Short circuit protection circuit and display device

Abstract

This application relates to the field of display technology and provides a short-circuit protection circuit and display device. The short-circuit protection circuit includes an output module, a first feedback module, and a second feedback module. The first feedback module is electrically connected to the node under test (DUT) and the output module, and is used to charge the DUT and provide an enable signal to the output module based on the DUT's charging voltage. The second feedback module is also electrically connected to the DUT and the output module, and is used to provide an adjustment signal to the output module based on the actual voltage of the DUT. The output module is electrically connected to the DUT and is used to output a target voltage based on the enable signal and the adjustment signal. This application detects the voltage at the DUT before the output module operates, thereby protecting the downstream power supply module connected to the target voltage.

Description

Technical Field

[0001] This application relates to the field of display technology, specifically to a short-circuit protection circuit and a display device. Background Technology

[0002] In the backlight of a display device, a boost / buck circuit is typically used to regulate the supply voltage to provide the driving voltage for normal illumination. However, when using a power management chip to control the boost / buck circuit for voltage boosting and bucking, the protection measures for the power management chip are often insufficient, making it prone to short circuits and other malfunctions.

[0003] Considering the design cost of power management chips and common short-circuit conditions, the short-circuit protection design of power management chips is located between adjacent pins. However, in extreme cases such as short circuits during soldering, electrostatic discharge, and electrical overstress, the output voltage provided by the power management chip can reach or approach the input voltage connected to the power management chip, which will further damage the downstream power modules electrically connected to the power management chip, causing the boost and buck operation of the power management chip to be unstable, and thus affecting the normal illumination of the display device. Summary of the Invention

[0004] This application provides a short-circuit protection circuit and display device. Before the output module is in working state, the device pre-charges the node under test and detects the voltage of the node under test, thereby preventing damage to the downstream power supply module due to faults such as short circuits when the output module is in working state.

[0005] In a first aspect, this application provides a short-circuit protection circuit, including: an output module, a first feedback module, and a second feedback module;

[0006] The first feedback module is electrically connected to the node under test and the output module. The first feedback module is used to charge the node under test and provide an enable signal to the output module according to the charging voltage of the node under test.

[0007] The second feedback module is electrically connected to the node under test and the output module. The second feedback module is used to provide an adjustment signal to the output module according to the actual voltage of the node under test.

[0008] The output module is electrically connected to the node under test, and the output module is used to output a target voltage based on the enable signal and the adjustment signal.

[0009] In the short-circuit protection circuit provided in this application, the first feedback module includes a pre-charge unit, a preset voltage unit, and a comparison unit;

[0010] The pre-charge unit is electrically connected to the node under test, and the pre-charge unit is used to charge the node under test to obtain the charging voltage;

[0011] The preset voltage unit is electrically connected to the comparison unit, and the preset voltage unit is used to provide a preset voltage to the comparison unit.

[0012] The comparison unit is electrically connected to the node under test, the preset voltage unit, and the output module, respectively. The comparison unit is used to provide the enable signal to the output module based on the charging voltage and the preset voltage.

[0013] In the short-circuit protection circuit provided in this application, the first feedback module further includes a delay unit;

[0014] The delay unit is electrically connected to the node under test and the comparison unit respectively. The delay unit is used to obtain a delay voltage according to the charging voltage and provide the delay voltage to the comparison unit so that the comparison unit provides the enable signal to the output module based on the delay voltage and the preset voltage.

[0015] In the short-circuit protection circuit provided in this application, the delay unit includes a delay device and an AND gate;

[0016] The delay device is used to obtain an initial delay voltage based on the charging voltage; the AND gate is used to obtain the delay voltage according to the charging voltage and the initial delay voltage, and provide the delay voltage to the comparison unit.

[0017] In the short-circuit protection circuit provided in this application, the comparison unit includes a first comparator, which is configured to provide the enable signal to the output module when the charging voltage is greater than or equal to the preset voltage.

[0018] In the short-circuit protection circuit provided in this application, the pre-charge unit includes a current source, which is electrically connected to the node under test to charge the node under test.

