CN202737435U - Overvoltage protection circuit and power supply module - Google Patents
Overvoltage protection circuit and power supply module Download PDFInfo
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- CN202737435U CN202737435U CN 201220353948 CN201220353948U CN202737435U CN 202737435 U CN202737435 U CN 202737435U CN 201220353948 CN201220353948 CN 201220353948 CN 201220353948 U CN201220353948 U CN 201220353948U CN 202737435 U CN202737435 U CN 202737435U
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Abstract
The utility model discloses an overvoltage protection circuit and a power supply module. The power supply module is applied in a liquid crystal display product, comprises the overvoltage protection circuit and further comprises an energy-saving control circuit; the overvoltage protection circuit comprises a first main power voltage and a second main power voltage, the first main power voltage is used as power supplying input end voltage of an LED driving circuit of an LED lamp tube of a liquid crystal panel, and the second main power voltage is used for providing power required by an inner circuit for the liquid crystal display product. The overvoltage protection circuit is used for providing overvoltage protection for the first main power voltage and the second main power voltage, and the energy-saving control circuit is used for saving more energy when the liquid crystal display product stays in a standby mode.
Description
Technical field
The utility model relates to the product of liquid crystal display and liquid crystal display, relates in particular to a kind of excess voltage protection and power module.
Background technology
Fig. 1 is a kind of calcspar of power module of existing high-power liquid crystal display product.See also Fig. 1; power module 1 comprises electromagnetic interference (Electro Magnetic Interference; EMI) filter circuit 11, bridge rectifier 12, power factor correction (Power Factor Correction; PFC) circuit 13, main power conversion circuit 14, light-emitting diode (Light-Emitting Diode, LED) drive circuit 15, standby power change-over circuit 16, energy-saving control circuit 17 and excess voltage protection 18.Electric main (as 90～264Vac) through the bus voltage Vbus(of generation direct current after EMI filter circuits 11 filtering Conducted EMI noises, bridge rectifier 12 full-wave rectifications, pfc circuit 13 correcting current waveforms and the filtering as: about 400V).
Main power conversion circuit 14 receives bus voltage Vbus and carries out step-down conversion and export the first main power voltage Vm1(such as 24V) and the second main power voltage Vm2(such as 12V), wherein, but the first main power voltage Vm1 is again through producing the voltage of driving LED lamp source work after led drive circuit 15 boost conversion, the second main power voltage Vm2 then provide liquid crystal display product inner as: the required power supplys such as liquid crystal panel drive circuit (Panel Driver Circuit) and message circuit (Audio Circuit).Standby power change-over circuit 16 receive bus voltage Vbus and carry out step-down conversion export standby power voltage Vsb(as: 5V) offer energy-saving control circuit 17, excess voltage protection 18 is inner such as required power supplys such as mainboard image processors with liquid crystal display product; in addition, the auxiliary winding voltage of the transformer in the standby power change-over circuit 16 produces accessory power supply voltage Vaux(such as 12～19V) after over commutation and filtering.Energy-saving control circuit 17 can make liquid crystal display product turn off pfc circuit 13 and main power conversion circuit 14 under standby mode, makes liquid crystal display product more power saving under standby mode.Excess voltage protection 18 can provide the over-voltage protection function of the first main power voltage Vm1 and the second main power voltage Vm2.
Fig. 2 A and Fig. 2 B are respectively the circuit diagram of energy-saving control circuit 17 shown in Figure 1 and excess voltage protection 18.Please be simultaneously referring to Fig. 1, Fig. 2 A, Fig. 2 B, energy-saving control circuit 17 comprises capacitor C1 and C2, diode D1, optical coupler OC1, transistor Q1～Q3, resistor R1～R7 and Zener (Zener) diode ZD1.When liquid crystal display product works, mainboard control circuit control electric power starting leads ends PS_ON is high potential, this moment transistor Q1 and Q2 conducting, the LED of optical coupler OC1 input side has electric current to pass through and so that the photistor conducting of its outlet side, so that transistor Q3 conducting, so that accessory power supply voltage Vaux can provide internal power source voltage Vcc to controller 131 and 141 required power supplys in pfc circuit 13 and the main power conversion circuit 14 by transistor Q3, thus during normal operation pfc circuit 13 and main power conversion circuit 14 under the control of controller 131 and 141 regular event to carry out voltage transitions.
When liquid crystal display product enters standby mode, mainboard control circuit control electric power starting leads ends PS_ON is electronegative potential, transistor Q1 and Q2 cut-off this moment, the LED of optical coupler OC1 input side does not have electric current to pass through and so that the photistor of its outlet side cut-off, so that transistor Q3 cut-off, so that accessory power supply voltage Vaux can't provide internal power source voltage Vcc to controller 131 and 141 required power supplys in pfc circuit 13 and the main power conversion circuit 14 by transistor Q3, therefore pfc circuit 13 stops more power saving of action with main power conversion circuit 14 because controller 131 and 141 is closed under standby mode.
