Short-circuit recovery soft start circuit for voltage stabilizing power supply circuit and voltage stabilizing power supply circuit

Abstract

Embodiments of the present disclosure provide a short-circuit recovery soft-start circuit and a voltage regulator circuit. The short-circuit recovery soft-start circuit comprises a first constant current source, an energy storage circuit, a first voltage comparison circuit, a short-circuit control circuit, and a pull-down circuit. The first constant current source provides a first constant current to the energy storage circuit via a first node. The energy storage circuit stores charges from the first constant current to generate a soft-start signal. The first voltage comparison circuit has a first input and a second input, and a first offset voltage between the first input and the second input. The first voltage comparison circuit generates a pull-down control signal. The pull-down control signal is at an active level when a voltage of the soft-start signal is greater than a sum of a feedback voltage and the first offset voltage. The short-circuit control circuit causes the pull-down control signal to be at an inactive level when a short-circuit indication signal is at the inactive level, and otherwise does not affect the pull-down control signal. The pull-down circuit pulls down the soft-start signal when the pull-down control signal is at the active level.

Description

Technical Field

[0001] The embodiments of this disclosure relate to the field of integrated circuit technology, and more specifically, to a short-circuit recovery soft-start circuit and a regulated power supply circuit for use in a regulated power supply circuit. Background Technology

[0002] Regulated power supply circuits (e.g., DC-DC converters, low-dropout linear regulators (LDOs)) act as power management chips, providing a load-carrying supply voltage to downstream electronic systems. During operation, regulated power supply circuits need to maintain a stable output, such as minimizing overshoot. To ensure that the gate voltage of the power transistors in the regulated power supply circuit smoothly reaches a stable value during power-up, a soft-start function is typically designed into the regulated power supply circuit.

[0003] In practical applications, situations may arise where the load changes drastically, such as a sudden short circuit in the output of the regulated power supply circuit followed by an instantaneous recovery from the short circuit state. This short-circuit recovery can cause output overshoot in the regulated power supply circuit, thus affecting subsequent electronic systems. Summary of the Invention

[0004] The embodiments described herein provide a short-circuit recovery soft-start circuit and a voltage regulator circuit for use in a voltage regulator circuit.

[0005] According to a first aspect of this disclosure, a short-circuit recovery soft-start circuit for a regulated power supply circuit is provided. The short-circuit recovery soft-start circuit includes: a first constant current source, an energy storage circuit, a first voltage comparator circuit, a short-circuit control circuit, and a pull-down circuit. The first constant current source is configured to provide a first constant current to the energy storage circuit via a first node. The energy storage circuit is configured to store charge from the first constant current to generate a soft-start signal at the first node. A first input terminal of the first voltage comparator circuit is provided with a feedback voltage from the regulated power supply circuit. A second input terminal of the first voltage comparator circuit is provided with the soft-start signal. A first offset voltage exists between the first and second input terminals of the first voltage comparator circuit. The first voltage comparator circuit is configured to generate a pull-down control signal at the second node based on the soft-start signal, the feedback voltage, and the first offset voltage. The pull-down control signal is active when the voltage of the soft-start signal is greater than the sum of the feedback voltage and the first offset voltage. The short-circuit control circuit is configured to: disable the pull-down control signal when the short-circuit indicator signal of the regulated power supply circuit is at an invalid level, and not affect the pull-down control signal when the short-circuit indicator signal is at an active level. The pull-down circuit is configured to: pull down the soft-start signal when the pull-down control signal is at an active level.

[0006] In some embodiments of this disclosure, the short-circuit recovery soft-start circuit further includes a second voltage comparison circuit. The second voltage comparison circuit is configured to generate a pull-down control current based on the soft-start signal and a reference voltage, and provide the pull-down control current to the pull-down circuit. The pull-down control current is used to control the speed at which the soft-start signal is pulled down. When the soft-start signal is greater than the reference voltage, the pull-down control current is equal to a first control current. When the soft-start signal is less than or equal to the reference voltage, the pull-down control current is equal to a second control current, where the first control current is greater than the second control current.

[0007] In some embodiments of this disclosure, the first voltage comparison circuit includes: a second constant current source, a first transistor to an eighth transistor, and a first resistor. The second constant current source is powered by a first voltage from a first voltage terminal. The second constant current source is coupled to a first terminal of the first transistor and a first terminal of the first resistor. The control terminal of the first transistor is coupled to a first node. The second terminal of the first transistor is coupled to the control terminal and the second terminal of the second transistor. The first terminal of the second transistor is coupled to a second voltage terminal. A feedback voltage is provided to the control terminal of a third transistor. The first terminal of the third transistor is coupled to the second terminal of the first resistor. The second terminal of the third transistor is coupled to the control terminal and the second terminal of the fourth transistor and the control terminal of the fifth transistor. The first terminal of the fourth transistor is coupled to the second voltage terminal. The first terminal of the fifth transistor is coupled to the control terminal and the second terminal of the sixth transistor and the control terminal of the seventh transistor. The second terminal of the seventh transistor is coupled to the second terminal of the eighth transistor and the second node. The control terminal of the eighth transistor is coupled to the control terminal of the second transistor. The first terminal of the eighth transistor is coupled to the second voltage terminal.

[0008] In some embodiments of this disclosure, the short-circuit control circuit includes a ninth transistor. The control electrode of the ninth transistor is provided with a short-circuit indication signal. The first electrode of the ninth transistor is coupled to a second voltage terminal. The second electrode of the ninth transistor is coupled to a second node.

[0009] In some embodiments of this disclosure, the pull-down circuit includes a tenth transistor and an eleventh transistor. The control electrode of the tenth transistor is coupled to a second node. The first electrode of the tenth transistor is coupled to the second electrode of the eleventh transistor. The second electrode of the tenth transistor is coupled to a first node. The control electrode of the eleventh transistor is coupled to a bias voltage terminal. The first electrode of the eleventh transistor is coupled to a second voltage terminal.

