Chip output short circuit protection circuit

Abstract

The present invention provides a chip output short-circuit protection circuit, which includes a driving module, a first transistor, a first capacitor, a second capacitor, a first inductor, a second inductor, a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, a short-circuit switch, a diode and a detection module; the detection module is used to detect whether the voltage at the negative terminal of the diode is negative to trigger the driving module; wherein the first end of the detection module is connected to the input end of the driving module, the second end of the detection module is respectively connected to the positive terminal of the diode and the first end of the fifth inductor, and the third end of the detection module is connected to the source of the first transistor. Compared with the related art, the chip output short-circuit protection of the present invention has high reliability.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a chip output short circuit protection circuit applied to an overvoltage and overcurrent protection chip. Background Art

[0002] At present, with the increasing use of mobile devices such as smart phones, wearable devices, power tools, and drones, the lithium-ion battery power supply application in the mobile devices is an important part. Due to the stability problem of lithium-ion batteries, overvoltage and overcurrent protection chips are used as front-end applications of lithium-ion battery chargers to protect lithium-ion batteries and chargers. Among them, overvoltage and overcurrent protection chips can realize multiple protection functions, such as input power supply and lithium battery overvoltage protection, load current limiting protection, and output short circuit protection.

[0003] The battery protection circuit of the related art sets the charging and discharging current limits to the same value, or performs fixed charging and discharging currents through internal circuits. Figure 1 As shown, Figure 1 The following is an application circuit diagram of an overvoltage and overcurrent protection chip of the related technology. U1 is an overvoltage and overcurrent protection chip. U2 is the AC adapter circuit of the charging power supply, U3 is the charging circuit, U4 is the post-stage system circuit, and U5 is a lithium battery. Among them, S0 is an analog short-circuit switch inside the overvoltage and overcurrent protection chip U1, which is generally a power tube.

[0004] However, when the overvoltage and overcurrent protection chip U1 works normally, S0 is disconnected, and the output voltage VOUT is approximately equal to the power supply voltage VIN input by the AC adapter circuit U2 of the charging power supply, which serves as the power supply for the subsequent system circuit U4. If VOUT is suddenly short-circuited to the ground, the drain end of the power tube in the analog short-circuit switch S0 will instantly withstand a voltage much higher than VIN, and a negative voltage will appear at the source end of the power tube; at this time, the drain and source of the power tube will produce a very large voltage difference. If the withstand voltage of the power tube is not enough to withstand such a high voltage, the power tube will be damaged, thereby burning the overvoltage and overcurrent protection chip U1.

[0005] Therefore, it is necessary to provide a new circuit to solve the above problems. Summary of the invention

[0006] In view of the above deficiencies in the prior art, the present invention provides a chip output short circuit protection circuit with high reliability for chip output short circuit protection.

[0007] In order to solve the above technical problems, the present invention provides a chip output short-circuit protection circuit, which is applied to an overvoltage and overcurrent protection chip. The chip output short-circuit protection circuit includes a driving module, a first transistor, a first capacitor, a second capacitor, a first inductor, a second inductor, a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, a short-circuit switch, a diode and a detection module; wherein the first transistor is a power switch tube, and the diode is an ESD device; the detection module is used to detect whether the voltage at the negative end of the diode is a negative value to trigger the driving module; wherein,

[0008] The output end of the driving module is connected to the gate of the first transistor;

[0009] The drain of the first transistor is respectively connected to the second end of the fourth inductor and the first end of the first capacitor, and the source of the first transistor is respectively connected to the first end of the third inductor and the negative terminal of the diode;

[0010] The first end of the fourth inductor serves as a power supply voltage input end of the chip output short-circuit protection circuit;

[0011] The second end of the third inductor is respectively connected to the first end of the second capacitor and the first end of the short-circuit switch, and serves as a power supply voltage output end of the chip output short-circuit protection circuit;

[0012] The positive terminal of the diode is connected to the first terminal of the fifth inductor;

[0013] The second end of the first capacitor is connected to the first end of the first inductor;

[0014] The second end of the second capacitor is connected to the first end of the second inductor;

[0015] The second end of the short-circuit switch is connected to the first end of the sixth inductor;

[0016] The second end of the first inductor, the second end of the second inductor, the second end of the sixth inductor and the second end of the fifth inductor are all connected to ground;

[0017] The first end of the detection module is connected to the input end of the driving module, the second end of the detection module is respectively connected to the positive end of the diode and the first end of the fifth inductor, and the third end of the detection module is connected to the source of the first transistor.

