Undervoltage protection circuit and electronic equipment

Abstract

The invention relates to an under-voltage protection circuit and electronic equipment. The under-voltage protection circuit comprises an energy storage circuit, a comparison circuit and a bleeder circuit. The energy storage circuit is used for accessing power supply voltage. A first input end of the comparison circuit is connected with the energy storage circuit, and a second input end is connected with power supply voltage; the control end of the bleeder circuit is connected with the output end of the comparison circuit, the input end of the bleeder circuit is connected with voltage to be discharged, and the output end of the bleeder circuit is grounded. When the power supply voltage is greater than or equal to a preset under-voltage threshold value, the energy storage circuit is charged, and the comparison circuit outputs a first level signal; under the condition that the power supply voltage is smaller than the preset under-voltage threshold value, the energy storage circuit discharges, and the comparison circuit outputs a second level signal; the bleeder circuit bleeds the voltage to be discharged according to the second level signal and stops discharging according to the first level signal. When the power supply voltage drops suddenly, the bleeder circuit can rapidly discharge the to-be-discharged voltage, thereby reducing the damage risk of the internal module of the PMIC caused by abnormal power failure, and improving the use reliability of the PMIC.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to an undervoltage protection circuit and electronic equipment. Background Art

[0002] In power electronics devices, control chips integrate a large number of built-in functional modules (such as analog-to-digital conversion and sampling modules, communication interface modules, and pulse-width modulation signal generation modules). These modules must strictly adhere to preset timings during power-up and power-down to control the power supply sequence. Power management integrated circuits (PMICs) provide time-sharing power supply capabilities, adapting to the timing requirements of different control chips and ensuring stable operation.

[0003] However, in applications such as energy storage converters, grid fluctuations and frequent AC / DC conversion can cause unexpected power outages on the controller motherboard, causing the power supply voltage of the PMIC in the energy storage converter to drop to an extremely low value. In this case, the high-voltage modules within the PMIC may experience voltage overshoots or logic errors due to uncontrolled power-down timing, leading to functional failure and reduced PMIC reliability. Summary of the Invention

[0004] Based on this, it is necessary to solve the above technical problems and provide an undervoltage protection circuit and electronic equipment that can improve the reliability of the power management chip.

[0005] An undervoltage protection circuit, comprising:

[0006] An energy storage circuit, the energy storage circuit being used to access a power supply voltage;

[0007] a comparison circuit, wherein a first input terminal of the comparison circuit is connected to the energy storage circuit, and a second input terminal of the comparison circuit is used to access the supply voltage;

[0008] a discharge circuit, wherein a control end of the discharge circuit is connected to the output end of the comparison circuit, an input end of the discharge circuit is used to receive the voltage to be discharged, and an output end of the discharge circuit is grounded;

[0009] When the supply voltage is greater than or equal to a preset undervoltage threshold, the energy storage circuit is charged, and the comparison circuit outputs a first level signal; when the supply voltage is less than the preset undervoltage threshold, the energy storage circuit is discharged, and the comparison circuit outputs a second level signal; and the discharge circuit discharges the voltage to be discharged when receiving the second level signal, and stops discharging when receiving the first level signal.

[0010] In one embodiment, the output end of the comparison circuit is further used to connect to a chip to be controlled, and the second level signal is used to control the chip to be controlled to shut down.

[0011] In one embodiment, the energy storage circuit includes an undervoltage detection circuit and a charge-discharge circuit; the input end of the undervoltage detection circuit is used to access the supply voltage, the output end of the undervoltage detection circuit is connected to the charge-discharge circuit, and the charge-discharge circuit is also connected to the first input end of the comparison circuit;

[0012] The undervoltage detection circuit is used to transmit the supply voltage to the charge and discharge circuit when the supply voltage is greater than or equal to the preset undervoltage threshold, and is also used to stop transmitting the supply voltage when the supply voltage is less than the preset undervoltage threshold.

[0013] In one embodiment, the undervoltage detection circuit includes a detection switch tube; the first pole of the detection switch tube is used to connect to the power supply voltage, the control pole of the detection switch tube is connected to the first pole, and the second pole of the detection switch tube is connected to the charge and discharge circuit; the on-voltage of the detection switch tube is equal to the preset undervoltage threshold.

[0014] In one embodiment, the charging and discharging circuit includes an energy storage capacitor; a first end of the energy storage capacitor is connected to the output end of the undervoltage detection circuit, and a second end of the energy storage capacitor is grounded.

[0015] In one embodiment, the discharge circuit includes a discharge transistor; a control electrode of the discharge transistor is connected to the output end of the comparison circuit, a first electrode of the discharge transistor is used to access the voltage to be discharged, and a second electrode of the discharge transistor is grounded.