[0010] In some embodiments of this disclosure, the second voltage comparison circuit includes: a third constant current source, a fourth constant current source, a twelfth transistor, a thirteenth transistor, a fourteenth transistor, and a second resistor. The third constant current source is powered by a first voltage from a first voltage terminal. The third constant current source is coupled to the first terminals of the twelfth and thirteenth transistors. The control terminal of the twelfth transistor is coupled to a first node. The second terminal of the twelfth transistor is coupled to a second voltage terminal and the first terminal of the fourteenth transistor. The control terminal of the thirteenth transistor is provided with a reference voltage. The second terminal of the thirteenth transistor is coupled to the first terminal of the second resistor. The fourth constant current source is powered by the first voltage. The fourth constant current source is coupled to the first terminal of the second resistor. The second terminal of the second resistor is coupled to the control terminal and the second terminal of the fourteenth transistor. The second terminal of the fourteenth transistor is coupled to a pull-down circuit. The current flowing through the fourteenth transistor is the pull-down control current.

[0011] In some embodiments of this disclosure, the pull-down circuit includes a tenth transistor and an eleventh transistor. The control electrode of the tenth transistor is coupled to a second node. The first electrode of the tenth transistor is coupled to the second electrode of the eleventh transistor. The second electrode of the tenth transistor is coupled to a first node. The control electrode of the eleventh transistor is coupled to the second electrode of the fourteenth transistor. The first electrode of the eleventh transistor is coupled to a second voltage terminal.

[0012] In some embodiments of this disclosure, the regulated power supply circuit includes an error amplifier. A feedback voltage is provided at a first input terminal of the error amplifier. A soft-start signal is provided at a second input terminal of the error amplifier. A second offset voltage exists between the first and second input terminals of the error amplifier. A first offset voltage is greater than the second offset voltage.

[0013] According to a second aspect of this disclosure, a short-circuit recovery soft-start circuit for a regulated power supply circuit is provided. The short-circuit recovery soft-start circuit includes: a first constant current source to a fourth constant current source, a capacitor, a first transistor to a fourteenth transistor, a first resistor, and a second resistor. The first constant current source is powered by a first voltage from a first voltage terminal. The first constant current source provides a first constant current to a first terminal of the capacitor to generate a soft-start signal at the first terminal of the capacitor. The second terminal of the capacitor is coupled to a second voltage terminal. The second constant current source is powered by the first voltage. The second constant current source is coupled to a first electrode of the first transistor and a first terminal of the first resistor. The control electrode of the first transistor is coupled to the first terminal of the capacitor. The second electrode of the first transistor is coupled to the control electrode and the second electrode of the second transistor. The first electrode of the second transistor is coupled to the second voltage terminal. The control electrode of a third transistor is provided with a feedback voltage for the regulated power supply circuit. The first electrode of the third transistor is coupled to the second terminal of the first resistor. The second electrode of the third transistor is coupled to the control electrode and the second electrode of the fourth transistor and the control electrode of the fifth transistor. The first electrode of the fourth transistor is coupled to the second voltage terminal. The first electrode of the fifth transistor is coupled to the second voltage terminal. The second terminal of the fifth transistor is coupled to the control terminal and second terminal of the sixth transistor, as well as the control terminal of the seventh transistor. The first terminal of the sixth transistor is coupled to the first voltage terminal and the first terminal of the seventh transistor. The second terminal of the seventh transistor is coupled to the second terminal of the eighth transistor and the control terminal of the tenth transistor. The control terminal of the eighth transistor is coupled to the control terminal of the second transistor. The first terminal of the eighth transistor is coupled to the second voltage terminal. The control terminal of the ninth transistor is provided with a short-circuit indication signal for the regulated power supply circuit. The first terminal of the ninth transistor is coupled to the second voltage terminal. The second terminal of the ninth transistor is coupled to the control terminal of the tenth transistor. The first terminal of the tenth transistor is coupled to the second terminal of the eleventh transistor. The second terminal of the tenth transistor is coupled to the first terminal of a capacitor. The control terminal of the eleventh transistor is coupled to the second terminal of the fourteenth transistor. The first terminal of the eleventh transistor is coupled to the second voltage terminal. The third constant current source is powered by the first voltage. The third constant current source is coupled to the first terminals of the twelfth and thirteenth transistors. The control terminal of the twelfth transistor is coupled to the first terminal of a capacitor. The second terminal of the twelfth transistor is coupled to the second voltage terminal and the first terminal of the fourteenth transistor. The control terminal of the thirteenth transistor is provided with a reference voltage. The second terminal of the thirteenth transistor is coupled to the first terminal of a second resistor. The fourth constant current source is powered by the first voltage. The fourth constant current source is coupled to the first terminal of the second resistor. The second terminal of the second resistor is coupled to the control terminal and the second terminal of the fourteenth transistor.

[0014] According to a third aspect of this disclosure, a regulated power supply circuit is provided. The regulated power supply circuit includes: a short-circuit recovery soft-start circuit as described in the first or second aspect of this disclosure. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly described below. It should be understood that the drawings described below only relate to some embodiments of this disclosure and are not intended to limit this disclosure, wherein:

[0016] Figure 1 This is an exemplary circuit diagram of a low dropout linear regulator (LDO) with a soft-start circuit;

[0017] Figure 2 This is an exemplary circuit diagram of an LDO with a short-circuit recovery soft-start circuit according to an embodiment of the present disclosure;

[0018] Figure 3 This is a schematic block diagram of a short-circuit recovery soft-start circuit according to an embodiment of the present disclosure;

[0019] Figure 4 This is another schematic block diagram of a short-circuit recovery soft-start circuit according to an embodiment of the present disclosure;

[0020] Figure 5 yes Figure 3 An exemplary circuit diagram of a short-circuit recovery soft-start circuit is shown;

[0021] Figure 6 yes Figure 4 An exemplary circuit diagram of a short-circuit recovery soft-start circuit is shown.

