Overelectric stress protection circuit

Abstract

The utility model discloses an over-electric stress protection circuit, which comprises an over-electric stress detection circuit connected between power supply equipment and a switching circuit or connected between the switching circuit and a load and used for detecting whether over-electric stress exists on a circuit between the power supply equipment and the load or not. And an over-electric stress signal is output to the driving judgment circuit when over-electric stress exists, so that the driving judgment circuit controls the switching circuit to be switched off when receiving a conduction control signal and the over-electric stress signal output by the main controller. Visibly, whether the circuit between the power supply equipment and the load has the over-electric stress or not is detected through the over-electric stress detection circuit, and the switching circuit is controlled by the driving judgment circuit instead of the main controller, so that the switching circuit can be disconnected in time when the over-electric stress exists; and the device damage caused by the fact that the main controller cannot respond to the over-electric stress in time due to multi-thread operation is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, in particular to an over-electrical stress protection circuit. Background Art

[0002] When the main controller controls the power supply device to output power to the load so that the load is powered on and working, if the load malfunctions, it may cause overstress in the circuit between the power supply device and the load, which may in turn cause damage to components. Therefore, the circuit between the power supply device and the load needs to be protected from overstress.

[0003] The power output control circuit in the prior art includes a main controller and a switching circuit. The switching circuit is arranged between the power supply device and the load. The main controller controls the switching circuit. When the switching circuit is turned on, the power supply device outputs power to the load through the switching circuit. The main controller judges the over-electrical stress state on the circuit between the power supply device and the load, and feeds back the judgment result to the main controller so that the main controller can adjust the output strategy when over-electrical stress occurs in the circuit. However, since the main controller is generally in a multi-threaded working mode, it cannot respond to the over-electrical stress in the circuit in a timely manner, which will lead to untimely over-electrical stress protection in the circuit, overvoltage damage to the devices in the circuit, and even worse, safety issues such as failure of the main controller. Utility Model Content

[0004] The purpose of the utility model is to provide an over-stress protection circuit, which detects whether over-stress exists in the circuit between the power supply equipment and the load through the over-stress detection circuit, and controls the switch circuit by the driving judgment circuit rather than the main controller, so that the switch circuit can be disconnected in time when over-stress exists, avoiding device damage caused by the main controller's multi-threaded operation and failure to respond to over-stress in time.

[0005] To solve the above technical problems, the present invention provides an over-stress protection circuit, which is applied to a power output control circuit. The power output control circuit also includes a main controller and a switch circuit. The switch circuit is connected between a power supply device and a load. The over-stress protection circuit includes:

[0006] an over-electrical stress detection circuit, connected to the circuit between the power supply device and the load, and having a control end connected to the signal output end of the main controller, and configured to output an over-electrical stress signal when receiving a conduction control signal output by the main controller and detecting the presence of over-electrical stress in the circuit between the power supply device and the load;

[0007] A drive judgment circuit, wherein a first input end is connected to the signal output end of the main controller, a second input end is connected to the signal output end of the over-electrical stress detection circuit, and an output end is connected to the control end of the switch circuit, and is used to control the switch circuit to be disconnected when the conduction control signal and the over-electrical stress signal are received; and to control the switch circuit to be turned on when the conduction control signal is received but the over-electrical stress signal is not received.

[0008] Preferably, the over-voltage stress detection circuit includes:

[0009] a sampling module, connected to the circuit between the power supply device and the load, and configured to collect current on the circuit between the power supply device and the load;

[0010] an over-electrical stress judgment module, whose input end is connected to the sampling module and is used to output a preset level when the current meets a preset current threshold;

[0011] A latch circuit, wherein the input end is connected to the output end of the over-electrical stress judgment module, the output end is connected to the drive judgment circuit, and the reset end is connected to the signal output end of the main controller, and is used to latch the preset level and generate the over-electrical stress signal when the conduction control signal and the preset level are received; and reset when the conduction control signal is not received.

[0012] Preferably, the latch circuit comprises:

[0013] a first latch resistor, a first end of which is connected to the signal output end of the main controller, and a second end of which is connected to the control end of the first latch switch;

[0014] a first latch switch, a first end of which is connected to the signal output end of the main controller, and a second end of which is connected to the output end of the over-voltage stress judgment module and the input end of the main controller, and configured to be turned on when the second latch switch is turned on, so that the main controller stops outputting the conduction control signal after a preset time has passed after outputting the conduction control signal and the first latch switch is turned on;

[0015] The second latch switch has a control end connected to the output end of the over-electrical stress judgment module, a first end connected to the control end of the first latch switch, and a second end connected to the ground, and is configured to be turned on when the over-electrical stress judgment module outputs the preset level to output the over-electrical stress signal to the second input end of the drive judgment circuit, and interlocked with the first latch switch after the first latch switch is turned on;

[0016] The second end of the driving judgment circuit is connected to one of the first end, the second end or the control end of the second latch switch.

[0017] Preferably, the second end of the driving judgment circuit is connected to the first end of the second latch switch;

[0018] The latch circuit further includes:

[0019] A first latching diode, having an input end connected to the control end of the first latching switch and an output end connected to the output end of the over-voltage stress judgment module, is configured to be turned on when receiving the conduction control signal and the preset level, and when the preset level is a low level, so as to turn on the first latching switch.

[0020] Preferably, the second terminal of the drive judgment circuit is connected to the control terminal of the second latch switch;

[0021] The latch circuit further includes:

[0022] A second latch diode, whose input end is connected to the output end of the over-electrical stress judgment module, and whose output end is connected to the control end of the second latch switch, is used to be turned on when receiving the conduction control signal and the preset level, and the preset level is a high level, so as to turn on the second latch switch.

