Short-circuit protection device for switch

Abstract

A short-circuit protection device for a switch is disclosed. A short-circuit protection device according to a first embodiment of the present invention may comprise: a voltage measurement unit that outputs a measurement voltage corresponding to an output voltage of the switch; a filter unit that attenuates the measurement voltage by a preset attenuation voltage and then filters same with a specified bandwidth to output a first voltage; and a comparison unit that compares the first voltage with a specified reference voltage.

Description

Short circuit protection device of the switch

[0001] The present invention relates to a short circuit protection device for a switch, and more specifically, to a short circuit protection device for a switch that detects a short circuit of the switch and protects the switch.

[0002] Power devices are semiconductor components that convert or control electric power. Rectifier diodes, power transistors, triacs, and other components are widely used in various fields such as industry, information, communications, transportation, electricity, and homes. Representative power devices include MOSFETs (metal oxide semiconductor field effect transistors), IGBTs (insulated gate bipolar transistors), BJTs (bipolar junction transistors), and power integrated circuits (ICs). Among these, MOSFETs, which enable high-speed switching and have low driving circuit losses, are attracting particular attention.

[0003] For MOSFETs to be applied in diverse applications, device stability must be ensured. In particular, a short circuit in a MOSFET switch can cause it to break down within hundreds of nanoseconds, necessitating a device capable of quickly determining switch short-circuit status.

[0004] Fig. 1 is a diagram showing a short-circuit protection circuit of a power switch according to the prior art.

[0005] Referring to Fig. 1, a conventional power switch (20) short-circuit protection circuit (10) can measure the drain voltage of the power switch (20) in the voltage measurement unit (30) and output a measured voltage (Vs) through a capacitor (40). Then, a comparison unit (150) can compare the measured voltage (Vs) with a preset reference voltage (V*), and if the measured voltage (Vs) is higher than the reference voltage (V*), the comparison unit (150) can determine that the power switch (20) is short-circuited.

[0006] The short-circuit protection circuit (10) of the power switch (20) according to the prior art is vulnerable to noise caused by fluctuations in the drain voltage occurring in the switching operation of the power switch (20) because it measures the drain voltage of the power switch (20).

[0007] This noise is added to the measured voltage (Vs) measured by the voltage measuring unit (30), and can cause the measured voltage (Vs) to become higher than the reference voltage (V*) even though the power switch (20) is operating normally, which can cause a malfunction of the short-circuit protection circuit (10).

[0008] To reduce such malfunctions, a method may be considered to increase the size of the capacitor (40) to slow down the rate at which the measured voltage (Vs) increases, thereby reducing the influence of noise generated during the switching transient of the power switch (20). However, this method slows down the rate at which the measured voltage (Vs) increases even when the power switch (20) is short-circuited, which means that the short-circuit protection speed is slowed down, which may result in a breakdown of the power switch (20).

[0009] Therefore, in the short-circuit protection circuit (10) according to the prior art, there is a problem in that it is difficult to satisfy both the noise resistance and the short-circuit protection speed performance as they are trade-offs.

[0010] In addition, since the measurement voltage (Vs), which is the output of the voltage measurement unit (30) of the prior art, depends on the drain voltage of the power switch (20), if the drain voltage of the power switch (20) is too small, the measurement voltage (Vs) may also form a small value. In this case, the reference voltage (V*) of the comparison unit (150) for determining a short circuit must also inevitably be set to a small value, which reduces the margin between the reference voltage (V*) and the measurement voltage (Vs), and there is a problem that the short circuit protection circuit (10) becomes vulnerable to external noise.

[0011] The matters described in the technical background of this invention are for understanding the background of the invention, and cannot be determined to be prior art already known to a person with ordinary skill in the field to which this technology belongs.

[0012] The present invention aims to provide a short circuit protection device for a switch that can prevent a break down of the switch by detecting a rapidly rising drain voltage as a measurement voltage and quickly turning off the switch when a short circuit occurs in the switch.

[0013] In addition, it is intended to provide a short-circuit protection device for a switch that can increase resistance to noise by compensating for the difference between the measured voltage and the switch voltage.

[0014] In addition, it is intended to provide a device that can protect the switch from short circuit more precisely by stabilizing the voltage for voltage measurement.