[0019] In the short-circuit protection circuit provided in this application, the pre-charge unit includes a voltage source and a resistor;

[0020] The first and second ends of the resistor are electrically connected to the first and second ends of the voltage source, respectively, and one of the first and second ends of the resistor is electrically connected to the node under test to charge the node under test.

[0021] In the short-circuit protection circuit provided in this application, the second feedback module includes a threshold comparison unit and a threshold voltage unit;

[0022] The threshold voltage unit is electrically connected to the threshold comparison unit, and the threshold voltage unit is used to provide a threshold voltage to the threshold comparison unit;

[0023] The threshold comparison unit is electrically connected to the node under test and the output module respectively. The threshold comparison unit is used to provide the adjustment signal to the output module based on the target voltage and the threshold voltage.

[0024] In the short-circuit protection circuit provided in this application, the threshold comparison unit includes a second comparator, which is configured to provide the adjustment signal to the output module when the target voltage is greater than the threshold voltage.

[0025] Secondly, this application also provides a display device that includes the short-circuit protection circuit described above.

[0026] The short-circuit protection circuit and display device provided in this application precharge the node under test and detect the voltage at the node under test through the first feedback module before the output module is in working state. Based on the detected charging voltage, an enable signal is provided to the output module, so that the output module starts working according to the received enable signal and provides the target voltage to the downstream power supply module. This avoids the output module outputting an excessively large target voltage due to faults such as short circuits when it is in working state, thereby avoiding damage to the downstream power supply module and protecting the downstream power supply module. On the other hand, the output module adjusts the output target voltage according to the enable signal provided by the first feedback module and the adjustment signal provided by the second feedback module, so that the target voltage output by the output module is the voltage actually required by the downstream power supply module, further protecting the downstream power supply module, which is beneficial to providing the driving voltage required for normal light emission of the backlight of the display device. Attached Figure Description

[0027] Figure 1 A first circuit diagram of a short-circuit protection circuit provided in an embodiment of this application;

[0028] Figure 2 A second circuit diagram of the short-circuit protection circuit provided in the embodiments of this application;

[0029] Figure 3 A third circuit diagram of the short-circuit protection circuit provided in the embodiments of this application;

[0030] Figure 4 A fourth circuit diagram of the short-circuit protection circuit provided in the embodiments of this application;

[0031] Figure 5 This is a fifth circuit diagram of a short-circuit protection circuit provided in an embodiment of this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0033] Furthermore, the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. Since the source and drain of the transistor used in this application are symmetrical, their sources and drains are interchangeable. According to the configuration shown in the drawings, the middle terminal of the transistor is designated as the gate, the signal input terminal as the source, and the output terminal as the drain.

[0034] Please see Figure 1 , Figure 1 This is a first circuit diagram of a short-circuit protection circuit provided in an embodiment of this application. Figure 1 As shown, the short-circuit protection circuit 100 includes an output module 10, a first feedback module 20, and a second feedback module 30. The output module 10 is electrically connected to the node under test P; the first feedback module 20 is electrically connected to the node under test P and the output module 10; the second feedback module 30 is electrically connected to the node under test P and the output module 10.

[0035] The first feedback module 20 is used to charge the node under test P and provide an enable signal EN1 to the output module 10 according to the charging voltage of the node under test P; the second feedback module 30 is used to provide an adjustment signal EN2 to the output module 10 according to the actual voltage of the node under test P; the output module 10 is used to output the target voltage DVDD based on the enable signal and the adjustment signal.

[0036] For details, please continue reading. Figure 1The output module 10 includes a buck control unit 101, a first transistor P1, a second transistor P2, an inductor L, a first capacitor C1, a second capacitor C2, a first resistor R1, and a second resistor R2. The buck control unit 101 is electrically connected to the first feedback module 20, the second feedback module 30, the gate of the first transistor P1, and the gate of the second transistor P2. One of the source and drain of the first transistor P1 is connected to the initial voltage VIN and the first terminal of the first capacitor C1, respectively. The other of the source and drain of the first transistor P1 is electrically connected to one of the source and drain of the second transistor P2 and the first terminal of the inductor L, respectively. The second terminal of the first capacitor C1 is electrically connected to ground. The other of the source and drain of the second transistor P2 is electrically connected to ground. The second terminal of the inductor L is electrically connected to the first terminal of the second capacitor C2, the first terminal of the first resistor R1, and the output terminal, respectively. The second terminal of the second capacitor C2 is electrically connected to ground. The second terminal of the first resistor R1 is electrically connected to the node under test P and the first terminal of the second resistor R2, respectively. The second end of the second resistor R2 is electrically connected to the ground terminal.

