CN212969038U - Overvoltage protection circuit and electronic equipment - Google Patents
Overvoltage protection circuit and electronic equipment Download PDFInfo
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- CN212969038U CN212969038U CN202021672694.0U CN202021672694U CN212969038U CN 212969038 U CN212969038 U CN 212969038U CN 202021672694 U CN202021672694 U CN 202021672694U CN 212969038 U CN212969038 U CN 212969038U
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Abstract
The embodiment of the application discloses overvoltage crowbar and electronic equipment relates to circuit technical field, includes: the control unit is used for outputting a gate pole signal to the switch driving unit under the starting time of the skip cycle mode, and the switch driving unit is used for converting the gate pole signal into a direct current signal and sending the direct current signal to the switch unit; the switch unit is used for being conducted when receiving a direct current signal so as to enable the first voltage division unit and the second voltage division unit to work and enable the control unit to detect the bus voltage through the multifunctional and communication pin; the control unit is further used for stopping outputting the gate pole signal at the closing time of the skip cycle mode so as to enable the switch driving unit to stop sending the direct current signal, and the switch unit is further used for being disconnected when the direct current signal is not received so as to enable the first voltage division unit and the second voltage division unit to stop working. The overvoltage protection circuit can reduce the loss of the voltage dividing circuit in the overvoltage protection circuit when the electronic equipment is in standby.
Description
Technical Field
The embodiment of the application relates to the technical field of circuits, in particular to an overvoltage protection circuit and electronic equipment.
Background
In the circuit, an OverVoltage Protection (OVP) refers to a Protection method for disconnecting a power supply or reducing a voltage of a controlled device when a protected line voltage exceeds a predetermined maximum value. In order to ensure that the large electrolysis does not fail, an independent overvoltage protection circuit is arranged in the electronic equipment for the large electrolysis. Fig. 1 is a schematic structural diagram of an overvoltage protection circuit in the prior art, referring to fig. 1, a bus voltage is connected to a signal ground through a voltage dividing resistor R5 and a voltage dividing resistor R6, and one end of the voltage dividing resistor R5 connected to the voltage dividing resistor R6 is connected to an OVP voltage pin of a power chip. At this time, the power supply chip can realize overvoltage protection by detecting the OVP voltage.
However, in the overvoltage protection circuit, the resistance of the voltage dividing resistor is usually large, and a large loss is generated when the electronic device is in standby, for example, in fig. 1, the resistance of R5 and R6 is 6Mohm, and when the bus voltage is 390V, the consumption of the voltage dividing resistor is 390V2And/6000000 25 mW. Generally speaking, when the electronic device is in standby, the required power consumption is less than 300mW, and at this time, the overvoltage protection circuit occupies 8% of the power consumption, which greatly increases the difficulty in implementing low standby power consumption of the electronic device.
In summary, how to reduce the loss of the voltage divider circuit in the overvoltage protection circuit when the electronic device is in standby mode is an urgent technical problem to be solved.
SUMMERY OF THE UTILITY MODEL
The application provides an overvoltage protection circuit and electronic equipment to when electronic equipment awaits the opportune moment, reduce the loss of voltage division circuit among the overvoltage protection circuit.
In a first aspect, an embodiment of the present application provides an overvoltage protection circuit, including: the switch unit, the control unit, the first voltage division unit, the second voltage division unit and the switch driving unit;
the first end of the switch unit is connected with the first end of the first voltage division unit; the second end of the switch unit is connected with the first end of the second voltage division unit, the second end of the switch unit is also connected with the multifunctional and communication pin of the control unit, and the control end of the switch unit is connected with the first end of the switch driving unit;
the second end of the switch driving unit is connected with a gate signal output pin of the control unit;
and the second end of the first voltage division unit is connected with the bus voltage, and the second end of the second voltage division unit is grounded.
Further, the switch driving unit comprises a diode unit, a first resistor and a first capacitor;
the anode of the diode unit is connected with a gate signal output pin of the control unit;
the first end of the first resistor is connected with the cathode of the diode unit, and the second end of the first resistor is respectively connected with the first end of the first capacitor and the control end of the switch unit;
the second end of the first capacitor is grounded.
Further, the switch driving unit further includes: and the first end of the second resistor is connected with the second end of the first resistor, and the second end of the second resistor is grounded.
Further, the diode unit comprises a first diode, and the gate signal output pin of the control unit comprises a first output pin for outputting a PFC gate signal;
the anode of the first diode is connected with the first output pin, and the cathode of the first diode is connected with the first end of the first resistor.
Further, the diode unit further comprises a second diode, and the gate signal output pin of the control unit further comprises a second output pin for outputting an LLC gate signal;
the anode of the second diode is connected with the second output pin; and the cathode of the second diode is connected with the first end of the first resistor.
Further, the switch unit is an N-type MOS tube;
the grid electrode of the N-type MOS tube corresponds to the control end of the switch unit, the drain electrode of the N-type MOS tube corresponds to the first end of the switch unit, and the source electrode of the N-type MOS tube corresponds to the second end of the switch unit.
Further, the first voltage dividing unit includes a first voltage dividing resistor, and the second voltage dividing unit includes a second voltage dividing resistor.