[0022] It should be noted that the elements in the attached diagram are schematic and not drawn to scale. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are also within the scope of protection of this disclosure.

[0024] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter pertains. It will be further understood that terms such as those defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the context of the specification and in the related art, and shall not be interpreted in an idealized or overly formal form unless otherwise explicitly defined herein. As used herein, statements that “connect” or “couple” two or more parts together shall mean that these parts are directly joined together or joined through one or more intermediate components. Furthermore, terms such as “first” and “second” are used only to distinguish one component (or part of a component) from another component (or another part of a component).

[0025] Figure 1 An exemplary circuit diagram of a low-dropout linear regulator (LDO) with a soft-start circuit is shown. The LDO includes: a soft-start circuit 100, an error amplifier EA, a power transistor Mpout, a first feedback resistor Rf1, a second feedback resistor Rf2, and an output capacitor Cout. Figure 1 The load resistor Rload is also shown. The feedback voltage VFB is obtained by dividing the LDO's output voltage VOUT using the first feedback resistor Rf1 and the second feedback resistor Rf2. The feedback voltage VFB increases as the output voltage VOUT increases. The soft-start circuit 100 includes a current source IB0 and a capacitor Css. During the LDO's startup phase, the output voltage VOUT is zero. The current IB0 output by the current source IB0 charges the capacitor Css to generate a soft-start signal SS. The non-inverting input of the error amplifier EA is supplied with the feedback voltage VFB. The first inverting input of the error amplifier EA is supplied with the soft-start signal SS, and the second inverting input of the error amplifier EA is supplied with the reference voltage VREF.

[0026] To ensure the error amplifier EA outputs a high level in the initial state of the LDO, a second offset voltage Vos_ea is designed between the feedback voltage VFB and the soft-start signal SS. Thus, when the feedback voltage VFB is zero, the voltage at the first inverting input of the error amplifier EA is lower than the voltage at the non-inverting input by Vos_ea, causing the error amplifier EA to output a high level and the LDO to be in the off state.

[0027] Figure 1The soft-start process of the LDO is as follows: During the LDO power-up process, when the power supply reaches a stable state, the current source IB0 outputs a constant current IB0 to charge the capacitor Css, causing the soft-start signal SS to rise slowly until it approaches the power supply voltage VDD. During this process, under the action of the loop, the feedback voltage VFB also rises slowly along with the soft-start signal SS until it reaches the reference voltage VREF. At this point, the loop stabilizes, and the LDO output reaches a stable state. Since the output voltage VOUT and the feedback voltage VFB rise at the same rate, the soft-start function achieves a smooth rise in the output voltage VOUT during power-up.

[0028] In practical applications, LDOs may experience rapid load changes, such as a sudden output short circuit followed by an instantaneous recovery. During a short circuit, to prevent high current from damaging the circuit, the LDO is typically operated in current-limiting mode. However, during rapid recovery, because the loop response requires time, and the power transistor Mpout often operates under high current-limiting conditions, a large current will charge the output capacitor Cout. This results in a significant instantaneous overshoot in the LDO's output voltage VOUT, which can severely damage subsequent circuitry, potentially even burning it out.

[0029] The embodiments of this disclosure propose to add a soft-start function during output short-circuit recovery to the power-on soft-start function of the regulated power supply circuit, so as to improve the operating safety of the regulated power supply circuit.

[0030] Figure 2 An exemplary circuit diagram of an LDO with a short-circuit recovery soft-start circuit according to an embodiment of the present disclosure is shown. The LDO includes: a short-circuit recovery soft-start circuit 200, an error amplifier EA, a power transistor Mpout, a first feedback resistor Rf1, a second feedback resistor Rf2, and an output capacitor Cout. Figure 2 The diagram also shows the load resistor Rload. The first input of the error amplifier EA is supplied with a feedback voltage VFB. The second input of the error amplifier EA is supplied with a soft-start signal SS. The third input of the error amplifier EA is supplied with a reference voltage VREF. A second offset voltage Vos_ea exists between the first and second inputs of the error amplifier EA, causing the error amplifier EA to output an invalid level (high level) during startup, controlling the LDO to be in the off state. Figure 2 In the example, the first input of the error amplifier EA is the non-inverting input, and the second and third inputs of the error amplifier EA are the inverting inputs.

[0031] The following description uses an LDO (Low-Dropout Regulated Power Supply) circuit as an example to illustrate the operation of the short-circuit recovery soft-start circuit 200. Those skilled in the art will understand that the short-circuit recovery soft-start circuit 200 according to embodiments of this disclosure can also be applied to a DC-DC converter. The regulated power supply circuit according to embodiments of this disclosure can be a low-dropout linear regulator, a DC-DC converter, or a similar circuit requiring short-circuit recovery soft-start functionality.

[0032] Figure 3 A schematic block diagram of a short-circuit recovery soft-start circuit 300 according to an embodiment of the present disclosure is shown. The short-circuit recovery soft-start circuit 300 includes: a first constant current source 310, an energy storage circuit 320, a first voltage comparator circuit 330, a short-circuit control circuit 340, and a pull-down circuit 350.

[0033] The output of the first constant current source 310 is coupled via a first node N1 to the outputs of the energy storage circuit 320, the pull-down circuit 350, and the short-circuit recovery soft-start circuit 300. The first constant current source 310 is also coupled to a first voltage terminal V1. The first constant current source 310 is powered by a first voltage V1 from the first voltage terminal V1. The first constant current source 310 is configured to provide a first constant current IB1 to the energy storage circuit 320 via the first node N1.

[0034] The energy storage circuit 320 is coupled via a first node N1 to the output of the first constant current source 310, the output of the pull-down circuit 350, and the output of the short-circuit recovery soft-start circuit 300. The energy storage circuit 320 is configured to store charge from the first constant current IB1 to generate a soft-start signal SS at the first node N1.