[0023] Preferably, the sampling module is a first sampling resistor connected between the power supply device and the load;

[0024] The over-electrical stress judgment module includes:

[0025] a voltage amplifier, having a first input end connected to the first end of the first sampling resistor, a second input end connected to the second end of the first sampling resistor, and configured to output the voltage across the first sampling resistor;

[0026] A voltage comparator, having a first input terminal connected to the output terminal of the voltage amplifier and a second terminal connected to a preset voltage threshold, is configured to output the preset level when the voltage across the first sampling resistor is greater than the preset voltage threshold corresponding to the preset current threshold.

[0027] Preferably, the sampling module is a second sampling resistor connected between the power supply device and the load;

[0028] The over-electrical stress judgment module includes a first sampling switch having a first end connected to the first end of the second sampling resistor, a control end connected to the second end of the second sampling resistor, and a second end connected to the input end of the latch circuit. The first sampling switch is configured to be turned on when the voltage across the second sampling resistor is greater than a preset voltage threshold corresponding to the preset current threshold, so as to output the preset level from its second end.

[0029] Preferably, the driving judgment circuit includes:

[0030] a driving module, having a first input end connected to the signal output end of the main controller, a second input end connected to the output end of the over-electrical stress detection circuit, and an output end connected to the control end of the first driving switch, and configured to control the first driving switch to be turned off when receiving the conduction control signal and the over-electrical stress signal; and to control the first driving switch to be turned on when receiving the conduction control signal but not receiving the over-electrical stress signal;

[0031] The first drive switch has a first end connected to the control end of the switch circuit and a second end grounded, and is used to control the switch circuit to be turned on when the first drive switch is turned on; and to control the switch circuit to be turned off when the first drive switch is turned off.

[0032] Preferably, the driving module includes:

[0033] An AND gate, having a first input terminal connected to the signal output terminal of the main controller, a second input terminal connected to the signal output terminal of the over-electrical stress detection circuit, and an output terminal connected to the control terminal of the first drive switch, configured to output a first electrical level upon receiving the conduction control signal and the over-electrical stress signal to control the first drive switch to be turned off; and output a second electrical level upon receiving the conduction control signal but not receiving the over-electrical stress signal to control the first drive switch to be turned on; the first electrical level is opposite to the second electrical level.

[0034] Preferably, the driving module includes:

[0035] A second drive switch, having a control end connected to the output end of the over-electrical stress detection circuit, a first end connected to the control end of the first drive switch and the output end of the main controller, and a second end connected to ground, is configured to be turned off when the over-electrical stress signal is not received to turn on the first drive switch; and to be turned on when the over-electrical stress signal is received to turn off the first drive switch.

[0036] The present application provides an overstress protection circuit, including an overstress detection circuit connected between a power supply device and a switching circuit, or connected between a switching circuit and a load, for detecting whether overstress exists in the circuit between the power supply device and the load, and outputting an overstress signal to a drive judgment circuit when overstress exists, so that the drive judgment circuit controls the switching circuit to disconnect when receiving a conduction control signal and an overstress signal output by a main controller. It can be seen that in the present application, the overstress detection circuit is used to detect whether overstress exists in the circuit between the power supply device and the load, and the switch circuit is controlled by the drive judgment circuit rather than the main controller, so that the switch circuit can be disconnected in time when overstress exists, thereby avoiding damage to the device caused by the main controller's multi-threaded operation and inability to respond to overstress in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 A schematic structural diagram of an over-voltage stress protection circuit provided by the utility model;

[0039] Figure 2 A schematic diagram of the specific structure of the first over-voltage stress protection circuit provided by the present invention;

[0040] Figure 3 A schematic diagram of the specific structure of the second over-stress protection circuit provided by the present invention;

[0041] Figure 4 The present invention provides a specific structural diagram of a latch circuit. DETAILED DESCRIPTION

[0042] The core of this utility model is to provide an overstress protection circuit. The overstress detection circuit detects whether there is overstress in the circuit between the power supply equipment and the load. The driving judgment circuit rather than the main controller controls the switching circuit, so that the switching circuit can be disconnected in time when overstress exists, avoiding device damage caused by the main controller's multi-threaded operation and failure to respond to overstress in time.

[0043] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of an over-stress protection circuit provided by the present invention. The over-stress protection circuit is applied to a power output control circuit. The power output control circuit also includes a main controller 13 and a switch circuit 16. The switch circuit 16 is connected between a power supply device 14 and a load 15. The over-stress protection circuit includes:

[0045] The over-stress detection circuit 11 is connected to the circuit between the power supply device 14 and the load 15, and the control end is connected to the signal output end of the main controller 13, and is configured to output an over-stress signal when it receives a conduction control signal output by the main controller 13 and detects that there is over-stress in the circuit between the power supply device 14 and the load 15;

[0046] The driving judgment circuit 12 has a first input end connected to the signal output end of the main controller 13, a second input end connected to the signal output end of the over-electrical stress detection circuit 11, and an output end connected to the control end of the switch circuit 16. It is used to control the switch circuit 16 to be disconnected when a conduction control signal and an over-electrical stress signal are received; and to control the switch circuit 16 to be turned on when a conduction control signal is received but no over-electrical stress signal is received.

