A power supply circuit and a temperature sensor

Abstract

This utility model relates to the field of power supply technology and discloses a power supply circuit and a temperature sensor, including: an energy storage circuit, a first switching circuit, a regulated power supply, a comparator circuit, and a second switching circuit. By setting up the energy storage circuit and the first switching circuit, the first switching circuit is turned on only when the voltage of the energy storage circuit reaches the turn-on voltage of the first switching circuit, and the DC voltage is then delivered to the regulated power supply, thereby avoiding leakage current in the downstream equipment.

Description

Technical Field

[0001] This utility model relates to the field of power supply technology, specifically to a power supply circuit and a temperature sensor. Background Technology

[0002] In power systems, there are numerous temperature measurement scenarios requiring long-term maintenance-free operation and no need for batteries or other external power sources, such as cable joints, switchgear, transformer bushings, and busbar connections—areas prone to heat generation. Therefore, inductively coupled temperature sensors that obtain energy by sensing line current have become widely used.

[0003] The core principle of this type of sensor is to use a coil to induce current in a current-carrying circuit to charge a capacitor; the capacitor stores energy to power subsequent circuits, and the sensor can only work stably when the charging speed is faster than the discharging speed.

[0004] During this process, controlling or reducing the leakage current of the entire circuit is crucial—because the subsequent circuits are not yet functioning properly during the charging phase, and the discharge at this time is mainly caused by the leakage current of each component. Typically, the sensor can function normally when a small current of 5A flows through the circuit; however, if the leakage current is too large, the sensor will enter a state of charge-discharge equilibrium or even a state where discharge exceeds charging. In this case, unless the circuit current is increased to boost the capacitor's charging current, the sensor will not function properly. Utility Model Content

[0005] In view of this, the present invention provides a power supply circuit and a temperature sensor to solve the problem of how to achieve stable start-up under low current sensing power conditions.

[0006] In a first aspect, this utility model provides a power supply circuit, comprising: an energy storage circuit, a first switching circuit, a regulated power supply, a comparator circuit, and a second switching circuit. The first terminal of the energy storage circuit is connected to a positive DC voltage, and the second terminal of the energy storage circuit is connected to a negative DC voltage and then grounded. The first terminal of the first switching circuit is connected to the first terminal of the energy storage circuit, the second terminal of the first switching circuit is connected to the first terminal of the regulated power supply, and the control terminal of the first switching circuit is connected to the second terminal of the energy storage circuit. The ground terminal of the regulated power supply is connected to the second terminal of the energy storage circuit. The first terminal of the comparator circuit is connected to the second terminal of the regulated power supply, the second terminal of the comparator circuit is connected to the third terminal of the regulated power supply, the positive power supply terminal of the comparator circuit is connected to the second terminal of the regulated power supply, and the negative power supply terminal of the comparator circuit is grounded. The first terminal of the second switching circuit is connected to the second terminal of the regulated power supply, the second terminal of the second switching circuit is grounded, the control terminal of the second switching circuit is connected to the third terminal of the comparator circuit, and the third terminal of the second switching circuit outputs a power supply voltage.

[0007] By setting up an energy storage circuit and a first switching circuit, the first switching circuit is only turned on when the voltage of the energy storage circuit reaches the turn-on voltage of the first switching circuit, and the DC voltage is then delivered to the regulated power supply, thereby avoiding leakage current in the downstream equipment.

[0008] In one alternative implementation, the energy storage circuit includes an energy storage capacitor.

[0009] In one optional embodiment, the first switching circuit includes: a first resistor, a second resistor, and a first transistor, wherein a first end of the first resistor is connected to a first end of the energy storage circuit and a first end of the first transistor, a second end of the first resistor is connected to a control terminal of the first transistor and a first end of the second resistor; a second end of the second resistor is grounded to a second end of the energy storage circuit; and a second end of the first transistor is connected to a first end of the regulated power supply.

[0010] In one optional embodiment, the regulated power supply includes: a linear voltage regulator chip and a plurality of filter capacitors, wherein a first terminal of the linear voltage regulator chip is connected to a second terminal of a first switching circuit, a second terminal of the linear voltage regulator chip is connected to a first terminal of a comparator circuit and a first terminal of a second switching circuit, and a ground terminal of the linear voltage regulator chip is connected to a second terminal of an energy storage circuit; the plurality of filter capacitors are connected in parallel between the first terminal of the linear voltage regulator chip and the ground terminal of the linear voltage regulator chip.

