DC-DC conversion circuit and output overvoltage self-locking circuit thereof

Abstract

The utility model provides a DC-DC conversion circuit and an output overvoltage self-locking circuit thereof, the output overvoltage self-locking circuit comprises a voltage-regulator tube D1, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a switching tube Q1, the negative electrode of the voltage-regulator tube D1 is connected with a node A, and the positive electrode of the voltage-regulator tube D1 is connected with a node B through the resistor R2; one end of the resistor R4 is connected with the node B, and the other end is grounded; one end of the resistor R1 is connected with the power supply end, and the other end is connected with the node C; one end of the resistor R3 is connected with the node C, and the other end is grounded; the first connecting end of the switch tube Q1 is connected with the node C, the second connecting end is grounded, and the control end is connected with the node B; the node C is connected with the enabling end of the DCDC chip; and the node A is connected with the output voltage of the DCDC chip. Compared with the prior art, the overvoltage protection circuit can set an overvoltage protection value, and when the output voltage value of the DCDC exceeds the set overvoltage protection value, the DCDC output can be automatically closed, so that the overvoltage protection effect is achieved, and the overvoltage protection circuit has flexibility.

Description

[Technical field]

[0001] The utility model relates to the technical field of circuit design, in particular to a direct current-to-direct current conversion circuit and an output overvoltage self-locking circuit thereof. [Background technology]

[0002] DCDC (DC-DC converter) is a voltage conversion chip, and its output end supplies power to the subsequent stage. Some DCDC chips have an output overvoltage protection function, and the overvoltage value is fixed and cannot be adjusted; some DCDC chips do not have an overvoltage protection function, and the output voltage is too high, which may damage the DCDC subsequent circuit. Therefore, DCDC output overvoltage protection is very important. Among them, DCDC refers to a device that converts a DC power supply of a certain voltage level into a DC power supply of other voltage levels.

[0003] For DCDC chips with overvoltage protection function, the overvoltage value is fixed and cannot be adjusted, and the overvoltage protection voltage value cannot be set according to actual needs; most DCDC chips do not have overvoltage protection function, and excessive output voltage will pose a risk of damaging the DCDC post-stage circuit.

[0004] Therefore, it is necessary to propose a new technical solution to solve the above problems. [Utility Model Content]

[0005] One of the purposes of the utility model is to provide a DC-DC conversion circuit and an output overvoltage self-locking circuit thereof, which can set an overvoltage protection value according to actual needs. When the output voltage value of DCDC exceeds the set overvoltage protection value, the DCDC output can be automatically turned off, thereby playing an overvoltage protection role and having flexibility.

[0006] According to one aspect of the utility model, the utility model provides an output overvoltage self-locking circuit of a DC-DC conversion circuit, which includes a voltage regulator tube D1, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a switch tube Q1, wherein the negative electrode of the voltage regulator tube D1 is connected to the node A, and the positive electrode thereof is connected to the node B via the resistor R2; one end of the resistor R4 is connected to the node B, and the other end thereof is grounded; one end of the resistor R1 is connected to the power supply end VDD1, and the other end thereof is connected to the node C; one end of the resistor R3 is connected to the node C, and the other end thereof is grounded; the first connection end of the switch tube Q1 is connected to the node C, the second connection end thereof is grounded, and the control end thereof is connected to the node B; the node C is connected to the enable end of the DCDC chip in the DC-DC conversion circuit; the node A is connected to the output voltage Vdcdc of the DCDC chip, and the node A is connected to the output end Vout of the DC-DC conversion circuit.

[0007] According to another aspect of the utility model, the utility model provides a DC-DC conversion circuit, which includes: an output terminal Vout; a DCDC chip, which is used to convert a DC power supply of one voltage level into a DC power supply of another voltage level; an output overvoltage self-locking circuit, which includes a voltage regulator tube D1, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a switch tube Q1, wherein the negative electrode of the voltage regulator tube D1 is connected to the node A, and the positive electrode thereof is connected to the node B via the resistor R2; one end of the resistor R4 is connected to the node B, and the other end thereof is grounded ; One end of the resistor R1 is connected to the power supply terminal VDD1, and the other end thereof is connected to the node C; One end of the resistor R3 is connected to the node C, and the other end thereof is grounded; The first connection end of the switch tube Q1 is connected to the node C, the second connection end thereof is grounded, and the control end thereof is connected to the node B; The node C is connected to the enable end of the DCDC chip in the DC-DC conversion circuit; The node A is connected to the output voltage Vdcdc of the DCDC chip, and the node A is connected to the output end Vout of the DC-DC conversion circuit.