[0047] In the prior art, a switch circuit 16 is usually provided between the power supply device 14 and the load 15. The main controller 13 controls the conduction of the switch circuit 16 by outputting a conduction control signal, so that the power supply device 14 can output power to the load 15. However, if the load 15 malfunctions, the current in the circuit between the power supply device 14 and the load 15 may be too large, resulting in over-stress. Therefore, in order to avoid damage to the components due to over-stress, it is necessary to perform over-stress detection on the circuit between the power supply device 14 and the load 15, and feed the over-stress detection result back to the main controller 13, so that the main controller 13 controls the switch circuit 16 to be disconnected when over-stress occurs in the circuit. However, since the working mode of the main controller 13 is a multi-threaded working mode, when over-stress occurs in the circuit, the main controller 13 may be performing other tasks and cannot respond to the over-stress in a timely manner. This may not only damage the components in the circuit, but may also cause the main controller 13 to malfunction.

[0048] Another over-stress protection method is to directly modulate the detection result on the conduction control signal of the main controller 13 that controls the switch circuit 16 when over-stress occurs in the circuit, so that the main controller 13 disconnects the switch circuit 16 while outputting the conduction control signal. However, this will cause the switch circuit 16 to frequently switch between on and off, causing the switch circuit 16 to bear greater switching losses, or cause the devices in the switch circuit 16 to operate in the linear region, resulting in greater conduction losses.

[0049] Another method is to select a control chip with an over-voltage stress protection function when selecting the main controller 13. However, the selection of this chip needs to consider its compatibility and versatility, and the cost is relatively high.

[0050] Therefore, in the present application, when implementing overstress protection, a drive judgment circuit 12 is additionally provided in the main controller 13 and the switch circuit 16. An overstress detection circuit 11 is connected to the circuit between the power supply device 14 and the load 15. Upon receiving a conduction control signal, the overstress detection circuit 11 detects whether overstress exists in the circuit and outputs an overstress signal to the drive judgment circuit 12 when overstress exists. Furthermore, the conduction control signal output by the main controller 13 is not directly applied to the switch circuit 16, but is instead output to the drive judgment circuit 12, thereby causing the drive judgment circuit 12 to control the conduction and shutoff of the switch circuit 16. Specifically, when the drive judgment circuit 12 receives only the conduction control signal but not the overstress signal, it controls the switch circuit 16 to conduct, causing the power supply device 14 to output power to the load 15. However, when the drive judgment circuit 12 receives both the conduction control signal and the overstress signal, it turns the switch circuit 16 off, causing the power supply device 14 to stop outputting power to the load 15. Based on this, the driving judgment circuit 12 reacts to the over-electrical stress and turns off the switch circuit 16 in time, thereby reducing the probability of device damage.

[0051] In summary, in this application, the over-electrical stress detection circuit 11 is used to detect whether there is over-electrical stress in the circuit between the power supply device 14 and the load 15, and the driving judgment circuit 12 rather than the main controller 13 controls the switching circuit 16, so that the switching circuit 16 can be disconnected in time when over-electrical stress exists, avoiding device damage caused by the main controller 13's multi-threaded operation and failure to respond to over-electrical stress in time.

[0052] Based on the above embodiment:

[0053] Please refer to Figure 2 and Figure 3 , Figure 2 This is a specific structural diagram of the first over-voltage stress protection circuit provided by the utility model. Figure 3 This is a specific structural diagram of the second over-voltage stress protection circuit provided by the utility model.

[0054] As a preferred embodiment, the over-voltage stress detection circuit 11 includes:

[0055] The sampling module 111 is connected to the circuit between the power supply device 14 and the load 15 and is used to collect the current in the circuit between the power supply device 14 and the load 15;

[0056] An over-electrical stress judgment module 112, whose input end is connected to the sampling module 111, is used to output a preset level when the current meets a preset current threshold;

[0057] The latch circuit 113 has an input end connected to the output end of the over-electrical stress judgment module 112, an output end connected to the drive judgment circuit 12, and a reset end connected to the signal output end of the main controller 13. It is used to latch the preset level when receiving the conduction control signal and the preset level, and generate an over-electrical stress signal; and reset when not receiving the conduction control signal.

[0058] In this embodiment, the overstress detection circuit 11 specifically includes a sampling module 111, an overstress detection module, and a latch circuit 113. The sampling module 111 is connected to the circuit between the power supply device 14 and the load 15, and can collect the current in the circuit. The overstress judgment module 112 determines whether the current in the circuit is greater than a preset current threshold. If the current is greater than the preset current threshold, overstress exists in the circuit, and a preset level is output to the latch circuit 113. The latch circuit 113 latches the preset level and outputs an overstress signal to prevent the main controller 13 from continuing to output a conduction control signal after the drive judgment circuit 12 disconnects the switch circuit 16 based on the preset level when the preset level is not latched, causing the switch circuit 16 to be turned on again, causing the switch circuit 16 to be frequently turned on and off, and increasing losses. The level of the overstress signal and the preset level can be the same or opposite, and this application is not limited to this.

[0059] It should be noted that when the main controller 13 outputs a conduction control signal, the latch circuit 113 is enabled and can latch the preset level. If the main controller 13 does not output a conduction control signal, the latch circuit 113 is reset and cannot latch the preset level, thereby reducing control loss.

[0060] The preset current threshold in this embodiment can be set according to the parameters of each device in the actual circuit, and this application does not limit this.

[0061] As a preferred embodiment, the latch circuit 113 includes:

[0062] A first latch resistor R11, having a first end connected to the signal output end of the main controller 13, and a second end connected to the control end of the first latch switch Q11;

[0063] A first latch switch Q11, having a first end connected to a signal output terminal of the main controller 13 and a second end connected to an output terminal of the over-voltage stress determination module 112 and an input terminal of the main controller 13, is configured to be turned on when the second latch switch Q12 is turned on, so that the main controller 13 outputs a conduction control signal and stops outputting the conduction control signal after a preset time has passed since the first latch switch Q11 was turned on;

[0064] A second latch switch Q12 has a control end connected to the output end of the over-electrical stress judgment module 112, a first end connected to the control end of the first latch switch Q11, and a second end grounded. The second latch switch Q12 is configured to be turned on when the over-electrical stress judgment module 112 outputs a preset level to output an over-electrical stress signal to the second input end of the drive judgment circuit 12, and to be interlocked with the first latch switch Q11 after the first latch switch Q11 is turned on.