[0016] In one embodiment, there are multiple discharge transistors, and each of the discharge transistors is connected in sequence, with the second electrode of the discharge transistor being connected to the first electrode of the adjacent discharge transistor; the first electrode of the discharge transistor at the first position is used to access the voltage to be discharged, and the second electrode of the discharge transistor at the last position is grounded, and the control electrode of each of the discharge transistors is connected to the output end of the comparison circuit.

[0017] In one embodiment, the comparison circuit includes a first voltage divider unit, a second voltage divider unit and a comparator; the input end of the first voltage divider unit is connected to the energy storage circuit, and the output end of the first voltage divider unit is connected to the first input end of the comparator; the input end of the second voltage divider unit is used to access the power supply voltage, and the output end of the second voltage divider unit is connected to the second input end of the comparator; the output end of the comparator is connected to the control end of the discharge circuit.

[0018] In one embodiment, the first voltage dividing unit includes a first resistor and a second resistor; a first end of the first resistor is connected to the energy storage circuit, a second end of the first resistor is grounded via the second resistor, and the second end of the first resistor is also connected to the first input end of the comparator;

[0019] The second voltage divider unit includes a third resistor and a fourth resistor; the first end of the third resistor is used to access the supply voltage, the second end of the third resistor is grounded via the fourth resistor, and the second end of the third resistor is also connected to the second input end of the comparator.

[0020] In one embodiment, the undervoltage protection circuit further includes a current limiting resistor, a first end of the current limiting resistor is used to access the supply voltage, and a second end of the current limiting resistor is respectively connected to the energy storage circuit and the first input end of the comparison circuit.

[0021] In one embodiment, the undervoltage protection circuit further includes a filter capacitor, a first end of the filter capacitor is connected to the first end of the current limiting resistor, and a second end of the filter capacitor is grounded.

[0022] An electronic device includes a power management chip and an undervoltage protection circuit as described above, wherein the input end of the discharge circuit is connected to the power management chip and receives the voltage to be discharged from the power management chip, and the power input end of the power management chip receives the supply voltage.

[0023] In one embodiment, the electronic device is an energy storage converter.

[0024] The above-mentioned undervoltage protection circuit and electronic device include an energy storage circuit, a comparison circuit and a discharge circuit. The energy storage circuit is used to access the power supply voltage; the first input end of the comparison circuit is connected to the energy storage circuit, and the second input end of the comparison circuit is used to access the power supply voltage; the control end of the discharge circuit is connected to the output end of the comparison circuit, the input end of the discharge circuit is connected to the voltage to be discharged, and the output end of the discharge circuit is grounded. When the power supply voltage is greater than or equal to the preset undervoltage threshold, the energy storage circuit is charged and the comparison circuit outputs a first level signal; when the power supply voltage is less than the preset undervoltage threshold, the energy storage circuit is discharged and the comparison circuit outputs a second level signal; the discharge circuit discharges the voltage to be discharged according to the second level signal and stops discharging according to the first level signal. In this way, the undervoltage protection circuit can share the power supply voltage with the chip to be protected (such as PMIC). When the power supply voltage drops below the preset undervoltage threshold due to voltage fluctuation or abnormal power failure, the energy storage circuit discharges and triggers the comparison circuit to output the second level signal, so that the discharge circuit quickly discharges the voltage to be discharged (such as the high voltage of the PMIC high voltage module) to avoid voltage overshoot or logic error. This significantly reduces the risk of damage to PMIC internal modules due to abnormal power outages and improves the reliability of PMIC use. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 1 is a schematic diagram of a module of an undervoltage protection circuit in one embodiment;

[0027] Figure 2 is a module schematic diagram of an undervoltage protection circuit in another embodiment;

[0028] Figure 3 1 is a schematic diagram of the circuit structure of an undervoltage protection circuit in one embodiment;

[0029] Figure 4 2 is a schematic diagram of the circuit structure of an undervoltage protection circuit in another embodiment;

[0030] Figure 5 FIG. 4 is a schematic diagram of a module of an electronic device in an embodiment. DETAILED DESCRIPTION

[0031] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0033] It will be understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor without departing from the scope of this application. The first resistor and the second resistor are both resistors, but they are not the same resistor.

[0034] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if there is transmission of electrical signals or data between the connected circuits, modules, units, etc.

[0035] It is understood that “at least one” refers to one or more, “a plurality” refers to two or more, and “at least a portion of an element” refers to a portion or all of an element.

[0036] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0037] In one exemplary embodiment, an undervoltage protection circuit is provided. The undervoltage protection circuit is used to detect undervoltage conditions on the supply voltage of a chip to be protected. This circuit is applicable to a variety of chip types, including but not limited to power management chips (PMICs) and communication chips. During chip operation, the supply voltage may drop transiently or even experience an abnormal power outage due to factors such as grid voltage fluctuations and electromagnetic interference.

[0038] Undervoltage occurs when the power supply voltage falls below the preset undervoltage threshold. When the supply voltage is undervoltage, the chip being protected may malfunction, experience performance degradation, or even be damaged. For example, if the PMIC's power supply voltage unexpectedly fails, the PMIC's internal high-voltage modules may experience voltage overshoot or logic errors due to uncontrolled power-down timing, leading to functional failure.

