Short circuit protection circuit and dc-dc circuit

Abstract

The utility model discloses a short circuit protection circuit and DC-DC circuit, short circuit protection circuit is used for the short circuit protection of DC-DC circuit, and DC-DC circuit has the positive input end and negative input end of receiving input voltage through the bus and the positive output end and negative output end for output voltage, and the positive output end and negative output end are used for being connected with the battery, and the negative input end is connected with the bus and negative output end and forms the negative pole branch, and short circuit protection circuit includes switching unit and bias unit, and switching unit is connected in series in the negative pole branch to control the on-off of negative pole branch, and the first end of bias unit is connected with the control end of switching unit, and the second end of bias unit is used to receive the control voltage based on the input voltage and is used for controlling the opening of switching unit, the utility model discloses short circuit protection circuit and DC-DC circuit, and the switching unit is turned off under the condition of bus short circuit to block the short circuit of battery formed by the parasitic diode of DC-DC circuit internal output MOS tube, to prevent damaging the battery.

Description

Technical Field

[0001] This utility model belongs to the field of circuit protection technology, specifically relating to a short-circuit protection circuit and a DC-DC circuit. Background Technology

[0002] In existing DC-DC circuits, especially Buck-Boost circuits, the negative output terminal is directly connected to the negative terminal of the bus (common negative). Typically, two output MOSFETs are placed at the output of the DC-DC circuit (one of which is used for reverse connection protection). In practical applications, Buck-Boost circuits have multiple outputs. To save costs, a single MOSFET is sometimes used (i.e., the reverse connection protection MOSFET is removed). The resulting problem is that if the bus (positive and negative terminals) at the input of the DC-DC circuit is short-circuited, the battery connected to the output of the DC-DC circuit will short-circuit through the parasitic diode of the output MOSFET. This will damage the battery and further burn out the circuit board due to the short-circuit current, making subsequent repairs difficult.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this utility model and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Utility Model Content

[0004] The purpose of this invention is to provide a short-circuit protection circuit and a DC-DC circuit that can disconnect the existing short-circuit path when the busbar is short-circuited.

[0005] To achieve the above objectives, a specific embodiment of this utility model provides the following technical solution: a short-circuit protection circuit for short-circuit protection of a DC-DC circuit, wherein the DC-DC circuit has a positive input terminal and a negative input terminal for receiving input voltage through a bus, and a positive output terminal and a negative output terminal for output voltage. The positive output terminal and the negative output terminal are used to connect to a battery. The negative input terminal is connected to the bus and the negative output terminal to form a negative branch. The short-circuit protection circuit includes a switching unit and a biasing unit. The switching unit is connected in series in the negative branch to control the on / off state of the negative branch. The first end of the biasing unit is connected to the control terminal of the switching unit, and the second end of the biasing unit is used to receive a control voltage generated based on the input voltage to control the switching unit to turn on.

[0006] In one or more embodiments of the present invention, the switching unit includes a transistor, the transistor being connected in series in the negative branch through its first and second terminals, and the control terminal of the transistor being connected to the first terminal of the biasing unit.

[0007] In one or more embodiments of the present invention, the transistor includes a MOS transistor, which is connected in series in the negative branch through its first and second terminals, and the control terminal of the MOS transistor is connected to the first terminal of the bias unit.

[0008] In one or more embodiments of the present invention, the biasing unit includes a biasing resistor, the first end of which is connected to the control terminal of the switching unit, and the second end of which is used to receive a control voltage generated based on the input voltage.

[0009] In one or more embodiments of the present invention, the short-circuit protection circuit further includes a voltage control circuit, which is connected to the bus to receive the input voltage and generate a control voltage based on the input voltage.

[0010] In one or more embodiments of this utility model, the voltage control circuit includes a transformer module, the input terminal of which is connected to a bus to receive an input voltage, and the transformer module is used to transform the input voltage to generate a control voltage.

[0011] In one or more embodiments of this utility model, the voltage control circuit further includes a control circuit connected to the input terminal of the transformer module, the control circuit being used to control the connection and disconnection between the input terminal of the transformer module and the bus based on the input voltage.

[0012] In one or more embodiments of this utility model, the control circuit includes a PWM controller module and a switching transistor. The switching transistor is connected in series between the input terminal of the transformer module and the bus through its first and second terminals. The PWM controller module is connected to the bus to be powered by the input voltage. The control terminal of the switching transistor is connected to the PWM controller module to receive the PWM control signal generated by the PWM controller module.

