Voltage reduction circuit output ground short circuit detection circuit

Abstract

The invention discloses a voltage reduction circuit output ground short circuit detection circuit which comprises an input voltage detection circuit, an output short circuit detection circuit, an output short circuit confirmation circuit and an output short circuit judgment circuit. The input voltage detection circuit is used for comparing the voltage of the first preset voltage end with the voltage of the input voltage end of the step-down circuit; the output short-circuit confirmation circuit is used for charging the step-down circuit to a voltage greater than a second preset voltage when the output voltage end of the step-down circuit is normal; the output short circuit judgment circuit is used for comparing the output voltage end of the step-down circuit with the second preset voltage; the output end of the input voltage detection circuit and the output end of the output short circuit confirmation circuit are connected with the two input ends of the output short circuit judgment circuit respectively. The output short-circuit judgment circuit outputs a detection result according to the input signal. According to the invention, the problem of voltage reduction circuit output ground short circuit can be rapidly and effectively detected.

Description

Technical Field

[0001] The invention relates to the field of electronic technology, and in particular to a short-circuit detection circuit for a step-down circuit output to ground. Background Art

[0002] During the design and production of the step-down circuit, various mistakes or accidents may cause the circuit to short-circuit to the ground. When the output of the step-down circuit is short-circuited to the ground, a huge current to the ground will be generated. The huge current generated will cause the product to smoke or even catch fire, threatening personal safety.

[0003] In order to avoid serious consequences caused by the short circuit problem of the buck circuit output to the ground, it is necessary to provide an effective means to detect the short circuit problem of the buck circuit output to the ground. Summary of the invention

[0004] The purpose of the present application is to provide a buck circuit output short-circuit to ground detection circuit, which can quickly and effectively detect the buck circuit output short-circuit to ground problem before the buck circuit starts working.

[0005] The technical solution provided by this application is:

[0006] A step-down circuit output short-circuit to ground detection circuit, comprising an input voltage detection circuit, an output short-circuit detection circuit, an output short-circuit confirmation circuit and an output short-circuit judgment circuit;

[0007] The input voltage detection circuit is used to compare the voltage at the first preset voltage terminal and the input voltage terminal of the step-down circuit;

[0008] The output short circuit confirmation circuit is used to charge the output voltage terminal of the step-down circuit to a voltage greater than a second preset voltage when the output voltage terminal is normal;

[0009] The output short circuit judgment circuit is used to compare the output voltage end of the step-down circuit with the second preset voltage;

[0010] The output ends of the input voltage detection circuit and the output short circuit confirmation circuit are respectively connected to the two input ends of the output short circuit judgment circuit; the output short circuit judgment circuit outputs the detection result according to the input signal.

[0011] In a possible implementation, the input voltage detection circuit includes a first comparator; two input terminals of the first comparator are respectively connected to a first preset voltage terminal and an input voltage terminal of the step-down circuit;

[0012] The output short circuit confirmation circuit comprises a second comparator; two input terminals of the second comparator are respectively connected to a second preset voltage terminal and an output voltage terminal of the step-down circuit;

[0013] The output short circuit detection circuit comprises a third comparator and an electronic switch; two input terminals of the third comparator are respectively connected to a third preset voltage terminal and an output voltage terminal of the step-down circuit; an output terminal of the third comparator is connected to a first terminal of the electronic switch, a second terminal of the electronic switch is connected to a positive power supply terminal, and a third terminal of the electronic switch is connected to an output voltage terminal of the step-down circuit; the first terminal of the electronic switch is a control terminal of the electronic switch, and is used to control the on-off between the second terminal and the third terminal of the electronic switch;

[0014] The second preset voltage is less than or equal to the third preset voltage;

[0015] The output terminals of the first comparator and the second comparator are respectively connected to the two input terminals of the output short circuit judgment circuit;

[0016] The output short circuit judgment circuit outputs a detection result according to an input signal.

[0017] The input voltage Vin and the output voltage Vout of the buck circuit are voltages at the input voltage terminal and the output voltage terminal of the buck circuit respectively.

[0018] In a possible implementation, the input voltage detection circuit includes a first resistor R1 and a second resistor R2; the positive power supply end of the step-down circuit is grounded through the first resistor R1 and the second resistor R2 connected in series, and a first preset voltage is derived from a connection point between the first resistor R1 and the second resistor R2.