[0011] In one optional embodiment, the comparator circuit includes: a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a comparator, a first capacitor, a second capacitor, and a first diode. The first terminal of the third resistor is connected to the second terminal of the first switching circuit, and the second terminal of the third resistor is connected to the first terminal of the first capacitor, the first terminal of the fourth resistor, and the positive input terminal of the comparator. The second terminal of the fourth resistor is connected to the second terminal of the first capacitor and the second terminal of the energy storage circuit. The first terminal of the fifth resistor is connected to the second terminal of the regulated power supply, and the second terminal of the fifth resistor is connected to the first terminal of the second capacitor, the first terminal of the sixth resistor, and the inverting input terminal of the comparator. The second terminal of the sixth resistor is connected to the second terminal of the second capacitor and the second terminal of the energy storage circuit. The positive power supply terminal of the comparator's comparison circuit is connected to the second terminal of the regulated power supply, the negative power supply terminal of the comparator is grounded, and the output terminal of the comparator is connected to the anode of the first diode. The cathode of the first diode is connected to the first terminal of the seventh resistor. The second terminal of the seventh resistor is connected to the control terminal of the second switching circuit.

[0012] In one optional embodiment, the second switching circuit includes: an eighth resistor, a ninth resistor, a tenth resistor, a second transistor, a third capacitor, a third transistor, and a second diode. The first terminal of the second transistor is connected to the third terminal of the regulated power supply and the first terminal of the eighth resistor. The second terminal of the second transistor outputs the supply voltage. The second terminal of the second transistor is connected to the anode of the second diode. The control terminal of the second transistor is connected to the second terminal of the eighth resistor and the first terminal of the third transistor. The second terminal of the third transistor is grounded. The control terminal of the third transistor is connected to the second terminal of the ninth resistor, the first terminal of the tenth resistor, the first terminal of the third capacitor, and the third terminal of the comparator circuit. The cathode of the second diode is connected to the first terminal of the ninth resistor. The second terminal of the tenth resistor is connected to the second terminal of the third capacitor and the second terminal of the third transistor.

[0013] In one alternative embodiment, the power supply circuit further includes a third diode, wherein the cathode of the third diode is connected to a first terminal of the energy storage circuit, and the anode of the third diode is connected to a second terminal of the energy storage circuit.

[0014] In one optional embodiment, the power supply circuit further includes an induction coil and a rectifier circuit, wherein the first end and the second end of the induction coil output a positive DC voltage and a negative DC voltage, respectively; the first end of the rectifier circuit is connected to the first end of the induction coil, and the second end of the rectifier circuit is connected to the first end of the energy storage circuit.

[0015] In one alternative implementation, the rectifier circuit includes a fourth diode, wherein the anode of the fourth diode is connected to a first terminal of the induction coil, and the cathode of the fourth diode is connected to a first terminal of the energy storage circuit.

[0016] Secondly, this utility model provides a temperature sensor, comprising: a power supply circuit and a temperature sensing chip according to the first aspect and any optional embodiment thereof, wherein a first terminal of an energy storage circuit is connected to a positive DC voltage, and a second terminal of the energy storage circuit is connected to a negative DC voltage and grounded; a first terminal of a first switching circuit is connected to the first terminal of the energy storage circuit, a second terminal of the first switching circuit is connected to the first terminal of a regulated power supply, and a control terminal of the first switching circuit is connected to the second terminal of the energy storage circuit; a ground terminal of the regulated power supply is connected to the second terminal of the energy storage circuit; a first terminal of a comparator circuit is connected to the second terminal of the regulated power supply, a second terminal of the comparator circuit is connected to the first terminal of the regulated power supply, a positive power supply terminal of the comparator circuit is connected to the second terminal of the regulated power supply, and a negative power supply terminal of the comparator circuit is grounded; a first terminal of a second switching circuit is connected to the third terminal of the regulated power supply, a second terminal of the second switching circuit is grounded, a control terminal of the second switching circuit is connected to the third terminal of the comparator circuit, and a third terminal of the second switching circuit is connected to the power supply terminal of the temperature sensing chip. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a diagram illustrating the composition of the power supply circuit according to an embodiment of the present utility model;

[0019] Figure 2 This is a circuit diagram of the power supply circuit according to an embodiment of the present utility model;

[0020] Figure 3 This is a circuit diagram of a temperature sensing chip according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0022] This embodiment provides a power supply circuit, such as Figure 1 As shown, it includes: energy storage circuit 1, first switching circuit 2, regulated power supply 3, comparator circuit 4, and second switching circuit 5.