[0065] The second terminal of the driving determination circuit 12 is connected to one of the first terminal, the second terminal or the control terminal of the second latch switch Q12 .

[0066] Please refer to Figure 2 The latch circuit 113 in this embodiment specifically includes a first latch resistor R11, a first latch switch Q11, and a second latch switch Q12. The second latch switch Q12 is turned on when the over-voltage stress determination module 112 outputs a preset voltage level, thereby turning on the first latch switch Q11. The first latch switch Q11 and the second latch switch Q12 interlock to latch the preset voltage level. The first terminal of the second latch switch Q12 then outputs a preset over-voltage stress signal to the drive determination circuit 12, causing the drive determination circuit 12 to control the switch circuit 16.

[0067] After the first latch switch Q11 and the second latch switch Q12 are interlocked, if the main control circuit does not output a conduction control signal, the first latch switch Q11 is turned off, and accordingly, the second latch switch Q12 is also turned off, thereby resetting the latch circuit 113.

[0068] In addition, if Figure 2 As shown, the latch circuit 113 may further include:

[0069] A second latch resistor R12, having a first end connected to the second end of the first latch resistor R11, and a second end connected to the first end of the second latch switch Q12;

[0070] a third latch resistor R13 , having a first end connected to the second end of the first latch switch Q11 , and a second end connected to the output end of the over-electrical stress judgment module 112 ;

[0071] The fourth latch resistor R14 has a first end connected to the output end of the over-electrical stress judgment module 112 and a second end grounded.

[0072] It should be noted that the first latch resistor R11 can limit the drive current of the control terminal of the first latch switch Q11, preventing the first latch switch Q11 from being damaged by excessive transient drive current, and can also act as a discharge resistor between the control terminal and the first terminal of the first latch switch Q11, protecting the area between the control terminal and the first terminal from electrostatic damage. The third latch resistor R13 can limit the drive current of the control terminal of the second latch switch Q12, preventing the second latch switch Q12 from being damaged by excessive transient drive current, and can also act as a discharge resistor between the control terminal and the second terminal of the second latch switch Q12, protecting the area between the control terminal and the second terminal from electrostatic damage. The second latch resistor R12 can limit the current input to the second latch switch Q12 to prevent the second latch switch Q12 from being damaged by overcurrent. The fourth latch resistor R14 is used to lower the voltage of the control terminal of the second latch switch Q12 to prevent it from being mis-conducted when the over-stress judgment module 112 does not output a preset level.

[0073] The first latch switch Q11 can be, but is not limited to, a PNP transistor, wherein the base of the PNP transistor is the control terminal, the emitter is the first terminal, and the collector is the second terminal; the second latch switch Q12 can be, but is not limited to, an NPN transistor, wherein the base of the NPN transistor is the control terminal, the collector is the first terminal, and the emitter is the second terminal. Therefore, when the preset level output by the over-voltage stress judgment module 112 is a high level, the base voltage of the second latch switch Q12 is greater than the emitter voltage and is turned on, thereby pulling down the base voltage of the first latch switch Q11 and being less than the emitter voltage. The first latch switch Q11 is turned on, and the voltage of the control terminal of the second latch switch Q12 is pulled up, thereby achieving interlocking between the first latch switch Q11 and the second latch switch Q12, wherein the output over-voltage stress signal is a low level.

[0074] Please refer to Figure 3 In addition, the latch circuit 113 may further include:

[0075] The fifth latch resistor R15 has a first end connected to the second end of the second latch switch Q12 and a second end grounded.

[0076] The fifth latch resistor R15 can limit the current input to the second latch switch Q12 to prevent the second latch switch Q12 from being damaged by overcurrent.

[0077] Figure 2 and Figure 3The second end of the first latch switch Q11 is connected to the input end of the main controller 13, so that the main controller 13 stops outputting the conduction control signal after a preset time after outputting the conduction control signal and the first latch switch Q11 is turned on, thereby reducing losses. By setting the preset time, it can be ensured that after the switch circuit is disconnected, the main controller 13 stops outputting the conduction control signal and resets the latch circuit. Furthermore, the main controller 13 can also stop the power supply equipment 14 from outputting power after stopping outputting the conduction control signal, thereby further saving costs. Of course, this application is not limited to this.

[0078] As a preferred embodiment, the present invention further comprises:

[0079] a temperature detection module, whose output end is connected to the input end of the latch circuit 113, and is used to output a preset level when detecting that the temperature of the circuit between the power supply device and the load is greater than a preset temperature;

[0080] The latch circuit 113 is further configured to latch the preset level when the temperature detection module outputs a preset level, and generate an over-temperature signal so that the drive judgment circuit controls the switch circuit to turn off.

[0081] In this embodiment, a temperature detection module is additionally provided. That is, when over-electrical stress or over-temperature occurs in the circuit, the latch circuit 113 will receive a preset level, thereby performing over-electrical stress protection and over-temperature protection to ensure the normal operation of each device in the circuit.

[0082] Please refer to Figure 4 , Figure 4 This is a schematic diagram of a specific structure of a latch circuit 113 provided by the present invention.