Further, the overvoltage protection circuit further comprises: and the first end of the second capacitor is connected with the second end of the switch unit, and the second end of the second capacitor is grounded.
Further, the control unit is an IC chip.
In a second aspect, the present application further provides an electronic device, where the electronic device includes the overvoltage protection circuit according to the first aspect.
The overvoltage protection circuit and the electronic equipment are characterized in that a switch unit is arranged, a first end of the switch unit is connected with bus voltage through a first voltage division unit, a second end of the switch unit is grounded through a second voltage division unit, meanwhile, a second end of the switch unit is also connected with a multifunctional and communication pin of a control unit, a control end of the switch unit is connected with a gate pole signal output pin of the control unit through a switch driving unit, in a standby mode, when the control unit outputs a gate pole signal in the on time of a skip cycle mode, the switch driving unit converts the gate pole signal into a direct current signal and sends the direct current signal to the switch unit, the switch unit is conducted according to the direct current signal, the first voltage division unit and the second voltage division unit are connected into a circuit to bear voltage division work, meanwhile, the control unit detects the bus voltage, and when the control unit stops outputting the gate pole signal in the off time of, the switch unit stops receiving the direct current signal, at the moment, the switch unit is switched off, the first voltage division unit and the second voltage division unit are excluded from the circuit, and no power consumption is generated, so that the loss of the overvoltage protection circuit is reduced, and the standby power consumption of the electronic equipment is further reduced.
Drawings
FIG. 1 is a schematic diagram of a prior art overvoltage protection circuit;
fig. 2 is a schematic structural diagram of an overvoltage protection circuit according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a gate signal provided in accordance with an embodiment of the present application;
fig. 4 is a schematic structural diagram of another overvoltage protection circuit provided in the embodiment of the present application;
fig. 5 is a schematic structural diagram of another overvoltage protection circuit provided in the embodiment of the present application.
Detailed Description
The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are for purposes of illustration and not limitation. It should be further noted that, for the convenience of description, only some of the structures related to the present application are shown in the drawings, not all of the structures.
Fig. 2 is a schematic structural diagram of an overvoltage protection circuit according to an embodiment of the present application. The overvoltage protection circuit is integrated in an electronic device, and the electronic device can be an intelligent tablet computer, a television and the like. Specifically, referring to fig. 2, the overvoltage protection circuit includes: a switching unit 11, a control unit 12, a first voltage dividing unit 13, a second voltage dividing unit 14, and a switch driving unit 15;
the first end of the switch unit 11 is connected with the first end of the first voltage division unit 13; the second end of the switch unit 11 is connected to the first end of the second voltage dividing unit 14, the second end of the switch unit 11 is further connected to the multi-function and communication pin of the control unit 12, and the control end of the switch unit 11 is connected to the first end of the switch driving unit 15;
a second end of the switch driving unit 15 is connected to a gate signal output pin of the control unit 12;
the second end of the first voltage division unit 13 is connected to the bus voltage, and the second end of the second voltage division unit 14 is grounded.
The control unit 12 is configured to output a gate signal to the switch driving unit 15 at an on time of a skip cycle mode, and the switch driving unit 15 is configured to convert the gate signal into a dc signal and send the dc signal to the switching unit 11; the switch unit 11 is configured to be turned on when receiving a dc signal, so that the first voltage dividing unit 13 and the second voltage dividing unit 14 divide the voltage, and the control unit 12 detects the bus voltage through the multifunctional and communication pin; the control unit 12 is further configured to stop outputting the gate signal at the off time of the skip cycle mode, so that the switch driving unit 15 stops generating the dc signal, and the switch unit 11 is further configured to turn off when the control signal is not received, so that the first voltage dividing unit 13 and the second voltage dividing unit 14 stop dividing the voltage.
Specifically, the switching unit 11 includes at least one switching element. The switching device refers to a device having a switching function, and for example, the switching device is a field effect transistor (MOS transistor), a triode, a single-pole single-throw switch, or the like. In the embodiment, the switching unit 11 is used to control the conduction relationship between the first voltage dividing unit 13 and the second voltage dividing unit 14. Further, the switch unit 11 includes a first end, a second end and a control end, wherein the control end can control a connection state between the first end and the second end through an accessed control signal, and further control a conduction relationship between the first voltage dividing unit 13 and the second voltage dividing unit 14. The control signal is an electrical signal capable of controlling the switch unit 11 to be turned on and off, and in the embodiment, the control signal is a dc signal obtained by the switch driving unit 15. It is understood that when the connection state is on, an electric signal can flow between the first terminal and the second terminal, and when the connection state is off, an electric signal cannot flow between the first terminal and the second terminal. Optionally, when the switch unit 11 includes a plurality of switch components, as long as the first voltage dividing unit 13 and the second voltage dividing unit 14 are turned on, whether all the plurality of switch components are turned on or not is determined that the switch unit is turned on, and as long as the first voltage dividing unit 13 and the second voltage dividing unit 14 are turned off, whether all the plurality of switch components are turned off or not is determined that the switch unit is turned off.