[0019] In a possible implementation, the step-down circuit includes a step-down regulation circuit and an inductor L1; the input voltage end of the step-down circuit is connected to the output voltage end of the step-down circuit through the step-down regulation circuit and the inductor L1 in sequence;

[0020] The output short circuit confirmation circuit includes a fourth resistor R4 and a seventh resistor R7;

[0021] The positive power supply terminal is grounded through a fourth resistor R4 and a seventh resistor R7 connected in series, and a second preset voltage is derived from a connection point between the fourth resistor R4 and the seventh resistor R7.

[0022] In a possible implementation, the first comparator is a first operational amplifier M1; a non-inverting input terminal and an inverting input terminal of the first operational amplifier M1 are respectively connected to a first preset voltage terminal and an input voltage terminal of the buck circuit.

[0023] In a possible implementation, the second comparator is a second operational amplifier M2; a non-inverting input terminal and an inverting input terminal of the second operational amplifier M2 are respectively connected to a second preset voltage terminal and an output voltage terminal of the buck circuit.

[0024] In a possible implementation, the third comparator is a third operational amplifier M3; a non-inverting input terminal and an inverting input terminal of the third operational amplifier M3 are respectively connected to a third preset voltage terminal and an output voltage terminal of the step-down circuit; an output terminal of the third operational amplifier M3 is connected to a first terminal of the electronic switch;

[0025] The electronic switch is NMOS.

[0026] In a possible implementation, the output short circuit determination circuit is an AND gate M4.

[0027] In a possible implementation manner, the output end of the output short circuit judgment circuit is connected to an alarm circuit.

[0028] How this application works:

[0029] Input voltage detection circuit:

[0030] When the output voltage terminal of the step-down circuit is short-circuited to the ground, a large current will be generated in a very short time, directly causing a serious drop in the voltage at the input voltage terminal. This circuit detects this situation. When the input voltage Vin is lower than the set voltage divider value of the first resistor R1 and the second resistor R2 to the positive power supply Vcc, the first operational amplifier M1 outputs a high level.

[0031] The first operational amplifier M1 uses the positive power supply Vcc as a driver. When the positive power supply Vcc fails, this circuit cannot work. This ensures that this circuit will output a high level only when the input voltage Vin and the positive power supply Vcc voltage are normal, avoiding false triggering that causes abnormality in the back-end judgment circuit.

[0032] Since the buck circuit needs to wait for the control signal Enable to be valid after the input voltage Vin and the positive power supply Vcc voltage are in place before it can start working and have a normal output voltage, this solution immediately starts to perform short-circuit detection on the output voltage end of the buck circuit after Vin and the positive power supply Vcc are in place and before the control signal Enable is valid, thereby completing the output short-circuit detection before the buck circuit starts working.

[0033] Output short circuit detection circuit:

[0034] When the output voltage terminal of the step-down circuit is short-circuited to the ground, the inverting input terminal of the third operational amplifier M3 continues to be at 0 voltage, which is lower than the voltage divided by the positive power supply Vcc of the non-inverting input terminals R5 and R6, causing the third operational amplifier M3 to output a high level.

[0035] When the output voltage end of the step-down circuit is normal, at the beginning, since the output voltage end of the step-down circuit is not charged, the third operational amplifier M3 outputs a high level, causing the electronic switch (N-Mosfet) Q3 to be turned on, and the positive power supply Vcc charges the output voltage end of the step-down circuit through the voltage divider R3, until the output voltage end of the step-down circuit is higher than the voltage of the non-inverting input end of the third operational amplifier M3, that is, the voltage divider R5 and R6 divides the positive power supply Vcc, causing the third operational amplifier M3 to output a low level, and the electronic switch Q3 is disconnected. At this time, the output voltage end of the step-down circuit will still maintain a certain level of voltage (greater than the second preset voltage).

[0036] Output short circuit confirmation circuit:

[0037] When the output voltage terminal of the buck circuit is short-circuited to the ground, the output voltage Vout of the output voltage terminal of the buck circuit is maintained at zero, so the inverting input terminal of M2 continues to be 0 voltage, which is lower than the voltage divided by the positive power supply Vcc of the non-inverting input terminal R4 and R7, so M2 outputs a high level.