[0015] According to one aspect of the present invention, a short circuit protection device for a switch is disclosed, comprising: a voltage measuring unit for outputting a measurement voltage corresponding to an output voltage of the switch; a filter unit for attenuating the measurement voltage by a preset attenuation voltage and then filtering it with a designated bandwidth to output a first voltage; and a comparison unit for comparing the first voltage with a designated reference voltage.

[0016] According to another aspect of the present invention, a device for detecting and protecting a short circuit of a switch, comprising: a voltage measuring unit for outputting a measured voltage corresponding to an output voltage of the switch; an amplifier unit for amplifying and outputting the measured voltage, which is an input voltage, by a preset amount corresponding to a difference between the measured voltage and the output voltage of the switch; and a comparison unit for comparing the first voltage with a designated reference voltage.

[0017] According to another aspect of the present invention, a device for detecting and protecting a short circuit of a switch is disclosed, comprising: a voltage measuring unit for outputting a measurement voltage corresponding to an output voltage of the switch; a filter unit for attenuating the measurement voltage by a preset attenuation voltage and then filtering it with a specified bandwidth to output a first voltage; an amplifier unit for amplifying the first voltage, which is an input voltage, to a preset magnitude and outputting the amplified voltage; and a comparison unit for comparing a specified reference voltage with the voltage output from the amplifier unit.

[0018] In some embodiments, the amplifier may attenuate and then amplify the input voltage to adjust the margin between the reference voltages.

[0019] In some embodiments, the amplifier may attenuate the input voltage by using a negative voltage applied to the switch.

[0020] According to an embodiment, the filter unit may include a Zener diode that attenuates the measurement voltage by the attenuation voltage.

[0021] According to an embodiment, a resistor is connected between the first terminal of the voltage measurement unit and the second terminal of the switch, the measured voltage of the first terminal corresponds to the sum of the output voltage of the second terminal and the resistance voltage applied to the resistor, and the attenuation voltage may correspond to the resistance voltage.

[0022] According to an embodiment, the short-circuit protection device of the switch may further include a driving unit that operates the switch when an input voltage is applied; and a voltage improvement unit that generates a flattened voltage by flattening the input voltage and applies the flattened voltage to the voltage measurement unit.

[0023] According to an embodiment, the driving unit may determine whether to supply the input voltage to the switch based on an input control signal, and the voltage improvement unit may determine whether to supply the flattening voltage to the voltage measurement unit based on the control signal.

[0024] According to an embodiment, the voltage improvement unit may include a time delay unit that delays the control signal by a preset time when the control signal is input so that the flattening voltage is output simultaneously with the input voltage output of the driving unit.

[0025] The short-circuit protection device of a switch according to an embodiment of the present invention has the advantage of being able to prevent break down of the switch by detecting the accurately and rapidly rising drain voltage as a measurement voltage and quickly turning off the switch when a short-circuit occurs in the switch.

[0026] Figure 1 is an example diagram of a short-circuit protection circuit of a power switch according to the prior art.

[0027] FIG. 2 is a block diagram illustrating a short circuit protection device according to the first embodiment of the present invention.

[0028] Fig. 3 is a circuit diagram illustrating a short-circuit protection device according to the first embodiment of the present invention.

[0029] FIG. 4 is a diagram illustrating changes in input voltage applied to a voltage measuring unit according to the first embodiment of the present invention.

[0030] FIG. 5 is a block diagram illustrating a short circuit protection device according to a second embodiment of the present invention.

[0031] Fig. 6 is a circuit diagram illustrating a short-circuit protection device according to a second embodiment of the present invention.

[0032] Figure 7 shows the results of a double pulse test experiment of a short-circuit protection device according to the prior art.

[0033] Figure 8 shows the results of a double pulse test experiment of a short-circuit protection device according to an embodiment of the present invention.

[0034] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0035] In describing the present invention, detailed descriptions of related known technologies will be omitted if they are deemed to unnecessarily obscure the gist of the present invention. Furthermore, numbers (e.g., "first," "second," etc.) used throughout the description of this specification are merely identifiers used to distinguish one component from another.

[0036] Additionally, throughout the specification, when a component is referred to as being "connected" or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but may also be connected or connected via another component in between, unless otherwise specifically stated.

[0037] Additionally, throughout the specification, when a part is said to "include" a component, this does not exclude other components, but rather implies the inclusion of other components, unless otherwise specifically stated. Furthermore, terms such as "part" and "module" used in the specification mean a unit that processes at least one function or operation, which may be implemented using one or more pieces of hardware, software, or a combination of hardware and software.