[0013] This utility model also discloses a DC-DC circuit, including the aforementioned short-circuit protection circuit.

[0014] In one or more embodiments of this utility model, the DC-DC circuit includes a first control transistor, a second control transistor, an inductor, a capacitor, and an output control transistor. The control terminals of the first control transistor, the second control transistor, and the output control transistor are respectively used to receive corresponding control signals. The second terminal of the first control transistor is connected to the positive input terminal, the first terminal of the second control transistor is connected to the negative output terminal, the first terminal of the first control transistor is connected to the second terminal of the second control transistor and the first terminal of the inductor, the second terminal of the inductor is connected to the first terminal of the capacitor and the second terminal of the output control transistor, the second terminal of the capacitor is connected to the negative output terminal, and the first terminal of the output control transistor is connected to the positive output terminal.

[0015] Compared with the prior art, the short-circuit protection circuit and DC-DC circuit of this utility model can protect the battery connected to the output terminal of the DC-DC circuit with Buck-Boost topology with only a few additional components. By turning off the switching unit in the event of a bus short circuit, the short circuit to the battery caused by the parasitic diode of the output MOS transistor inside the DC-DC circuit is blocked, thereby preventing damage to the battery. It is low in cost, effective, and highly reliable. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a circuit diagram of a DC-DC circuit in one embodiment of the present invention.

[0018] Figure 2 This is a circuit diagram of a short-circuit protection circuit in one embodiment of the present invention.

[0019] Figure 3 This is a circuit diagram of the control circuit in one embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0021] The terms "coupled," "connected," or "linked" in the specification include both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as an electrical conduction medium, which may have parasitic inductance or capacitance. Indirect connections may also include connections made through other active or passive devices to achieve the same or similar functional purpose, such as connections through switches, follower circuits, or other circuits or components. Furthermore, in the invention, terms such as "first" and "second" are primarily used to distinguish one technical feature from another, and do not necessarily require or imply any actual relationship, quantity, or order between these technical features.

[0022] In the detailed description of this specification, reference is made to the accompanying drawings, which form a part thereof, wherein like reference numerals always denote like parts, and wherein exemplary embodiments are shown by way of example that may be implemented. It should be understood that other embodiments may be utilized, and structural or logical changes may be made, without departing from the scope of this disclosure. Therefore, the following detailed description should not be considered limiting.

[0023] The various operations in the specification may be described sequentially as multiple discrete actions or operations in a manner most conducive to understanding the claimed subject matter. However, the order of description should not be construed as implying that these operations must be sequentially related. Specifically, these operations may not be performed in the order presented. The described operations may be performed in a different order than in the described embodiments. Various additional operations may be performed in additional embodiments and / or the described operations may be omitted.

[0024] For the purposes of this disclosure, the phrase “A and / or B” means (A), (B), or (A and B). For the purposes of this disclosure, the phrase “A, B and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0025] Various components and devices may be referred to or shown in the singular (e.g., “transistor”, “transistor”, “switch”, etc.) in this document, but only for the convenience of discussion, and any element referred to in the singular may include multiple such elements as taught herein.

[0026] The description uses the phrases "in one embodiment," "in other embodiments," or "in some embodiments," each of which may refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," etc., used with respect to embodiments of this disclosure are synonymous.

[0027] like Figure 1 As shown, a DC-DC circuit has a positive input terminal and a negative input terminal for connecting to a bus (BUS bus) to receive an input voltage, and a positive output terminal OUT+ and a negative output terminal OUT- for outputting a voltage. The positive input terminal is connected to the positive terminal BUS+ of the bus, and the negative input terminal is connected to the negative terminal BUS- of the bus. The positive output terminal OUT+ and the negative output terminal OUT- are used to connect to a battery. The negative input terminal is connected to the negative terminal BUS- and the negative output terminal OUT- of the bus to form a negative branch. A short-circuit protection circuit 10 is connected in the negative branch to connect or disconnect the negative branch. In one embodiment, the input voltage is generated by an AC-DC circuit and transmitted to the DC-DC circuit via the bus.