[0039] The undervoltage protection circuit can monitor the chip's power supply voltage in real time. Once an undervoltage condition is detected, the high voltage of the chip will be discharged to prevent the chip from malfunctioning or being damaged due to internal voltage overshoot or logic errors, thereby improving the chip's reliability.

[0040] In some embodiments, as Figure 1 As shown, the undervoltage protection circuit includes a storage circuit 100, a comparison circuit 200 and a discharge circuit 300.

[0041] The energy storage circuit 100 is used to access the power supply voltage VIN. In practical applications, the energy storage circuit 100 and the power supply terminal of the chip are connected to the same power supply voltage VIN.

[0042] A first input terminal of the comparison circuit 200 is connected to the energy storage circuit 100 , and a second input terminal of the comparison circuit 200 is used to access the power supply voltage VIN.

[0043] The control terminal of the discharge circuit 300 is connected to the output terminal of the comparison circuit 200 , the input terminal of the discharge circuit 300 is used to receive the voltage V1 to be discharged, and the output terminal of the discharge circuit 300 is grounded.

[0044] When the supply voltage VIN is greater than or equal to the preset undervoltage threshold, the energy storage circuit 100 is charged and the comparison circuit 200 outputs a first level signal. When the supply voltage VIN is less than the preset undervoltage threshold, the energy storage circuit 100 is discharged and the comparison circuit 200 outputs a second level signal.

[0045] The preset undervoltage threshold is determined based on the minimum voltage threshold required for the chip to be protected to operate normally. For example, the preset undervoltage threshold can be equal to the minimum voltage threshold, or slightly higher than the minimum voltage threshold, for example, higher than 10% of the minimum voltage threshold.

[0046] When the supply voltage VIN is normal (i.e., the supply voltage VIN is greater than or equal to the preset undervoltage threshold), the energy storage circuit 100 can quickly store electrical energy, and its output voltage gradually rises to a stable value close to the supply voltage VIN, providing a reference voltage for the comparison circuit 200. When the supply voltage VIN connected to the second input terminal of the comparison circuit 200 is greater than or equal to the voltage provided by the energy storage circuit 100, the comparison circuit 200 outputs a first level signal.

[0047] When the power supply voltage VIN is abnormally powered off, the reference voltage output by the energy storage circuit 100 to the first input terminal of the comparison circuit 200 is still the power supply voltage VIN, but the power supply voltage VIN connected to the second input terminal of the comparison circuit 200 drops sharply. At this time, the output signal of the comparison circuit 200 changes to a second level signal. The voltage of the second level signal is different from that of the first level signal. Exemplarily, the first level signal is a low level signal (e.g., 0V) and the second level signal is a high level signal (e.g., 5V).

[0048] The discharge circuit 300 discharges the to-be-discharged voltage V1 when receiving the second level signal, and stops discharging when receiving the first level signal.

[0049] The voltage to be discharged V1 can be the internal high voltage of the chip to be protected. In actual implementation, the input end of the discharge circuit 300 is connected to the corresponding pin of the chip to discharge the high voltage of the high voltage module inside the chip through the pin when undervoltage occurs.

[0050] The above-mentioned undervoltage protection circuit includes a tank circuit 100, a comparison circuit 200, and a bleeder circuit 300. The tank circuit 100 is connected to the supply voltage VIN; the first input terminal of the comparison circuit 200 is connected to the tank circuit 100, and the second input terminal of the comparison circuit 200 is connected to the supply voltage VIN; the control terminal of the bleeder circuit 300 is connected to the output terminal of the comparison circuit 200, the input terminal of the bleeder circuit 300 is connected to the voltage to be discharged V1, and the output terminal of the bleeder circuit 300 is grounded. When the supply voltage VIN is greater than or equal to a preset undervoltage threshold, the tank circuit 100 is charged, and the comparison circuit 200 outputs a first-level signal. When the supply voltage VIN is less than the preset undervoltage threshold, the tank circuit 100 is discharged, and the comparison circuit 200 outputs a second-level signal. The bleeder circuit 300 discharges the voltage to be discharged V1 upon receiving the second-level signal and stops discharging upon receiving the first-level signal. As a result, the undervoltage protection circuit and the chip to be protected can share the same supply voltage VIN. When the supply voltage VIN drops below a preset undervoltage threshold, the energy storage circuit 100 discharges and triggers the comparison circuit 200 to output a second-level signal, causing the discharge circuit 300 to quickly discharge the voltage to be discharged V1 (such as the high voltage of the PMIC high-voltage module), thereby avoiding voltage overshoot or logic errors. This significantly reduces the risk of damage to the PMIC's internal modules due to abnormal power outages and improves the PMIC's reliability.