[0038] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0039]

[0040] FIG. 2 is a block diagram illustrating a short circuit protection device according to the first embodiment of the present invention.

[0041] Referring to FIG. 2, a short-circuit protection device (200) according to the first embodiment of the present invention may include a driving unit (210), a voltage measuring unit (230), a filter unit (240), an amplifier unit (250), and a comparison unit (260). Hereinafter, in describing the present invention, the switch (220) is exemplified as a power switch using a MOSFET, but the switch to which the present invention can be applied is not limited thereto. For example, the switch may be various switches using a MOSFET (metal oxide semiconductor field effect transistor), an IGBT (insulated gate bipolar transistor), a BJT (bipolar junction transistor), a power integrated circuit (IC), etc.

[0042] The driving unit (210) may be configured to supply power to the switch (220). For example, if the switch (220) is a MOSFET, the driving unit (210) may include a gate driver capable of providing gate power to the switch (220), and the MOSFET supplied with gate power through the gate driver may be turned on, thereby turning the switch (220) on. The driving unit (210) may be provided in various ways so that the switch (220) may be turned on / off.

[0043] The voltage measuring unit (230) according to the first embodiment of the present invention can measure the output voltage of the switch (220) and output it as a measured voltage (Vs). For example, if the switch (220) is a power switch implemented with a MOSFET, when the driving unit (210) provides a predetermined amount of power to the gate of the switch (220) MOSFET, the switch (220) becomes conductive, causing current to flow in the switch (220), and a voltage can be applied to the switch (220) by the internal resistance of the switch (220), etc. The voltage measuring unit (230) can measure a voltage corresponding to the drain voltage of the switch (220) and output it as a measured voltage (Vs).

[0044] The filter unit (240) according to the first embodiment of the present invention can receive a measurement voltage (Vs), filter it with a designated bandwidth, and output it as a first voltage (V1). At this time, the filter unit (240) can attenuate the measurement voltage by a preset attenuation voltage and then filter it with the designated bandwidth. If a short circuit occurs in the switch (220), the switch (220) can break down within several hundred nanoseconds, and therefore, the short circuit protection device (200) according to the embodiment of the present invention must be able to quickly determine whether the switch (220) is short-circuited.

[0045] However, when the switch (220) is turned on, the measured voltage (Vs) may be greater than the output voltage (ex. drain voltage) of the switch (220) due to the output voltage (drain voltage in the case of a MOSFET) of the switch (220) and the resistor(s) connected to the output terminal (drain in the case of a MOSFET) of the switch (220). That is, the measured voltage (Vs) may correspond to the sum of the output voltage (drain voltage) and the voltage of the resistor(s). As a result, the margin between the measured voltage (Vs) and the reference voltage (V*) of the comparison unit (260) may be reduced, which may increase the possibility of misjudging whether the switch (220) is short-circuited. Therefore, the filter unit (240) may attenuate the measured voltage by a preset attenuation voltage and then filter it with a designated bandwidth. At this time, the preset attenuation voltage may correspond to the 'voltage applied to the resistor(s) connected to the output terminal of the switch (220)'. Afterwards, the filter unit (240) can filter out high-frequency noise generated during switching operation by attenuating the measurement voltage (Vs) by the attenuation voltage.

[0046] Accordingly, the filter unit (240) may include an attenuation configuration capable of attenuating the measurement voltage (Vs) by an attenuation voltage. For example, the filter unit (240) may include a Zener diode capable of attenuating a constant voltage regardless of changes in current.

[0047] In addition, the filter unit (240) may include a filter having a bandwidth capable of filtering high-frequency noise generated during a switching operation. For example, the filter unit (240) may include a band pass filter capable of passing only a designated frequency range or a low pass filter capable of passing only low-frequency components. For example, the filter unit (240) may include one or more of passive filters such as a first-order RC low pass filter, a second-order RC low pass filter, a second-order RLC low pass filter, and a second-order RC band pass filter, and active filters such as a first-order RC active low pass filter with a built-in amplifier, and a Sallen-Key filter.

[0048] According to the first embodiment of the present invention, high-frequency noise included in the measured voltage (Vs) due to the change in drain voltage that occurs during the switching operation of the switch (220) is attenuated by the filter unit (240), thereby preventing malfunction of the short-circuit protection device (200) during normal operation of the switch (220).