[0028] Specifically, the DC-DC circuit includes a first control transistor Ma, a second control transistor Mb, an inductor L, a capacitor C, and an output control transistor M0 (some bias resistors, current-limiting resistors, etc. are not shown in the figure). The control terminals of the first control transistor Ma, the second control transistor, and the output control transistor M0 are used to receive corresponding control signals Con1, Con2, and Con3, respectively. The second terminal of the first control transistor Ma is connected to the positive input terminal, the first terminal of the second control transistor Mb is connected to the negative output terminal OUT-, the first terminal of the first control transistor Ma is connected to the second terminal of the second control transistor Mb and the first terminal of the inductor L, the second terminal of the inductor L is connected to the first terminal of the capacitor C and the second terminal of the output control transistor M0, the second terminal of the capacitor C is connected to the negative output terminal OUT-, and the first terminal of the output control transistor M0 is connected to the positive output terminal OUT+. Preferably, the short-circuit protection circuit 10 is connected between the negative terminal BUS- of the bus and the node connected by the first terminal of the second control transistor Mb and the second terminal of the capacitor C.

[0029] like Figure 2 As shown, the short-circuit protection circuit 10 includes a switching unit and a biasing unit. The switching unit is connected in series in the negative branch to control the opening and closing of the negative branch. The first end of the biasing unit is connected to the control end of the switching unit, and the second end of the biasing unit is used to receive a control voltage (5V) generated based on the input voltage to control the switching unit to turn on.

[0030] The switching unit includes a transistor M1, which is connected in series in the negative branch via its first and second terminals. In one embodiment, the second terminal of transistor M1 is connected to the negative terminal BUS- of the bus, and the first terminal of transistor M1 is connected to the negative output terminal OUT-. The control terminal of transistor M1 is connected to the first terminal of the bias unit.

[0031] In one embodiment, transistor M1 includes a MOSFET, which is connected in series in the negative branch via its first and second terminals. In another embodiment, the second terminal of the MOSFET is connected to the negative terminal BUS- of the bus, and the first terminal of the MOSFET is connected to the negative output terminal OUT-. The control terminal of the MOSFET is connected to the first terminal of the bias unit.

[0032] like Figure 2 As shown, the bias unit includes a bias resistor R1. The first end of the bias resistor R1 is connected to the control terminal of the transistor M1 of the switching unit, and the second end of the bias resistor R1 is used to receive a control voltage (5V) generated based on the input voltage.

[0033] The short-circuit protection circuit 10 also includes a voltage control circuit, which is connected to the bus to receive the input voltage and generate a control voltage based on the input voltage.

[0034] like Figure 3As shown, the voltage control circuit includes a control circuit and a transformer module T (some bias resistors, current-limiting resistors, etc., are not shown in the figure). The input terminal of the transformer module T is connected to the bus to receive the input voltage. The transformer module T is used to transform the input voltage to generate the control voltage. The control circuit is connected to the input terminal of the transformer module T and is used to control the connection and disconnection between the input terminal of the transformer module T and the bus based on the input voltage. Specifically, the first terminal of the primary side of the transformer module T is connected to the positive terminal BUS+ of the bus, and the second terminal of the primary side of the transformer module T is connected to the negative terminal BUS- of the bus through the control circuit.

[0035] like Figure 3 As shown, the control circuit includes a PWM controller module 11 and a switching transistor MK. The switching transistor MK is connected in series between the input terminal of the transformer module T and the bus through its first and second terminals. In one embodiment, the second terminal of the switching transistor MK is connected to the second terminal of the primary side of the transformer module T, and the first terminal of the switching transistor MK is connected to the negative terminal BUS- of the bus.

[0036] The PWM controller module 11 is connected to the bus to be powered by the input voltage. The control terminal of the switching transistor MK is connected to the PWM controller module 11 to receive the PWM control signal generated by the PWM controller module 11. Simultaneously, the PWM controller module 11 has a feedback terminal VFB and a sampling module connected to the feedback terminal VFB. The sampling module generates a sampling voltage based on the control voltage (5V) and feeds it back to the feedback terminal VFB. Based on the sampling voltage, the PWM controller module 11 can adjust the duty cycle of the PWM control signal, thereby stabilizing the output of the control voltage.

[0037] The first control transistor Ma, the second control transistor Mb, the output control transistor M0, the transistor M1, and the switch transistor MK are all N-channel MOSFETs. The first terminals of the first control transistor Ma, the second control transistor Mb, the output control transistor M0, the transistor M1, and the switch transistor MK are the sources. The second terminals of the first control transistor Ma, the second control transistor Mb, the output control transistor M0, the transistor M1, and the switch transistor MK are the drains. The control terminals of the first control transistor Ma, the second control transistor Mb, the output control transistor M0, the transistor M1, and the switch transistor MK are the gates. In other embodiments, the first control transistor Ma, the second control transistor Mb, the output control transistor M0, the transistor M1, and the switch transistor MK can be P-channel MOSFETs.