[0008] Compared with the prior art, the utility model can set the overvoltage protection value according to actual needs. When the output voltage value of DCDC exceeds the set overvoltage protection value, the DCDC output can be automatically turned off, thereby playing an overvoltage protection role and being flexible.

Brief Description of the Drawings

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0010] Figure 1 The present invention is a schematic circuit diagram of a DC-DC conversion circuit and an output overvoltage self-locking circuit thereof in one embodiment of the present invention. [Specific implementation method]

[0011] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0012] The "one embodiment" or "embodiment" referred to herein refers to specific features, structures or characteristics that may be included in at least one implementation of the present invention. The "in one embodiment" that appears in different places in this specification does not all refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments. Unless otherwise specified, the words "coupled", "connected", "connected" and "connected" in this document that indicate electrical connection all mean direct or indirect connection. For example, A is connected to B, which includes both direct electrical connection between A and B and A is connected to B through electrical components or circuits. In the present utility model, "greater than" means greater than, and "less than or equal to" means less than or equal to.

[0013] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "front", "back", "left", "right", "vertical", "perpendicular", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0014] Please refer to Figure 1 As shown, it is a circuit diagram of a DC-DC conversion circuit and its output overvoltage self-locking circuit in one embodiment of the utility model. Figure 1 The DC-DC conversion circuit shown includes an output overvoltage self-locking circuit 110, an output terminal Vout and a DCDC chip U1. The DCDC chip U1 is used to convert a DC power supply of a certain voltage level into a DC power supply of another voltage level.

[0015] The output overvoltage self-locking circuit 110 includes a voltage regulator tube D1, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a switch tube Q1. Among them, the negative electrode of the voltage regulator tube D1 is connected to the node A, and its positive electrode is connected to the node B through the resistor R2; one end of the resistor R4 is connected to the node B, and the other end thereof is grounded; one end of the resistor R1 is connected to the power supply terminal VDD1, and the other end thereof is connected to the node C; one end of the resistor R3 is connected to the node C, and the other end thereof is grounded; the first connection end of the switch tube Q1 is connected to the node C, the second connection end thereof is grounded, and the control end thereof is connected to the node B; the node C is connected to the enable end DCDC-enable of the DCDC chip (DC-to-DC converter, i.e., DC-DC converter) U1 in the DC-DC conversion circuit; the node A is connected to the output voltage Vdcdc of the DCDC chip U1, and the node A is connected to the output end Vout of the DC-DC conversion circuit. Among them, the power supply terminal VDD1 can be the input voltage of the DCDC chip U1 or other DC voltage.

[0016] exist Figure 1 In the specific embodiment shown, the switch tube Q1 is an NPN (ie, Negative-Positive-Negative) transistor, and the first connection terminal, the second connection terminal and the control terminal of the switch tube Q1 are respectively the collector, the emitter and the base of the NPN transistor.

[0017] exist Figure 1 In the specific embodiment shown, the output overvoltage self-locking circuit 110 of the DC-DC conversion circuit further includes a capacitor C1 , one end of the capacitor C1 is connected to the node A, and the other end thereof is grounded.