[0038] When the output voltage end of the buck circuit is normal, since the output short-circuit detection circuit has charged the output voltage end of the buck circuit, if there is no abnormality, the voltage will be maintained at a certain level for a long time. Therefore, the voltage at the inverting input end of M2 is continuously higher than the voltage divided by the positive power supply Vcc of the non-inverting input end R4 and R7, and thus M2 outputs a low level.

[0039] When the output voltage terminal of the step-down circuit is short-circuited to the ground, both M1 and M2 output high level, causing M3 to output high level, confirming that a short circuit has occurred, and outputting a Fault error signal.

[0040] When the output voltage end of the step-down circuit is normal, M2 outputs a low level, causing M3 to output a low level and not output a Fault error signal.

[0041] Beneficial effects:

[0042] The buck circuit output short-circuit detection circuit provided in the present application can quickly and effectively detect the buck circuit output short-circuit problem before the buck circuit starts working, and find the short-circuit problem in time. The detection is fast, can be adjusted freely, has a simple structure, and is easy to implement. This application is suitable for the design and application of various electronic products BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a circuit schematic diagram of an embodiment of the present application; wherein 1 is an input voltage detection circuit, 2 is an output short circuit detection circuit, 3 is an output short circuit confirmation circuit, and 4 is an output short circuit judgment circuit. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0045] It should be noted that the terms such as "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a specific relationship or order between these entities or operations. It should be understood that the words "first", "second" and the like do not limit the quantity and execution order, and the words "first" and "second" and the like do not limit them to be necessarily different. It should be understood that the data used in this way can be interchanged under appropriate circumstances. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, article or device including a series of elements includes not only those elements clearly listed, but also other elements that are not clearly listed, or may also include elements inherent to such process, method, product or device. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0046] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, "connection" 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 this application can be understood according to specific circumstances.

[0047] The following will refer to Figure 1 Specific embodiments according to the present application are described.

[0048] The embodiment of the present application discloses a buck circuit output short-circuit to ground detection circuit, including an input voltage detection circuit, an output short-circuit detection circuit, an output short-circuit confirmation circuit and an output short-circuit judgment circuit;

[0049] The input voltage detection circuit is used to compare the voltage at the first preset voltage terminal and the input voltage terminal of the step-down circuit;

[0050] The output short circuit confirmation circuit is used to charge the output voltage terminal of the step-down circuit to a voltage greater than a second preset voltage when the output voltage terminal is normal;

[0051] The output short circuit judgment circuit is used to compare the output voltage end of the step-down circuit with the second preset voltage;

[0052] The output ends of the input voltage detection circuit and the output short circuit confirmation circuit are respectively connected to the two input ends of the output short circuit judgment circuit; the output short circuit judgment circuit outputs the detection result according to the input signal.

[0053] In some embodiments, the input voltage detection circuit includes a first comparator; two input terminals of the first comparator are respectively connected to a first preset voltage terminal and an input voltage terminal of the buck circuit;

[0054] The output short circuit confirmation circuit comprises a second comparator; two input terminals of the second comparator are respectively connected to a second preset voltage terminal and an output voltage terminal of the step-down circuit;

[0055] The output short circuit detection circuit comprises a third comparator and an electronic switch; two input terminals of the third comparator are respectively connected to a third preset voltage terminal and an output voltage terminal of the step-down circuit; an output terminal of the third comparator is connected to a first terminal of the electronic switch, a second terminal of the electronic switch is connected to a positive power supply terminal, and a third terminal of the electronic switch is connected to an output voltage terminal of the step-down circuit; the first terminal of the electronic switch is a control terminal of the electronic switch, and is used to control the on-off between the second terminal and the third terminal of the electronic switch;

[0056] The second preset voltage is less than or equal to the third preset voltage;

[0057] The output terminals of the first comparator and the second comparator are respectively connected to the two input terminals of the output short circuit judgment circuit;

[0058] The output short circuit judgment circuit outputs a detection result according to an input signal.

[0059] The input voltage Vin and the output voltage Vout of the buck circuit are voltages at the input voltage terminal and the output voltage terminal of the buck circuit respectively.

[0060] Furthermore, the input voltage detection circuit includes a first resistor R1 and a second resistor R2; the positive power supply end of the step-down circuit is grounded through the first resistor R1 and the second resistor R2 connected in series, and the connection point of the first resistor R1 and the second resistor R2 leads to a first preset voltage.