[0037] The first capacitor C1 acts as a filter, used to rectify the initial input voltage VIN. The inductor L and the second capacitor C2 also act as filters, used to rectify the switching voltage output from the source or drain of the first transistor P1, and to generate the desired target voltage DVDD. The first resistor R1 and the second resistor R2 are used to generate the feedback voltage corresponding to the target voltage DVDD. The first transistor P1 and the second transistor P2 act as switches, thereby the buck control unit 101 controls the gates of the first transistor P1 and the second transistor P2 respectively, to control the first transistor P1 and the second transistor P2 to be in the on or off state respectively.

[0038] For details, please continue reading. Figure 1 The first feedback module 20 includes a pre-charge unit 201, a preset voltage unit 202, and a comparison unit 203. The pre-charge unit 201 is electrically connected to the node under test (DUT) P, the preset voltage unit 202 is electrically connected to the comparison unit 203, and the comparison unit 203 is electrically connected to the DUT P, the preset voltage unit 202, and the output module 10. The pre-charge unit 201 charges the DUT P to obtain its charging voltage. The preset voltage unit 202 provides a preset voltage to the comparison unit 203. The comparison unit 203 compares the charging voltage with the preset voltage, thereby providing an enable signal EN1 to the output module 10.

[0039] It is important to note that the purpose of the first feedback module 20 is to detect whether there are faults such as short circuits at the detection node P before the output module 10 is in operation, thereby protecting the downstream power supply modules connected to the target voltage DVDD. If there are faults such as short circuits at the detection node P, the charging voltage obtained after the pre-charging unit 201 charges the detection node P will be zero. Based on the comparison result that the pre-charging voltage is less than the preset voltage provided by the preset voltage unit 202, the comparison unit 203 provides an enable signal EN1 to the output module 10. Based on the received enable signal EN1, the output module 10 remains in a non-operating state, thus having no output voltage. Therefore, it avoids the situation where the target voltage DVDD output by the output module 10 approaches or reaches the input voltage VIN of the output module 10 due to a fault at the tested node P, thereby protecting the downstream power supply modules.

[0040] For details, please continue reading. Figure 1 The second feedback module 30 includes a threshold comparison unit 301 and a threshold voltage unit 302. The threshold voltage unit 302 is electrically connected to the threshold comparison unit 301, thereby providing a threshold voltage to the threshold comparison unit 301. The threshold comparison unit 301 is electrically connected to both the node under test (P) and the output module 10, comparing the actual voltage of the node under test (P) with the threshold voltage. Based on the comparison result, the threshold comparison unit 301 provides an adjustment signal EN2 to the output module 10. This allows the output module 10 to adjust the output voltage based on the received adjustment signal EN2 to output the target voltage DVDD, enabling the subsequent power supply module to connect to the required voltage.

[0041] It should be noted that the actual voltage at the node under test (DUT) P refers to the actual voltage at DUT P when the output module 10 is in working state based on the enable signal EN1 provided by the first feedback module 20. Figure 1 In the circuit diagram shown, the actual voltage of the node under test P is the feedback voltage corresponding to the target voltage DVDD, generated by the feedback circuit formed by the first resistor R1 and the second resistor R2 flowing through the target voltage DVDD. That is, the actual voltage at the node under test P = DVDD * R2 / (R1 + R2). Therefore, the actual voltage of the node under test P is not the charging voltage obtained by charging the node under test P through the first feedback module 20.