[0018] exist Figure 1 In the embodiment shown, the voltage regulator D1 plays the role of setting the overvoltage protection value, and the selection of the voltage regulator D1 needs to meet the requirement that the voltage regulation value (or working voltage) is less than the required overvoltage protection value (or the set overvoltage protection value). The selection of the resistor R2 and the resistor R4 needs to meet the following requirements: when the output voltage Vdcdc is greater than or equal to the overvoltage protection value set by the output overvoltage self-locking circuit 110, the voltage of the node B is greater than the turn-on voltage of the transistor Q1; when the output voltage Vdcdc is less than the overvoltage protection value set by the output overvoltage self-locking circuit 110 and greater than the voltage regulation value of the voltage regulator D1, the voltage of the node B is less than the turn-on voltage of the transistor Q1. Transistor Q1 acts as a switch tube. When the voltage at node B is less than the turn-on voltage value of transistor Q1, transistor Q1 is turned off (or closed). At this time, the voltage at node C is the divided voltage value of resistors R1 and R3. When the voltage at node B is greater than or equal to the turn-on voltage value of transistor Q1, transistor Q1 is turned on. At this time, the voltage at node C is pulled down, that is, it is a low level. The selection of resistor R1 and resistor R3 needs to meet the following requirements: when the transistor Q1 is turned off, the divided voltage value of the resistor R3 (i.e., the voltage of node C) is greater than the enable voltage value of the DCDC chip U1, i.e., the enable terminal DCDC-enable (or enable signal DCDC-enable) of the DCDC chip U1 is at a high level, so that the DCDC chip U1 is turned on and has an output voltage Vdcdc; when the switch tube Q1 is turned on, the voltage of node C is pulled down, and the voltage of node C is less than the enable voltage value of the DCDC chip U1, i.e., the enable terminal DCDC-enable (or enable signal DCDC-enable) of the DCDC chip U1 is at a low level, so that the DCDC chip U1 is turned off and has no output voltage Vdcdc.

[0019] The following is a detailed introduction Figure 1 The working principle of the output overvoltage self-locking circuit of the DC-DC conversion circuit shown.

[0020] When the output voltage Vdcdc of the DCDC chip U1 is less than the overvoltage protection value to be set and less than the voltage regulation value (or working voltage) of the voltage regulator D1, the voltage regulator D1 does not work, the voltage of node B is low, and the transistor Q1 is in a closed (or turned off) state. At this time, the voltage of node C is the voltage divided by the resistor R1 and the resistor R3. Since the selection of the resistor R1 and the resistor R3 needs to meet the requirement that when the transistor Q1 is turned off, the voltage of node C is greater than the enable voltage value of the DCDC chip U1, the enable terminal DCDC-enable (or enable signal DCDC-enable) of the DCDC chip U1 is high at this time, so that the DCDC chip U1 is in an open state (or working state), and can normally output the voltage Vdcdc to the output terminal Vout to power the subsequent circuit. That is to say, when the output voltage Vdcdc of the DCDC chip U1 is less than the overvoltage protection value that needs to be set and less than the voltage regulation value of the Zener diode D1, the Zener diode D1 does not work and the switch tube Q1 is turned off. At this time, the voltage of the node C is greater than the enable voltage value of the DCDC chip U1, so that the DCDC chip U1 is in the on state.

[0021] When the output voltage Vdcdc of the DCDC chip U1 is less than the overvoltage protection value to be set and greater than the voltage regulation value of the voltage regulator D1, the voltage regulator D1 is in the working state. Since the selection of resistors R2 and R4 needs to meet the requirement, when the output voltage Vdcdc is greater than the voltage regulation value of the voltage regulator D1 and less than the overvoltage protection value to be set, the voltage of node B is less than the turn-on voltage value of the transistor Q1, and the transistor Q1 is in the off state. At this time, the voltage of node C is the voltage divided by the resistor R1 and the resistor R3. Since the selection of resistors R1 and R3 needs to meet the requirement that when the transistor Q1 is turned off, the voltage of node C is greater than the enable turn-on voltage value of the DCDC chip U1, the enable terminal DCDC-enable (or enable signal DCDC-enable) of the DCDC chip U1 is at a high level at this time, so that the DCDC chip U1 is in the on state (or working state), and the voltage Vdcdc can be normally output to the output terminal Vout to power the subsequent circuit. That is to say, when the output voltage Vdcdc of the DCDC chip U1 is less than the overvoltage protection value to be set and greater than the voltage regulation value of the Zener diode D1, the Zener diode D1 works and the switch tube Q1 is turned off. At this time, the voltage of the node C is greater than the enable voltage value of the DCDC chip U1, so that the DCDC chip U1 is in the on state.