[0083] As a preferred embodiment, the second end of the driving judgment circuit is connected to the first end of the second latch switch;

[0084] The latch circuit 113 further includes:

[0085] The first latch diode D11 has an input end connected to the control end of the first latch switch Q11 and an output end connected to the output end of the over-voltage stress judgment module 112. The first latch diode D11 is configured to be turned on when receiving a conduction control signal and a preset level, and the preset level is a low level, so as to turn on the first latch switch Q11.

[0086] As a preferred embodiment, the second end of the driving judgment circuit 12 is connected to the control end of the second latch switch Q12;

[0087] The latch circuit 113 further includes:

[0088] The second latch diode D12 has an input end connected to the output end of the over-electrical stress judgment module 112, and an output end connected to the control end of the second latch switch Q12. It is used to be turned on when receiving a conduction control signal and a preset level, and the preset level is a high level, so as to turn on the second latch switch Q12.

[0089] The latch circuit 113 in this embodiment further includes a first latch diode D11 and a second latch diode D12. The output of the first latch diode D11 and the input of the second latch diode D12 can both be connected to the output of the over-stress determination module 112 and the output of the temperature detection module. The only difference is that the preset voltage levels required for the first latch diode D11 and the second latch diode D12 to conduct are different. When the preset level is high, the second latch diode D12 is turned on, while the first latch diode D11 is turned off. The level of the control end of the second latch switch Q12 is high, the second latch switch Q12 is turned on, and the level of the control end of the first latch switch Q11 is pulled down to a low level by the second latch switch Q12 and turned on. The first latch switch Q11 and the second latch switch Q12 are interlocked, latching the preset level output by the over-electrical stress judgment module 112 or the temperature detection module, and outputting an over-electrical stress signal or an over-temperature signal from the output end of the second latch diode D12 to the drive judgment circuit 12, so that the drive judgment circuit 12 controls the switch circuit 16 to be turned off. When the preset level is low, the first latch diode D11 is turned on, while the second latch diode D12 is turned off. The level of the control end of the first latch switch Q11 is low, the first latch switch Q11 is turned on, and the level of the control end of the second latch switch Q12 is pulled up to a high level by the first latch switch Q11 and turned on. The first latch switch Q11 and the second latch switch Q12 are interlocked, latching the preset level output by the over-stress judgment module 112 or the temperature detection module, and outputting an over-stress signal or an over-temperature signal from the input end of the first latch diode D11 to the drive judgment circuit 12, so that the drive judgment circuit 12 controls the switch circuit 16 to be turned off.

[0090] like Figure 4 As shown, the latch circuit 113 may further include:

[0091] The sixth latch resistor R16 has a first end connected to the control end of the first latch switch Q11 , and a second end connected to the second end of the first latch resistor R11 .

[0092] The sixth latch resistor R16 and the first latch resistor R11 can limit the driving current of the control end of the first latch switch Q11 to prevent the first latch switch Q11 from being damaged due to excessive instantaneous driving current, and can also act as a discharge resistor between the control end and the first end of the first latch switch Q11 to protect the control end and the first end from electrostatic damage.

[0093] It should be noted that when the main controller 13 does not output the conduction control signal, under normal circumstances, the level of the output end of the first latch diode D11 is suspended at a high level, and the level of the input end of the second latch diode D12 is suspended at a low level. Because, in order to avoid miscontrol of the switch circuit 16, a logical judgment is required, that is, when the conduction control signal is low, no matter whether the over-voltage stress signal at the input end of the second latch diode D12 is high or low, and no matter whether the over-voltage stress signal at the output end of the first latch diode D11 is high or low, the latch circuit 16 is switched on. The latch circuit 113 does not output an over-electric stress signal, that is, the output of the latch circuit 113 is invalid; when the conduction control signal is high, the over-electric stress signal at the output end of the first latch diode D11 is high, and the over-electric stress signal at the input end of the second latch diode D12 is low, the output of the latch circuit 113 is invalid; when the conduction control signal is high, the over-electric stress signal at the output end of the first latch diode D11 is low or the over-electric stress signal at the input end of the second latch diode D12 is high, the latch circuit 113 outputs an over-electric stress signal.

[0094] Figure 4 DRIVE is the conduction control signal, OPC1 and OPC2 are preset levels, STA1 and STA2 are over-stress signals, the input end of the first latch diode D11 and the output end of the second latch diode D12 are connected to the input end of the main controller 13. After the main controller 13 outputs the conduction control signal and the first latch diode D11 is turned on, it stops outputting the conduction control signal after a preset time, or stops outputting the conduction control signal after a preset time after the second latch diode D12 is turned on.

[0095] As a preferred embodiment, the sampling module 111 is a first sampling resistor R21 connected between the power supply device 14 and the load 15;

[0096] The over-electrical stress judgment module 112 includes:

[0097] A voltage amplifier U1, having a first input terminal connected to a first terminal of a first sampling resistor R21, and a second input terminal connected to a second terminal of the first sampling resistor R21, for outputting a voltage across the first sampling resistor R21;

[0098] The voltage comparator U2 has a first input terminal connected to the output terminal of the voltage amplifier U1 and a second terminal connected to a preset voltage threshold, and is used to output a preset level when the voltage across the first sampling resistor R21 is greater than the preset voltage threshold corresponding to the preset current threshold.

[0099] The sampling module 111 in this embodiment is a first sampling resistor R21, which is disposed between the power supply device 14 and the load 15. Specifically, the first sampling resistor R21 can be connected between the power supply device 14 and the switching circuit 16, or between the switching circuit 16 and the load 15, thereby sampling the current in the circuit between the power supply device 14 and the load 15. The voltage amplifier U1 samples the voltage across the first sampling resistor R21, converts the current signal into a voltage signal, and outputs the signal to the voltage comparator U2, thereby comparing the voltage Vr across the first sampling resistor R21 with a preset voltage threshold Vref. If the voltage Vr is greater than the preset voltage threshold, overstress occurs in the circuit.