[0035] The first voltage comparator circuit 330 is powered by a first voltage V1 from a first voltage terminal V1. A feedback voltage VFB from a regulated power supply circuit is provided to the first input terminal of the first voltage comparator circuit 330. A soft-start signal SS is provided to the second input terminal of the first voltage comparator circuit 330. A first offset voltage Vos_ss exists between the first and second input terminals of the first voltage comparator circuit 330. The output terminal of the first voltage comparator circuit 330 is coupled to the output terminal of a short-circuit control circuit 340 and the input terminal of a pull-down circuit 350 via a second node N2. The first voltage comparator circuit 330 is configured to generate a pull-down control signal VG at the second node N2 based on the soft-start signal SS, the feedback voltage VFB, and the first offset voltage Vos_ss. The pull-down control signal VG is active when the voltage of the soft-start signal SS is greater than the sum of the feedback voltage VFB and the first offset voltage Vos_ss. The pull-down control signal VG is inactive when the voltage of the soft-start signal SS is equal to or less than the sum of the feedback voltage VFB and the first offset voltage Vos_ss.

[0036] The input of the short-circuit control circuit 340 is provided with a short-circuit indication signal Voc_n from the regulated power supply circuit. The short-circuit indication signal Voc_n indicates whether the output of the regulated power supply circuit is short-circuited. The output of the short-circuit control circuit 340 is coupled via a second node N2 to the output of the first voltage comparator circuit 330 and the input of the pull-down circuit 350. The short-circuit control circuit 340 is configured to: disable the pull-down control signal VG when the short-circuit indication signal Voc_n is at an invalid level, and not affect the pull-down control signal VG when the short-circuit indication signal Voc_n is at an active level.

[0037] The input of pull-down circuit 350 is coupled to the output of first voltage comparator circuit 330 and short-circuit control circuit 340 via second node N2. The output of pull-down circuit 350 is coupled to the output of first constant current source 310, energy storage circuit 320, and short-circuit recovery soft-start circuit 300 via first node N1. Pull-down circuit 350 is also coupled to second voltage terminal V2. Pull-down circuit 350 is configured to pull down soft-start signal SS when pull-down control signal VG is at an active level, and not affect soft-start signal SS when pull-down control signal VG is at an inactive level.

[0038] exist Figure 3 In the example, a high voltage signal is input from the first voltage terminal V1, and the second voltage terminal V2 is grounded.

[0039] In some embodiments of this disclosure, the first offset voltage Vos_ss is greater than the second offset voltage Vos_ea.

[0040] When the LDO is working normally, the short-circuit indication signal Voc_n is at an invalid level, so the pull-down control signal VG is at an invalid level, and the voltage of the soft-start signal SS can rise to close to the first voltage V1.

[0041] When the LDO output is short-circuited, the short-circuit indicator signal Voc_n is at an active level, and the short-circuit control circuit 340 does not affect the pull-down control signal VG. At this time, the output voltage VOUT = 0V, and simultaneously the feedback voltage VFB also drops to 0V. Therefore, the voltage of the soft-start signal SS is greater than the sum of the feedback voltage VFB and the first offset voltage Vos_ss (SS > (0 + Vos_ss)). Thus, the pull-down control signal VG is at an active level, thereby pulling the soft-start signal SS low from the first voltage V1. When the soft-start signal SS is pulled down to the first offset voltage Vos_ss, the pull-down control signal VG is at an inactive level, and the soft-start signal SS is no longer pulled down. Therefore, when the LDO output is short-circuited, the soft-start signal SS eventually stabilizes at the first offset voltage Vos_ss.

[0042] When the LDO output recovers from the short-circuit state, the short-circuit indication signal Voc_n is at an invalid level, and therefore the pull-down control signal VG is also at an invalid level. At this time, the energy storage circuit 320 stores the charge from the first constant current IB1, causing the voltage of the soft-start signal SS to slowly rise from the first offset voltage Vos_ss. Under the action of the LDO loop, the feedback voltage VFB will track the rise of the soft-start signal SS and rise slowly until it reaches the reference voltage VREF. Since the output voltage VOUT and the feedback voltage VFB rise at the same rate, a smooth rise of the output voltage VOUT is achieved, thereby eliminating the overshoot caused by the LDO output recovering from the short-circuit state.

[0043] The inventors of this application have noticed that when the LDO output is short-circuited, the pull-down speed of the soft-start signal SS should not be too large or too small. On the one hand, it is desirable for the LDO to operate at a preset current limit value during the short-circuit state. If the pull-down speed of the soft-start signal SS is too large, it will quickly pull the soft-start signal SS to near the second voltage V2, which is lower than the second offset voltage Vos_ea between the feedback voltage VFB in the error amplifier EA and the soft-start signal SS. At this time, the error amplifier EA will output a high level, thereby turning off the LDO. Thus, the LDO cannot operate at the preset current limit value. On the other hand, the pull-down speed of the soft-start signal SS should not be too small either. When the LDO output is quickly short-circuited and then quickly recovered, the soft-start signal SS may not have had time to be pulled down to the first offset voltage Vos_ss before it starts to rise again under the action of the first constant current IB1. In this case, the soft-start signal SS will remain at a high level, resulting in a very limited soft-start effect, and thus the LDO output will still have overshoot.

[0044] To address the aforementioned issues, embodiments of this disclosure propose a phased adjustment of the pull-down speed of the soft-start signal SS. Figure 4 A schematic block diagram of a short-circuit recovery soft-start circuit 400 according to an embodiment of the present disclosure is shown. Figure 3 Based on the example, Figure 4 The short-circuit recovery soft-start circuit 400 also includes a second voltage comparison circuit 460.