[0022] When the output voltage Vdcdc of the DCDC chip U1 is greater than or equal to the overvoltage protection value that needs to be set, according to the selection of the above-mentioned voltage regulator D1, the voltage regulator D1 is in a working state. Since the selection of the resistor R2 and the resistor R4 needs to meet, when the output voltage Vdcdc is greater than or equal to the overvoltage protection value that needs to be set, the voltage of the node B is greater than the turn-on voltage value of the transistor Q1, and the transistor Q1 is in a conducting state. At this time, the voltage of the node C is pulled down to a low level, and the voltage of the node C is less than the enable turn-on voltage value of the DCDC chip U1. Therefore, at this time, the enable terminal DCDC-enable (or enable signal DCDC-enable) of the DCDC chip U1 is a low level, so that the DCDC chip U1 is in a closed state (or non-working state), and the voltage Vdcdc cannot be output to the output terminal Vout, and the subsequent circuit cannot be powered. In this way, when the output voltage Vdcdc of the DCDC chip U1 is greater than or equal to the overvoltage protection value that needs to be set, the DCDC chip U1 can be self-locked, thereby protecting the subsequent circuit. That is to say, when the output voltage Vdcdc of the DCDC chip U1 is greater than or equal to the overvoltage protection value to be set, the voltage regulator D1 works and the switch Q1 is turned on. At this time, the voltage of the node C is less than the enable voltage value of the DCDC chip U1, so that the DCDC chip U1 is in the off state.

[0023] It should be noted that Figure 1 The voltage regulator D1, resistor R1, resistor R2, resistor R3, resistor R4 and switch Q1 are all core components and are theoretically indispensable. Among them, the voltage regulator D1 plays the role of setting the overvoltage protection value. The selection of the voltage regulator needs to meet the requirement that the voltage regulation value is less than the required overvoltage protection value. Resistors R2 and R4 play the role of resistor voltage division. The selection of resistors R2 and R4 needs to meet the following requirements: when the output voltage Vdcdc is greater than or equal to the overvoltage protection value, the voltage at node B is greater than the turn-on voltage of transistor Q1; when the output voltage Vdcdc is less than the overvoltage protection value and greater than the voltage regulation value of the voltage regulator D1, the voltage at node B is less than the turn-on voltage of transistor Q1. Resistors R1 and R3 play the role of resistor voltage division. The selection of resistors R1 and R3 needs to meet the following requirements: when the transistor Q1 is turned off, the voltage division voltage value of resistor R3 (i.e., the voltage at node C) is greater than the enable turn-on voltage value of the DCDC chip U1. The transistor Q1 acts as a switch. When the voltage at the node B is less than the turn-on voltage of the transistor Q1, the transistor Q1 is turned off (or closed); when the voltage at the node B is greater than or equal to the turn-on voltage of the transistor Q1, the transistor Q1 is turned on. Figure 1 The capacitor C1 in the circuit is a non-core component. The capacitor C1 plays a filtering role, reducing the DCDC output voltage ripple and making the DCDC output voltage more stable.

[0024] In summary, the DC-DC conversion circuit and its output overvoltage self-locking circuit provided by the utility model can set the output overvoltage protection value. When the output voltage value Vdcdc of the DCDC chip U1 exceeds the set overvoltage protection value, the DCDC chip U1 can be locked. U1 The enable signal DCDC-enable is pulled low, thereby shutting down the DCDC chip U1 , so that the DCDC chip U1 The output is turned off, which can protect the DCDC back-end power supply circuit. In addition, the DCDC output overvoltage protection value can be set according to the needs, which plays an overvoltage protection role and is flexible.

[0025] The innovative features and corresponding beneficial effects of the utility model are as follows:

[0026] 1. The utility model can set the DCDC output overvoltage protection value according to actual needs, which is flexible.