Further, a first end of the switch unit 11 is connected to a first end of the first voltage dividing unit 13, and a second end of the first voltage dividing unit 13 is connected to the bus voltage. The bus bar can connect all current-carrying branch loops in the power distribution device (electronic equipment) together and plays a role in collecting, distributing and transmitting electric energy. The bus voltage is the voltage at which current can be transmitted in the bus. In one embodiment, a Power Factor Correction (PFC) circuit outputs a dc bus voltage, and the bus voltage is adjustable within a certain range according to a change in a load. In this case, the bus voltage may be referred to as a PFC voltage. In particular, for power supplies with relatively high input power (e.g., greater than or equal to 75 watts), PFC is typically used. The power factor refers to a relationship between the effective power and the total power consumption (apparent power), that is, a ratio of the effective power divided by the total power consumption (apparent power). Power factor can be used to measure the power efficiency of an electronic device, and the technology for increasing the power factor of an electronic device is called PFC. The PFC circuit is a circuit for implementing PFC, and a specific structural embodiment thereof is not limited. Furthermore, the PFC circuit may force the input current to vary with the variation of the input voltage, such that any electrical load appears as a resistor to the voltage source supplying the load, and the PFC voltage is adjusted according to the variation of the load to improve the power factor. Further, the first voltage dividing unit 13 has a function of dividing the voltage of the bus, that is, implementing overvoltage protection. The first voltage dividing unit 13 may also be understood as a voltage dividing circuit, and the type of components, the number of components, and the connection relationship between the components included in the voltage dividing circuit may be set according to actual conditions.
The second terminal of the switching unit 11 is connected to the first terminal of the second voltage dividing unit 14, and the second terminal of the second voltage dividing unit 14 is grounded. The second voltage dividing unit 14 has a function of dividing the voltage of the bus, that is, implementing overvoltage protection. The second voltage dividing unit 14 may also be understood as a voltage dividing circuit, and the type of components, the number of components, and the connection relationship between the components included in the voltage dividing circuit may be set according to actual conditions. Alternatively, the circuit configuration of the second voltage division unit 14 may be the same as that of the first voltage division unit 13. It should be noted that, in practical applications, the first voltage dividing unit 13 and the second voltage dividing unit 14 may be regarded as two sub-units of the voltage dividing circuit, and in this embodiment, the first voltage dividing unit 13 and the second voltage dividing unit 14 are described as two units according to the port of the switch unit 11.
Further, the second terminal of the switch unit 11 is also connected to a multi-function and communication (MCOM) pin of the control unit 12. In the embodiment, the control unit 12 is described as an IC chip, in which an integrated circuit formed by a large number of microelectronic components (transistors, resistors, capacitors, and the like) is placed on a plastic substrate to form a chip. Further, the IC chip includes a plurality of pins. Through each pin, the IC chip can be connected with different components to control, detect and other functions of the components. In one embodiment, the IC chip at least includes an MCOM pin, and the IC chip can detect the bus voltage through the MCOM pin. Because the bus voltage is adjusted within a certain range according to the change condition of the load, the size of the load can be determined by detecting the bus voltage.
The control terminal of the switch unit 11 is connected to the first terminal of the switch driving unit 15, and the second terminal of the switch driving unit 15 is connected to the gate signal output pin of the control unit 12. In one embodiment, the setting IC chip further includes at least a gate signal output pin. The gate signal output pin is used for outputting a gate signal, which may also be understood as a gate trigger signal, and in this embodiment, the gate signal is used for triggering the switch unit 11 to conduct. In one embodiment, the gate signal is a Pulse Width Modulation (PWM) signal, where PWM is an analog control method, and the on-time of the switch unit 11 can be changed by the PWM signal. Typically, the IC chip determines whether to generate a gate signal according to the driving condition of the PFC circuit. When the electronic equipment is in a standby state, the IC chip determines whether the PFC circuit works, if so, a gate signal is generated, and if not, the gate signal is not generated. It should be noted that, in the standby state, the load of the current electronic device is very small (may be light load or no load), the bus voltage becomes small (the IC chip obtains the bus voltage through the MCOM pin), and at this time, the IC chip controls the PFC circuit to operate intermittently, that is, the PFC circuit is in the skip cycle mode. In the skip cycle mode, according to the size of the load, the PFC circuit skips one or more ac cycles, that is, the PFC circuit is turned off in one or more ac cycles and turned on again when the next ac cycle arrives, thereby ensuring the performance of the PFC circuit. When the PFC circuit is turned on, the IC chip can be considered to be in the turn-on time of the skip cycle mode currently, and accordingly, the gate signal is output by the IC chip. In addition, when the electronic device is in a normal working state, the load of the electronic device is large, the PFC circuit continuously works, at the moment, the PFC voltage continuously works, and the IC chip continuously outputs the gate pole signal. FIG. 3 is a schematic diagram of a gate signal according to an embodiment of the present application, referring to FIG. 3, which is a schematic diagram of a gate signal displayed by a filter, wherein the display parameter of the filter is 20 ms/div. At this time, line 1 is a reference signal for indicating the period of the gate signal, and line 2 is a waveform diagram of the gate signal at the on time of the skip period mode, and it can be seen from line 2 that the gate signal (PWM signal) is a pulse signal. Line 3 is a waveform diagram of the output of the gate signal output pin at the off time of the skip cycle mode, which is a low level signal. It should be noted that, for the convenience of understanding, fig. 3 shows three signal diagrams, and in practical applications, the filter will display corresponding waveform diagrams according to the current output signal.
