gate of the third transistor is also connected to the current limiting module.

5. The starting circuit according to claim 1, wherein: The current limiting module includes: a fourth transistor connected between the coupling boost module and the third node, wherein a gate of the fourth transistor is connected to the reference circuit; a bandgap reference voltage of the reference circuit is used to adjust a conduction state of the fourth transistor; A fifth transistor is connected between the third node and the ground terminal, and a gate of the fifth transistor is connected to the second node; the voltage of the second node is used to adjust the conduction state of the fifth transistor.

6. The starting circuit according to claim 1, wherein: The conversion module includes: a first inverter and a second inverter, wherein the first inverter is connected between the first node and the second inverter, and the second inverter is connected between the first inverter and the second node; A second capacitor is connected between the power supply terminal and the second node.

7. The starting circuit according to claim 1, wherein: The startup circuit further includes: An indication signal module is connected to the second node and is used to generate an indication signal according to the voltage of the second node.

8. The starting circuit according to claim 1, wherein: The startup circuit further includes a voltage divider module, and the voltage divider module is provided in at least one of the following: between the current limiting module and the coupling boost module; between the startup control module and the ground terminal; Between the coupling boost module and the power supply terminal; between the conversion module and the power supply terminal; and between the conversion module and the ground terminal.

9. The starting circuit according to claim 8, characterized in that: The voltage divider module includes a voltage divider MOSFET, and the gate and drain of the voltage divider MOSFET are connected.

10. A low-power reference source, characterized in that: The invention comprises a reference circuit and the startup circuit according to any one of claims 1 to 9.

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