[0023] The first terminal of the energy storage circuit 1 is connected to a positive DC voltage, and the second terminal of the energy storage circuit 1 is connected to a negative DC voltage and then grounded. The first terminal of the first switching circuit 2 is connected to the first terminal of the energy storage circuit 1, the second terminal of the first switching circuit 2 is connected to the first terminal of the regulated power supply 3, and the control terminal of the first switching circuit 2 is connected to the second terminal of the energy storage circuit 1. The ground terminal of the regulated power supply 3 is connected to the second terminal of the energy storage circuit 1. The first terminal of the comparator circuit 4 is connected to the second terminal of the regulated power supply 3, the second terminal of the comparator circuit 4 is connected to the first terminal of the regulated power supply 3, the positive power supply terminal of the comparator circuit 4 is connected to the second terminal of the regulated power supply 3, and the negative power supply terminal of the comparator circuit 4 is grounded. The first terminal of the second switching circuit 5 is connected to the third terminal of the regulated power supply 3, the second terminal of the second switching circuit 5 is grounded, the control terminal of the second switching circuit 5 is connected to the third terminal of the comparator circuit 4, and the third terminal of the second switching circuit 5 outputs the supply voltage.

[0024] Specifically, DC voltage can be the voltage obtained by converting the alternating current induced by the induction coil into direct current.

[0025] Specifically, during the initial startup phase of the power supply circuit, the following situations exist:

[0026] (1) DC voltage charges the energy storage circuit 1. When the voltage of the energy storage circuit 1 does not reach the opening voltage of the first switch circuit 2, the first switch circuit 2 is disconnected. At this time, the regulated power supply 3 is in the off state, and the second switch circuit 5 is in the off state and does not output the supply voltage.

[0027] (2) DC voltage charges the energy storage circuit 1. When the voltage of the energy storage circuit 1 reaches the open state of the first switch circuit 2, the first switch circuit 2 is turned on. At this time, the regulated power supply 3 is turned on and outputs voltage. The comparison circuit 4 compares the preset voltage threshold and the output voltage. When the input voltage of the regulated power supply 3 is higher than the preset voltage threshold, the comparison circuit 4 outputs a conduction signal to the second switch circuit 5. The second switch circuit 5 is turned on and outputs the power supply voltage.

[0028] (3) DC voltage charges the energy storage circuit 1. When the voltage of the energy storage circuit 1 reaches the open state of the first switch circuit 2, the first switch circuit 2 is turned on. At this time, the regulated power supply 3 is in the open state and outputs voltage. The comparison circuit 4 compares the preset voltage threshold and the output voltage. When the input voltage of the regulated power supply 3 is lower than the preset voltage threshold, the comparison circuit 4 outputs a shutdown signal to the second switch circuit 5. The second switch circuit 5 is in the shutdown state and does not output power supply voltage.

[0029] Based on the above analysis, when the DC voltage is a very small induced voltage, in order to avoid the regulated power supply 3 working whenever the energy storage circuit 1 is charging, which would cause leakage current at the device to be powered, a first switching circuit 2 is set up. The first switching circuit 2 will only be turned on and the regulated power supply 3 can only start when the voltage of the energy storage circuit 1 reaches the turn-on voltage of the first switching circuit 2.

[0030] In one alternative implementation, such as Figure 2 As shown, the energy storage circuit 1 includes an energy storage capacitor CIN.

[0031] In one alternative implementation, such as Figure 2 As shown, the first switching circuit 2 includes: a first resistor R1, a second resistor R2, and a first transistor Q1. The first end of the first resistor R1 is connected to the first end of the energy storage circuit 1 (i.e., CIN) and the first end of the first transistor Q1. The second end of the first resistor R1 is connected to the control terminal of the first transistor Q1 and the first end of the second resistor R2. The second end of the second resistor R2 is grounded to the second end of the energy storage circuit 1. The second end of the first transistor Q1 is connected to the first end of the regulated power supply 3 (i.e., U1).