Further, the gate signal is converted into a dc signal through the switch driving unit 15. The direct current signal is specifically used to control the switching unit 11 to be turned from off to on. The specific circuit structure embodiment of the switch driving unit 15 is not limited, and the switch driving unit 15 has a low-pass filtering function to convert the pulse-form gate signal into a dc signal, and further control the switch unit 11 through the dc signal, that is, control the conduction of the first end and the second end of the switch unit 11 through the dc signal. It can be understood that when the switch driving unit 15 does not receive the gate signal, a direct current signal for conduction is not transmitted to the switching unit 11, and at this time, the first terminal and the second terminal of the switching unit 11 are turned off.
The following description exemplarily describes the working mode of the overvoltage protection circuit, when the electronic device normally works, the control unit 12 outputs a gate signal through a gate signal output pin, the gate signal is converted into a direct current signal through the switch driving unit 15 and then input to the control end of the switch unit 11, when the switch unit 11 receives the control signal, the first end and the second end are conducted, an MCOM (PFC feedback signal) pin of the control unit 12 detects a bus voltage, and when the control signal is detected, the first voltage dividing unit 13 and the second voltage dividing unit 14 divide the bus voltage. When the electronic device is standby, the control unit 12 outputs a gate signal from the gate signal output pin at the on time of the skip cycle mode (i.e. when the PFC circuit is on), the gate signal is converted into a dc signal by the switch driving unit 15 and then input to the control terminal of the switch unit 11, when the switch unit 11 receives the dc signal, the first terminal and the second terminal are turned on, the MCOM pin of the control unit 12 detects the bus voltage, and when the bus voltage is detected, the first voltage dividing unit 13 and the second voltage dividing unit 14 divide the bus voltage, accordingly, the control unit 12 does not output the gate signal at the off time of the skip cycle mode (i.e. when the PFC circuit is off), at this time, the switch driving unit 15 does not generate the dc signal for conduction, the first terminal and the second terminal of the switch unit 11 are turned off, at this time, the first voltage dividing unit 13 and the second voltage dividing unit 14 do not work, i.e, therefore, no loss is generated.
The overvoltage protection circuit is characterized in that a switch unit is arranged, a first end of the switch unit is connected with bus voltage through a first voltage division unit, a second end of the switch unit is grounded through a second voltage division unit, meanwhile, a second end of the switch unit is also connected with a multifunctional and communication pin of a control unit, a control end of the switch unit is connected with a gate pole signal output pin of the control unit through a switch driving unit, in a standby mode, when the control unit outputs a gate pole signal in the on time of a skip cycle mode, the gate pole signal is converted into a direct current signal by the switch driving unit and is sent to the switch unit, the switch unit is conducted according to the direct current signal, the first voltage division unit and the second voltage division unit are connected into a circuit to bear voltage division work, meanwhile, the control unit detects the bus voltage, in the standby mode, when the control unit stops outputting the gate pole signal in the off time of the skip, the switch unit stops receiving the direct current signal for conduction, at the moment, the switch unit is switched off, the first voltage division unit and the second voltage division unit are excluded from the circuit, and no power consumption is generated, so that the loss of the overvoltage protection circuit is reduced, and the standby power consumption of the electronic equipment is further reduced.
On the basis of the above embodiments, fig. 4 is a schematic structural diagram of another overvoltage protection circuit provided in the embodiments of the present application. Fig. 4 is an embodiment of the overvoltage protection circuit shown in fig. 2. Specifically, referring to fig. 4, the switch driving unit 15 includes a diode unit 151, a first resistor R1, and a first capacitor C1, wherein an anode of the diode unit 151 is connected to a gate signal output pin of the control unit 12; a first end of the first resistor R1 is connected to the cathode of the diode unit 151, and a second end of the first resistor R1 is connected to a first end of the first capacitor C1 and a control end of the switch unit 11, respectively; the second terminal of the first capacitor C1 is grounded.
Typically, the switch driving unit 15 includes a diode unit 151, a first resistor R1, and a first capacitor C1. The diode unit 151 includes at least one diode, wherein the diode has a unidirectional conductive property, that is, when a forward voltage is applied to an anode and a cathode of the diode, the diode is turned on, and when a reverse voltage is applied to the anode and the cathode, the diode is turned off. At this time, the on and off of the diode corresponds to the on and off of the switch, and therefore, the diode can be considered as one switching element. Further, anodes of the diodes in the diode unit 151 constitute an anode of the diode unit 151, and are connected to a gate signal output pin of the control unit 12. The cathode of each diode in diode unit 151 constitutes the cathode of diode unit 151 and is connected to a first terminal of a first resistor R1. The diode unit 151 is used to introduce the gate signal output from the control unit 12. Specifically, the gate signal output by the control unit 12 is a pulse signal, and when the diode unit 151 receives the pulse signal, it may be turned on and off repeatedly according to the level of the pulse signal, that is, the switching operation is repeated, and when it is turned on, the gate signal is output, and when it is turned off, the gate signal is not output. At this time, the gate signal output through the diode unit 151 is still a pulse signal.