[0100] A filter resistor may be connected in parallel across the first sampling resistor R21 to filter and decouple the voltage across the first sampling resistor R21 .

[0101] Resistors may be provided at the first input terminal and the second input terminal of the voltage amplifier U1 to perform current limiting protection.

[0102] Accordingly, the first input terminal and the second input terminal of the voltage comparator U2 may be connected to a resistor and a capacitor for filtering and parameter control.

[0103] A reverse-bias diode may be provided at the output of the voltage comparator U2. The input of the reverse-bias diode is connected to the output of the voltage comparator U2, and the output of the diode is connected to the latch circuit 113 to prevent reverse voltage input to the voltage comparator U2, which could damage the voltage comparator U2. The output of the reverse-bias diode may be connected to a filter capacitor, the other end of which is grounded.

[0104] It should be noted that when collecting the current in the circuit, the current can be converted into a voltage across the resistor for collection. Accordingly, the preset voltage threshold is also determined based on the preset current threshold and the set resistance value of the first sampling resistor R21. This application does not limit how to collect the current in the circuit.

[0105] As a preferred embodiment, the sampling module 111 is a second sampling resistor R22 connected between the power supply device 14 and the load 15;

[0106] The over-electrical stress determination module 112 includes a first sampling switch Q21 having a first end connected to the first end of the second sampling resistor R22, a control end connected to the second end of the second sampling resistor R22, and a second end connected to the input end of the latch circuit 113. The first sampling switch Q21 is configured to be turned on when the voltage across the second sampling resistor R22 is greater than a preset voltage threshold corresponding to a preset current threshold, thereby outputting a preset voltage level from its second end.

[0107] The sampling module 111 in this embodiment is a second sampling resistor R22, which is disposed between the power supply device 14 and the load 15. Specifically, the second sampling resistor R22 can be connected between the power supply device 14 and the switching circuit 16, or between the switching circuit 16 and the load 15, thereby sampling the current in the circuit between the power supply device 14 and the load 15. If the current in the second sampling resistor R22 is too large, the voltage across the second sampling resistor R22 is also too large. If the voltage is greater than a preset voltage threshold, the first sampling switch Q21 is turned on, and a preset voltage level is output from the second end of the first sampling switch Q21.

[0108] The first sampling switch Q21 may be, but is not limited to, a PNP transistor, with a base as a control terminal, an emitter as a first terminal, and a collector as a second terminal. When the voltage across the second sampling resistor R22 is greater than a preset voltage threshold, the base voltage of the PNP transistor is greater than the emitter voltage and the transistor is turned on. At this time, the preset level output from the collector of the PNP transistor is a high level.

[0109] It should be noted that a protection resistor may be provided between the control terminal of the first sampling switch Q21 and the second end of the second sampling resistor R22 to limit the drive current at the control terminal of the first sampling switch Q21, thereby preventing damage to the first sampling switch Q21 caused by an instantaneous excessive drive current. The protection resistor may also function as a discharge resistor between the control terminal and the first end of the first sampling switch Q21, thereby protecting the control terminal and the first end from electrostatic damage.

[0110] As a preferred embodiment, the driving judgment circuit 12 includes:

[0111] a driving module, wherein a first input end is connected to a signal output end of a main controller, a second input end is connected to an output end of an over-electrical stress detection circuit, and an output end is connected to a control end of a first driving switch, and is configured to control the first driving switch to be turned off when a conduction control signal and an over-electrical stress signal are received; and to control the first driving switch to be turned on when a conduction control signal is received but an over-electrical stress signal is not received;

[0112] The first driving switch Q31 has a first end connected to the control end of the switching circuit 16 and a second end grounded, and is used to control the switching circuit 16 to be turned on when the first driving switch Q31 is turned on, and to control the switching circuit 16 to be turned off when the first driving switch Q31 is turned off.

[0113] The drive determination circuit 12 in this embodiment includes a drive module and a first drive switch Q31. When the main controller 13 outputs a conduction control signal, the drive module controls the first drive switch Q31 to be turned on, thereby controlling the switch circuit 16 to be turned on. If the over-stress detection circuit 11 outputs an over-stress signal, the drive module controls the first drive switch Q31 to be turned off, thereby controlling the switch circuit 16 to be turned off.

[0114] The first drive switch Q31 can be, but is not limited to, an NPN transistor. The base of the NPN transistor is the control terminal, the collector is the first terminal, and the emitter is the second terminal. When the over-voltage stress determination module 112 outputs a preset voltage level, the drive module pulls down the base voltage of the first drive switch Q31 to a voltage lower than the emitter voltage, and the first drive switch Q31 is turned off, thereby turning off the switch circuit 16.

[0115] A current-limiting resistor may be provided between the control terminal of the first drive switch Q31 and the signal output terminal of the main controller 13 to limit the drive current of the control terminal of the first drive switch Q31, thereby preventing the first drive switch Q31 from being damaged due to an instantaneous excessive drive current. The resistor may also function as a discharge resistor between the control terminal and the second terminal of the first drive switch Q31, thereby protecting the resistor between the control terminal and the second terminal from electrostatic damage.