[0032] Specifically, when the electrical signal output by the energy storage circuit 1 is transmitted to the gate of Q1 through R1, the voltage divider network composed of R1 and R2 will adjust the gate potential, thereby controlling the conduction and cutoff of the transistor: when the gate potential reaches the conduction threshold, a path is formed between the source and drain of Q1, and the energy storage circuit 1 and the regulated power supply 3 realize energy interaction through the transistor; when the gate potential is lower than the threshold, the transistor is cut off, cutting off the connection between the two, thereby realizing the switching control function of the circuit.

[0033] In one alternative implementation, such as Figure 2 As shown, the regulated power supply 3 includes: a linear voltage regulator chip U1 and multiple filter capacitors (C5, C6). The first terminal of the linear voltage regulator chip U1 is connected to the second terminal of the first switching circuit 2 (i.e., Q1), the second terminal of the linear voltage regulator chip U1 is connected to the first terminal of the comparator circuit 4 (i.e., R5) and the first terminal of the second switching circuit 5 (i.e., Q2), and the ground terminal of the linear voltage regulator chip U1 is connected to the second terminal of the energy storage circuit 1 (i.e., CIN). The multiple filter capacitors are connected in parallel between the first terminal of the linear voltage regulator chip U1 and the ground terminal of the linear voltage regulator chip U1.

[0034] Specifically, multiple filter capacitors (C5, C6) are connected in parallel to the circuit, specifically between the first terminal (input terminal) of the linear regulator chip U1 and the ground terminal. This parallel structure has a significant synergistic filtering effect: from the perspective of capacitor characteristics, capacitors of different capacitance values ​​have different abilities to suppress ripple noise at different frequencies (for example, if C5 is an electrolytic capacitor, it can filter out low-frequency ripple, while if C6 is a ceramic capacitor, it focuses on suppressing high-frequency noise). The parallel connection of the two can cover a wider frequency range and effectively smooth the voltage fluctuations at the input terminal of U1. When the first switching circuit 2 causes ripple in the input voltage due to switching action, the filter capacitor will absorb the voltage peak and replenish the voltage valley through the charging and discharging process, converting the fluctuating input voltage into a relatively smooth DC signal, providing a more stable input basis for the voltage regulation operation of U1, and avoiding output voltage instability caused by sudden changes in input voltage.

[0035] From an overall functional perspective, the regulated power supply 3 achieves dual voltage regulation through a collaborative mechanism of "linear voltage regulator chip U1 regulation + filter capacitor smoothing": U1 dynamically adjusts the output through its internal reference voltage and error amplifier circuit, ensuring that the output voltage is unaffected by input voltage fluctuations and load changes; while the parallel filter capacitor suppresses input noise at the source, creating favorable conditions for the precise regulation of U1. This module acts as a "voltage purification station" in the circuit system, both receiving energy from the first switching circuit 2 and providing high-quality and stable power to the subsequent comparator circuit 4 and the second switching circuit 5, making it a crucial link in ensuring the reliable operation of the entire circuit system.

[0036] In one alternative implementation, such as Figure 2As shown, the comparator circuit 4 includes: a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a comparator U2, a first capacitor C1, a second capacitor C2, and a first diode D1. The first terminal of the third resistor R3 is connected to the second terminal of the first switching circuit 2 (i.e., Q1). The second terminal of the third resistor R3 is connected to the first terminal of the first capacitor C1, the first terminal of the fourth resistor R4, and the positive input terminal of the comparator U2. The second terminal of the fourth resistor R4 is connected to the second terminal of the first capacitor C1 and the second terminal of the energy storage circuit 1 (i.e., CIN). The first terminal of the fifth resistor R5 is connected to the regulated power supply 3 (…). The second end of U1 is connected; the second end of the fifth resistor R5 is connected to the first end of the second capacitor C2, the first end of the sixth resistor R6, and the inverting input of comparator U2; the second end of the sixth resistor R6 is connected to the second end of the second capacitor C2 and the second end of the energy storage circuit 1; the positive power supply terminal of the comparator circuit 4 of comparator U2 is connected to the second end of the regulated power supply 3; the negative power supply terminal of comparator U2 is grounded; the output terminal of comparator U2 is connected to the anode of the first diode D1; the cathode of the first diode D1 is connected to the first end of the seventh resistor R7; and the second end of the seventh resistor R7 is connected to the control terminal of the second switching circuit 5 (i.e., Q3).