[0045] A reference voltage Vref is provided to the first input terminal of the second voltage comparator circuit 460. A soft-start signal SS is provided to the second input terminal of the second voltage comparator circuit 460. The output terminal of the second voltage comparator circuit 460 is coupled to a pull-down circuit 350. The second voltage comparator circuit 460 is configured to generate a pull-down control current Id based on the soft-start signal SS and the reference voltage Vref, and provide the pull-down control current Id to the pull-down circuit 350. The pull-down control current Id is used to control the speed at which the soft-start signal SS is pulled down. When the soft-start signal SS is greater than the reference voltage Vref, the pull-down control current Id is equal to a first control current. When the soft-start signal SS is less than or equal to the reference voltage Vref, the pull-down control current Id is equal to a second control current. The first control current is greater than the second control current.

[0046] In this way, when a short circuit occurs at the LDO output, the soft-start signal SS is pulled down quickly to prevent the soft-start function from being limited when the LDO output is rapidly short-circuited and then quickly recovered, thus avoiding overshoot in the LDO output. When the soft-start signal SS drops to the reference voltage Vref, it is pulled down more slowly to prevent the soft-start signal SS from being quickly pulled up to near the second voltage V2 and thus turning off the LDO.

[0047] The value of the reference voltage Vref can be set according to the actual application.

[0048] Figure 5 Show Figure 3 An exemplary circuit diagram of the short-circuit recovery soft-start circuit 300 is shown.

[0049] exist Figure 5 In the short-circuit recovery soft-start circuit 500 shown, the energy storage circuit 520 includes a capacitor Css. The first terminal of the capacitor Css is coupled to a first constant current source 510 via a first node N1. The second terminal of the capacitor Css is coupled to a second voltage terminal V2. The first constant current source 510 outputs a first constant current IB1.

[0050] The first voltage comparator circuit 530 includes: a second constant current source IB2, first transistors M1 to M8, and a first resistor R1. The second constant current source IB2 is powered by a first voltage V1 from a first voltage terminal V1. The second constant current source IB2 outputs a second constant current IB2. The second constant current source IB2 is coupled to the first terminal of the first transistor M1 and the first terminal of the first resistor R1. The control terminal of the first transistor M1 is coupled to a first node N1. The second terminal of the first transistor M1 is coupled to the control terminal and the second terminal of the second transistor M2. The first terminal of the second transistor M2 is coupled to a second voltage terminal V2. The control terminal of the third transistor M3 is provided with a feedback voltage VFB. The first terminal of the third transistor M3 is coupled to the second terminal of the first resistor R1. The second terminal of the third transistor M3 is coupled to the control terminal and the second terminal of the fourth transistor M4 and the control terminal of the fifth transistor M5. The first terminal of the fourth transistor M4 is coupled to the second voltage terminal V2. The first terminal of the fifth transistor M5 is coupled to the second voltage terminal V2. The second terminal of the fifth transistor M5 is coupled to the control terminal and the second terminal of the sixth transistor M6 and the control terminal of the seventh transistor M7. The first terminal of the sixth transistor M6 is coupled to the first voltage terminal V1 and the first terminal of the seventh transistor M7. The second terminal of the seventh transistor M7 is coupled to the second terminal of the eighth transistor M8 and the second node N2. The control terminal of the eighth transistor M8 is coupled to the control terminal of the second transistor M2. The first terminal of the eighth transistor M8 is coupled to the second voltage terminal V2.

[0051] The first resistor R1 is used to introduce a first offset voltage Vos_ss between the soft-start signal SS and the feedback voltage VFB. The value of the first resistor R1 can be set according to the actual application.

[0052] The short-circuit control circuit 540 includes a ninth transistor M9. The control terminal of the ninth transistor M9 is provided with a short-circuit indication signal Voc_n. The first terminal of the ninth transistor M9 is coupled to a second voltage terminal V2. The second terminal of the ninth transistor M9 is coupled to a second node N2.

[0053] The pull-down circuit 550 includes a tenth transistor M10 and an eleventh transistor M11. The control electrode of the tenth transistor M10 is coupled to the second node N2. The first electrode of the tenth transistor M10 is coupled to the second electrode of the eleventh transistor M11. The second electrode of the tenth transistor M10 is coupled to the first node N1. The control electrode of the eleventh transistor M11 is coupled to the bias voltage terminal VB. The first electrode of the eleventh transistor M11 is coupled to the second voltage terminal V2. By setting the voltage at the bias voltage terminal VB, the current flowing through the eleventh transistor M11 can be controlled, thereby limiting the current I6 flowing through the tenth transistor M10.

[0054] exist Figure 5In the example, a high-voltage signal is input from the first voltage terminal V1, and the second voltage terminal V2 is grounded. The first transistor M1, the third transistor M3, the sixth transistor M6, and the seventh transistor M7 are PMOS transistors. The second transistor M2, the fourth transistor M4, the fifth transistor M5, and the eighth to eleventh transistors M11 are NMOS transistors. Those skilled in the art will understand that, based on the above inventive concept... Figure 5 Any modifications to the circuit shown should also fall within the scope of this disclosure. In such modifications, the transistor and voltage terminals may also have the same characteristics as described above. Figure 5 The examples shown have different settings.

[0055] The second transistor M2 and the eighth transistor M8 form a current mirror. The fourth transistor M4 and the fifth transistor M5 form a current mirror. The sixth transistor M6 and the seventh transistor M7 form a current mirror.

[0056] In some embodiments of this disclosure, the width-to-length ratio of the second transistor M2 to the eighth transistor M8 is 1:1. The width-to-length ratio of the fourth transistor M4 to the fifth transistor M5 is 1:1. The width-to-length ratio of the sixth transistor M6 to the seventh transistor M7 is 1:1.

[0057] Figure 6 Show Figure 4 An exemplary circuit diagram of the short-circuit recovery soft-start circuit 400 is shown.

