Hysteresis type power supply voltage detection circuit and detection method

Abstract

The invention relates to the technical field of integrated circuits, and discloses a hysteresis type power supply voltage detection circuit, which comprises a sampling circuit connected with a power supply and used for sampling a power supply voltage to obtain a sampling voltage; one input end of the comparator is connected with the sampling voltage, the other input end of the comparator is connected with the reference voltage, and the output end of the comparator outputs a feedback control signal; the switch gating circuit comprises two switch gating branches controlled by the feedback control signal, the switch gating circuit is connected between the sampling circuit and the comparator, and the connection points of the two switch gating branches and the sampling circuit are different; and the sampling voltage is updated through on-off state control of the two switch gating branches. When the circuit is used for power-on / power-off detection of a power supply, power-on / power-off alarm threshold voltages are different, and the comparator forms a hysteresis effect. Furthermore, false alarm is avoided. The invention further discloses a hysteresis type power supply voltage detection method.

Description

Technical Field

[0001] The present application relates to the field of integrated circuit technology, for example, to a hysteresis type power supply voltage detection circuit and detection method. Background Art

[0002] The Power Management Unit (PMU) provides a stable operating voltage and bias current for the NFC (Near Field Communication) chip of a mobile phone, among which the power supply voltage detection circuit (Voltage Detection, VD) is a key component inside the PMU. Figure 1 The schematic diagram of the NFC power supply structure is shown. When the external battery voltage starts to power on, VD detects that the battery voltage has reached the preset standard and sends a power-on indication signal to the digital module. The digital module starts to work and controls the output voltage of the low dropout regulator (LDO) to supply power to other modules. When the external battery voltage is turned off and powered off, VD detects that the battery voltage is lower than the preset standard and sends a power-off indication signal to the digital module. The digital module controls the shutdown of the entire chip.

[0003] The structure diagram of the existing power supply voltage up / down detection circuit is as follows Figure 2 As shown in the figure, it is mainly composed of sampling circuit, comparator and alarm signal processing circuit. When the power is turned on, the sampling circuit of VD will sample and obtain the sampling voltage V SA (usually a voltage divider of the battery voltage) is output to the negative input of the comparator, which compares V REF and V SA When V SA Higher than V REF When VD outputs a low level indication signal, the power supply voltage value at this time is called the power-on indication threshold V TH_ON When V SA Lower than V REF When VD outputs a high level indication signal, the power supply voltage value at this time is called the power-off alarm threshold V TH_OFF .

[0004] Since the sources of the sampling voltage and the preset reference voltage are fixed, V TH_ON and V TH_OFF Considering the influence of chip production process, operating temperature, etc., the above VD detection method often has the problem of "false alarm". For example, when the power supply voltage has risen enough to start the system, but V SA But lower than V TH_OFF , VD outputs a high-level alarm signal, causing the system to shut down abnormally. Summary of the invention

[0005] To provide a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary is not a general review, nor is it intended to identify key / important constituent elements or delineate the scope of protection of these embodiments. Instead, it serves as a preamble to the detailed description that follows.

[0006] Embodiments of the present disclosure provide a hysteresis-type power supply voltage detection circuit and a detection method to avoid false alarms.

[0007] In some embodiments, the hysteresis-type power supply voltage detection circuit includes:

[0008] A sampling circuit, connected to a power supply, for sampling the power supply voltage to obtain a sampled voltage; a comparator, one input terminal connected to the sampled voltage, the other input terminal connected to a reference voltage, and an output terminal outputting a feedback control signal; a switch selection circuit, including two switch selection branches controlled by the feedback control signal, connected between the sampling circuit and the comparator, and the connection points of the two switch selection branches with the sampling circuit are different; by controlling the switch states of the two switch selection branches, the sampled voltage is updated.

[0009] In some embodiments, the hysteresis-type power supply voltage detection circuit includes:

[0010] A sampling circuit, connected to a power supply, for sampling the power supply voltage to obtain a sampled voltage; a comparator, one input terminal connected to the sampled voltage, the other input terminal connected to a reference voltage, and an output terminal outputting a feedback control signal; a switch selection circuit, connected between the reference voltage and the comparator, including two switch selection branches controlled by the feedback control signal; wherein, the reference voltage includes a first reference voltage and a second reference voltage; by controlling the switch states of the two switch selection branches, the other input terminal of the comparator is connected to the first reference voltage or the second reference voltage.