[0061] Furthermore, the step-down circuit comprises a step-down regulating circuit and an inductor L1; the input voltage end of the step-down circuit is connected to the output voltage end of the step-down circuit through the step-down regulating circuit and the inductor L1 in sequence;

[0062] The output short circuit confirmation circuit includes a fourth resistor R4 and a seventh resistor R7;

[0063] The positive power supply terminal is grounded through a fourth resistor R4 and a seventh resistor R7 connected in series, and a second preset voltage is derived from a connection point between the fourth resistor R4 and the seventh resistor R7.

[0064] Furthermore, the first comparator is a first operational amplifier M1; a non-inverting input terminal and an inverting input terminal of the first operational amplifier M1 are respectively connected to a first preset voltage terminal and an input voltage terminal of the buck circuit.

[0065] Furthermore, the second comparator is a second operational amplifier M2; a non-inverting input terminal and an inverting input terminal of the second operational amplifier M2 are respectively connected to a second preset voltage terminal and an output voltage terminal of the buck circuit.

[0066] Further, the third comparator is a third operational amplifier M3; the non-inverting input terminal and the inverting input terminal of the third operational amplifier M3 are respectively connected to the third preset voltage terminal and the output voltage terminal of the buck circuit; the output terminal of the third operational amplifier M3 is connected to the first terminal of the electronic switch;

[0067] The electronic switch is NMOS.

[0068] Furthermore, the output short circuit judgment circuit is an AND gate M4.

[0069] Furthermore, the output end of the output short circuit judgment circuit is connected to an alarm circuit.

[0070] Based on the above embodiments, the working principle of this application is described as follows:

[0071] like Figure 1 As shown, when the output voltage terminal of the step-down circuit is short-circuited to the ground, a large current will be generated in a very short time, directly causing the voltage at the input voltage terminal to drop seriously synchronously. This circuit detects this situation. When the input voltage Vin is lower than the set voltage division value of the first resistor R1 and the second resistor R2 to the positive power supply Vcc, the first operational amplifier M1 outputs a high level.

[0072] When the output voltage terminal of the step-down circuit is short-circuited to the ground, the inverting input terminal of the third operational amplifier M3 is continuously at 0 voltage, which is lower than the divided voltage of the positive power supply Vcc by the non-inverting input terminals R5 and R6 (the divided voltage value can be lower than 100mV), so the third operational amplifier M3 outputs a high level.

[0073] When the output voltage end of the step-down circuit is normal, at the beginning, since the output voltage end of the step-down circuit is not charged, the third operational amplifier M3 outputs a high level, causing the electronic switch (N-Mosfet) Q3 to be turned on, and the positive power supply Vcc charges the output voltage end of the step-down circuit through the voltage divider R3, until the output voltage end of the step-down circuit is higher than the voltage of the non-inverting input end of the third operational amplifier M3, that is, the voltage divider R5 and R6 divides the positive power supply Vcc, causing the third operational amplifier M3 to output a low level, and the electronic switch Q3 is disconnected. At this time, the output voltage end of the step-down circuit will still maintain a certain level of voltage (greater than the second preset voltage).

[0074] When the output voltage terminal of the buck circuit is short-circuited to the ground, the output voltage Vout of the output voltage terminal of the buck circuit is maintained at zero, so the inverting input terminal of M2 continues to be 0 voltage, which is lower than the voltage divided by the positive power supply Vcc of the non-inverting input terminal R4 and R7 (the voltage divided value can be less than 100mV), so M2 outputs a high level.

[0075] When the output voltage end of the buck circuit is normal, since the output short-circuit detection circuit has charged the output voltage end of the buck circuit, if there is no abnormality, the voltage will be maintained at a certain level for a long time. Therefore, the voltage at the inverting input end of M2 is continuously higher than the voltage divided by the positive power supply Vcc of the non-inverting input end R4 and R7, and thus M2 outputs a low level.

[0076] When the output voltage terminal of the step-down circuit is short-circuited to the ground, both M1 and M2 output high level, causing M3 to output high level, confirming that a short circuit has occurred, and outputting a Fault error signal.

[0077] When the output voltage end of the step-down circuit is normal, M2 outputs a low level, causing M3 to output a low level and not output a Fault error signal.