[0058] exist Figure 6In the short-circuit recovery soft-start circuit 600 shown, the second voltage comparison circuit 660 includes: a third constant current source IB3, a fourth constant current source IB4, a twelfth transistor M12, a thirteenth transistor M13, a fourteenth transistor M14, and a second resistor R2. The third constant current source IB3 is powered by a first voltage V1 from a first voltage terminal V1. The third constant current source IB3 outputs a third constant current IB3. The third constant current source IB3 is coupled to the first terminal of the twelfth transistor M12 and the first terminal of the thirteenth transistor M13. The control terminal of the twelfth transistor M12 is coupled to the first node N1 (the first terminal of capacitor Css). The second terminal of the twelfth transistor M12 is coupled to the second voltage terminal V2 and the first terminal of the fourteenth transistor M14. The control terminal of the thirteenth transistor M13 is provided with a reference voltage Vref. The second terminal of the thirteenth transistor M13 is coupled to the first terminal of the second resistor R2. The fourth constant current source IB4 is powered by the first voltage V1. The fourth constant current source IB4 outputs a fourth constant current IB4. The fourth constant current source IB4 is coupled to the first terminal of the second resistor R2. The second terminal of the second resistor R2 is coupled to the control terminal and the second terminal of the fourteenth transistor M14. The second terminal of the fourteenth transistor M14 is coupled to the pull-down circuit 550. The current I8 flowing through the fourteenth transistor M14 is equal to the pull-down control current Id.

[0059] The second resistor R2 is the current-limiting resistor for the branch of the thirteenth transistor M13 and the fourteenth transistor M14.

[0060] exist Figure 6 In the example, the pull-down circuit 550 includes a tenth transistor M10 and an eleventh transistor M11. The control electrode of the tenth transistor M10 is coupled to the second node N2. The first electrode of the tenth transistor M10 is coupled to the second electrode of the eleventh transistor M11. The second electrode of the tenth transistor M10 is coupled to the first node N1. The control electrode of the eleventh transistor M11 is coupled to the second electrode of the fourteenth transistor M14. The first electrode of the eleventh transistor M11 is coupled to the second voltage terminal V2.

[0061] exist Figure 6 In the example, a high-voltage signal is input from the first voltage terminal V1, and the second voltage terminal V2 is grounded. The first transistor M1, third transistor M3, sixth transistor M6, seventh transistor M7, twelfth transistor M12, and thirteenth transistor M13 are PMOS transistors. The second transistor M2, fourth transistor M4, fifth transistor M5, eighth transistors M8 through eleventh transistors M11, and fourteenth transistor M14 are NMOS transistors. Those skilled in the art will understand that, based on the above inventive concept... Figure 6 Any modifications to the circuit shown should also fall within the scope of this disclosure. In such modifications, the transistor and voltage terminals may also have the same characteristics as described above. Figure 6The examples shown have different settings.

[0062] The following is combined Figure 6 The following example illustrates the operation of the short-circuit recovery soft-start circuit 600 according to an embodiment of the present disclosure.

[0063] The first transistor M1 and the third transistor M3 are the two input transistors of the first voltage comparator circuit 330. The current I1 in the first transistor M1 is replicated to the eighth transistor M8 through a 1:1 current mirror formed by the second transistor M2 and the eighth transistor M8, i.e., I1 = I4. The current I2 in the third transistor M3 is replicated to the seventh transistor M7 through a 1:1 current mirror formed by the fourth transistor M4 and the fifth transistor M5, and a 1:1 current mirror formed by the sixth transistor M6 and the seventh transistor M7, i.e., I5 = I3 = I2.

[0064] When the LDO is operating normally, the short-circuit indication signal Voc_n is at an invalid level (high level), the ninth transistor M9 is turned on, the voltage of the second node N2 is pulled low to ground, and the pull-down control signal VG is at an invalid level (low level). At this time, the tenth transistor M10 is turned off, and the voltage of the soft-start signal SS increases as the first constant current IB1 charges the capacitor Css. The voltage of the soft-start signal SS can rise to close to the first voltage V1.

[0065] When the LDO output is short-circuited, the short-circuit indication signal Voc_n is at an active level (low level), the ninth transistor M9 is turned off, and the voltage of the second node N2 is determined by the magnitudes of the fifth current I5 and the fourth current I4. When the tenth transistor M10 is turned on, the current Id flowing through the eleventh transistor M11 is used to limit the magnitude of the current I6 flowing through the tenth transistor M10.

[0066] When the LDO output is short-circuited, the LDO output voltage VOUT = 0V, and simultaneously the feedback voltage VFB also drops to 0V. At this time, the voltage of the soft-start signal SS is greater than the sum of the feedback voltage VFB and the first offset voltage Vos_ss, therefore I2 = IB2, I1 = 0. Since I5 = I2 = IB2, I4 = I1 = 0, I5 > I4, the pull-down control signal VG is at an active level (high level), and the tenth transistor M10 is turned on, thus pulling the soft-start signal SS low from the first voltage V1. When the soft-start signal SS is pulled low to the first offset voltage Vos_ss, I1 = IB2, I2 = 0, therefore I4 = I1 = IB2, I5 = I2 = 0, therefore I5 ​​< I4, which will pull the pull-down control signal VG low, and the tenth transistor M10 will be turned off, thus no longer pulling down the soft-start signal SS. Therefore, when the LDO output is short-circuited, the soft-start signal SS eventually stabilizes at the level of the first offset voltage Vos_ss.

[0067] When the LDO output recovers from a short circuit, the short-circuit indication signal Voc_n is at an inactive level (high level), the ninth transistor M9 is turned on, and the pull-down control signal VG is pulled low to the second voltage V2. At this time, the capacitor Css is charged again through the first constant current IB1. Thus, the voltage of the soft-start signal SS slowly rises from the first offset voltage Vos_ss. Under the action of the LDO loop, the feedback voltage VFB tracks the rise of the soft-start signal SS and rises slowly until it reaches the reference voltage VREF. Since the output voltage VOUT rises at the same rate as the feedback voltage VFB, a smooth rise in the output voltage VOUT is achieved, thereby eliminating the overshoot caused by the LDO output recovering from a short circuit.