[0116] As a preferred embodiment, the driving module includes:

[0117] The AND gate U3 has a first input terminal connected to the signal output terminal of the main controller 13, a second input terminal connected to the signal output terminal of the over-electrical stress detection circuit 11, and an output terminal connected to the control terminal of the first drive switch Q31. The AND gate U3 is configured to output a first electrical level when receiving a conduction control signal and an over-electrical stress signal to control the first drive switch to be turned off; and to output a second electrical level when receiving a conduction control signal but not receiving an over-electrical stress signal to control the first drive switch to be turned on; the first level is opposite to the second level.

[0118] The driver module in this embodiment includes an AND gate U3. When and only when receiving a conduction control signal and not receiving an over-stress signal, the AND gate U3 outputs a second level, turning on the first drive switch Q31 and controlling the switch circuit 16 to conduct. If not receiving a conduction control signal and / or receiving an over-stress signal, the AND gate U3 outputs a first level, turning off the first drive switch Q31 and controlling the switch circuit 16 to shut down, thereby protecting the circuit. The AND gate not only has simple logic but also low cost.

[0119] The first drive switch Q31 is an NMOS transistor, with a gate as a control terminal, a drain as a first terminal, and a source as a second terminal. When the second level output by the AND gate U3 is high, the gate voltage is greater than the source voltage, the NMOS transistor conducts, grounding the control terminal of the switch circuit 16, thereby turning on the switch circuit 16. When the first level output by the AND gate U3 is low, the gate voltage is less than the source voltage, the NMOS transistor turns off, and the control terminal of the switch circuit 16 is pulled high, thereby turning off the switch circuit 16. Therefore, in this embodiment, the conduction control signal is high, and the over-stress signal is low.

[0120] A current limiting resistor may also be provided between the first input terminal of the AND gate U3 and the main controller 13 .

[0121] As a preferred embodiment, the driving module includes:

[0122] The second drive switch has a control end connected to the output end of the over-electrical stress detection circuit 11, a first end connected to the control end of the first drive switch Q31 and the output end of the main controller 13, and a second end connected to the ground. The second drive switch is configured to be turned off when no over-electrical stress signal is received, so that the first drive switch Q31 is turned on; and to be turned on when an over-electrical stress signal is received, so that the first drive switch Q31 is turned off.

[0123] The driving module in this embodiment may be a second driving switch Q32. When the main controller 13 outputs a conduction control signal, the first driving switch Q31 is turned on to control the switch circuit 16 to be turned on. If the over-stress detection circuit 11 outputs an over-stress signal, the second driving switch Q32 is turned on, thereby turning off the first driving switch Q31 to control the switch circuit 16 to be turned off.

[0124] The second drive switch Q32 can be, but is not limited to, an NPN transistor. The base of the NPN transistor is the control terminal, the collector is the first terminal, and the emitter is the second terminal. When the preset level output by the over-voltage stress judgment module 112 is high, the base voltage of the second drive switch Q32 is greater than the emitter voltage and the second drive switch Q32 is turned on, thereby pulling down the base voltage of the first drive switch Q31 and making it less than the emitter voltage. The first drive switch Q31 is turned off, thereby turning off the switch circuit 16.

[0125] A current-limiting resistor can be set between the control end of the second drive switch Q32 and the output end of the over-electrical stress judgment circuit 11 to limit the driving current of the control end of the second drive switch Q32, thereby preventing the instantaneous driving current from being too large and causing damage to the second drive switch Q32. The resistor can also act as a discharge resistor between the control end and the second end of the second drive switch Q32 to protect the resistor between the control end and the second end from electrostatic damage.

[0126] To solve the above technical problems, the present invention provides a power output control circuit, including the over-stress protection circuit as described above, and also including a main controller 13 and a switch circuit 16 , wherein the switch circuit 16 is connected between the power supply device 14 and the load 15 .

[0127] For an introduction to the power output control circuit provided by the present invention, please refer to the above-mentioned over-stress protection circuit embodiment, which will not be described in detail in this application.

[0128] As a preferred embodiment, the switch circuit 16 includes:

[0129] The power switch Q111 has a first end connected to the power supply device 14, a second end connected to the load 15, and a control end connected to the over-stress protection circuit, and is used to be turned on or off based on the control of the over-stress protection circuit.

[0130] In this embodiment, the switch circuit 16 includes a power switch Q111 , and the over-voltage stress protection circuit can protect the circuit by controlling the power switch Q111 to be turned on or off.

[0131] Among them, the power supply switch Q111 can be not limited to PMOS, the gate is the control end, the source is the first end, and the drain is the second end. When the over-stress protection circuit outputs a low level, the PMOS is turned on, and when the over-stress protection circuit outputs a high level, the PMOS is turned off.

[0132] A resistor may be provided between the first terminal and the control terminal of the power switch Q111 to limit the drive current at the control terminal of the power switch Q111, preventing damage to the power switch Q111 caused by excessive instantaneous drive current. The resistor may also function as a discharge resistor between the control terminal and the first terminal of the power switch Q111, protecting the area between the control terminal and the first terminal from electrostatic damage. A filter capacitor may also be provided between the control terminal and the first terminal of the power switch Q111.

[0133] The MOS tubes and transistors selected in this application have high efficiency, fast switching speed, low drive power, high reliability, small size and relatively low price. Of course, this application does not limit the specific selection of switches.

[0134] It should also be noted that, in this specification, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0135] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An over-voltage stress protection circuit, characterized in that: Applied to a power output control circuit, the power output control circuit further includes a main controller and a switch circuit, the switch circuit is connected between the power supply device and the load, and the over-voltage stress protection circuit includes: an over-electrical stress detection circuit, connected to the circuit between the power supply device and the load, and having a control end connected to the signal output end of the main controller, and configured to output an over-electrical stress signal when receiving a conduction control signal output by the main controller and detecting the presence of over-electrical stress in the circuit between the power supply device and the load; A drive judgment circuit, wherein a first input end is connected to the signal output end of the main controller, a second input end is connected to the signal output end of the over-electrical stress detection circuit, and an output end is connected to the control end of the switch circuit, and is used to control the switch circuit to be disconnected when the conduction control signal and the over-electrical stress signal are received; and to control the switch circuit to be turned on when the conduction control signal is received but the over-electrical stress signal is not received.