[0049] The amplifier (250) according to the first embodiment of the present invention can amplify the first voltage (V1) with a predetermined amplification ratio (gain, hereinafter referred to as “gain”) and output it as a second voltage (V2). The amplifier (250) can have a sufficient bandwidth to pass a voltage that rapidly increases when the switch (220) is short-circuited. Therefore, the short-circuit protection device (200) according to the embodiment of the present invention can recognize that a short-circuit has occurred in the switch (220) by recognizing the measured voltage (Vs) that rapidly increases when a short-circuit occurs in the switch (220), and thus has the advantage of being able to quickly protect the switch (220).

[0050] For example, the amplifier (250) may be any one of various amplifiers known at the time of application of the present invention, such as an inverting / non-inverting amplifier utilizing an amplifier (e.g., OP-AMP). In addition, the amplifier (250) may also be used as a voltage follower with a gain of 1 depending on the characteristics of the switch (220). In addition, as described above, the amplifier (250) has the advantage of being able to adjust the margin between the second voltage (V2) and the reference voltage (V*) by amplifying the first voltage (V1) with a predetermined gain and outputting it as the second voltage (V2).

[0051] If the attenuation configuration of the filter unit (240) is 'not included' in the short-circuit protection device (200), the amplifier unit (250) can output the measured voltage (Vs), which is the input voltage, by attenuating and amplifying it by a preset amount corresponding to the difference between the measured voltage (Vs) and the output voltage of the switch (220). At this time, the preset amount may correspond to the "voltage applied to the resistor(s) connected to the output terminal of the switch (220)".

[0052] Meanwhile, if the attenuation configuration of the filter unit (240) is 'included' in the short circuit protection device (200), the amplifier unit (250) may be able to output only the amount of attenuation voltage that has not been attenuated by the filter unit (240). That is, in this case, the preset size may correspond to the "unfiltered voltage among the attenuation voltages (hereinafter referred to as 'residual voltage')". This is because there may not be a Zener diode that completely matches the attenuation voltage.

[0053] Below, the operation of the amplifier (250) will be described in more detail.

[0054] The short circuit protection device (200) needs to maintain a margin between the measurement voltage (Vs) and the reference voltage (V*) at a certain level or higher to prevent false short circuit detection due to noise of the switch (220) itself and / or noise caused by external factors.

[0055] According to the conventional short-circuit protection circuit (10) illustrated in Fig. 1, in a situation where the drain voltage of the switch (20 in Fig. 1) has a small value, the reference voltage (V*) is also inevitably set to a small value, and as a result, the margin between the measured voltage (Vs) and the reference voltage (V*) may become small.

[0056] Here, when a damping voltage is added to the output voltage (i.e., drain voltage) of the switch (220) to form a measurement voltage (Vs), the margin between the measurement voltage (Vs) and the reference voltage (V*) becomes smaller, so that even though the switch (20 in FIG. 1) is operating normally, the possibility that the short-circuit protection circuit (10 in FIG. 1) will mistake the switch (20) for a short-circuit may become very high.

[0057] The amplifier unit (250) according to the first embodiment of the present invention can process the first voltage (V1) with a specified gain so that the 'residual voltage' included in the first voltage (V1), which is the output of the filter unit (240), is attenuated, thereby outputting the second voltage (V2). As a result, even the residual voltage of the attenuated voltage included in the measured voltage (Vs) can be removed. In this case, as a result, the margin between the second voltage (V2) and the reference voltage (V*) increases, and thus the short-circuit protection device (200) according to the first embodiment of the present invention can have higher resistance to external noise.

[0058] The comparison unit (260) according to the first embodiment of the present invention can compare the second voltage (V2) with the reference voltage (V*). Here, the value output by the comparison unit (260) when the second voltage (V2) is lower than the reference voltage (V*) and the value output by the comparison unit (260) when the second voltage (V2) is higher than the reference voltage (V*) can be set to be different. Accordingly, the short-circuit protection device (200) can determine whether the switch (220) is short-circuited through the output value of the comparison unit (260).

[0059] As described above, the driving unit (210) can supply driving power to the power switch to turn on / off the switch, which may be one of various configurations known at the time of application of the present invention. In addition, the short-circuit protection device (200) according to the first embodiment of the present invention may include a control unit (not shown) that controls the driving unit (210) according to the output of the comparison unit (260), thereby turning on or off the switch (220). Here, the control unit (not shown) may be implemented by being integrated into any of the above-described configurations as a software module, or may be implemented as a separate configuration independent in hardware, and may be provided in various ways depending on the environment to which the present invention is applied.