[0068] When the LDO is operating normally, the voltage of the soft-start signal SS (which can be close to V1) is higher than the reference voltage Vref, so I8 = IB3 + IB4. At this time, the value of I8 is relatively large, and the current reflected by the current mirror formed by the fourteenth transistor M14 and the eleventh transistor M11 is also large, resulting in a large current I6 flowing through the tenth transistor M10. This leads to a rapid pull-down of the soft-start signal SS. When the soft-start signal SS is pulled down below the reference voltage Vref, the third constant current IB3 is almost entirely shunted to the twelfth transistor M12, so I8 = IB4. This reduces the current reflected by the current mirror formed by the fourteenth transistor M14 and the eleventh transistor M11, thus reducing the current I6 flowing through the tenth transistor M10, and consequently slowing down the pull-down of the soft-start signal SS.

[0069] In this way, when a short circuit occurs at the LDO output, the soft-start signal SS is pulled down quickly to prevent the soft-start function from being limited when the LDO output is rapidly short-circuited and then quickly recovered, thus avoiding overshoot in the LDO output. When the soft-start signal SS drops to the reference voltage Vref, it is pulled down more slowly to prevent the soft-start signal SS from being quickly pulled up to near the second voltage V2 and thus turning off the LDO.

[0070] Embodiments of this disclosure also provide a regulated power supply circuit. This regulated power supply circuit includes a short-circuit recovery soft-start circuit according to embodiments of this disclosure.

[0071] In summary, the short-circuit recovery soft-start circuit according to the embodiments of this disclosure enables the regulated power supply circuit to also have a soft-start function during short-circuit recovery, thus solving the problem of overshoot in the output voltage of the regulated power supply circuit during short-circuit recovery. Furthermore, during the output short-circuit phase of the regulated power supply circuit, the short-circuit recovery soft-start circuit according to the embodiments of this disclosure can adjust the pull-down speed of the soft-start signal in stages, improving the reliability of the soft-start function.

[0072] Unless otherwise expressly indicated by the context, the singular form of words used herein and in the appended claims includes the plural form, and vice versa. Thus, when referring to the singular, the plural form of the corresponding term is generally included. Similarly, the terms “comprising” and “including” shall be interpreted as including rather than exclusively. Likewise, the terms “including” and “or” shall be interpreted as including unless such interpretation is expressly prohibited herein. Where the term “example” is used herein, particularly when it follows a set of terms, the “example” is merely exemplary and illustrative and should not be considered exclusive or extensive.

[0073] Further aspects and scope of adaptation become apparent from the description provided herein. It should be understood that various aspects of this application may be implemented individually or in combination with one or more other aspects. It should also be understood that the descriptions and specific embodiments herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0074] Several embodiments of this disclosure have been described in detail above. However, it is obvious that those skilled in the art can make various modifications and variations to the embodiments of this disclosure without departing from the spirit and scope of this disclosure. The scope of protection of this disclosure is defined by the appended claims.

Claims

1. A short-circuit recovery soft-start circuit for a regulated power supply circuit, comprising: First constant current source, energy storage circuit, first voltage comparator circuit, short-circuit control circuit, pull-down circuit. The first constant current source is configured to provide a first constant current to the energy storage circuit via a first node; The energy storage circuit is configured to store charge from the first constant current to generate a soft-start signal at the first node; The first input terminal of the first voltage comparator circuit is provided with the feedback voltage of the regulated power supply circuit, the second input terminal of the first voltage comparator circuit is provided with the soft-start signal, a first offset voltage exists between the first input terminal and the second input terminal of the first voltage comparator circuit, and the first voltage comparator circuit is configured to generate a pull-down control signal at a second node based on the soft-start signal, the feedback voltage, and the first offset voltage, wherein the pull-down control signal is at an active level when the voltage of the soft-start signal is greater than the sum of the feedback voltage and the first offset voltage; The short-circuit control circuit is configured to: make the pull-down control signal invalid when the short-circuit indication signal of the regulated power supply circuit is at an invalid level, and not affect the pull-down control signal when the short-circuit indication signal is at an active level; The pull-down circuit is configured to pull down the soft-start signal when the pull-down control signal is at the active level. The short-circuit recovery soft-start circuit further includes: a second voltage comparator circuit. The second voltage comparison circuit is configured to generate a pull-down control current based on the soft-start signal and the reference voltage, and provide the pull-down control current to the pull-down circuit. The pull-down control current is used to control the speed at which the soft-start signal is pulled down. When the soft-start signal is greater than the reference voltage, the pull-down control current is equal to a first control current. When the soft-start signal is less than or equal to the reference voltage, the pull-down control current is equal to a second control current. The first control current is greater than the second control current. The first voltage comparison circuit includes: a second constant current source, a first transistor to an eighth transistor, and a first resistor. The second constant current source is powered by a first voltage from the first voltage terminal, and the second constant current source is coupled to the first terminal of the first transistor and the first terminal of the first resistor; The control electrode of the first transistor is coupled to the first node, and the second electrode of the first transistor is coupled to the control electrode and the second electrode of the second transistor. The first terminal of the second transistor is coupled to the second voltage terminal; The control electrode of the third transistor is provided with the feedback voltage, the first electrode of the third transistor is coupled to the second terminal of the first resistor, and the second electrode of the third transistor is coupled to the control electrode and the second electrode of the fourth transistor and the control electrode of the fifth transistor. The first terminal of the fourth transistor is coupled to the second voltage terminal; The first terminal of the fifth transistor is coupled to the second voltage terminal, and the second terminal of the fifth transistor is coupled to the control terminal and the second terminal of the sixth transistor and the control terminal of the seventh transistor. The first terminal of the sixth transistor is coupled to the first voltage terminal and the first terminal of the seventh transistor; The second terminal of the seventh transistor is coupled to the second terminal of the eighth transistor and the second node; The control electrode of the eighth transistor is coupled to the control electrode of the second transistor, and the first electrode of the eighth transistor is coupled to the second voltage terminal; The second voltage comparator circuit includes: a third constant current source, a fourth constant current source, a twelfth transistor, a thirteenth transistor, a fourteenth transistor, and a second resistor. The third constant current source is powered by a first voltage from the first voltage terminal, and the third constant current source is coupled to the first terminal of the twelfth transistor and the first terminal of the thirteenth transistor; The control electrode of the twelfth transistor is coupled to the first node, and the second electrode of the twelfth transistor is coupled to the second voltage terminal and the first electrode of the fourteenth transistor; The control electrode of the thirteenth transistor is provided with the reference voltage, and the second electrode of the thirteenth transistor is coupled to the first terminal of the second resistor; The fourth constant current source is powered by the first voltage, and the fourth constant current source is coupled to the first terminal of the second resistor; The second terminal of the second resistor is coupled to the control terminal and the second terminal of the fourteenth transistor; The second terminal of the fourteenth transistor is coupled to the pull-down circuit, and the current flowing through the fourteenth transistor is the pull-down control current.