[0037] Specifically, the first terminal of the third resistor R3 is connected to the second terminal of the first switching circuit 2, meaning that R3 receives the dynamic voltage signal processed by the first switching circuit 2. The second terminal of R3 forms a positive sampling node, which is simultaneously connected to the first terminal of the first capacitor C1, the first terminal of the fourth resistor R4, and the positive input (non-inverting input) of comparator U2. This connection allows R3 to perform a dual function of current limiting and voltage division: on the one hand, it limits the current intensity of the input signal to prevent excessive current from impacting the input terminal of comparator U2; on the other hand, it cooperates with subsequent components to form a signal conditioning circuit.

[0038] Specifically, the first capacitor C1 and the fourth resistor R4 form a positive input RC filter network: the second end of C1 and the second end of R4 are connected to the second end (ground end) of the energy storage circuit 1, so that C1 can filter out the high frequency ripple in the signal transmitted by R3 through charging and discharging, while R4 stabilizes the filtered voltage signal by impedance matching with C1, and finally provides a smooth and stable sampling voltage for the non-inverting input of comparator U2.

[0039] Specifically, the reverse reference circuit is symmetrical to the forward sampling circuit: the first end of the fifth resistor R5 is connected to the second end of the regulated power supply 3 (stable output voltage VCC), and its second end forms the reverse reference node. This node is connected to the first end of the second capacitor C2, the first end of the sixth resistor R6, and the inverting input (inverting terminal) of the comparator U2. R5 and R6 form a voltage divider circuit, which proportionally divides the output voltage of the regulated power supply 3 to form a stable reference voltage. The second capacitor C2 is connected in parallel across its two ends (the other end is grounded), further filtering out minor fluctuations in the reference voltage and ensuring its stability.

[0040] Specifically, when the voltage at the non-inverting input of comparator U2 is higher than the voltage at the inverting input, comparator U2 outputs a high level; otherwise, it outputs a low level. This high and low level signal will be transmitted to subsequent circuits as a control command.

[0041] Specifically, in the signal output path, the output terminal of comparator U2 is connected to the anode of the first diode D1, and the cathode of D1 is connected to the first terminal of the seventh resistor R7. D1 acts as a unidirectional conductor here: it only allows the positive signal output by comparator U2 to pass through, preventing reverse current from flowing back to the output terminal of comparator U2, thus protecting comparator U2 from reverse voltage damage. The second terminal of the seventh resistor R7 is directly connected to the control terminal of the second switching circuit 5. Its main function is current limiting; by limiting the current flowing into the control terminal of the second switching circuit 5, it prevents damage to the switching elements due to instantaneous large currents.

[0042] In one alternative implementation, such as Figure 2 As shown, the second switching circuit 5 includes: an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a second transistor Q2, a third capacitor C3, a third transistor Q3, and a second diode D2. The first terminal of the second transistor Q2 is connected to the third terminal of the regulated power supply 3 (i.e., U1) and the first terminal of the eighth resistor R8. The second terminal of the second transistor Q2 outputs the supply voltage. The second terminal of the second transistor Q2 is connected to the anode of the second diode D2. The control terminal of the second transistor Q2 is connected to the second terminal of the eighth resistor R8 and the first terminal of the third transistor Q3. The second terminal of the third transistor Q3 is grounded. The control terminal of the third transistor Q3 is connected to the second terminal of the ninth resistor R9, the first terminal of the tenth resistor R10, the first terminal of the third capacitor C3, and the third terminal of the comparator circuit 4 (i.e., R7). The cathode of the second diode D2 is connected to the first terminal of the ninth resistor R9. The second terminal of the tenth resistor R10 is connected to the second terminal of the third capacitor C3 and the second terminal of the third transistor Q3.

[0043] Specifically, the third transistor Q3 acts as the driving switch for Q2, with its second terminal directly connected to ground, forming a defined current loop reference point. The control terminal of Q3 constitutes a composite control node, which is simultaneously connected to the second terminal of the ninth resistor R9, the first terminal of the tenth resistor R10, the first terminal of the third capacitor C3, and the third terminal of the comparator circuit 4. This means that the base signal of Q3 comes directly from the control command of the comparator circuit 4 and is simultaneously regulated by the circuit network composed of R9, R10, and C3.