[0042] The short-circuit protection circuit 100 provided in this embodiment first pre-charges the node under test P and detects the voltage of the node under test P through the first feedback module 20. Then, based on the detected charging voltage, it provides an enable signal EN1 to the output module 10. The output module 10 then enters the working state based on the enable signal EN1 and outputs the target voltage DVDD to provide voltage to the downstream power supply module. This avoids the output module 10 providing excessive voltage to the downstream power supply module due to faults such as short circuits while in the working state, thus protecting the downstream power supply module. The input voltage VIN is typically 12V, while the actual voltage required by the downstream power supply module is generally less than or equal to 3.3V. If a short circuit occurs at the node under test P, the target voltage DVDD output by the output module 10 may reach or approach 12V, which is much greater than the actual voltage required by the downstream power supply module. On the other hand, the second feedback module 30 can provide an adjustment signal EN2 to the output module 10 according to the actual voltage of the node under test P, so that the output module 10 adjusts the target voltage DVDD based on the adjustment signal EN2, thereby the target voltage DVDD output by the output module 10 is the voltage actually required by the downstream power consumption module, and further protects the downstream power consumption module.

[0043] In some embodiments, please refer to Figure 2 , Figure 2 This is a second circuit diagram of a short-circuit protection circuit provided in an embodiment of this application. (See diagram below.) Figure 2 As shown, the pre-charge unit 201 includes a current source electrically connected to the node under test P, thereby charging the node under test P. Optionally, a current source of 90-110 microamps is selected to charge the node under test P.

[0044] In some embodiments, please refer to Figure 3 , Figure 3 This is a third circuit diagram of a short-circuit protection circuit provided in an embodiment of this application. (See diagram below.) Figure 3 As shown, the pre-charge unit 201 includes a voltage source and a resistor R0. The first and second ends of the resistor R0 are electrically connected to the first and second ends of the voltage source, respectively. Furthermore, one of the first and second ends of the resistor R0 is electrically connected to the node P under test. In this embodiment, by connecting the voltage source and the resistor R0 in parallel, the electrical connection relationship between the voltage source, the resistor R0, and the node P under test is equivalent to... Figure 2 The electrical connection between the current source and the node under test P is shown, so that the node under test P can be charged through the voltage source and the resistor R0.

[0045] In some embodiments, please refer to Figure 2 as well as Figure 3The comparison unit 203 includes a first comparator. The first input terminal of the first comparator is electrically connected to the preset voltage unit 202 to obtain a preset voltage provided by the preset voltage unit 202; the second input terminal of the first comparator is electrically connected to the node under test P to obtain the charging voltage of the node under test P; the output terminal of the first comparator is electrically connected to the output module 10 to provide an enable signal EN1 to the output module 10 based on the comparison result of the preset voltage and the charging voltage. Optionally, the preset voltage provided by the preset voltage unit 202 is set to 150 mA to 200 mA.

[0046] In one specific embodiment, the first comparator is configured to provide an enable signal to the output module 10 when the charging voltage is greater than or equal to a preset voltage; and not to provide an enable signal to the output module 10 when the charging voltage is less than the preset voltage. The output module 10 operates when it receives the enable signal EN1, and does not operate when it does not receive the enable signal EN1. Therefore, the feedback result from the first feedback module 20 on the output module 10 can protect the downstream power consumption modules, especially the downstream low-voltage power consumption modules, before the output module 10 starts operating.

[0047] In one specific embodiment, the first comparator is configured to provide an enable signal EN1 high-level signal to the output module 10 when the charging voltage is greater than or equal to a preset voltage. If a fault such as a short circuit occurs at the node under test P, the charging voltage obtained after the pre-charging unit 201 charges the node under test P will be zero. Therefore, based on the comparison result that the charging voltage is less than the preset voltage, the first comparator provides an enable signal EN1 low-level signal to the output module 10. The output module 10 operates when the enable signal EN1 is high-level signal and does not operate when the enable signal EN1 is low-level signal.