2. The over-stress protection circuit according to claim 1, wherein: The over-voltage stress detection circuit comprises: a sampling module, connected to the circuit between the power supply device and the load, and configured to collect current on the circuit between the power supply device and the load; an over-electrical stress judgment module, whose input end is connected to the sampling module and is used to output a preset level when the current meets a preset current threshold; A latch circuit, wherein the input end is connected to the output end of the over-electrical stress judgment module, the output end is connected to the drive judgment circuit, and the reset end is connected to the signal output end of the main controller, and is used to latch the preset level and generate the over-electrical stress signal when the conduction control signal and the preset level are received; and reset when the conduction control signal is not received.

3. The over-stress protection circuit according to claim 2, wherein: The latch circuit comprises: a first latch resistor, a first end of which is connected to the signal output end of the main controller, and a second end of which is connected to the control end of the first latch switch; a first latch switch, a first end of which is connected to the signal output end of the main controller, and a second end of which is connected to the output end of the over-voltage stress judgment module and the input end of the main controller, and configured to be turned on when the second latch switch is turned on, so that the main controller stops outputting the conduction control signal after a preset time has passed after outputting the conduction control signal and the first latch switch is turned on; The second latch switch has a control end connected to the output end of the over-electrical stress judgment module, a first end connected to the control end of the first latch switch, and a second end connected to the ground, and is configured to be turned on when the over-electrical stress judgment module outputs the preset level to output the over-electrical stress signal to the second input end of the drive judgment circuit, and interlocked with the first latch switch after the first latch switch is turned on; The second end of the driving judgment circuit is connected to one of the first end, the second end or the control end of the second latch switch.

4. The over-stress protection circuit according to claim 3, wherein: The second end of the driving judgment circuit is connected to the first end of the second latch switch; The latch circuit further includes: A first latching diode, having an input end connected to the control end of the first latching switch and an output end connected to the output end of the over-voltage stress judgment module, is configured to be turned on when receiving the conduction control signal and the preset level, and when the preset level is a low level, so as to turn on the first latching switch.

5. The over-stress protection circuit according to claim 3, wherein: The second terminal of the drive judgment circuit is connected to the control terminal of the second latch switch; The latch circuit further includes: A second latch diode, whose input end is connected to the output end of the over-electrical stress judgment module, and whose output end is connected to the control end of the second latch switch, is used to be turned on when receiving the conduction control signal and the preset level, and the preset level is a high level, so as to turn on the second latch switch.

6. The overstress protection circuit according to claim 2, wherein: The sampling module is a first sampling resistor connected between the power supply device and the load; The over-electrical stress judgment module includes: a voltage amplifier, having a first input end connected to the first end of the first sampling resistor, a second input end connected to the second end of the first sampling resistor, and configured to output the voltage across the first sampling resistor; A voltage comparator, having a first input terminal connected to the output terminal of the voltage amplifier and a second terminal connected to a preset voltage threshold, is configured to output the preset level when the voltage across the first sampling resistor is greater than the preset voltage threshold corresponding to the preset current threshold.

7. The over-stress protection circuit according to claim 2, wherein: The sampling module is a second sampling resistor connected between the power supply device and the load; The over-electrical stress judgment module includes a first sampling switch having a first end connected to the first end of the second sampling resistor, a control end connected to the second end of the second sampling resistor, and a second end connected to the input end of the latch circuit. The first sampling switch is configured to be turned on when the voltage across the second sampling resistor is greater than a preset voltage threshold corresponding to the preset current threshold, so as to output the preset level from its second end.

8. The overstress protection circuit according to any one of claims 1 to 7, wherein: The driving judgment circuit includes: a driving module, having a first input end connected to the signal output end of the main controller, a second input end connected to the output end of the over-electrical stress detection circuit, and an output end connected to the control end of the first driving switch, and configured to control the first driving switch to be turned off when receiving the conduction control signal and the over-electrical stress signal; and to control the first driving switch to be turned on when receiving the conduction control signal but not receiving the over-electrical stress signal; The first drive switch has a first end connected to the control end of the switch circuit and a second end grounded, and is used to control the switch circuit to be turned on when the first drive switch is turned on; and to control the switch circuit to be turned off when the first drive switch is turned off.

9. The over-stress protection circuit according to claim 8, wherein: The driving module includes: An AND gate, having a first input terminal connected to the signal output terminal of the main controller, a second input terminal connected to the signal output terminal of the over-electrical stress detection circuit, and an output terminal connected to the control terminal of the first drive switch, configured to output a first electrical level upon receiving the conduction control signal and the over-electrical stress signal to control the first drive switch to be turned off; and output a second electrical level upon receiving the conduction control signal but not receiving the over-electrical stress signal to control the first drive switch to be turned on; the first electrical level is opposite to the second electrical level.

10. The over-stress protection circuit according to claim 8, wherein: The driving module includes: A second drive switch, having a control end connected to the output end of the over-electrical stress detection circuit, a first end connected to the control end of the first drive switch and the output end of the main controller, and a second end connected to ground, is configured to be turned off when the over-electrical stress signal is not received to turn on the first drive switch; and to be turned on when the over-electrical stress signal is received to turn off the first drive switch.

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