[0051] In some embodiments, as Figure 2 As shown, the output end of the comparison circuit 200 is also used to connect to the chip to be controlled, and the second level signal V2 is used to control the chip to be controlled to shut down.

[0052] The chip to be controlled can be a control chip such as a microprocessor. When the supply voltage VIN is less than a preset undervoltage threshold, the comparison circuit 200 outputs a second-level signal. This second-level signal indicates a sudden drop in the current supply voltage VIN or an abnormal power outage, triggering the control chip to execute a shutdown process, thereby improving operational abnormalities or even damage to these control chips caused by abnormal power outages.

[0053] Since the undervoltage protection circuit is provided with an energy storage circuit 100, the PMIC can be powered by the energy storage circuit 100 during undervoltage, so that the PMIC can continue to power these control chips before the control chips are shut down, effectively avoiding sudden abnormal power failure of these control chips.

[0054] In some embodiments, as Figure 3 As shown, the energy storage circuit 100 includes an undervoltage detection circuit 110 and a charge-discharge circuit 120. The input terminal of the undervoltage detection circuit 110 is used to receive the power supply voltage VIN, and the output terminal of the undervoltage detection circuit 110 is connected to the charge-discharge circuit 120. The charge-discharge circuit 120 is also connected to the first input terminal of the comparison circuit 200.

[0055] The undervoltage detection circuit 110 is used to transmit the supply voltage VIN to the charge and discharge circuit 120 when the supply voltage VIN is greater than or equal to a preset undervoltage threshold, and is also used to stop transmitting the supply voltage VIN when the supply voltage VIN is less than the preset undervoltage threshold.

[0056] The undervoltage detection circuit 110 can determine in real time whether the supply voltage VIN has reached a preset undervoltage threshold and dynamically control the transmission of the supply voltage VIN based on the determination result. Specifically, when the supply voltage VIN is normal, the undervoltage detection circuit 110 transmits the supply voltage VIN directly to the charge-discharge circuit 120 to provide charging energy. If the supply voltage VIN is undervoltage, the undervoltage detection circuit 110 stops transmitting, disconnecting the input source of the charge-discharge circuit 120 and triggering it to enter a discharge state.

[0057] When the supply voltage VIN is normal, the charge-discharge circuit 120 can quickly store electrical energy, and its voltage gradually rises to a stable value close to the supply voltage VIN, providing a reference voltage for the comparison circuit 200. When the supply voltage VIN is undervoltage, the reference voltage output to the first input terminal of the comparison circuit 200 remains unchanged, and the comparison circuit 200 outputs a second-level signal.

[0058] In this embodiment, undervoltage detection circuit 110 performs the dual functions of detecting the supply voltage VIN and dynamically controlling charge and discharge. By real-time monitoring the relationship between the supply voltage VIN and a preset undervoltage threshold, it can precisely control the operating mode of charge and discharge circuit 120, thereby quickly isolating abnormal inputs and triggering the charge and discharge circuit 120 to release energy during an undervoltage condition. Charge and discharge circuit 120 discharges when the supply voltage VIN is abnormal, providing a stable reference voltage for comparison circuit 200, enabling comparison circuit 200 to accurately identify undervoltage conditions and thereby improving the control accuracy of bleeder circuit 300. This improves the reliability of the undervoltage protection circuit, and consequently, the operational reliability of the PMIC.

[0059] In some embodiments, the undervoltage detection circuit 110 includes a detection switch T1. A first terminal of the detection switch T1 is connected to the supply voltage VIN, a control terminal of the detection switch T1 is connected to the first terminal, and a second terminal of the detection switch T1 is connected to the charge-discharge circuit 120. The on-state voltage of the detection switch T1 is equal to a preset undervoltage threshold.

[0060] The first electrode of the detection switch tube T1 serves as the input end of the undervoltage detection circuit 110 , and the second electrode of the detection switch tube T1 serves as the output end of the undervoltage detection circuit 110 .

[0061] The transistor type of the detection switch tube T1 can be set according to the specific situation. Its first electrode, second electrode, and control electrode can be determined according to the transistor type. As an example, the detection switch tube T1 is an NMOS (N-Metal-Oxide-Semiconductor Field-Effect Transistor, N-type field-effect transistor), with its drain electrode serving as the first electrode, the gate electrode serving as the control electrode, and the source electrode serving as the second electrode.

[0062] When the supply voltage VIN reaches or exceeds the turn-on voltage of the detection switch T1, the detection switch T1 enters the on state, and its source voltage changes with the supply voltage VIN, providing charging energy for the charge-discharge circuit 120. When the supply voltage VIN is undervoltage, the detection switch T1 is turned off, cutting off the input source of the charge-discharge circuit 120 and triggering it to discharge. This ensures that the comparison circuit 200 can accurately identify the undervoltage state and trigger the discharge circuit 300 to discharge the high voltage of the PMIC, thereby protecting the PMIC.