[0048] In some embodiments, please continue reading Figure 2 as well as Figure 3 The threshold comparison unit 301 includes a second comparator. The first input terminal of the second comparator is electrically connected to the threshold voltage unit 302 to obtain the threshold voltage provided by the threshold voltage unit 302; the second input terminal of the second comparator is electrically connected to the node under test P to obtain the actual voltage of the node under test P; and the output terminal of the second comparator is electrically connected to the output module 10 to provide an adjustment signal EN2 to the output module 10 based on the comparison result between the threshold voltage and the actual voltage.

[0049] In one specific embodiment, the second comparator is configured such that when the actual voltage is greater than the threshold voltage, the adjustment signal EN2 provided by the second comparator to the output module 10 is a step-down adjustment signal, and the output module 10 performs step-down processing on the target voltage DVDD required by the downstream power module; when the actual voltage is less than the threshold voltage, the adjustment signal EN2 provided by the second comparator to the output module 10 is a step-up adjustment signal, and the output module 10 performs step-up processing on the target voltage DVDD required by the downstream power module; when the actual voltage is equal to the threshold voltage, the adjustment signal provided by the second comparator to the output module is a voltage regulation adjustment signal, and the output module 10 does not perform step-up or step-down processing on the voltage required by the downstream power module, directly outputting the target voltage DVDD. Therefore, by implementing feedback from the second feedback module 30 to the output module 10, after the output module 10 is turned on, the target voltage DVDD output by the output module 10 is the voltage actually required by the downstream power module.

[0050] In some embodiments, please refer to Figure 4 , Figure 4 This is a fourth circuit diagram of a short-circuit protection circuit provided in an embodiment of this application. (See diagram below.) Figure 4 As shown, the short-circuit protection circuit provided in this embodiment differs from the short-circuit protection circuit provided in the previous embodiment in that the first feedback module 20 in the short-circuit protection circuit 100 provided in this embodiment further includes a delay unit 204. The delay unit 204 is electrically connected to both the node under test P and the comparison unit 203. The delay unit 204 is used to obtain a delayed voltage based on the charging voltage of the node under test P, and provides the delay to the comparison unit 203, so that the comparison unit 203 provides an enable signal EN1 to the output module 10 based on the delayed voltage and a preset voltage.

[0051] It is worth mentioning that the purpose of setting the delay unit 204 in this embodiment is to prevent jitter interference and avoid the comparison unit 203 from misjudging whether the test node P is short-circuited due to possible glitches in the charging voltage obtained by the comparison unit 203.

[0052] In one specific embodiment, please refer to Figure 5 , Figure 5 This is a fifth circuit diagram of a short-circuit protection circuit provided in an embodiment of this application. (See diagram below.) Figure 5As shown, the short-circuit protection circuit provided in this embodiment differs from the short-circuit protection circuit provided in the previous embodiment in that: in the short-circuit protection circuit 100 provided in this embodiment, the delay unit 204 includes a delay device 2041 and an AND gate 2042. The delay device 2041 is electrically connected to the node under test P and the first input terminal of the AND gate 2042, thereby obtaining an initial delay voltage based on the charging voltage of the node under test P. The second input terminal of the AND gate 2042 is electrically connected to the node under test P, thereby acquiring the charging voltage of the node under test P. The output terminal of the AND gate 2042 is electrically connected to the comparison unit 203, thereby obtaining a delay voltage by multiplying the charging voltage and the initial delay voltage, and providing the delay voltage to the comparison unit 203. This allows the comparison unit 203 to provide an enable signal EN1 to the output module 10 based on the delay voltage and a preset voltage.

[0053] It should be noted that in this embodiment, the delay unit 204 is not limited to the connection relationship described in the above embodiments. It can be any monostable trigger composed of several of the following: resistor, capacitor, digital simulator, AND gate, NOT gate, NAND gate, etc.

[0054] Another aspect of this application proposes a display device that includes the short-circuit protection circuit mentioned in any of the foregoing embodiments. In the display device provided by this application, by setting the short-circuit protection circuit mentioned in any of the foregoing embodiments, the target voltage output by the output module is made to be the voltage actually required by the downstream power consumption module, thereby protecting the downstream power consumption module, especially the downstream low-voltage power consumption module, and thus providing the driving voltage required for normal light emission of the backlight of the display device.