[0011] In some embodiments, the hysteresis-type power supply voltage detection method is based on the foregoing hysteresis-type power supply voltage detection circuit; the method includes: when detecting the power supply voltage, obtaining the feedback control signal output by the comparator; according to the feedback control signal, controlling the switch states of each branch in the switch selection circuit to select the corresponding sampled voltage or reference voltage to cause a hysteresis effect in the comparator.

[0012] The hysteresis-type power supply voltage detection circuit and detection method provided by the embodiments of the present disclosure can achieve the following technical effects:

[0013] A switch gating circuit is set between the comparator and the sampling circuit to input sampling voltages from different sources into the comparator based on the feedback control signal of the comparator. In this way, when the power is powered on / off, the power on / off alarm threshold voltage is different, and the comparator forms a hysteresis effect. Thus, the occurrence of false alarms is avoided.

[0014] The above general description and the following description are exemplary and explanatory only and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by corresponding drawings, which do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements, and the drawings do not constitute a scale limitation, and wherein:

[0016] Figure 1 It is a schematic diagram of a power supply structure of a power management unit in the prior art provided by an embodiment of the present disclosure;

[0017] Figure 2 It is a structural schematic diagram of a power supply voltage detection circuit in the prior art provided by an embodiment of the present disclosure;

[0018] Figure 3 is a structural schematic diagram of a hysteresis type power supply voltage detection circuit provided by an embodiment of the present disclosure;

[0019] Figure 4 is a structural schematic diagram of another hysteresis type power supply voltage detection circuit provided by an embodiment of the present disclosure;

[0020] Figure 5 is a structural schematic diagram of another hysteresis type power supply voltage detection circuit provided by an embodiment of the present disclosure;

[0021] Figure 6 is a structural schematic diagram of another hysteresis type power supply voltage detection circuit provided in an embodiment of the present disclosure.

[0022] Reference numerals:

[0023] 10: sampling circuit; 20: comparator; 30: switch gating circuit; 40: inverter; 50: alarm signal processing circuit;

[0024] R1: first resistor; R2: second resistor; R3: third resistor; 31: first switch selection branch; 32: second switch selection branch. DETAILED DESCRIPTION

[0025] In order to be able to understand the features and technical contents of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.

[0026] The terms "first", "second", etc. in the specification and claims of the embodiments of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the embodiments of the present disclosure described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0027] In the embodiments of the present disclosure, the terms "upper", "lower", "inside", "middle", "outside", "front", "back" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. These terms are mainly intended to better describe the embodiments of the present disclosure and their embodiments, and are not intended to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction. Moreover, in addition to being used to indicate directions or positional relationships, some of the above terms may also be used to indicate other meanings. For example, the term "upper" may also be used to indicate a certain dependency or connection relationship in certain circumstances. For those of ordinary skill in the art, the specific meanings of these terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0028] In addition, the terms "disposed", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0029] Unless otherwise stated, the term "plurality" means two or more.

[0030] In the embodiment of the present disclosure, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B indicates: A or B.

[0031] The term "and / or" is a description of the association relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.

[0032] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other.

[0033] Combination Figure 3 As shown, the embodiment of the present disclosure provides a hysteresis type power supply voltage detection circuit, including a sampling circuit 10, a comparator 20 and a switch gating circuit 30. The sampling circuit 10 is connected to the power supply and is used to sample the power supply voltage to obtain a sampled voltage V SA The comparator 20 has an input terminal and a sampling voltage V SA The other input terminal is connected to the reference voltage V REF The switch gating circuit 30 includes two switch gating branches controlled by the feedback control signal, connected between the sampling circuit 10 and the comparator 20, and the connection points of the two switch gating branches and the sampling circuit are different. The switch states of the two switch gating branches are controlled to update the sampling voltage V SA .

[0034] Here, a switch gating circuit 30 is introduced between the sampling circuit 10 and the comparator 20 of the power supply voltage detection circuit, and is controlled by the feedback control signal of the comparator 20. Thus, the sampling voltages corresponding to different sampling points of the sampling circuit 10 are input into the comparator 20 to update the sampling voltage. This makes the thresholds for the output signal of the comparator 20 flip different, that is, the power supply voltage power-on / power-off alarm threshold voltages are different.