[0044] Specifically, the cathode of the second diode D2 is connected to the first terminal of the ninth resistor R9, forming a feedback path from Q2 to Q3. When Q2 is on, the output voltage is transmitted to Q3 through D2 and R9, acting as a clamp to prevent the gate voltage of Q3 from being too high; when Q2 is off, D2 is reverse-biased, preventing reverse current from affecting the output. The second terminal of the tenth resistor R10 and the second terminal of the third capacitor C3 are connected to the gate (grounded) of Q3. The two are connected in parallel to form an RC filter network. C3 filters out high-frequency noise in the output signal of the comparator circuit 4 through charging and discharging, while R10 stabilizes the filtered control signal through impedance matching with C3, preventing Q3 from being falsely triggered due to signal fluctuations.

[0045] Specifically, when the comparator circuit 4 outputs a high-level signal, the signal is transmitted to the gate of Q3 through R7, causing Q3 to conduct. At this time, the gate of Q2 is pulled to ground potential, Q2 is cut off, and there is no voltage output at the output terminal. When the comparator circuit 4 outputs a low-level signal, the gate of Q3 is cut off due to the lack of driving current. The regulated power supply 3 provides bias current to the base of Q2 through R8, causing Q2 to conduct, and the output terminal outputs a stable supply voltage.

[0046] In one alternative implementation, such as Figure 2 As shown, the power supply circuit also includes a third diode D3, wherein the cathode of the third diode D3 is connected to the first terminal of the energy storage circuit 1, and the anode of the third diode D3 is connected to the second terminal of the energy storage circuit 1.

[0047] Specifically, the core function of D3 is to prevent reverse voltage or reverse discharge in the energy storage circuit 1. When the energy storage circuit 1 is working normally, its first terminal outputs a positive voltage (relative to the second terminal being grounded). At this time, D3 is in a reverse bias state (cathode voltage is higher than anode voltage), exhibiting high-impedance cutoff characteristics. It will not affect the normal charging and discharging process of the energy storage circuit 1, ensuring that the energy storage circuit 1 can stably supply power to subsequent modules (such as the regulated power supply 3 and the comparator circuit 4) through the first switching circuit 2.

[0048] When abnormal situations occur (such as reverse polarity of energy storage circuit 1, external circuit faults causing reverse voltage to be applied across energy storage circuit 1, or reverse electromotive force generated due to induction after energy storage circuit 1 has finished discharging), the cathode voltage of D3 will be lower than the anode voltage, causing it to enter the forward conduction state. At this time, D3 exhibits low resistance characteristics, quickly discharging the reverse voltage to the ground terminal through the anode, preventing the reverse voltage from spreading along the first terminal of energy storage circuit 1 to the first switching circuit 2, the regulated power supply 3, and other front-end modules, thereby protecting the transistors, chips, and other components in these modules from reverse voltage breakdown damage.

[0049] In one optional embodiment, the power supply circuit further includes an induction coil and a rectifier circuit, wherein the first end and the second end of the induction coil output a positive DC voltage and a negative DC voltage, respectively; the first end of the rectifier circuit is connected to the first end of the induction coil, and the second end of the rectifier circuit is connected to the first end of the energy storage circuit 1.

[0050] In one alternative implementation, such as Figure 2 As shown, the rectifier circuit includes a fourth diode D2, wherein the anode of the fourth diode D2 is connected to the first end of the induction coil, and the cathode of the fourth diode D2 is connected to the first end of the energy storage circuit 1.

[0051] In a practical application, based on Figure 2 P1 and P2 are the output terminals of the induction coil, which charge CIN after rectification by D4. The resistance values ​​of R1 and R2 determine the value of VIN when the PMOS transistor (Q1) is turned on. After Q1 is turned on, the LDO chip (U1) outputs VCC. The two voltage groups of R3, R4 and R5, R6 determine the value of VIN+ through comparator U2. When VIN+ is higher than a certain value, U2 outputs a high level, Q2 and Q3 are turned on, and VD is powered. Figure 3 U3 is used in the process.