Further, a second terminal of the first resistor R1 is connected to the control terminal of the switch unit 11 and the first terminal of the first capacitor C1, respectively, and a second terminal of the first capacitor C1 is grounded. The resistance of the first resistor R1 can be set according to practical situations, and in the embodiment, the first resistor R1 is 1.5Mohm as an example. Further, the first capacitor C1 is an NC capacitor, wherein the NC capacitor means that the first capacitor C1 is compatible with the NC capacitor. The specific capacitance of the first capacitor may be set according to actual conditions, generally speaking, if the capacitance of the first capacitor C1 is small, the filtering effect of the first capacitor C1 and the first resistor R1 may be affected, and if the capacitance of the first capacitor C1 is large, the response time of the first capacitor C1 and the first resistor R1 may be affected to be slow, for example, the capacitance of the first capacitor C1 is between 1000pF and 2000 pF. Further, the first capacitor C1 and the first resistor R1 form a low-pass filter, wherein the low-pass filter can allow low-frequency signals to normally pass through, and block or attenuate high-frequency signals exceeding a set threshold. In one embodiment, the gate signal is input to a low pass filter formed by a first capacitor C1 and a first resistor R1, and the gate signal (pulse signal) is filtered to a dc signal. Specifically, since the switch unit 11 needs to be turned on when the control unit 12 outputs the gate signal, and the gate signal output by the diode unit 151 is a pulse signal, which is not beneficial to controlling the switch unit 11, in the embodiment, a low-pass filter is provided to filter the gate signal and obtain the dc signal after filtering. Then, the dc signal is input to the control terminal of the switching unit 11, so that the switching unit 11 is turned on according to the dc signal.
As described above, the switch driving unit includes the diode unit for introducing the gate signal and the low pass filter (the first resistor R1 and the first capacitor C1) for converting the gate signal into the dc signal, so as to control the switch unit and convert the gate signal (the pulse signal) into the dc signal, so that the switch unit can control the first voltage dividing unit and the second voltage dividing unit, thereby ensuring that the first voltage dividing unit and the second voltage dividing unit accurately perform the voltage dividing function.
On the basis of the above embodiment, referring to fig. 4, the switch driving unit 15 further includes a second resistor R2, a first end of the second resistor R2 is connected to a second end of the first resistor R1, and a second end of the second resistor R2 is grounded.
Specifically, the switch driving unit 15 further includes a second resistor R2, wherein a first end of the second resistor R2 is connected to a second end of the first resistor R1, and a second end of the second resistor R2 is connected to the ground together with a second end of the first capacitor C1. The specific resistance of the second resistor R2 can be set according to practical situations, and in the embodiment, the second resistor R2 is 50kohm as an example. Furthermore, the second resistor R2 and the first resistor R1 may form a voltage dividing resistor together, so as to protect components in the overvoltage protection circuit. In addition, the second resistor R2 can also play a role in slight current limiting.
In an embodiment, the second resistor R2 includes only one resistor, and in practical applications, a plurality of resistors may be integrated in the second resistor R2, and the resistance value of each resistor may be set according to practical situations.
Further, after the second resistor R2 is provided, the second resistor R2 and the first resistor R1 may perform a voltage division function to protect components in the overvoltage protection circuit.
On the basis of the above embodiment, referring to fig. 4, the diode unit 151 includes a first diode D1, and the gate signal output pin of the control unit 12 includes a first output pin for outputting a PFC gate signal; an anode of the first diode D1 is connected to the first output pin, and a cathode of the first diode D1 is connected to a first terminal of the first resistor R1.
Specifically, the setting gate signal includes a PFC gate signal, and in fig. 4, the PFC gate signal is denoted as a PFC gate. The PFC gate signal refers to a gate signal generated by the control unit 12 according to the PFC circuit, that is, a PFC gate signal is generated when the PFC circuit operates, and the PFC gate signal is not generated when the PFC circuit does not operate. At this time, the gate signal output pin of the control unit 12 includes a first output pin for outputting the PFC gate signal.
Further, the gate signal of the PFC is introduced through the first diode D1, and the type of the first diode D1 can be set according to practical situations, and in the embodiment, the first diode D1 is a 1N4148 diode, wherein the 1N4148 diode is a small high-speed switching diode, and the switching on or off is relatively fast. Further, an anode of the first diode D1 is connected to the first output pin, so as to be turned on when the control unit 12 outputs the PFC gate signal, thereby implementing introduction of the PFC gate signal. Further, the cathode of the first diode D1 is connected to a first terminal of a first resistor R1 to send the PFC gate signal to the low pass filter.