[0018] Preferably, the detection module includes an NPN transistor and a logic module, and the logic module is used to control the driving module to drive the first transistor to turn on when the detection module detects that the voltage at the cathode end of the diode is a negative value; wherein the collector of the NPN transistor is connected to the input end of the logic module, the base of the NPN transistor serves as the second end of the detection module, and the emitter of the NPN transistor serves as the third end of the detection module; and the output end of the logic module serves as the first end of the detection module.

[0019] Preferably, the detection module is an NMOS tube, the drain of the NMOS tube serves as the first end of the detection module, the gate of the NMOS tube serves as the second end of the detection module, and the source of the NMOS tube serves as the third end of the detection module.

[0020] Preferably, the chip output short-circuit protection circuit also includes a third capacitor, the first end of the third capacitor is respectively connected to the output end of the driving module and the gate of the first transistor; the second end of the third capacitor is respectively connected to the drain of the first transistor, the second end of the fourth inductor and the first end of the first capacitor.

[0021] Compared with the related art, the chip output short-circuit protection circuit of the present invention includes a driving module, a first transistor, a first capacitor, a second capacitor, a first inductor, a second inductor, a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, a short-circuit switch, a diode detection module and a logic module. The circuit detects whether the voltage at the cathode end of the diode is negative through the detection module, and when the detection module detects that the voltage at the cathode end of the diode is negative, the driving module is controlled to drive the first transistor to turn on. When the overvoltage and overcurrent protection chip has a chip output short circuit, the detection module controls the driving module to trigger the diode (power switch tube) to turn on instantly. The instantaneous opening of the power tube provides a discharge path for the input and output currents, avoids damage to the power switch tube, and reduces the impact of the output short circuit on the front-stage adapter, thereby making the chip output short circuit protection highly reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be described in detail below in conjunction with the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made in conjunction with the following drawings. In the accompanying drawings:

[0023] Figure 1 It is an application circuit diagram of an overvoltage and overcurrent protection chip of the related technology;

[0024] Figure 2 This is a circuit structure diagram of the chip output short-circuit protection circuit of the present invention;

[0025] Figure 3FIG. 1 is a circuit structure diagram of a first embodiment of a chip output short-circuit protection circuit of the present invention;

[0026] Figure 4 This is a circuit structure diagram of a second embodiment of a chip output short-circuit protection circuit of the present invention;

[0027] Figure 5 This is a circuit structure diagram of Embodiment 3 of the chip output short-circuit protection circuit of the present invention. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] The specific implementation modes / embodiments recorded herein are specific implementation modes of the present invention, which are used to illustrate the concept of the present invention, are explanatory and exemplary, and should not be interpreted as limiting the implementation modes of the present invention and the scope of the present invention. In addition to the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims and the specification of this application, and these technical solutions include any obvious replacement and modification of the embodiments recorded herein, which are within the protection scope of the present invention.

[0030] Please refer to Figure 2 As shown, the present invention provides a chip output short circuit protection circuit 100.

[0031] The chip output short circuit protection circuit 100 is applied to an overvoltage and overcurrent protection chip. The overvoltage and overcurrent protection chip can realize multiple protection functions, such as input power supply and lithium battery overvoltage protection, load current limiting protection and output short circuit protection.

[0032] The chip output short circuit protection circuit 100 includes a driving module DRI, a first transistor M1, a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, a third inductor L3, a fourth inductor L4, a fifth inductor L5, a sixth inductor L6, a short circuit switch K, a diode D and a detection module TEST.