2. The short-circuit recovery soft-start circuit according to claim 1, wherein, The short-circuit control circuit includes: a ninth transistor. The control electrode of the ninth transistor is provided with the short-circuit indication signal, the first electrode of the ninth transistor is coupled to the second voltage terminal, and the second electrode of the ninth transistor is coupled to the second node.

3. The short-circuit recovery soft-start circuit according to claim 1, wherein, The pull-down circuit includes: a tenth transistor and an eleventh transistor. Wherein, the control electrode of the tenth transistor is coupled to the second node, the first electrode of the tenth transistor is coupled to the second electrode of the eleventh transistor, and the second electrode of the tenth transistor is coupled to the first node; The control electrode of the eleventh transistor is coupled to the bias voltage terminal, and the first electrode of the eleventh transistor is coupled to the second voltage terminal.

4. The short-circuit recovery soft-start circuit according to claim 1, wherein, The pull-down circuit includes: a tenth transistor and an eleventh transistor. Wherein, the control electrode of the tenth transistor is coupled to the second node, the first electrode of the tenth transistor is coupled to the second electrode of the eleventh transistor, and the second electrode of the tenth transistor is coupled to the first node; The control electrode of the eleventh transistor is coupled to the second electrode of the fourteenth transistor, and the first electrode of the eleventh transistor is coupled to the second voltage terminal.

5. The short-circuit recovery soft-start circuit according to claim 1, wherein, The regulated power supply circuit includes an error amplifier. The error amplifier's first input terminal is supplied with the feedback voltage, its second input terminal is supplied with the soft-start signal, and a second offset voltage exists between the first and second input terminals. The first offset voltage is greater than the second offset voltage.

6. A short-circuit recovery soft-start circuit for a regulated power supply circuit, comprising: First to fourth constant current sources, capacitor, first to fourteenth transistors, first resistor, second resistor, Wherein, the first constant current source is powered by a first voltage from a first voltage terminal, and the first constant current source provides a first constant current to the first terminal of the capacitor to generate a soft-start signal at the first terminal of the capacitor; The second terminal of the capacitor is coupled to the second voltage terminal; The second constant current source is powered by the first voltage, and the second constant current source is coupled to the first terminal of the first transistor and the first end of the first resistor; The control electrode of the first transistor is coupled to the first terminal of the capacitor, and the second electrode of the first transistor is coupled to the control electrode and the second electrode of the second transistor. The first terminal of the second transistor is coupled to the second voltage terminal; The control electrode of the third transistor is provided with the feedback voltage of the regulated power supply circuit. The first electrode of the third transistor is coupled to the second terminal of the first resistor. The second electrode of the third transistor is coupled to the control electrode and the second electrode of the fourth transistor and the control electrode of the fifth transistor. The first terminal of the fourth transistor is coupled to the second voltage terminal; The first terminal of the fifth transistor is coupled to the second voltage terminal, and the second terminal of the fifth transistor is coupled to the control terminal and the second terminal of the sixth transistor and the control terminal of the seventh transistor. The first terminal of the sixth transistor is coupled to the first voltage terminal and the first terminal of the seventh transistor; The second terminal of the seventh transistor is coupled to the second terminal of the eighth transistor and the control terminal of the tenth transistor; The control electrode of the eighth transistor is coupled to the control electrode of the second transistor, and the first electrode of the eighth transistor is coupled to the second voltage terminal; The control electrode of the ninth transistor is provided with a short-circuit indication signal for the regulated power supply circuit. The first electrode of the ninth transistor is coupled to the second voltage terminal, and the second electrode of the ninth transistor is coupled to the control electrode of the tenth transistor. The first terminal of the tenth transistor is coupled to the second terminal of the eleventh transistor, and the second terminal of the tenth transistor is coupled to the first terminal of the capacitor; The control electrode of the eleventh transistor is coupled to the second electrode of the fourteenth transistor, and the first electrode of the eleventh transistor is coupled to the second voltage terminal. The third constant current source is powered by the first voltage, and the third constant current source is coupled to the first terminal of the twelfth transistor and the first terminal of the thirteenth transistor; The control terminal of the twelfth transistor is coupled to the first terminal of the capacitor, and the second terminal of the twelfth transistor is coupled to the second voltage terminal and the first terminal of the fourteenth transistor; The control electrode of the thirteenth transistor is provided with a reference voltage, and the second electrode of the thirteenth transistor is coupled to the first terminal of the second resistor; The fourth constant current source is powered by the first voltage, and the fourth constant current source is coupled to the first terminal of the second resistor; The second end of the second resistor is coupled to the control electrode and the second electrode of the fourteenth transistor.

7. A regulated power supply circuit, comprising: The short-circuit recovery soft-start circuit according to any one of claims 1 to 6.

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