[0063] In this embodiment, the self-biasing characteristics of detection switch T1 eliminate the need for additional comparators or other devices for undervoltage detection, resulting in a reduced component count and effectively lower circuit costs. Furthermore, the on-resistance of detection switch T1 is typically low (e.g., in the milliohm range), resulting in minimal charging path losses. The fast switching speed of detection switch T1 improves the response speed of the undervoltage protection circuit.

[0064] In some embodiments, the charge-discharge circuit 120 includes an energy storage capacitor CX. A first terminal of the energy storage capacitor CX is connected to the output terminal of the undervoltage detection circuit 110, and a second terminal of the energy storage capacitor CX is grounded.

[0065] Specifically, the first end of the energy storage capacitor CX is connected to the second terminal of the detection switch tube T1, and the second end of the energy storage capacitor CX is grounded. When the supply voltage VIN is normal, the detection switch tube T1 is turned on, providing power to the energy storage capacitor CX, and the energy storage capacitor CX is charged. When the supply voltage VIN is undervoltage, the detection switch tube T1 is turned off, and the energy storage capacitor CX is discharged. This ensures that the comparison circuit 200 can accurately identify the undervoltage state and trigger the discharge circuit 300 to discharge the high voltage inside the PMIC, thereby protecting the PMIC.

[0066] In this embodiment, the energy storage capacitor CX can be an electrolytic capacitor or other capacitor. Charging and discharging can be completed through the energy storage capacitor CX, which has a simple circuit structure and low circuit cost. In actual implementation, the energy storage capacitor CX can also be replaced with an energy storage device such as a button battery.

[0067] In some embodiments, the comparison circuit 200 includes a first voltage divider unit 210, a second voltage divider unit 220, and a comparator U1. The input of the first voltage divider unit 210 is connected to the energy storage circuit 100, and the output of the first voltage divider unit 210 is connected to the first input of the comparator U1. The input of the second voltage divider unit 220 is connected to the supply voltage VIN, and the output of the second voltage divider unit 220 is connected to the second input of the comparator U1. The output of the comparator U1 is connected to the control terminal of the discharge circuit 300.

[0068] The first voltage divider 210 divides the output voltage of the energy storage circuit 100 by a preset ratio to obtain and output a reference voltage signal that matches the input range of the comparator U1. The second voltage divider 220 divides the supply voltage VIN by a preset ratio to obtain and output a comparison signal.

[0069] When the power supply voltage VIN is normal, the comparison signal is greater than or equal to the reference voltage signal, and the comparator U1 outputs a first level signal; when the power supply voltage VIN is undervoltage, the comparison signal is less than the reference voltage signal, the output of the comparator U1 changes, and outputs a second level signal.

[0070] In this embodiment, comparator U1 is selected to quickly output a second-level signal when the supply voltage VIN suddenly drops, thereby improving the response speed of the undervoltage protection circuit. By adjusting the voltage-dividing ratio of the first voltage-dividing unit 210 and the second voltage-dividing unit 220, the voltage input to comparator U1 can be adjusted, thereby increasing the supply voltage VIN range that the undervoltage protection circuit can adapt to. For example, by adjusting the voltage-dividing ratio of the first voltage-dividing unit 210 and the second voltage-dividing unit 220, comparator U1 can be adapted to different supply voltage VIN ranges, such as 3.3V, 5V, 12V, 24V, etc.

[0071] In some embodiments, the first voltage divider 210 includes a first resistor R4 and a second resistor R5. The first resistor R4 has a first terminal connected to the tank circuit 100, a second terminal connected to ground via the second resistor R5, and a second terminal connected to the first input terminal of the comparator U1.

[0072] The second voltage divider 220 includes a third resistor R2 and a fourth resistor R3. The first end of the third resistor R2 is connected to the power supply voltage VIN, the second end of the third resistor R2 is grounded via the fourth resistor R3, and the second end of the third resistor R2 is connected to the second input of the comparator U1.

[0073] The resistance values ​​of the first resistor R4, the second resistor R5, the third resistor R2, and the fourth resistor R3 can be set according to specific circumstances. As an example, when the power supply voltage VIN is normal, the voltage at node X is always greater than the voltage at node y, and the comparator U1 outputs a first level signal. When the power supply voltage VIN drops sharply, the voltage at node X decreases accordingly. At this time, the voltage at node X is less than the voltage at node y, and the comparator U1 outputs a second level signal.

[0074] In this embodiment, dual-channel voltage-dividing sampling is accomplished using four resistors: first resistor R4, second resistor R5, third resistor R2, and fourth resistor R3. This results in a simple and efficient circuit structure. Because the resistors have high resistance precision and are less affected by factors such as temperature, the stability of the voltage-dividing ratio is ensured, reducing detection errors caused by resistor deviations and thus improving the accuracy and reliability of undervoltage detection.

[0075] In some embodiments, the discharge circuit 300 includes a discharge transistor T2 , wherein a control electrode of the discharge transistor T2 is connected to an output terminal of the comparison circuit, a first electrode of the discharge transistor T2 is connected to a voltage to be discharged, and a second electrode of the discharge transistor T2 is grounded.