[0035] Specifically, the switch gating circuit 30 includes two switch gating branches, and the two switch gating branches are connected between the sampling circuit 10 and an input terminal of the comparator 20. And the two switch gating branches are respectively connected to different sampling points of the sampling circuit 10, that is, when the power supply is at the same voltage, the sampling voltage values ​​output by different sampling points are different. Based on the feedback control signal, the switch state of the two switch gating branches is controlled. When the power supply is powered on and powered off, the switch states of the two switch gating branches are different, so that the sampling voltages of the power-on detection and the power-off detection come from different sampling points. In this way, it is ensured that the power supply power-on / power-off alarm threshold voltages are different, and the comparator forms a hysteresis effect, thereby avoiding false alarms caused by the same threshold voltage.

[0036] The hysteresis type power supply voltage detection circuit provided by the embodiment of the present disclosure is used, and a switch gating circuit is set between the comparator and the sampling circuit to input sampling voltages from different sources into the comparator based on the feedback control signal of the comparator. In this way, when the power supply is powered on / off, the power-on / power-off alarm threshold voltage is different, and the comparator forms a hysteresis effect. In addition, the occurrence of false alarms is avoided.

[0037] Optionally, the sampling circuit 10 includes a plurality of resistors connected in series to form a first sampling voltage V SA1 and the second sampling voltage V SA2 The input terminal of the first switch gating branch SW1 of the switch gating circuit 30 is connected to the first sampling voltage V SA1 The input end of the second switch selection branch SW2 is connected to the second sampling voltage V SA2 The output end of the switch gating circuit 30 is connected to an input end of the comparator 10 .

[0038] Here, the sampling circuit 10 includes a plurality of resistors connected in series. It can be understood that the sampling circuit 10 forms two sampling points, and the number of the series resistors is greater than or equal to three. In the embodiment of the present disclosure, the sampling circuit includes a first resistor R1, a second resistor R2, and a third resistor R3. The connection point between the first resistor R1 and the second resistor R2 is a first sampling point, and the first sampling voltage V is output. SA1 The connection point between the second resistor R2 and the third resistor R3 is the second sampling point, which outputs the second sampling voltage V SA2 In this way, the source of the sampling voltage when the power is powered on and powered off is different; thus, the corresponding power-on / power-off alarm threshold voltage is different.

[0039] In addition, in the embodiment of the present disclosure, the first switch gating branch and the second switch gating branch are both connected to the inverting input terminal of the comparator, and the non-inverting input terminal of the comparator is connected to the reference voltage. In addition, the input signal of the comparator is set based on the demand, and the reference voltage can also be connected to the non-inverting input terminal of the comparator.

[0040] Optionally, the first sampling voltage V SA1 Greater than the second sampling voltage V SA2 .

[0041] Here, one end of the first resistor R1 is connected to the power supply voltage, and one end of the third resistor R3 is grounded. Therefore, the first sampling voltage V SA1 Greater than the second sampling voltage V SA2 In the embodiment of the present disclosure, it is not limited to the first sampling voltage V SA1 Greater than the second sampling voltage V SA2 The second sampling voltage may also be greater than the first sampling voltage V SA1 The sampling voltage values ​​of the two are different, and there is a certain difference. In addition, the reference voltage is the first sampling voltage V when the power supply voltage reaches the power-on indication threshold. SA1 , and the second sampling voltage V when the power supply voltage reaches the power-off indication threshold SA2 The interval value of .

[0042] When the power is turned on, the first sampling voltage V SA1As the input signal of the comparator; at the first sampling voltage V SA1 Reaching the reference voltage V REF After that, the comparator outputs a power-on detection alarm signal. Then, the second sampling voltage V SA2 As the input signal of the comparator. SA2 Less than the first sampling voltage V SA1 , so that the power-on indication threshold is greater than the power-off indication threshold. Therefore, after the power-on detection alarm, the comparator forms a hysteresis effect. Only when the power is turned off, the second sampling voltage V SA2 Reaching the reference voltage V REF The comparator will output the power failure detection alarm signal only after the power failure detection alarm signal is output. No false alarm will be generated before the power failure detection alarm signal is output, thus ensuring that the chip system can work normally.