Further, the control unit 12 outputs the PFC gate signal during the on time of the skip cycle mode, and the control unit 12 does not output the PFC gate signal during the off time of the skip cycle mode. In the normal operation mode, that is, when the electronic device normally operates, the PFC circuit normally operates, and at this time, the control unit 12 may continuously output the PFC gate signal. Alternatively, the PFC gate signal can be referred to fig. 3. Illustratively, when the control unit 12 outputs the PFC gate signal, the low-pass filter receives the PFC gate signal through the first diode D1, and then converts the received PFC gate signal into a direct current signal to control the switching unit 11 to be turned on, so as to enable the first voltage dividing unit 13 and the second voltage dividing unit 14 to perform the voltage dividing function. When the control unit 12 does not output the PFC gate signal, the low pass filter does not operate, and at this time, the switching unit 11 is turned off.
As described above, by providing the first diode for introducing the PFC gate signal in the overvoltage protection circuit, the control of the switch unit by the PFC gate signal can be realized, and further, the control of the first voltage division unit and the second voltage division unit can be realized, so that when the electronic device is in standby, the first voltage division unit 13 and the second voltage division unit 14 are controlled to be excluded from the circuit according to the closing of the PFC circuit, and further, the standby loss is reduced.
On the basis of the above embodiments, fig. 5 is a schematic structural diagram of another overvoltage protection circuit provided in the embodiments of the present application. Compared to fig. 4, a second diode D2 for introducing the LLC gate signal is added in fig. 5. The other component connection structure in fig. 5 is the same as that in fig. 4, and is not described herein again.
Specifically, referring to fig. 5, the diode unit 151 further includes a second diode D2; the gate signal output pin of the control unit 12 further includes a second output pin for outputting an LLC gate signal; an anode of the second diode D2 is connected to the second output pin, and a cathode of the second diode D2 is connected to a first terminal of the first resistor R1.
Specifically, the set gate signals may include an LLC gate signal and a PFC gate signal, denoted as LLC LS gate and PFC gate, respectively, in FIG. 5. Where LLC refers to a resonant circuit, which is a single port network containing inductive, capacitive and resistive elements, which can resonate at certain frequencies. An LLC gate signal refers to a gate signal generated by the control unit 12 from the LLC. Further, the gate signal output pin of the control unit 12 includes two pins, one is a second output pin for outputting the LLC gate signal, and the other is a first output pin for outputting the PFC gate signal.
In the embodiments, the LLC may be understood as a switching power supply, wherein the principle of the switching power supply is to convert a power-frequency ac into a dc and then convert the dc into a high-frequency ac. Specifically, in the standby state, when the PFC circuit is in the skip mode, in addition to the intermittent operation of the PFC circuit, the LLC also operates intermittently, that is, the LLC is periodically turned on or off, and at this time, the LLC may also be regarded as the skip mode. Accordingly, when the LLC is turned on (i.e., operational), the control unit 12 outputs a corresponding LLC gate signal for the turn-on time that is currently in the skip cycle mode. When the LLC is off (i.e., not operational), the control unit 12 may not output the LLC gate signal for the off time that is currently in the skip cycle mode. Accordingly, the gate signals output by the control unit 12 may include the LLC gate signal or/and the PFC gate signal during the on-time of the skip-cycle mode, and the control unit 12 does not output the LLC gate signal and the PFC gate signal during the off-time of the skip-cycle mode. In the normal operation mode, that is, when the electronic device is operating normally, the LLC and/or PFC circuits are operating normally, and at this time, the control unit 12 may continuously output the LLC gate signal or/and the PFC gate signal. Alternatively, both the LLC gate signal and the PFC gate signal can be referenced in FIG. 3.
In one embodiment, the LLC gate signal is introduced through the second diode D2, and the model of the second diode D2 and the first diode D1 may be set according to the actual situation, and may be the same or different. In the embodiment, the first diode D1 and the second diode D2 are the same in type and are both 1N4148 type diodes. Further, an anode of the second diode D2 is connected to the second output pin to be turned on when the control unit 12 outputs the LLC gate signal, so as to enable the LLC gate signal to be introduced. The cathode of the second diode D2 is connected to a first terminal of a first resistor R1 to input the LLC gate signal to the low-pass filter.
Further, during the start period of the skip cycle mode, the low-pass filter receives the gate signal, and at this time, no matter the gate signal is the LLC gate signal, the PFC gate signal or the mixed signal of the LLC gate signal and the PFC gate signal, the low-pass filter converts the received gate signal into a direct-current signal to control the switching unit 11 to be turned on, so that the first voltage division unit 13 and the second voltage division unit 14 undertake the voltage division function. During the off period of the skip cycle mode, the low pass filter does not receive the gate signal, and at this time, the low pass filter does not generate the control signal, the switch unit 11 is turned off, and the first voltage division unit 13 and the second voltage division unit 14 are excluded from the circuit, thereby reducing the standby power consumption. When the electronic device normally works, the low-pass filter receives the gate signal, and at this time, no matter the gate signal is the LLC gate signal, the PFC gate signal or the mixed signal of the LLC gate signal and the PFC gate signal, the low-pass filter converts the received gate signal into a direct-current signal to control the switch unit 11 to be turned on, so that the first voltage division unit 13 and the second voltage division unit 14 undertake the voltage division function.