[0078] The above description of the embodiments of the present application is only a partial embodiment of the present application, which is used to enable professionals in the field to implement or use the content of the present application, and is not used to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A buck circuit output short-circuit detection circuit, characterized in that: It includes an input voltage detection circuit, an output short circuit detection circuit, an output short circuit confirmation circuit and an output short circuit judgment circuit; The input voltage detection circuit is used to compare the voltage at the first preset voltage terminal and the input voltage terminal of the step-down circuit; The output short circuit confirmation circuit is used to charge the output voltage terminal of the step-down circuit to a voltage greater than a second preset voltage when the output voltage terminal is normal; The output short circuit judgment circuit is used to compare the output voltage end of the step-down circuit with the second preset voltage; The output ends of the input voltage detection circuit and the output short circuit confirmation circuit are respectively connected to the two input ends of the output short circuit judgment circuit; the output short circuit judgment circuit outputs the detection result according to the input signal.

2. The buck circuit output short-circuit detection circuit to ground according to claim 1, characterized in that: The input voltage detection circuit comprises a first comparator; two input terminals of the first comparator are respectively connected to a first preset voltage terminal and an input voltage terminal of the step-down circuit; The output short circuit confirmation circuit comprises a second comparator; two input terminals of the second comparator are respectively connected to a second preset voltage terminal and an output voltage terminal of the step-down circuit; The output short circuit detection circuit comprises a third comparator and an electronic switch; two input terminals of the third comparator are respectively connected to a third preset voltage terminal and an output voltage terminal of the step-down circuit; an output terminal of the third comparator is connected to a first terminal of the electronic switch, a second terminal of the electronic switch is connected to a positive power supply terminal, and a third terminal of the electronic switch is connected to an output voltage terminal of the step-down circuit; the first terminal of the electronic switch is a control terminal of the electronic switch, and is used to control the on-off between the second terminal and the third terminal of the electronic switch; The second preset voltage is less than or equal to the third preset voltage; The output ends of the input voltage detection circuit and the output short circuit confirmation circuit are respectively connected to the two input ends of the output short circuit judgment circuit, including: the output ends of the first comparator and the second comparator are respectively connected to the two input ends of the output short circuit judgment circuit.

3. The buck circuit output short-circuit detection circuit according to claim 2, characterized in that: The input voltage detection circuit includes a first resistor R1 and a second resistor R2; the positive power supply end of the step-down circuit is grounded through the first resistor R1 and the second resistor R2 connected in series, and a first preset voltage is derived from a connection point between the first resistor R1 and the second resistor R2.

4. The buck circuit output short-circuit detection circuit to ground according to claim 3, characterized in that: The step-down circuit comprises a step-down regulating circuit and an inductor L1; the input voltage end of the step-down circuit is connected to the output voltage end of the step-down circuit through the step-down regulating circuit and the inductor L1 in sequence; The output short circuit confirmation circuit includes a fourth resistor R4 and a seventh resistor R7; The positive power supply terminal is grounded through a fourth resistor R4 and a seventh resistor R7 connected in series, and a second preset voltage is derived from a connection point between the fourth resistor R4 and the seventh resistor R7.

5. The buck circuit output short-circuit detection circuit to ground according to claim 4, characterized in that: The first comparator is a first operational amplifier M1; a non-inverting input terminal and an inverting input terminal of the first operational amplifier M1 are connected to a first preset voltage terminal and an input voltage terminal of the buck circuit respectively.

6. The buck circuit output short-circuit detection circuit to ground according to claim 5, characterized in that: The second comparator is a second operational amplifier M2; the non-inverting input terminal and the inverting input terminal of the second operational amplifier M2 are respectively connected to the second preset voltage terminal and the output voltage terminal of the buck circuit.

7. The buck circuit output short-circuit detection circuit to ground according to claim 6, characterized in that: The third comparator is a third operational amplifier M3; the non-inverting input terminal and the inverting input terminal of the third operational amplifier M3 are respectively connected to the third preset voltage terminal and the output voltage terminal of the step-down circuit; the output terminal of the third operational amplifier M3 is connected to the first terminal of the electronic switch; The electronic switch is NMOS.

8. The buck circuit output short-circuit detection circuit to ground according to claim 7, characterized in that: The output short circuit judgment circuit is an AND gate M4.

9. The buck circuit output short-circuit detection circuit according to any one of claims 1 to 6, characterized in that: The output end of the output short circuit judgment circuit is connected to the alarm circuit.

Images