[0043] Optionally, during power-on detection, the first switch selection branch SW1 is in an on state, and the second switch selection branch SW2 is in an off state.

[0044] Here, the first switch gate branch SW1 is connected to the first sampling voltage V SA1 The second switch selection branch SW2 is connected to the second sampling voltage V SA2 ; and the first sampling voltage V SA1 Greater than the second sampling voltage V SA2 . Therefore, when the power supply is powered on, the first switch selection branch SW1 is turned on by default, that is, the first sampling voltage is used as the input signal of the comparator. The second switch selection branch SW1 is in the off state. After the power-on detection is completed, the feedback control signal controls the state of the switch selection circuit, so that the first switch selection branch SW1 is closed and the second switch selection branch SW2 is opened. In this way, the comparison action of the comparator forms a hysteresis until the power supply voltage rises to the target value. Then, when the power supply starts to slowly power off, the power supply power-off detection alarm is completed.

[0045] Optionally, the hysteresis power supply voltage detection circuit further includes an inverter 40, an input end of the inverter 40 is connected to an output end of the comparator 20 to invert the feedback control signal.

[0046] Wherein, when the switch state of the first switch gating branch SW1 is controlled by the feedback control signal output by the comparator, the switch state of the second switch gating branch SW2 is controlled by the flipped feedback control signal.

[0047] In the disclosed embodiment, the controlled signal control logic of the first switch gating branch SW1 and the second switch gating branch SW2 is the same. Exemplarily, the first switch gating branch SW1 and the second switch gating branch SW2 are both turned on when the signal is high and turned off when the signal is low. In order to make the states of the first switch gating branch SW1 and the second switch gating branch SW2 different, an inverter is provided here to flip the feedback control signal output by the comparator. In this way, two logically opposite control signals are generated to control the two switch gating branches respectively, so that the switch states of the two switch gating branches are different.

[0048] Combination Figure 4 , the hysteresis type power supply voltage detection circuit and the working process are described in detail. The first sampling voltage V of the sampling circuit SA1 and the second sampling voltage V SA2 , respectively connected to the input end of the first switch gating branch SW1 and the second switch gating branch SW2. The output end of the first switch gating branch SW1 and the second switch gating branch SW2 are connected to the inverting input end of the comparator 10. The reference voltage V REF The output end of the comparator 10 is connected to the control end of the first switch gating branch SW1, that is, the feedback control signal VD_O is used as the control signal of the first switch gating branch SW1. The output end of the inverter 40 is connected to the control end of the second switch gating branch SW2, that is, the inverted feedback control signal VD_O_N is used as the control signal of the second switch gating branch SW2.

[0049] When the power supply starts to slowly power on, the comparator outputs a high level signal, the first switch gating branch SW1 is in the on state, and the second switch gating branch SW2 is in the off state. The first sampling voltage V SA1 Gradually rise to the reference voltage V REF , the comparator 10 outputs a low level signal, and the inverter 40 outputs a high level signal. At this time, the detection circuit completes the power-on detection alarm, and the current power supply voltage is the power-on indication threshold V TH_ON At the same time, the first switch gating branch SW1 is controlled to be turned off, and the second switch gating branch SW2 is controlled to be turned on. The sampling circuit outputs the second sampling voltage V SA2 The comparison action of the comparator 20 forms a hysteresis until the power supply voltage rises to the target value. Then, the power supply is turned off and the power supply starts to power down slowly. The second sampling voltage V SA2 The target value slowly decreases until the second sampling voltage V SA2 Drop to the reference voltage V REF The comparator 10 outputs a high level signal, and the inverter outputs a low level signal. At this time, the detection circuit completes the power-off detection alarm, and the current power supply voltage is the power-off indication threshold V TH_OFFIn this way, the power-on indication threshold and the power-off indication threshold are different, thereby avoiding false alarms.

[0050] In addition, it can be understood that the controlled signal control logic of the first switch gating branch SW1 and the second switch gating branch SW2 may be different. At this time, the two switch gating branches can be controlled by the feedback control signal output by the comparator at the same time. In addition, the power supply voltage detection circuit in the embodiment of the present disclosure also includes an alarm signal processing circuit 50, which is arranged between the comparator and the inverter. It is used to receive the output signal of the comparator to confirm the power supply power-on / power-off detection alarm and output a corresponding signal. In this case, the controlled signal of the switch gating circuit is the output signal of the alarm signal processing circuit 50.