[0038] During normal operation, transformer module T outputs a 5V control voltage to turn on transistor M1. When the bus (positive terminal BUS+, negative terminal BUS-) is short-circuited, the entire circuit is de-energized, PWM controller module 11 cannot generate a PWM control signal, and switching transistor MK is turned off. The control voltage becomes 0V, transistor M1 is turned off, and the battery connected to the positive output terminal OUT+ and the negative output terminal OUT- cannot discharge through the parasitic diodes of output control transistor M0 and the first control transistor Ma, thus protecting the battery.

[0039] By adding short-circuit protection circuit 10, the dual-transistor blocking at the output of the multi-channel Buck-Boost circuit can be changed to a single-transistor blocking circuit, thereby saving costs and making it safer and more reliable.

[0040] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0041] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A short-circuit protection circuit, characterized in that, This short-circuit protection circuit is used for a DC-DC circuit. The DC-DC circuit has a positive input terminal and a negative input terminal for receiving input voltage through a bus, and a positive output terminal and a negative output terminal for output voltage. The positive and negative output terminals are used to connect to a battery. The negative input terminal is connected to the bus and the negative output terminal to form a negative branch. The short-circuit protection circuit includes a switching unit and a biasing unit. The switching unit is connected in series in the negative branch to control the on / off state of the negative branch. The first terminal of the biasing unit is connected to the control terminal of the switching unit, and the second terminal of the biasing unit is used to receive a control voltage generated based on the input voltage to control the switching unit to turn on.

2. The short-circuit protection circuit according to claim 1, characterized in that, The switching unit includes a transistor, which is connected in series in the negative branch through its first and second terminals, and the control terminal of the transistor is connected to the first terminal of the bias unit.

3. The short-circuit protection circuit according to claim 2, characterized in that, The transistor includes a MOS transistor, which is connected in series in the negative branch through its first and second terminals, and the control terminal of the MOS transistor is connected to the first terminal of the bias unit.

4. The short-circuit protection circuit according to claim 1, characterized in that, The bias unit includes a bias resistor, the first end of which is connected to the control terminal of the switching unit, and the second end of which is used to receive a control voltage generated based on the input voltage.

5. The short-circuit protection circuit according to claim 1, characterized in that, The short-circuit protection circuit also includes a voltage control circuit, which is connected to the bus to receive the input voltage and generate a control voltage based on the input voltage.

6. The short-circuit protection circuit according to claim 5, characterized in that, The voltage control circuit includes a transformer module, the input terminal of which is connected to the bus to receive the input voltage. The transformer module is used to transform the input voltage to generate a control voltage.

7. The short-circuit protection circuit according to claim 6, characterized in that, The voltage control circuit also includes a control circuit connected to the input terminal of the transformer module. The control circuit is used to control the connection and disconnection between the input terminal of the transformer module and the bus based on the input voltage.

8. The short-circuit protection circuit according to claim 7, characterized in that, The control circuit includes a PWM controller module and a switching transistor. The switching transistor is connected in series between the input terminal of the transformer module and the bus via its first and second terminals. The PWM controller module is connected to the bus to be powered by the input voltage. The control terminal of the switching transistor is connected to the PWM controller module to receive the PWM control signal generated by the PWM controller module.

9. A DC-DC circuit, characterized in that, Includes the short-circuit protection circuit as described in any one of claims 1 to 8.

10. The DC-DC circuit according to claim 9, characterized in that, The DC-DC circuit includes a first control transistor, a second control transistor, an inductor, a capacitor, and an output control transistor. The control terminals of the first control transistor, the second control transistor, and the output control transistor are respectively used to receive corresponding control signals. The second terminal of the first control transistor is connected to the positive input terminal, the first terminal of the second control transistor is connected to the negative output terminal, the first terminal of the first control transistor is connected to the second terminal of the second control transistor and the first terminal of the inductor, the second terminal of the inductor is connected to the first terminal of the capacitor and the second terminal of the output control transistor, the second terminal of the capacitor is connected to the negative output terminal, and the first terminal of the output control transistor is connected to the positive output terminal.

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