[0027] 2. For DCDC chips that do not have an output overvoltage protection function, the utility model can be used to implement an overvoltage protection function to protect the DCDC back-end power supply circuit from being damaged due to input voltage overvoltage.

[0028] 3. The circuit design of the utility model is simple and can realize DCDC output overvoltage protection at a relatively low cost.

[0029] It should be noted that any changes made by those skilled in the art to the specific implementation of the present invention do not deviate from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited to the aforementioned specific implementation.

Claims

1. An output overvoltage self-locking circuit of a DC-DC conversion circuit, characterized in that: It includes a voltage regulator tube D1, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a switch tube Q1. The cathode of the voltage regulator D1 is connected to the node A, and the anode thereof is connected to the node B via the resistor R2; one end of the resistor R4 is connected to the node B, and the other end thereof is grounded; one end of the resistor R1 is connected to the power supply terminal VDD1, and the other end thereof is connected to the node C; one end of the resistor R3 is connected to the node C, and the other end thereof is grounded; the first connection end of the switch tube Q1 is connected to the node C, the second connection end thereof is grounded, and the control end thereof is connected to the node B; the node C is connected to the enable end of the DCDC chip in the DC-DC conversion circuit; the node A is connected to the output voltage Vdcdc of the DCDC chip, and the node A is connected to the output end Vout of the DC-DC conversion circuit.

2. The output overvoltage self-locking circuit of the DC-DC conversion circuit according to claim 1, characterized in that: When the output voltage Vdcdc is less than the overvoltage protection value to be set and less than the voltage stabilization value of the voltage regulator D1, the voltage regulator D1 does not work, and the switch Q1 is turned off. At this time, the voltage of the node C is greater than the enable voltage value of the DCDC chip, so that the DCDC chip is in the on state; When the output voltage Vdcdc is less than the overvoltage protection value to be set and greater than the voltage stabilization value of the voltage regulator D1, the voltage regulator D1 works and the switch Q1 is turned off. At this time, the voltage of the node C is greater than the enable voltage value of the DCDC chip, so that the DCDC chip is in the on state; When the output voltage Vdcdc is greater than or equal to the overvoltage protection value to be set, the voltage regulator D1 works and the switch Q1 is turned on. At this time, the voltage at the node C is less than the enable voltage value of the DCDC chip, so that the DCDC chip is in the off state. The voltage stabilization value of the voltage regulator tube D1 is less than the overvoltage threshold of the output overvoltage self-locking circuit.

3. The output overvoltage self-locking circuit of the DC-DC conversion circuit according to claim 2, characterized in that: The switch tube Q1 is an NPN type triode, and the first connection end, the second connection end and the control end of the switch tube Q1 are respectively the collector, the emitter and the base of the NPN type triode.

4. The output overvoltage self-locking circuit of the DC-DC conversion circuit according to claim 3, characterized in that: The voltage regulator tube D1 is selected so that the voltage regulation value is less than the overvoltage protection value; The selection of the resistor R2 and the resistor R4 satisfies: when the output voltage Vdcdc is greater than or equal to the overvoltage protection value, the voltage of the node B is greater than the turn-on voltage of the switch tube Q1; when the output voltage Vdcdc is less than the overvoltage protection value and greater than the voltage stabilizing value of the voltage stabilizing tube D1, the voltage of the node B is less than the turn-on voltage of the transistor Q1; The resistor R1 and the resistor R3 are selected to meet the following conditions: when the switch tube Q1 is turned off, the voltage of the node C is greater than the enable voltage value of the DCDC chip; when the switch tube Q1 is turned on, the voltage of the node C is less than the enable voltage value of the DCDC chip.

5. The output overvoltage self-locking circuit of the DC-DC conversion circuit according to any one of claims 1 to 4, characterized in that: It also includes capacitor C1, One end of the capacitor C1 is connected to the node A, and the other end thereof is grounded.

6. A DC-DC conversion circuit, characterized in that: It includes: Output terminal Vout; A DCDC chip is used to convert a DC power supply of one voltage level into a DC power supply of another voltage level; An output overvoltage self-locking circuit for a DC-DC converter circuit as claimed in any one of claims 1 to 5.

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