As described above, by providing the second diode for introducing the LLC gate signal and the first diode for introducing the PFC gate signal in the overvoltage protection circuit, the control of the switching unit by the LLC gate signal and/or the PFC gate signal can be realized, and the control of the first voltage division unit and the second voltage division unit can be further realized, so that when the electronic device is in standby, the first voltage division unit 13 and the second voltage division unit 14 are controlled to be excluded from the circuit according to the closing of the PFC circuit or the LLC, and the standby loss is further reduced.
It should be noted that, in practical applications, any scheme may be selected according to practical situations, that is, the PFC gate signal is selectively introduced into the overvoltage protection circuit, or the PFC gate signal and the LLC gate signal are selectively introduced into the overvoltage protection circuit.
On the basis of the above embodiment, referring to fig. 4 and fig. 5, the switch unit 11 is an N-type MOS transistor, a gate of the N-type MOS transistor corresponds to the control end of the switch unit 11, a drain of the N-type MOS transistor corresponds to the first end of the switch unit 11, and a source of the N-type MOS transistor corresponds to the second end of the switch unit 11.
Specifically, the switching unit 11 is a MOS transistor, wherein the specific type of the MOS transistor can be set according to actual conditions. In the embodiment, the MOS transistor is an N-type MOS transistor. The model of the N-type MOS transistor can be set according to actual conditions, and in the embodiment, the model of the N-type MOS transistor can be selected to be BSS 127. Further, the gate of the N-type MOS transistor corresponds to the control terminal of the switch unit 11, the drain of the N-type MOS transistor corresponds to the first terminal of the switch unit 11, and the source of the N-type MOS transistor corresponds to the second terminal of the switch unit 11. When a direct current signal flows into the gate of the N-type MOS transistor, the gate of the N-type MOS transistor is connected to a high level, the drain and the source of the N-type MOS transistor are conducted, and the first voltage division unit 13 and the second voltage division unit 14 operate. When there is no dc signal, the gate of the N-type MOS transistor is at a low level, the drain and the source of the N-type MOS transistor are disconnected, and the first voltage dividing unit 13 and the second voltage dividing unit 14 are excluded from the circuit.
It should be noted that, in practical applications, the switch unit 11 may further include a plurality of MOS transistors, and other peripheral components may be disposed around the MOS transistors.
In the above, the N-type MOS transistor is used as the switching unit, so that the switching unit has a simple structure and is convenient to control.
On the basis of the above embodiment, the first voltage dividing unit 13 includes the first voltage dividing resistor R3. The second voltage dividing unit 14 includes a second voltage dividing resistor R4.
Specifically, the first voltage dividing unit 13 is composed of a first voltage dividing resistor R3, and in practical applications, the first voltage dividing unit 13 may further include a plurality of voltage dividing resistors or may further include other voltage dividing components. The resistance of the first voltage-dividing resistor R3 can be set according to practical situations, for example, the first voltage-dividing resistor R3 is 6 Mohm.
The second voltage dividing unit 14 is composed of a second voltage dividing resistor R4, and in practical applications, the second voltage dividing unit 14 may further include a plurality of voltage dividing resistors or may further include other voltage dividing components. The resistance of the second voltage-dividing resistor R4 can be set according to practical situations, the second voltage-dividing resistor R4 can be the same as or different from the first voltage-dividing resistor R3, and in the embodiment, the second voltage-dividing resistor R4 is the same as the first voltage-dividing resistor R3.
When the switch unit 11 is turned on, the first voltage-dividing resistor R3 and the second voltage-dividing resistor R4 can perform voltage-dividing function, and the first voltage-dividing resistor R3 and the second voltage-dividing resistor R4 can prevent other components (such as the control unit 12) in the circuit from being damaged when the bus voltage is too large, so as to realize overvoltage protection.
On the basis of the above embodiment, referring to fig. 4 and 5, the overvoltage protection circuit further includes: a second capacitor C2, wherein a first terminal of the second capacitor C2 is connected to the second terminal of the switch unit 11, and a second terminal of the second capacitor C2 is grounded.
Specifically, the picofarad value of the second capacitor C2 may be set according to an actual situation, in the embodiment, taking the second capacitor as 470P as an example, in an actual application, the capacitance value of the second capacitor may be changed in combination with the actual situation of the overvoltage protection circuit. The first end of the second capacitor C2 is connected to the second end of the switch unit 11, and the second end of the second capacitor C2 is grounded together with the second end of the second voltage-dividing resistor R4, which can also be understood as an RC parallel circuit formed by the second capacitor C2 and the second voltage-dividing resistor R4 connected in parallel to be connected to the overvoltage protection circuit. The second capacitor C2 may perform a filtering function, and further perform a protection function on the switch unit 11.