[0051] Combination Figure 5 As shown, the embodiment of the present disclosure provides another hysteresis type power supply voltage detection circuit, including a sampling circuit 10, a comparator 20 and a switch gating circuit 30. The sampling circuit 10 is connected to the power supply and is used to sample the power supply voltage to obtain a sampled voltage V SA The comparator 20 has an input terminal and a sampling voltage V SA The other input terminal is connected to the reference voltage V REF The switch gating circuit 30 includes two switch gating branches controlled by the feedback control signal and connected to the reference voltage V REF and comparator 10. Among them, the reference voltage V REF Including the first reference voltage V REF1 and the second reference voltage V REF2 Through the switch state control of the two switch gating branches, the comparator 20 and the first reference voltage V REF1 Or the second reference voltage V REF2 connect.

[0052] Here, the reference voltage V REF Including the first reference voltage V REF1 and the second reference voltage V REF2 . At the reference voltage V REF A switch gating circuit 30 is introduced between the comparator 20 and the comparator 20, and is controlled by the feedback control signal of the comparator 10. Different reference voltages are input into the comparator 10, so that the comparator 10 generates hysteresis by updating the reference voltage. As a result, the thresholds for the output signal of the comparator 10 to flip are different, that is, the power supply voltage power-on / power-off alarm threshold voltages are different.

[0053] Specifically, the switch gating circuit 30 includes two switch gating branches. One end of the first switch gating branch 31 is connected to the first reference voltage V REF1 , and the other end is connected to an input end of the comparator 20; one end of the second switch selection branch 32 is connected to the second reference voltage VREF2 , and the other end is connected to an input end of the comparator 10 together with the first switch gating branch 31. Based on the feedback control signal, the switch states of the two switch gating branches are controlled. When the power supply is powered on and powered off, the switch states of the two switch gating branches are different, so that the reference voltages of the power-on detection and the power-off detection are different. In this way, the power supply power-on / power-off alarm threshold voltages are different, and the comparator forms a hysteresis effect, thereby avoiding false alarms caused by the same threshold voltage.

[0054] The hysteresis type power supply voltage detection circuit provided by the embodiment of the present disclosure is used to set two reference voltages, and the reference voltage and the comparator are connected through a switch gating circuit. When the power supply voltage is detected, the switch gating circuit is controlled by the feedback control signal of the comparator so that the corresponding reference voltage is connected to the comparator. In this way, when the power supply is powered on / off, the power-on / power-off alarm threshold voltage is different, and the comparator forms a hysteresis effect. In addition, the occurrence of false alarms is avoided.

[0055] Optionally, the first reference voltage V REF1 Greater than the second reference voltage V REF2 .

[0056] In the embodiment of the present disclosure, the first reference voltage V REF1 and the second reference voltage V REF2 When the power is turned on, the first reference voltage V REF1 As the input signal of the comparator 10; when the sampling voltage V SA Reaching the first reference voltage V REF1 After that, the comparator 10 outputs a power-on detection alarm signal. Then, the second reference voltage V REF2 As the input signal of the comparator 10. Since the second reference voltage V REF2 Less than the first reference voltage V REF1 , so that the power-on indication threshold is greater than the power-off indication threshold. Therefore, after the power-on detection alarm, the comparator 10 forms a hysteresis effect. Only when the power supply is turned off, the sampling voltage reaches the second reference voltage V REF2 After that, the comparator 10 will output the power-off detection alarm signal. Before the power-off detection alarm signal is output, no false alarm will be generated, thus ensuring that the chip system can work normally.

[0057] In addition, it is not limited to the first reference voltage V REF1 Greater than the second reference voltage V REF2 It can also be a second reference voltage V REF2 Greater than the first reference voltage V REF1 .

[0058] Optionally, during power-on detection, the first switch selection branch SW1 is in an on state, and the second switch selection branch SW2 is in an off state.