[0033] Among them, the driving module DRI, the first transistor M1, the first capacitor C1, the second capacitor C2, the first inductor L1, the second inductor L2, the third inductor L3, the fourth inductor L4, the fifth inductor L5, the sixth inductor L6, the short-circuit switch K and the diode D are all components in the overvoltage and overcurrent protection chip, and the circuit composed of the above components is equivalent to the simplified circuit when the output power of the overvoltage and overcurrent protection chip is partially short-circuited. Of course, it is not limited to this, and other equivalent short-circuit circuits can also be substituted.

[0034] Among them, the first transistor M1 is a power switch tube. The diode D is an ESD device. The first inductor L1 is the parasitic inductance of the input capacitor of the overvoltage and overcurrent protection chip. The second inductor L2 is the parasitic inductance of the output capacitor of the overvoltage and overcurrent protection chip. The third inductor L3, the fourth inductor L4 and the fifth inductor L5 are parasitic inductors. The sixth inductor L6 is the parasitic inductance of the wire when the output of the overvoltage and overcurrent protection chip is short-circuited. The short-circuit switch K is a switch that simulates the output short-circuit moment. The driving module DRI provides a gate voltage for the first transistor M1.

[0035] The specific circuit structure of the equivalent simplified circuit when the output power of the overvoltage and overcurrent protection chip is partially short-circuited is:

[0036] The output terminal of the driving module DRI is connected to the gate of the first transistor M1.

[0037] The drain of the first transistor M1 is connected to the second end of the fourth inductor L4 and the first end of the first capacitor C1 respectively, and the source of the first transistor M1 is connected to the first end of the third inductor L3 and the cathode of the diode D respectively.

[0038] The first end of the fourth inductor L4 serves as the power voltage input terminal VIN of the chip output short-circuit protection circuit 100 .

[0039] The second end of the third inductor L3 is connected to the first end of the second capacitor C2 and the first end of the short-circuit switch K respectively, and serves as the power supply voltage output terminal VOUT of the chip output short-circuit protection circuit 100 .

[0040] An anode terminal of the diode D is connected to a first terminal of the fifth inductor L5 .

[0041] The second end of the first capacitor C1 is connected to the first end of the first inductor L1.

[0042] The second end of the second capacitor C2 is connected to the first end of the second inductor L2.

[0043] The second end of the short-circuit switch K is connected to the first end of the sixth inductor L6.

[0044] A second end of the first inductor L1 , a second end of the second inductor L2 , a second end of the sixth inductor L6 , and a second end of the fifth inductor L5 are all connected to the ground GND.

[0045] When the output power of the overvoltage and overcurrent protection chip is partially short-circuited, the equivalent simplified circuit working process is:

[0046] When the overvoltage and overcurrent protection chip is working normally, the short-circuit switch K is disconnected, the first transistor M1 is fully opened, and the voltage of the power supply voltage output terminal VOUT is approximately equal to the voltage of the power supply voltage input terminal VIN, which serves as the power supply for the subsequent system. If the power supply voltage output terminal VOUT is suddenly short-circuited to the ground, the short-circuit switch K is suddenly closed, and the power supply voltage output terminal VOUT discharges the charge through the sixth inductor L6. Since the inductance value of the sixth inductor L6 is very small, a large current will be generated instantly at the output terminal; since the first transistor M1 is always turned on, the power supply voltage input terminal VIN forms a path with the ground GND through the fourth inductor L4, the first transistor M1, the third inductor L3 and the sixth inductor L6, and the fourth inductor L4 also generates a large current; because the current capacity and response time of the power supply are insufficient, the instantaneous large current of the fourth inductor L4 causes the power supply voltage input terminal VIN to drop rapidly, and the lower voltage of the power supply voltage input terminal VIN will trigger the internal protection logic of the overvoltage and overcurrent protection chip, from The first transistor M1 is turned off; after the first transistor M1 is turned off, the external power supply and the first capacitor C1 provide a freewheeling path for the current of the fourth inductor L4, so that the voltage of the power supply voltage input terminal VIN rises rapidly, and at the same time, the fourth inductor L4 and the first capacitor C1 generate LC oscillation, resulting in a voltage much higher than the power supply voltage input terminal VIN being generated at the drain terminal of the first transistor M1; the output terminal current is discharged through the diode D, resulting in a negative voltage at the negative terminal of the diode D, that is, the source terminal of the first transistor M1; at this time, a very large voltage difference will be generated between the drain and the source of the first transistor M1. If the withstand voltage of the first transistor M1 is not enough to withstand such a high voltage, the first transistor M1 will be damaged, thereby burning the overvoltage and overcurrent protection chip.