[0055] The above are merely embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A short-circuit protection circuit, characterized in that, include: The module consists of an output module, a first feedback module, and a second feedback module; among which, The first feedback module is electrically connected to the node under test and the output module. The first feedback module is used to charge the node under test before the output module is in working state, and to provide an enable signal to the output module according to the charging voltage of the node under test. The output module works when it receives the enable signal and does not work when it does not receive the enable signal. The second feedback module is electrically connected to the node under test and the output module. The second feedback module is used to provide an adjustment signal to the output module according to the actual voltage of the node under test. The output module is electrically connected to the node under test and is used to output a target voltage based on the enable signal and the adjustment signal. The actual voltage of the node under test refers to the actual voltage at the node under test when the output module is in working state based on the enable signal provided by the first feedback module. Specifically, when the actual voltage is greater than the threshold voltage, the adjustment signal provided to the output module is a buck adjustment signal, so that the output module performs buck processing on the target voltage; when the actual voltage is less than the threshold voltage, the adjustment signal provided to the output module is a boost adjustment signal, so that the output module performs boost processing on the target voltage; when the actual voltage is equal to the threshold voltage, the adjustment signal provided to the output module by the second comparator is a voltage regulation adjustment signal, and the output module does not perform buck or boost processing on the voltage required by the downstream power module, and the output voltage is the target voltage.

2. The short-circuit protection circuit according to claim 1, characterized in that, The first feedback module includes a pre-charge unit, a preset voltage unit, and a comparison unit; The pre-charge unit is electrically connected to the node under test, and the pre-charge unit is used to charge the node under test to obtain the charging voltage; The preset voltage unit is electrically connected to the comparison unit, and the preset voltage unit is used to provide a preset voltage to the comparison unit. The comparison unit is electrically connected to the node under test, the preset voltage unit, and the output module, respectively. The comparison unit is used to provide the enable signal to the output module based on the charging voltage and the preset voltage.

3. The short-circuit protection circuit according to claim 2, characterized in that, The first feedback module also includes a delay unit; The delay unit is electrically connected to the node under test and the comparison unit respectively. The delay unit is used to obtain a delay voltage according to the charging voltage and provide the delay voltage to the comparison unit so that the comparison unit provides the enable signal to the output module based on the delay voltage and the preset voltage.

4. The short-circuit protection circuit according to claim 3, characterized in that, The delay unit includes a delay device and an AND gate; The delay device is used to obtain an initial delay voltage based on the charging voltage; the AND gate is used to obtain the delay voltage according to the charging voltage and the initial delay voltage, and provide the delay voltage to the comparison unit.

5. The short-circuit protection circuit according to claim 2, characterized in that, The comparison unit includes a first comparator, which is configured to provide the enable signal to the output module when the charging voltage is greater than or equal to the preset voltage.

6. The short-circuit protection circuit according to claim 2, characterized in that, The pre-charge unit includes a current source electrically connected to the node under test to charge the node under test.

7. The short-circuit protection circuit according to claim 2, characterized in that, The precharge unit includes a voltage source and a resistor; The first and second ends of the resistor are electrically connected to the first and second ends of the voltage source, respectively, and one of the first and second ends of the resistor is electrically connected to the node under test to charge the node under test.

8. The short-circuit protection circuit according to claim 1, characterized in that, The second feedback module includes a threshold comparison unit and a threshold voltage unit; The threshold voltage unit is electrically connected to the threshold comparison unit, and the threshold voltage unit is used to provide a threshold voltage to the threshold comparison unit; The threshold comparison unit is electrically connected to the node under test and the output module respectively. The threshold comparison unit is used to provide the adjustment signal to the output module based on the actual voltage and the threshold voltage.

9. The short-circuit protection circuit according to claim 8, characterized in that, The threshold comparison unit includes a second comparator, which is configured to provide the adjustment signal to the output module when the actual voltage is greater than the threshold voltage.

10. A display device, characterized in that, Includes the short-circuit protection circuit as described in any one of claims 1-9.

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