[0076] The transistor type of the discharge transistor T2 can be set according to specific circumstances, and its first electrode, second electrode, and control electrode can be determined according to the transistor type. As an example, the discharge transistor T2 is an NMOS transistor, with its drain serving as the first electrode, the gate serving as the control electrode, and the source serving as the second electrode.

[0077] By making the control electrode of the discharge transistor T2 directly driven by the output signal of the comparison circuit 200, it can be turned on in a very short time (such as nanoseconds), thereby quickly discharging the high voltage of the chip to be protected and improving the reliability of protection.

[0078] In some embodiments, there are multiple discharge transistors, each of which is connected in sequence, and the second electrode of the discharge transistor is connected to the first electrode of the adjacent next discharge transistor; the first electrode of the first discharge transistor is used to access the voltage to be discharged, and the second electrode of the last discharge transistor is grounded, and the control electrode of each discharge transistor is connected to the output end of the comparison circuit 200.

[0079] As an example, the number of bleeder transistors is 2, please refer to Figure 4 The two discharge transistors are discharge transistor T2 and discharge transistor T3. The first electrode of the first discharge transistor T3 is connected to the voltage to be discharged V1, and the second electrode is connected to the first electrode of the adjacent second discharge transistor T2. The second electrode of the discharge transistor T2 is grounded. The control electrodes of the discharge transistors T2 and T3 are both connected to the output terminal of the comparison circuit 200.

[0080] It should be noted that the greater the number of MOS transistors connected in series in the discharge circuit 300, the greater the total current carrying capacity of the circuit, thereby enabling a faster discharge speed during the discharge process. Therefore, by providing multiple discharge transistors, the discharge speed of the voltage V1 to be discharged can be increased, thereby improving the reliability of the protection.

[0081] In some embodiments, the undervoltage protection circuit further includes a current limiting resistor R1 , a first end of the current limiting resistor R1 is used to access the power supply voltage VIN, and a second end of the current limiting resistor R1 is connected to the first input ends of the energy storage circuit 100 and the comparison circuit 200 .

[0082] The resistance of the current limiting resistor R1 can be set according to actual needs. By setting the current limiting resistor R1, the energy storage circuit 100 and the comparison circuit 200 can be protected from damage caused by overcurrent, thereby improving the safety of the undervoltage protection circuit.

[0083] In some embodiments, the undervoltage protection circuit further includes a filter capacitor C1 , wherein a first terminal of the filter capacitor C1 is connected to a first terminal of the current limiting resistor R1 , and a second terminal of the filter capacitor C1 is grounded.

[0084] In this embodiment, the filter capacitor C1 can be provided to effectively filter out noise in the power supply voltage VIN, thereby improving the stability of the voltage input to the energy storage circuit 100 and the comparison circuit 200 , thereby improving the accuracy of the undervoltage protection.

[0085] The number of filter capacitors C1 can be multiple to further enhance the filtering effect. As an example, the undervoltage protection circuit includes filter capacitor C1 and filter capacitor C2, wherein a first end of filter capacitor C2 is connected to a first end of filter capacitor C1, and a second end of filter capacitor C2 is grounded.

[0086] In order to better understand the above embodiment, the following is a detailed explanation in conjunction with an optional embodiment. Figure 4 In one embodiment, the undervoltage protection circuit is used to provide undervoltage protection for the PMIC, and the undervoltage protection circuit includes a tank circuit 100, a comparison circuit 200, a discharge circuit 300, a filter capacitor C1, a filter capacitor C2, and a current limiting resistor R1.

[0087] The energy tank circuit 100 includes an undervoltage detection circuit 110 and a charge-discharge circuit 120. The charge-discharge circuit 120 includes an energy storage capacitor CX. The undervoltage detection circuit 110 includes a detection switch T1. The first electrode of the detection switch T1 is connected to the same supply voltage VIN as the PMIC. The control electrode of the detection switch T1 is connected to the first electrode, and the second electrode of the detection switch T1 is connected to the energy storage capacitor CX. The on-state voltage of the detection switch T1 is equal to a preset undervoltage threshold.

[0088] Comparator circuit 200 includes a first voltage divider unit 210, a second voltage divider unit 220, and a comparator U1. First voltage divider unit 210 includes a first resistor R4 and a second resistor R5. A first end of first resistor R4 is connected to tank circuit 100, a second end of first resistor R4 is connected to ground via second resistor R5, and a second end of first resistor R4 is also connected to a first input of comparator U1. Second voltage divider unit 220 includes a third resistor R2 and a fourth resistor R3. A first end of third resistor R2 is connected to supply voltage VIN, a second end of third resistor R2 is connected to ground via fourth resistor R3, and a second end of third resistor R2 is also connected to a second input of comparator U1.