[0047] In this embodiment, the driving module DRI is an analog circuit, but it is not limited thereto, and the driving module DRI may also be a mixed analog-digital circuit or a digital circuit.

[0048] In order to avoid burning the overvoltage and overcurrent protection chip, the chip output short circuit protection circuit 100 further includes a detection module TEST.

[0049] Specifically, the detection module TEST is used to detect whether the voltage at the cathode end of the diode D is negative to trigger the driving module DRI. When the detection module TEST determines that the voltage at the cathode end of the diode D is negative, it controls the driving module DRI to drive the first transistor M1 to turn on.

[0050] The specific circuit structure of the protection circuit is:

[0051] The first end of the detection module TEST is connected to the input end of the driving module DRI, the second end of the detection module TEST is respectively connected to the positive end of the diode D and the first end of the fifth inductor L5, and the third end of the detection module TEST is connected to the source of the first transistor M1.

[0052] The present invention detects the voltage at the negative terminal of the diode D at the output terminal quickly. When the voltage at the negative terminal of the diode D drops to a negative value, the detection module TEST triggers and drives the driving module DRI to turn on the first transistor M1 instantly. The instantaneous turning on of the first transistor M1 provides a discharge path for the input and output currents, avoiding damage to the first transistor M1, thereby suppressing the overshoot voltage at the power supply voltage input terminal VIN at the moment when the first transistor M1 is turned off.

[0053] The specific structure of the detection module TEST is used below to illustrate the short-circuit protection principle of the chip output short-circuit protection circuit 100 of the present invention.

[0054] (Example 1)

[0055] Please refer to Figure 3 As shown, this embodiment 1 provides a chip output short circuit protection circuit 200. The detection module TEST in the chip output short circuit protection circuit 200 in the embodiment 1 includes an NPN transistor Q and a logic module LOG.

[0056] The logic module LOG is used for controlling the driving module DRI to drive the first transistor M1 to turn on when it is determined that the voltage at the cathode end of the diode D is a negative value.

[0057] In this implementation, the logic module LOG is an analog circuit, but it is not limited thereto, and the logic module LOG may also be a mixed analog-digital circuit or a digital circuit.

[0058] The specific circuit connection structure is: the collector of the NPN transistor Q is connected to the input end of the logic module LOG, the base of the NPN transistor Q serves as the second end of the detection module TEST, the emitter of the NPN transistor Q serves as the third end of the detection module TEST, and the output end of the logic module LOG serves as the first end of the detection module.

[0059] The short circuit protection working process in the first embodiment is as follows:

[0060] When the overvoltage and overcurrent protection chip is working normally, the first transistor M1 is fully turned on, and the NPN transistor Q and the logic module LOG do not work; when the power supply voltage output terminal VOUT is suddenly short-circuited to the ground, the voltage of the power supply voltage output terminal VOUT drops rapidly, and the power supply voltage output terminal VOUT discharges the charge through the sixth inductor L6. Since the first transistor M1 is fully turned on, the fourth inductor L4 and the sixth inductor L6 will generate an instantaneous large current. The instantaneous large current causes the voltage of the power supply voltage input terminal VIN to drop, and the drop in the voltage of the power supply voltage input terminal VIN triggers the internal logic circuit of the overvoltage and overcurrent protection chip, thereby turning off the first transistor M1. After the first transistor M1 is turned off, the large current of the sixth inductor L6 is discharged through the diode D. When a negative voltage appears at the negative end of the diode D, the NPN transistor Q will be turned on. The conduction of the NPN transistor Q causes the logic module LOG to work, and the first transistor M1 is turned on instantly. The instantaneous opening of the first transistor M1 provides a discharge path for the large current of the fourth inductor L4 and the sixth inductor L6, thereby ensuring that the power supply voltage input terminal VIN maintains a low overshoot voltage. When the voltage of the power supply voltage input terminal VIN drops to a certain value, the first transistor M1 will be turned off again. Therefore, there will be no large voltage between the drain and source of the first transistor M1, suppressing the overshoot of the power supply voltage input terminal VIN. The circuit structure can greatly reduce the voltage between the drain and source of the first transistor M1, and improve the reliability of the overvoltage and overcurrent protection chip; at the same time, the voltage change amplitude of the power supply voltage input terminal VIN is very small, and the impact on the previous adapter and other overvoltage and overcurrent protection chips is small.

[0061] (Example 2)

[0062] Please refer to Figure 4 As shown, this second embodiment provides a chip output short-circuit protection circuit 300. The circuit in the chip output short-circuit protection circuit 300 in the second embodiment is basically the same as that in the first embodiment. The difference between the two embodiments is that the detection module TEST is an NMOS tube M2. The NMOS tube M2 detects whether the voltage at the negative end of the diode D is a negative value to directly trigger the driving module DRI. The NMOS tube M2 can directly trigger the driving module DRI, and there is no need to set the logic module LOG in the first embodiment, and the circuit is simpler.

[0063] The specific circuit connection structure is: the drain of the NMOS tube M2 is used as the first end of the detection module TEST, the gate of the NMOS tube M2 is used as the second end of the detection module TEST, and the source of the NMOS tube M2 is used as the third end of the detection module TEST.

[0064] The short circuit protection working process in the second embodiment is as follows:

[0065] The NMOS tube M2 and the NPN transistor Q of the first embodiment can also quickly detect the voltage of the negative terminal of the diode D at the output end. When a negative voltage appears at the negative terminal of the diode D, the NMOS tube M2 will be turned on. The turning on of the NMOS tube M2 puts the output end of the driving module DRI in a high-resistance state. During the rapid rise of the voltage at the power supply voltage input terminal VIN, the gate-drain capacitance of the first transistor M1 enables the first transistor M1 to be turned on instantly, providing a discharge path for the input and output currents, thereby suppressing the overshoot voltage at the power supply voltage input terminal VIN at the moment when the first transistor M1 is turned off, so that the reliability of the chip output short-circuit protection is high.

[0066] (Example 3)

[0067] Please refer to Figure 5 As shown, this embodiment 3 provides a chip output short circuit protection circuit 400. The circuit in the chip output short circuit protection circuit 300 in the embodiment 3 is basically the same as that in the embodiment 2. The difference between the two embodiments is that the chip output short circuit protection circuit 400 in the embodiment 3 adds a third capacitor C3 on the basis of the embodiment 2.

[0068] The first end of the third capacitor C3 is respectively connected to the output end of the driving module DRI and the gate of the first transistor M1; the second end of the third capacitor C3 is respectively connected to the drain of the first transistor M1, the second end of the fourth inductor L4 and the first end of the first capacitor C1.

[0069] The third capacitor C3 is the capacitance added by coupling the gate-drain capacitance of the first transistor M1. Its function is that, during the rapid rise of the voltage at the power supply voltage input terminal VIN, the first transistor M1 is turned on instantly through the combined action of the gate-drain capacitance of the first transistor M1 and the third capacitor C3. Compared with the gate-drain capacitance of the first transistor M1 in the second embodiment, the third capacitor C3 can make the first transistor M1 turn on instantly faster. A discharge path is provided for the input and output currents, thereby suppressing the overshoot voltage at the power supply voltage input terminal VIN at the moment when the first transistor M1 is turned off, thereby making the chip output short-circuit protection highly reliable.