[0060] Accordingly, the short circuit protection device (200) according to the first embodiment of the present invention can detect a rapidly rising drain voltage as a measurement voltage (Vs) when a short circuit occurs in the switch (220) and quickly turn off the switch, thereby preventing a breakdown of the switch (220), and can increase resistance to noise by attenuating the attenuation voltage and / or high-frequency noise included in the measurement voltage (Vs).

[0061] So far, the components and functions of the short-circuit protection device (200) according to the first embodiment of the present invention have been described with reference to FIG. 2. However, the components illustrated in FIG. 2 are merely one embodiment of the present invention, and it will be apparent to those skilled in the art, in light of the technical concept of the present invention, that, regardless of the names of the components included in the short-circuit protection device (200), depending on the environment to which the present invention is applied, the functions performed may be further subdivided and implemented with more components, or the functions performed may be combined and implemented with a smaller number of components.

[0062]

[0063] Fig. 3 is a circuit diagram illustrating a short-circuit protection device according to the first embodiment of the present invention.

[0064] Referring to FIG. 3, the voltage measurement unit (230), filter unit (240), amplifier unit (250), and comparison unit (260) included in the short circuit protection device (200) according to the first embodiment of the present invention are the same as those described above with reference to FIG. 2, so redundant descriptions are omitted, and a description will be focused on one embodiment of a circuit that can be implemented with each configuration.

[0065] For example, the voltage measuring unit (230) may include a first diode (140) whose cathode is connected to the output terminal of the switch (220), a first resistor (150) whose one end is connected to the anode of the first diode (140), a second resistor (160) connecting the other end of the first resistor (150) to a predetermined supply voltage (e.g., the output voltage of the driving unit (210), Gate Driver Output), and a second diode (170) connected in parallel with the second resistor (160). Here, the voltage measuring unit (230) may output the voltage at the other end of the first resistor (150) as a measurement voltage (Vs).

[0066] For example, the measured voltage (Vs) may correspond to the sum of the drain voltage of the switch (220), the voltage applied to the first diode (140), and the voltage applied to the first resistor (150). That is, when the switch (220) is turned on by the voltage applied from the driving unit (210), current may flow through the first diode (140) and the first resistor (150), so that voltage may be applied to these elements. Therefore, the measured voltage (Vs) may correspond to the sum of the drain voltage, the voltage of the first diode (140), and the voltage of the first resistor (150). In this case, the attenuation voltage may be the sum of the voltage of the first diode (140) and the voltage of the first resistor (150).

[0067] The filter unit (240) may include, for example, a third resistor (180) having one end connected to the other end of the first resistor (150), a Zener diode (310) having the other end of the third resistor (180) and the cathode connected, and a capacitor (190) having one end connected to the anode of the Zener diode (310). The third resistor (180) and the capacitor (190) may be RC filters capable of removing high frequencies that may be generated by a switching operation. In addition, the Zener diode (310) may attenuate the attenuation voltage. Accordingly, the filter unit (240) may remove all or part of the high frequencies and the attenuation voltage from the measurement voltage (Vs) and output the voltage applied to the capacitor (190) as the first voltage (V1). The filter unit (240) illustrated in FIG. 3 is illustrated as a first-order RC low pass filter, but it will be apparent to those skilled in the art in light of the technical concept of the present invention that it may include one or more of various passive filters and active filters known at the time of application of the present invention.

[0068] The amplifier (250) may include, for example, an amplifier (320) having a first input terminal (+) in which a negative voltage (negative voltage of the driver output voltage) is connected to one end of a capacitor (190) connected to a Zener diode (310), a fourth resistor (360) connecting the output terminal of the amplifier (320) and the second input terminal (-), and a fifth resistor (370) connecting the second input terminal (-) of the amplifier (320) and a predetermined ground, and may output the voltage at the output terminal of the amplifier (320) as a second voltage (V2). The gain set in the amplifier (320) may correspond to removing the residual voltage from the first voltage (V1). For this purpose, a negative voltage may be applied to the first input terminal (+) of the amplifier (320). FIG. 3 illustrates an example in which a negative voltage (Gate Driver Output (Negative)) among the output voltages of the gate driver of the driving unit (210) is applied to the first input terminal (+) of the amplifier (320). Accordingly, the second voltage (V2) may correspond to the drain voltage of the switch (220) with the attenuation voltage removed.