[0089] The discharge circuit 300 includes a discharge transistor T2 and a discharge transistor T3. The first electrode of the first discharge transistor T3 is connected to the PMIC and receives the voltage V1 to be discharged from the PMIC. The second electrode is connected to the first electrode of the adjacent second discharge transistor T2. The second electrode of the discharge transistor T2 is grounded. The control electrodes of the discharge transistors T2 and T3 are both connected to the output of the comparator U1.

[0090] The detection switch transistor T1, the discharge transistor T2, and the discharge transistor T3 are all NMOS transistors, and the discharge transistors T2 and T3 are enhancement-mode NMOS transistors. The MOS transistor T1 is selected to have a turn-on voltage that is consistent with the operating voltage of the PMIC.

[0091] When the power supply voltage VIN drops, the detection switch tube T1, as a voltage-controlled device, will be disconnected because the gate voltage cannot reach the tube's conduction voltage. During this process, the energy storage capacitor CX, as an energy storage device, starts with supplementary power supply and then becomes an independent power supply. At the same time, the disconnection of the detection switch tube T1 can also ensure that the power transmitted by the energy storage capacitor CX will not flow back, avoiding backflow and other problems.

[0092] Specifically, when the power supply voltage VIN is normal, the voltage at node X is always greater than the voltage at node Y. Therefore, under normal circumstances, the comparator U1 outputs a low-level signal (i.e., a first-level signal), and the discharge transistor T2 and the discharge transistor T3 are both in the disconnected state. At this time, the discharge circuit does not work.

[0093] When the supply voltage VIN input to the circuit's front-end drops, causing the voltage at node X to fall below the voltage at node Y, comparator U1 outputs a high-level signal (i.e., a second-level signal). The bleeder transistors T2 and T3 are both in the on state, enabling the bleeder circuit to controllably discharge the PMIC's internal high voltage.

[0094] In this embodiment, the backend of comparator U1 also outputs comparator U1's output signal V2, which is connected to the output pins of other control chips. When comparator U1 outputs a high-level signal, indicating an undervoltage in the power supply voltage VIN, the control chips will execute the normal shutdown process accordingly. Because the energy storage capacitor CX provides power to the PMIC, the PMIC will continue to provide normal power to these control chips before the external chips shut down, effectively preventing these control chips from suddenly losing power.

[0095] The above-described undervoltage protection circuit, through the coordinated efforts of the energy storage circuit 100, the comparison circuit 200, and the bleeder circuit 300, enables the PMIC to execute a correct chip shutdown method even in the event of an undervoltage or power failure. This prevents potential PMIC chip damage and malfunction caused by abnormal undervoltage or power failure. Furthermore, due to the inclusion of the energy storage circuit 100, the undervoltage protection circuit is the last to power down the PMIC in the event of a power failure. This protection circuit outputs a signal V2, providing real-time communication with other external control chips, effectively preventing damage to these chips due to undervoltage or power failure.

[0096] In an exemplary embodiment, the present application also provides an electronic device. Figure 5 As shown, the electronic device includes a power management chip and an undervoltage protection circuit. The undervoltage protection circuit can be configured with reference to the above embodiments and will not be described in detail here.

[0097] The input end of the discharge circuit 300 in the undervoltage protection circuit is connected to the power management chip and receives the voltage V1 to be discharged from the power management chip. The power input end of the power management chip receives the supply voltage.

[0098] In some embodiments, the output end of the comparison circuit 200 is further used to connect to a control chip to be controlled, and the second level signal V2 is used to control the control chip to be controlled to shut down.

[0099] When the power supply voltage VIN is less than the preset undervoltage threshold, the comparison circuit 200 outputs a second level signal. The second level signal indicates that the current power supply voltage VIN has experienced a sudden drop or abnormal power outage, triggering the control chip to execute the shutdown process, which can improve the operation abnormalities or even damage of these control chips caused by abnormal power outages.

[0100] Since the undervoltage protection circuit is provided with an energy storage circuit 100, the PMIC can be powered by the energy storage circuit 100 during undervoltage, so that the PMIC can continue to provide normal power to these control chips before the control chips are shut down, effectively avoiding sudden abnormal power failure of these control chips.

[0101] In some embodiments, the electronic device is an energy storage converter.

[0102] The coordinated efforts of the energy storage circuit 100, comparison circuit 200, and bleeder circuit 300 allow the PMIC of the energy storage converter to execute the correct chip shutdown method even in the event of an undervoltage or power outage, thus preventing potential PMIC chip damage and malfunction caused by abnormal undervoltage or power outages. Furthermore, the inclusion of the energy storage circuit 100 allows the PMIC to be powered down last during a power outage. This protection circuit outputs a signal V2, providing real-time communication with other external control chips, effectively preventing damage to these chips due to undervoltage or power outages.