[0059] Here, the first switch gate branch SW1 is connected to the first reference voltage V REF1 The second switch selection branch SW2 is connected to the second reference voltage V REF2 ; and the first reference voltage V REF1 Greater than the second reference voltage V REF2 Therefore, when the power is turned on, the first switch gating branch SW1 is turned on by default, that is, the first reference voltage V REF1 As the input signal of the comparator. The second switch gating branch SW2 is in the off state. After completing the power-on detection, the feedback control signal controls the state of the switch gating circuit, so that the first switch gating branch SW1 is turned off and the second switch gating branch SW2 is turned on. In this way, the comparison action of the comparator forms a hysteresis until the power supply voltage rises to the target value. Then, when the power supply starts to slowly power off, the power supply power-off detection alarm is completed.

[0060] Optionally, the power supply voltage detection circuit further includes an inverter 40, an input end of the inverter 40 is connected to an output end of the comparator 20 to invert the feedback control signal.

[0061] Wherein, when the switch state of the first switch gating branch SW1 is controlled by the feedback control signal output by the comparator 20 , the switch state of the second switch gating branch SW2 is controlled by the flipped feedback control signal.

[0062] In the disclosed embodiment, the controlled signal control logic of the first switch gating branch SW1 and the second switch gating branch SW2 is the same. Exemplarily, the first switch gating branch SW1 and the second switch gating branch SW2 are both turned on when the signal is high and turned off when the signal is low. In order to make the switch states of the first switch gating branch SW1 and the second switch gating branch SW2 different, an inverter 40 is provided here to flip the feedback control signal output by the comparator 20. In this way, two control signals with opposite logics are generated to control the two switch gating branches respectively, so that the switch states of the two switch gating branches are different.

[0063] Combination Figure 6 , the hysteresis type power supply voltage detection circuit and the working process are described in detail. The sampling voltage V of the sampling circuit 10 SA Connected to the inverting input terminal of the comparator 20. The first reference voltage V REF1 and the second reference voltage V REF2The input ends of the first switch gating branch SW1 and the second switch gating branch SW2 are connected respectively. The output ends of the first switch gating branch SW1 and the second switch gating branch SW2 are connected to the non-inverting input end of the comparator 20. The output end of the comparator 20 is connected to the control end of the first switch gating branch SW1, that is, the feedback control signal is used as the control signal of the first switch gating branch SW1. The output end of the inverter is connected to the control end of the second switch gating branch SW2, that is, the inverted feedback control signal is used as the control signal of the second switch gating branch SW2.

[0064] When the power supply starts to slowly power on, the first switch gating branch SW1 is in the on state, the second switch gating branch SW2 is in the off state, and the comparator 20 outputs a high level signal. SA Gradually rises to the first reference voltage V REF1 , the comparator 20 outputs a low level signal, and the inverter 40 outputs a high level signal. At this time, the detection circuit completes the power-on detection alarm, and the current power supply voltage is the power-on indication threshold V TH_ON At the same time, the first switch gating branch SW1 is controlled to be turned off, and the second switch gating branch SW2 is controlled to be turned on. The second reference voltage V REF2 The comparator 20 is connected. The comparison action of the comparator 20 forms a hysteresis until the power supply voltage rises to the target value. Then, the power supply is turned off and the power supply starts to power down slowly, and the sampling voltage slowly decreases from the target value until the sampling voltage drops to the second reference voltage V REF2 The comparator 20 outputs a high level signal, and the inverter 40 outputs a low level signal. At this time, the detection circuit completes the power-off detection alarm, and the current power supply voltage is the power-off indication threshold V TH OFF In this way, the power-on indication threshold and the power-off indication threshold are different, thereby avoiding false alarms.

[0065] Based on the aforementioned hysteresis type power supply voltage detection circuit; the embodiment of the present disclosure also discloses a hysteresis type power supply voltage detection method, including:

[0066] S101, when detecting the power supply voltage, obtaining a feedback control signal output by the comparator.

[0067] S102, according to the feedback control signal, controlling the switch state of each branch in the switch gating circuit to select the corresponding sampling voltage or reference voltage to make the comparator produce a hysteresis effect.