[0070] Compared with the related art, the chip output short-circuit protection circuit of the present invention includes a driving module, a first transistor, a first capacitor, a second capacitor, a first inductor, a second inductor, a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, a short-circuit switch, a diode detection module and a logic module. The circuit detects whether the voltage at the cathode end of the diode is negative through the detection module, and when the detection module detects that the voltage at the cathode end of the diode is negative, the driving module is controlled to drive the first transistor to turn on. When the overvoltage and overcurrent protection chip has a chip output short circuit, the detection module controls the driving module to trigger the diode (power switch tube) to turn on instantly. The instantaneous opening of the power tube provides a discharge path for the input and output currents, avoids damage to the power switch tube, and reduces the impact of the output short circuit on the front-stage adapter, thereby making the chip output short circuit protection highly reliable.

[0071] It should be noted that the various embodiments described above with reference to the accompanying drawings are only used to illustrate the present invention rather than to limit the scope of the present invention. Those skilled in the art should understand that any modification or equivalent substitution of the present invention without departing from the spirit and scope of the present invention should be included within the scope of the present invention. In addition, unless otherwise indicated by the context, words appearing in the singular include the plural form, and vice versa. In addition, unless otherwise specified, all or part of any embodiment may be used in combination with all or part of any other embodiment.

Claims

1. A chip output short-circuit protection circuit, which is applied to an overvoltage and overcurrent protection chip, the chip output short-circuit protection circuit comprising a driving module, a first transistor, a first capacitor, a second capacitor, a first inductor, a second inductor, a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, a short-circuit switch and a diode; The output end of the driving module is connected to the gate of the first transistor; The drain of the first transistor is respectively connected to the second end of the fourth inductor and the first end of the first capacitor, and the source of the first transistor is respectively connected to the first end of the third inductor and the negative terminal of the diode; The first end of the fourth inductor serves as a power supply voltage input end of the chip output short-circuit protection circuit; The second end of the third inductor is respectively connected to the first end of the second capacitor and the first end of the short-circuit switch, and serves as a power supply voltage output end of the chip output short-circuit protection circuit; The positive terminal of the diode is connected to the first terminal of the fifth inductor; The second end of the first capacitor is connected to the first end of the first inductor; The second end of the second capacitor is connected to the first end of the second inductor; The second end of the short-circuit switch is connected to the first end of the sixth inductor; The second end of the first inductor, the second end of the second inductor, the second end of the sixth inductor and the second end of the fifth inductor are all connected to ground; wherein, The first transistor is a power switch tube, and the diode is an ESD device; It is characterized in that the chip output short-circuit protection circuit also includes a detection module, and the detection module is used to detect whether the voltage at the negative end of the diode is a negative value to trigger the driving module; Wherein, the first end of the detection module is connected to the input end of the driving module, the second end of the detection module is respectively connected to the positive end of the diode and the first end of the fifth inductor, and the third end of the detection module is connected to the source of the first transistor; The detection module includes an NPN transistor and a logic module, and the logic module is used to control the driving module to drive the first transistor to turn on when the detection module detects that the voltage at the negative end of the diode is negative; wherein the collector of the NPN transistor is connected to the input end of the logic module, the base of the NPN transistor serves as the second end of the detection module, and the emitter of the NPN transistor serves as the third end of the detection module; and the output end of the logic module serves as the first end of the detection module.

2. The chip output short circuit protection circuit according to claim 1, characterized in that: The detection module is an NMOS tube, the drain of the NMOS tube serves as the first end of the detection module, the gate of the NMOS tube serves as the second end of the detection module, and the source of the NMOS tube serves as the third end of the detection module.

3. The chip output short circuit protection circuit according to claim 1, characterized in that: The chip output short-circuit protection circuit also includes a third capacitor, a first end of the third capacitor is respectively connected to the output end of the driving module and the gate of the first transistor; a second end of the third capacitor is respectively connected to the drain of the first transistor, the second end of the fourth inductor and the first end of the first capacitor.

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