[0103] In the description of this specification, reference to the terms "some embodiments" or "other embodiments" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0104] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0105] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. An undervoltage protection circuit, characterized in that: include: An energy storage circuit, the energy storage circuit being used to access a power supply voltage; a comparison circuit, wherein a first input terminal of the comparison circuit is connected to the energy storage circuit, and a second input terminal of the comparison circuit is used to access the supply voltage; a discharge circuit, wherein a control end of the discharge circuit is connected to the output end of the comparison circuit, an input end of the discharge circuit is used to receive the voltage to be discharged, and an output end of the discharge circuit is grounded; When the supply voltage is greater than or equal to a preset undervoltage threshold, the energy storage circuit is charged, and the comparison circuit outputs a first level signal; When the supply voltage is lower than the preset undervoltage threshold, the energy storage circuit discharges, and the comparison circuit outputs a second level signal; The discharge circuit discharges the voltage to be discharged when receiving the second level signal, and stops discharging when receiving the first level signal.

2. The undervoltage protection circuit according to claim 1, characterized in that: The output end of the comparison circuit is further used to connect to the chip to be controlled, and the second level signal is used to control the chip to be controlled to shut down.

3. The undervoltage protection circuit according to claim 1 or 2, characterized in that: The energy storage circuit includes an undervoltage detection circuit and a charge-discharge circuit; the input end of the undervoltage detection circuit is used to access the supply voltage, the output end of the undervoltage detection circuit is connected to the charge-discharge circuit, and the charge-discharge circuit is also connected to the first input end of the comparison circuit; The undervoltage detection circuit is used to transmit the supply voltage to the charge and discharge circuit when the supply voltage is greater than or equal to the preset undervoltage threshold, and is also used to stop transmitting the supply voltage when the supply voltage is less than the preset undervoltage threshold.

4. The undervoltage protection circuit according to claim 3, characterized in that: The undervoltage detection circuit includes a detection switch tube; the first electrode of the detection switch tube is used to connect to the power supply voltage, the control electrode of the detection switch tube is connected to the first electrode, and the second electrode of the detection switch tube is connected to the charge and discharge circuit; the on-voltage of the detection switch tube is equal to the preset undervoltage threshold.

5. The undervoltage protection circuit according to claim 3, characterized in that: The charging and discharging circuit includes an energy storage capacitor; a first end of the energy storage capacitor is connected to the output end of the undervoltage detection circuit, and a second end of the energy storage capacitor is grounded.

6. The undervoltage protection circuit according to claim 1 or 2, characterized in that: The discharge circuit includes a discharge transistor; a control electrode of the discharge transistor is connected to the output end of the comparison circuit, a first electrode of the discharge transistor is used to access the voltage to be discharged, and a second electrode of the discharge transistor is grounded.

7. The undervoltage protection circuit according to claim 6, characterized in that: There are multiple discharge transistors, and each of the discharge transistors is connected in sequence, with the second electrode of the discharge transistor being connected to the first electrode of the adjacent discharge transistor; the first electrode of the discharge transistor at the first position is used to connect to the voltage to be discharged, and the second electrode of the discharge transistor at the last position is grounded, and the control electrode of each of the discharge transistors is connected to the output end of the comparison circuit.

8. The undervoltage protection circuit according to claim 1, wherein: The comparison circuit includes a first voltage divider unit, a second voltage divider unit and a comparator; the input end of the first voltage divider unit is connected to the energy storage circuit, and the output end of the first voltage divider unit is connected to the first input end of the comparator; the input end of the second voltage divider unit is used to access the power supply voltage, and the output end of the second voltage divider unit is connected to the second input end of the comparator; the output end of the comparator is connected to the control end of the discharge circuit.

9. The undervoltage protection circuit according to claim 8, characterized in that: The first voltage divider unit includes a first resistor and a second resistor; a first end of the first resistor is connected to the energy storage circuit, a second end of the first resistor is grounded via the second resistor, and the second end of the first resistor is also connected to the first input end of the comparator; The second voltage divider unit includes a third resistor and a fourth resistor; the first end of the third resistor is used to access the supply voltage, the second end of the third resistor is grounded via the fourth resistor, and the second end of the third resistor is also connected to the second input end of the comparator.

10. The undervoltage protection circuit according to claim 1, wherein: It also includes a current limiting resistor, a first end of the current limiting resistor is used to access the power supply voltage, and a second end of the current limiting resistor is respectively connected to the first input end of the energy storage circuit and the comparison circuit.

11. The undervoltage protection circuit according to claim 10, wherein: It also includes a filter capacitor, a first end of the filter capacitor is connected to the first end of the current limiting resistor, and a second end of the filter capacitor is grounded.

12. An electronic device, characterized in that: It comprises a power management chip and an undervoltage protection circuit as described in any one of claims 1 to 11, wherein the input end of the discharge circuit is connected to the power management chip and is connected to the voltage to be discharged from the power management chip, and the power input end of the power management chip is connected to the supply voltage.

13. The electronic device according to claim 12, wherein: The electronic device is an energy storage converter.

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