[0068] Combination Figure 4 and Figure 6When the power supply voltage is detected, the power supply is slowly powered on, the first switch selection branch of the switch selection circuit is turned on, and the comparator outputs a high level signal. As the sampling voltage rises to the reference voltage, the comparator outputs a low level signal. The first switch selection branch is controlled to be turned off by the level signal, and the second switch selection branch is controlled to be turned on by the level signal. Thereby, the reference voltage or the sampling voltage is updated, that is, the source of the reference voltage or the sampling voltage is switched, so that the threshold value of the comparator output signal flipping up and down is different to form a hysteresis effect. Furthermore, the power supply power-on / off alarm threshold V TH_ON and V TH_OFF No longer equal, avoiding the occurrence of "false alarm".

[0069] The embodiment of the present disclosure further discloses a power management unit, comprising the hysteresis power supply voltage detection circuit as described above.

[0070] The above description and the accompanying drawings sufficiently illustrate the embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Unless explicitly required, individual components and functions are optional, and the order of operations may vary. Portions and features of some embodiments may be included in or replace portions and features of other embodiments. The embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A hysteresis type power supply voltage detection circuit, characterized in that: include: A sampling circuit, connected to the power supply, for sampling the power supply voltage to obtain a sampled voltage; A comparator, one input terminal of which is connected to the sampling voltage, the other input terminal of which is connected to the reference voltage, and the output terminal of which outputs a feedback control signal; The switch gating circuit includes two switch gating branches controlled by the feedback control signal, connected between the sampling circuit and the comparator, and the connection points of the two switch gating branches and the sampling circuit are different; the sampling voltage is updated by controlling the switch states of the two switch gating branches.

2. The hysteresis type power supply voltage detection circuit according to claim 1, characterized in that: The sampling circuit includes a plurality of resistors connected in series to form a first sampling voltage and a second sampling voltage; The input end of the first switch gating branch of the switch gating circuit is connected to the first sampling voltage, the input end of the second switch gating branch is connected to the second sampling voltage, and the output end of the switch gating circuit is connected to an input end of the comparator.

3. The hysteresis type power supply voltage detection circuit according to claim 2, characterized in that: The first sampling voltage is greater than the second sampling voltage.

4. The hysteresis type power supply voltage detection circuit according to claim 3, characterized in that: During the power-on detection, the first switch selection branch is in an open state, and the second switch selection branch is in a closed state.

5. The hysteresis type power supply voltage detection circuit according to any one of claims 1 to 4, characterized in that: It also includes an inverter, wherein the input end of the inverter is connected to the output end of the comparator to flip the feedback control signal; Wherein, when the switch state of the first switch gating branch is controlled by the feedback control signal output by the comparator, the switch state of the second switch gating branch is controlled by the inverted feedback control signal output by the inverter.

6. A hysteresis type power supply voltage detection circuit, characterized in that: include: A sampling circuit, connected to the power supply, for sampling the power supply voltage to obtain a sampled voltage; A comparator, one input terminal of which is connected to the sampling voltage, the other input terminal of which is connected to the reference voltage, and the output terminal of which outputs a feedback control signal; A switch gating circuit, connected between the reference voltage and the comparator, comprising two switch gating branches controlled by the feedback control signal; Wherein, the reference voltage includes a first reference voltage and a second reference voltage; The other input terminal of the comparator is connected to the first reference voltage or the second reference voltage by controlling the switch states of the two switch selection branches.

7. The hysteresis type power supply voltage detection circuit according to claim 6, characterized in that: The first reference voltage is greater than the second reference voltage.

8. The hysteresis type power supply voltage detection circuit according to claim 7, characterized in that: During the power-on detection, the first switch selection branch is in an open state, so that the first reference voltage is used as an input signal of the comparator.

9. The hysteresis power supply voltage detection circuit according to any one of claims 6 to 8, characterized in that: It also includes an inverter, wherein the input end of the inverter is connected to the output end of the comparator to flip the feedback control signal; Wherein, when the switch state of the first switch gating branch is controlled by the feedback control signal output by the comparator, the switch state of the second switch gating branch is controlled by the flipped feedback control signal.

10. A hysteresis power supply voltage detection method, characterized in that: Based on the hysteresis power supply voltage detection circuit according to any one of claims 1 to 9; the method comprises: When detecting the power supply voltage, obtaining the feedback control signal output by the comparator; According to the feedback control signal, the switch state of each branch in the switch gating circuit is controlled to select the corresponding sampling voltage or reference voltage to make the comparator produce a hysteresis effect.

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