On the basis of the above embodiment, the control unit 12 is an IC chip. An IC chip is also understood to be a microelectronic device, which is a chip made of a large number of integrated circuits formed by microelectronic components (transistors, resistors, capacitors, etc.) on a plastic substrate. Specifically, the role and function of the IC chip may be set according to the actual situation of the electronic device. For example, in an embodiment, the electronic device has a power module, and the power module is configured to provide power for each component in the electronic device when the electronic device is connected to a mains supply, and at this time, the IC chip is a power chip to control and protect the power module. Further, the IC chip includes a plurality of pins. Through each pin, the IC chip can be connected with different components to control, detect and other functions of the components. In one embodiment, the IC chip includes at least an MCOM pin and a first output pin when the gate signal comprises a PFC gate signal. The IC chip can detect the bus voltage to determine the current load, and when in a standby state, the PFC circuit enters a cycle skipping mode, and then the switch unit is controlled by outputting a gate signal, so that the first voltage division unit and the second voltage division unit bear a voltage division function or are excluded from the circuit, and the loss of the overvoltage protection circuit is reduced to the minimum under the standby state, and the power consumption of the electronic equipment is reduced. In another embodiment, the IC chip includes at least an MCOM pin, a first output pin, and a second output pin when the gate signals include a PFC gate signal and an LLC gate signal. The IC chip can detect the bus voltage to determine the current load, and in a standby state, the PFC circuit and the LLC can enter a skip cycle mode, and then the switch unit is controlled by outputting a gate pole signal, so that the first voltage division unit and the second voltage division unit can bear a voltage division function or the first voltage division unit and the second voltage division unit are excluded from the circuit, and in the standby state, the loss of the overvoltage protection circuit is reduced to the minimum, and the power consumption of the electronic equipment is reduced.
The embodiment of the application also provides the electronic equipment. The electronic equipment comprises the overvoltage protection circuit and has corresponding functions and beneficial effects. For technical details which are not described in detail in the electronic device, reference is made to the overvoltage protection circuit described above.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present application and the technical principles employed. It will be understood by those skilled in the art that the present application is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the application. Therefore, although the present application has been described in more detail with reference to the above embodiments, the present application is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present application, and the scope of the present application is determined by the scope of the appended claims.
Claims (10)
1. An overvoltage protection circuit, comprising: the switch unit, the control unit, the first voltage division unit, the second voltage division unit and the switch driving unit;
the first end of the switch unit is connected with the first end of the first voltage division unit; the second end of the switch unit is connected with the first end of the second voltage division unit, the second end of the switch unit is also connected with the multifunctional and communication pin of the control unit, and the control end of the switch unit is connected with the first end of the switch driving unit;
the second end of the switch driving unit is connected with a gate signal output pin of the control unit;
and the second end of the first voltage division unit is connected with the bus voltage, and the second end of the second voltage division unit is grounded.
2. The overvoltage protection circuit of claim 1, wherein the switch driving unit comprises a diode unit, a first resistor and a first capacitor;
the anode of the diode unit is connected with a gate signal output pin of the control unit;
the first end of the first resistor is connected with the cathode of the diode unit, and the second end of the first resistor is respectively connected with the first end of the first capacitor and the control end of the switch unit;
the second end of the first capacitor is grounded.
3. The overvoltage protection circuit of claim 2, wherein the switch drive unit further comprises: and the first end of the second resistor is connected with the second end of the first resistor, and the second end of the second resistor is grounded.
4. The overvoltage protection circuit of claim 2, wherein the diode unit comprises a first diode, and the gate signal output pin of the control unit comprises a first output pin for outputting a PFC gate signal;
the anode of the first diode is connected with the first output pin, and the cathode of the first diode is connected with the first end of the first resistor.
5. The overvoltage protection circuit of claim 4, wherein the diode unit further comprises a second diode, the gate signal output pin of the control unit further comprises a second output pin for outputting the LLC gate signal;
and the anode of the second diode is connected with the second output pin, and the cathode of the second diode is connected with the first end of the first resistor.
6. The overvoltage protection circuit of claim 1, wherein the switching unit is an N-type MOS transistor;
the grid electrode of the N-type MOS tube corresponds to the control end of the switch unit, the drain electrode of the N-type MOS tube corresponds to the first end of the switch unit, and the source electrode of the N-type MOS tube corresponds to the second end of the switch unit.
7. The overvoltage protection circuit of claim 1, wherein the first voltage divider unit comprises a first voltage divider resistor and the second voltage divider unit comprises a second voltage divider resistor.
8. The overvoltage protection circuit of claim 1, further comprising: and the first end of the second capacitor is connected with the second end of the switch unit, and the second end of the second capacitor is grounded.
9. The overvoltage protection circuit of claim 1, wherein the control unit is an IC chip.
10. An electronic device, characterized in that it comprises an overvoltage protection circuit as claimed in any one of claims 1 to 9.
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| CN202021672694.0U CN212969038U (en) | 2020-08-12 | 2020-08-12 | Overvoltage protection circuit and electronic equipment |
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| CN202021672694.0U CN212969038U (en) | 2020-08-12 | 2020-08-12 | Overvoltage protection circuit and electronic equipment |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116997044A (en) * | 2023-09-28 | 2023-11-03 | 深圳莱福德科技股份有限公司 | Low-power consumption standby intelligent dimming control method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116997044A (en) * | 2023-09-28 | 2023-11-03 | 深圳莱福德科技股份有限公司 | Low-power consumption standby intelligent dimming control method |
| CN116997044B (en) * | 2023-09-28 | 2023-12-15 | 深圳莱福德科技股份有限公司 | Low-power consumption standby intelligent dimming control method |
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