[0052] If Q1, R1, and R2 are not included in the circuit, CIN will supply power to U1 during charging. Since the LDO chip and comparator U2 have low-voltage follower characteristics, Q2 and Q3 may be turned on. When Q2 and Q3 are on, VD is energized, and power begins to supply U3. At this point, the leakage current of the entire circuit will increase. Because the induced voltage is very small at low current, the charging current to CIN will be relatively small, placing high demands on the leakage current of all subsequent components. If a regular LDO is chosen for U1, there will generally be several hundred μA of leakage current during the period from 0V to its operating state. Combined with the current consumed by U3 and other components, charging will not be as fast as discharging, causing the sensor to malfunction. In this case, U1 must be an LDO with a leakage current of only a few μA during the period from 0V to its operating state, which limits the selection. The leakage current of the components also changes with temperature; at high and low temperatures, there is a probability that the sensor will fail to start at low current. The purpose of adding Q1, R1, and R2 is to prevent power supply to subsequent circuits until CIN is charged to a certain voltage, thus preventing simultaneous charging and discharging. Only after the set voltage value is reached will the subsequent circuits start supplying power to the sensor to begin operation. Adding Q1, R1, and R2 reduces the limitations on the selection of components such as LDOs, allowing for a wider range of choices. The sensor's operation will also be more stable at low currents.

[0053] This embodiment provides a temperature sensor, including: the power supply circuit and temperature sensing chip U3 mentioned above. The first terminal of the energy storage circuit 1 is connected to a positive DC voltage, and the second terminal of the energy storage circuit 1 is connected to a negative DC voltage and grounded. The first terminal of the first switching circuit 2 is connected to the first terminal of the energy storage circuit 1, the second terminal of the first switching circuit 2 is connected to the first terminal of the regulated power supply 3, and the control terminal of the first switching circuit 2 is connected to the second terminal of the energy storage circuit 1. The ground terminal of the regulated power supply 3 is connected to the second terminal of the energy storage circuit 1. The first terminal of the comparison circuit 4 is connected to the second terminal of the regulated power supply 3, the second terminal of the comparison circuit 4 is connected to the first terminal of the regulated power supply 3, the positive power supply terminal of the comparison circuit 4 is connected to the second terminal of the regulated power supply 3, and the negative power supply terminal of the comparison circuit 4 is grounded. The first terminal of the second switching circuit 5 is connected to the third terminal of the regulated power supply 3, the second terminal of the second switching circuit 5 is grounded, the control terminal of the second switching circuit 5 is connected to the third terminal of the comparison circuit 4, and the third terminal of the second switching circuit 5 is connected to the power supply terminal of the temperature sensing chip U3.

[0054] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A power supply circuit, characterized by comprising: include: The circuit consists of an energy storage circuit, a first switching circuit, a regulated power supply, a comparator circuit, and a second switching circuit. The first terminal of the energy storage circuit is connected to a positive DC voltage, and the second terminal of the energy storage circuit is connected to a negative DC voltage and then grounded. The first terminal of the first switching circuit is connected to the first terminal of the energy storage circuit, the second terminal of the first switching circuit is connected to the first terminal of the regulated power supply, and the control terminal of the first switching circuit is connected to the second terminal of the energy storage circuit. The ground terminal of the regulated power supply is connected to the second terminal of the energy storage circuit; The first terminal of the comparator circuit is connected to the second terminal of the regulated power supply, the second terminal of the comparator circuit is connected to the first terminal of the regulated power supply, the positive power supply terminal of the comparator circuit is connected to the second terminal of the regulated power supply, and the negative power supply terminal of the comparator circuit is grounded. The first terminal of the second switching circuit is connected to the third terminal of the regulated power supply, the second terminal of the second switching circuit is grounded, the control terminal of the second switching circuit is connected to the third terminal of the comparator circuit, and the third terminal of the second switching circuit outputs the supply voltage.

2. The power supply circuit according to claim 1, characterized in that, The energy storage circuit includes an energy storage capacitor.

3. The power supply circuit of claim 1, wherein, The first switching circuit includes: a first resistor, a second resistor, and a first transistor, wherein, The first end of the first resistor is connected to the first end of the energy storage circuit and the first end of the first transistor, and the second end of the first resistor is connected to the control terminal of the first transistor and the first end of the second resistor. The second terminal of the second resistor is grounded to the second terminal of the energy storage circuit; The second terminal of the first transistor is connected to the first terminal of the regulated power supply.

4. The power supply circuit of claim 2, wherein, The regulated power supply includes: a linear voltage regulator chip and multiple filter capacitors, wherein, The first terminal of the linear voltage regulator chip is connected to the second terminal of the first switching circuit, the second terminal of the linear voltage regulator chip is connected to the first terminal of the comparator circuit and the first terminal of the second switching circuit, and the ground terminal of the linear voltage regulator chip is connected to the second terminal of the energy storage circuit. The plurality of filter capacitors are connected in parallel between the first terminal of the linear voltage regulator chip and the ground terminal of the linear voltage regulator chip.