[0069] Meanwhile, when the switch (220) is turned on, an input voltage for generating a flowing current can be connected, and the gate driver output voltage can be connected as an input voltage to the voltage measuring unit (230) of Fig. 5. Of course, an independent DC voltage other than the gate driver output voltage can be used as the input voltage, but the gate driver output voltage can be connected for cost and ease of manufacturing.

[0070] However, the gate driver output voltage (Gate driver output) may vary in voltage magnitude depending on the switching operation of the switch (220). Referring to Fig. 4, it can be confirmed that the output voltage (Vg) of the gate driver of the driving unit (210) fluctuates significantly due to switching noise when the switch (220) is switched. This may also cause the magnitude of the first voltage (V1) to vary, resulting in a problem of reduced circuit stability.

[0071] Accordingly, the short-circuit protection device (500) according to the second embodiment of the present invention may further include a voltage improvement unit (510). Hereinafter, the short-circuit protection device (500) according to the second embodiment of the present invention will be described with reference to FIGS. 5 and 6.

[0072]

[0073] FIG. 5 is a block diagram illustrating a short-circuit protection device according to a second embodiment of the present invention, and FIG. 6 is a circuit diagram illustrating a short-circuit protection device according to a second embodiment of the present invention.

[0074] Referring to FIG. 5, a short circuit protection device (500) according to a second embodiment of the present invention may further include a voltage improvement unit (510) in addition to the configuration of the short circuit protection device (200) according to the first embodiment. The voltage improvement unit (510) may have one end connected to the driving unit (210) and the other end connected to the voltage measurement unit (230).

[0075] The voltage improvement unit (510) can generate a 'flattened voltage' (Vout) by flattening the drive unit input voltage (Vin) applied for the operation of the switch (220) of the drive unit (210). In addition, the voltage improvement unit (510) can apply the flattened voltage (Vout) to the voltage measurement unit (230).

[0076] In addition, since the timing at which the flattening voltage (Vout) is applied to the voltage measurement unit (230) must be synchronized with the switching and operation of the driving unit (210), the voltage improvement unit (510) can simultaneously receive the control signal (PWM signal) applied to the driving unit (210). When the control signal (PWM signal) corresponds to 'ON', the voltage improvement unit (510) can apply the flattening voltage (Vout) to the voltage measurement unit (230), and when the control signal (PWM signal) corresponds to 'OFF', the flattening voltage (Vout) can not be applied to the voltage measurement unit (230). In addition, the voltage improvement unit (510) can include a time delay unit that can apply the flattening voltage (Vout) to the voltage measurement unit (230) simultaneously with the conduction of the switch (220).

[0077] Referring to Fig. 6, the voltage improvement unit (510) may include an LC filter (L1 and C3) for removing noise from the drive unit input voltage (Vin) and a regulator for flattening the high-frequency filtered input voltage (Vin). As a result, a flattened voltage may be generated.

[0078] In addition, the voltage improvement unit (510) is connected to a control signal (PWM signal) output unit (610) and can simultaneously receive a control signal input to the driving unit (210).

[0079] In addition, the voltage improvement unit (510) may include a gate driver or a photocoupler, so that when the switch (220) is turned ON by a control signal, the flattening voltage (Vout) may be applied to the voltage measurement unit (230) (Vk(on)), and when the switch (220) is turned OFF, the application of the flattening voltage (Vout) to the voltage measurement unit (230) may be released (Vk(off)). At this time, the voltage improvement unit (510) may include a time delay unit (R7 and C5). By adjusting the time constant of the time delay unit (R7 and C5), the switching timing and the application (ON) timing of the flattening voltage (Vout) may be synchronized.

[0080]

[0081] As described above, the short circuit protection device (200) according to the first embodiment of the present invention and / or the short circuit protection device (500) according to the second embodiment can sufficiently secure a margin between the second voltage (V2) and the reference voltage (V*), so that when a short circuit occurs in the switch (200), the switch can be quickly turned off by detecting the accurately and rapidly rising drain voltage as the measurement voltage, thereby preventing the switch from being damaged (break down).

[0082] Hereinafter, with reference to FIGS. 7 to 9, the simulation results of the short circuit protection device (200) of the present invention will be described.