5. The power supply circuit according to claim 1, characterized in that, The comparator circuit includes: a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a comparator, a first capacitor, a second capacitor, and a first diode, wherein... The first end of the third resistor is connected to the second end of the first switching circuit, and the second end of the third resistor is connected to the first end of the first capacitor, the first end of the fourth resistor, and the positive input end of the comparator, respectively. The second end of the fourth resistor is connected to the second end of the first capacitor and the second end of the energy storage circuit. The first end of the fifth resistor is connected to the second end of the regulated power supply, and the second end of the fifth resistor is connected to the first end of the second capacitor, the first end of the sixth resistor, and the inverting input of the comparator. The second end of the sixth resistor is connected to the second end of the second capacitor and the second end of the energy storage circuit. The positive power supply terminal of the comparator's comparison circuit is connected to the second terminal of the regulated power supply, the negative power supply terminal of the comparator is grounded, and the output terminal of the comparator is connected to the anode of the first diode. The cathode of the first diode is connected to the first end of the seventh resistor; The second end of the seventh resistor is connected to the control terminal of the second switching circuit.

6. The power supply circuit according to claim 1, characterized in that, The second switching circuit includes: an eighth resistor, a ninth resistor, a tenth resistor, a second transistor, a third capacitor, a third transistor, and a second diode, wherein, The first terminal of the second transistor is connected to the third terminal of the regulated power supply and the first terminal of the eighth resistor. The second terminal of the second transistor outputs the supply voltage. The second terminal of the second transistor is connected to the anode of the second diode. The control terminal of the second transistor is connected to the second terminal of the eighth resistor and the first terminal of the third transistor. The second terminal of the third transistor is grounded, and the control terminal of the third transistor is connected to the second terminal of the ninth resistor, the first terminal of the tenth resistor, the first terminal of the third capacitor, and the third terminal of the comparator circuit. The cathode of the second diode is connected to the first terminal of the ninth resistor; The second terminal of the tenth resistor is connected to the second terminal of the third capacitor and the second terminal of the third transistor.

7. The power supply circuit according to claim 1, characterized in that, Also includes: The third diode, of which... The cathode of the third diode is connected to the first terminal of the energy storage circuit, and the anode of the third diode is connected to the second terminal of the energy storage circuit.

8. The power supply circuit according to any one of claims 1-7, characterized in that, Also includes: Induction coil and rectifier circuit, among which, The first and second ends of the induction coil output the positive DC voltage and the negative DC voltage, respectively. The first end of the rectifier circuit is connected to the first end of the induction coil, and the second end of the rectifier circuit is connected to the first end of the energy storage circuit.

9. The power supply circuit according to claim 8, characterized in that, The rectifier circuit includes: a fourth diode, wherein, The anode of the fourth diode is connected to the first end of the induction coil, and the cathode of the fourth diode is connected to the first end of the energy storage circuit.

10. A temperature sensor, characterized in that, include: The power supply circuit and temperature sensing chip according to any one of claims 1-9, wherein, The first terminal of the energy storage circuit is connected to a positive DC voltage, and the second terminal of the energy storage circuit is connected to a negative DC voltage and then grounded. The first terminal of the first switching circuit is connected to the first terminal of the energy storage circuit, the second terminal of the first switching circuit is connected to the first terminal of the regulated power supply, and the control terminal of the first switching circuit is connected to the second terminal of the energy storage circuit. The ground terminal of the regulated power supply is connected to the second terminal of the energy storage circuit; The first terminal of the comparator circuit is connected to the second terminal of the regulated power supply, the second terminal of the comparator circuit is connected to the first terminal of the regulated power supply, the positive power supply terminal of the comparator circuit is connected to the second terminal of the regulated power supply, and the negative power supply terminal of the comparator circuit is grounded. The first terminal of the second switching circuit is connected to the third terminal of the regulated power supply, the second terminal of the second switching circuit is grounded, the control terminal of the second switching circuit is connected to the third terminal of the comparator circuit, and the third terminal of the second switching circuit is connected to the power supply terminal of the temperature sensing chip.

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