[0083]

[0084] Fig. 7 shows the results of a double pulse test experiment of a short-circuit protection device according to the prior art. Referring to Fig. 7, when the drain current of the switch (220) is 45 [A], the second voltage (V2, Vsense in Fig. 7) is 6.238 [V], the voltage margin for the reference voltage (V*) of 8 [V] is 1.762 [V], and the sensing sensitivity is 34 [mV / A].

[0085] Meanwhile, Fig. 8 is a double pulse test experimental result of a short-circuit protection device according to an embodiment of the present invention. Referring to Fig. 8, when the drain current of the switch (220) is 45 [A], it can be confirmed that the second voltage (V2, Vsense in Fig. 8) is 4.744 [V], the voltage margin for the reference voltage (V*) of 8 [V] is 3.256 [V], and the sensing sensitivity is 62.5 [mV / A]. When the drain current set as the overcurrent condition is 70 [A], when the second voltage (V2) exceeds the reference voltage (V*), the gate-source voltage (Vgs) and drain current (Id) of the power switch decrease, and protection against overcurrent can be performed.

[0086] As a result of comparison of FIGS. 7 and 8, it can be confirmed that the voltage margin is significantly larger than that of the conventional technology according to the embodiment of the present invention, and thus the sensing accuracy is improved.

[0087]

[0088] Although the present invention has been described above with reference to embodiments thereof, it will be readily understood by those skilled in the art that various modifications and changes to the present invention can be made without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. In a device that detects and protects against a short circuit in a switch, A voltage measuring unit that outputs a measurement voltage corresponding to the output voltage of the above switch; A filter unit that attenuates the above measurement voltage by a preset attenuation voltage and then filters it with a specified bandwidth to output a first voltage; and A comparison unit for comparing the first voltage with a specified reference voltage; A short-circuit protection device for a switch, including:

2. In a device that detects and protects against a short circuit in a switch, A voltage measuring unit that outputs a measurement voltage corresponding to the output voltage of the above switch; An amplifier unit that amplifies and outputs the measured voltage, which is an input voltage, by a preset amount corresponding to the difference between the measured voltage and the output voltage of the switch; and A comparison unit for comparing the first voltage with a specified reference voltage; A short-circuit protection device for a switch, including:

3. In a device that detects and protects against a short circuit in a switch, A voltage measuring unit that outputs a measurement voltage corresponding to the output voltage of the above switch; A filter unit that attenuates the above measurement voltage by a preset attenuation voltage and then filters it with a specified bandwidth to output a first voltage; An amplifier unit that amplifies the first voltage, which is an input voltage, to a preset size and outputs the amplified voltage; and A comparison unit that compares the voltage output from the amplifier unit with a specified reference voltage; A short-circuit protection device for a switch, including:

4. In paragraph 2 or 3, The above amplifier is a short-circuit protection device of a switch that attenuates and then amplifies the input voltage to adjust the margin between the reference voltages.

5. In paragraph 4, The above amplifier is a short-circuit protection device of the switch that attenuates the input voltage by using the negative voltage applied to the switch.

6. In paragraph 1 or paragraph 3, The above filter part, A zener diode that attenuates the above measurement voltage by the attenuation voltage; A short-circuit protection device for a switch, including:

7. In paragraph 6, A resistor is connected between the first terminal of the voltage measuring unit and the second terminal of the switch, The above measurement voltage of the above first terminal corresponds to the sum of the above output voltage of the above second terminal and the resistance voltage applied to the above resistor, The above attenuation voltage is a short-circuit protection device of the switch corresponding to the above resistance voltage.

8. In any one of paragraphs 1 to 3, A driving unit that operates the switch when an input voltage is applied; and A voltage improvement unit that generates a flattened voltage by flattening the input voltage and applies the flattened voltage to the voltage measurement unit; A short circuit protection device for a switch, further comprising:

9. In paragraph 8, The above driving unit determines whether to supply the input voltage to the switch according to the input control signal, The above voltage improvement unit is a short-circuit protection device of a switch that determines whether to supply the flattening voltage to the voltage measurement unit according to the above control signal.

10. In paragraph 9, The above voltage improvement unit is, A time delay device that delays the control signal by a preset time when the control signal is input so that the flattening voltage is output simultaneously with the input voltage output of the driving unit; A short-circuit protection device for a switch, including:

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