When the first main power voltage Vm1 or the second main power voltage Vm2 exceed the value of overvoltage protection point separately; the breakdown conducting of Zener diode ZD2 or ZD3; produce an electric current through resistor R8 and R9, so that the base terminal of transistor Q5 rises to emitter-base bandgap grading terminal voltage Vbe5.When voltage Vbe5 reaches conducting voltage, transistor Q5 conducting, so that the base terminal voltage Vb4 of transistor Q4 dragged down and make transistor Q4 conducting, and then makes transistor Q5 enter the saturation conduction state, cause voltage Vb4 to be pulled to minimum and make transistor Q4 also enter the saturation conduction state.At this moment; because the cathode terminal voltage (being voltage Vb4) of diode D4 is pulled to minimum; so that overvoltage protection leads ends OVP voltage (being the anode tap voltage of diode D4) is dragged down; the LED that causes optical coupler OC1 input side does not have electric current to pass through and so that the cut-off of the photistor of its outlet side; so that transistor Q3 cut-off; so that accessory power supply voltage Vaux can't provide internal power source voltage Vcc to controller 131 and 141 required power supplys in pfc circuit 13 and the main power conversion circuit 14 by transistor Q3, therefore pfc circuit 13 and main power conversion circuit 14 will stop action and can prevent the destroyed problem of other circuit because controller 131 and 141 is closed when the first main power voltage Vm1 or the second main power voltage Vm2 have overvoltage.
To sum up, there are problems in the above circuit, and is specific as follows:
(1) voltage stabilizing didoe ZD2 and ZD3 voltage stabilizing value bound differ greatly, and can cause different electrical power plate OVP overvoltage to protect point and differ greatly.
(2) still there are not leakage current Ir in voltage stabilizing didoe ZD2 and ZD3 before the conducting; when their body temperatures raise; leakage current can increase; if resistance R 8 and R9 resistance arrange when attitude is unreasonable; under hot and humid environment, easily be directed at the misoperation of Q5 NPN electric crystal because ZD2 and ZD3 leakage current increase, finally be directed at whole excess voltage protection misoperation and so that main power source be closed.
The D4 negative terminal voltage is greater than positive terminal voltage when (3) working; so that the D4 diode oppositely ends; but there is larger Ir reverse leakage current usually in this diode; when under hot and humid environment; this diode reverse leakage current increases; if this moment, the R12 resistance was set up too large; because of D4 reverse leakage flow problem; so that there is a pressure reduction △ V=R12*Ir at R12 resistance two ends; when pressure reduction was larger, PNP electric crystal Q4 began conducting, and the Q4 conducting produces an electric current so that electric crystal Q5 conducting at the generating utmost point and collection emitter-base bandgap grading; last Q4 and Q5 all are in the saturation conduction state, the time protective circuit misoperation appears.
This circuit is owing to existing above problem; not to be that very abundant engineer is difficult do very correct selection to all electronic components in this circuit to universal experience; if arranging a little, some Parameters of The Parts not very suitable; as: set resistance R 9/R12 resistance bigger than normal; under hot and humid condition with regard to this excess voltage protection misoperation problem of easy generation; therefore, need to provide solution for above problem.
Summary of the invention
The purpose of this utility model is to provide a kind of overvoltage protection more accurate; the protective circuit setting is more prone to; protective circuit can not leaked electricity problem and cause the excess voltage protection misoperation because of zener diode and diode reverse under hot conditions, and this circuit especially is fit to be applied to the power supply product of liquid crystal display and lcd-tv etc.
In order to solve the problems of the technologies described above, the technical scheme that the utility model adopts provides a kind of voltage protection circuit, be applied to image processor, described image processor comprises the digital-to-analogue conversion port, and described circuit comprises filter unit, the 8th to the 11 resistance, the first diode, the second diode, the first main power voltage and the second main power voltage; The 8th resistance is connected with the 9th resistance and is coupled between the first main power source and the ground, and the common node of the 8th resistance and the 9th resistance connects the anode of the first diode, and the negative electrode of the first diode is connected to the digital-to-analogue conversion port; The tenth resistance is connected with the 11 resistance and is coupled between the second main power source and the ground, and the common node of the tenth resistance and the 11 resistance connects the anode of the second diode, and the cathode terminal of the second diode connects the negative electrode of the first diode; One end ground connection of described filter unit, the cathode terminal of another termination first diode, the second diode.
Wherein, described filter unit comprises the 12 resistance and the 3rd electric capacity composition filter unit parallel with one another, one termination, first diode of the 12 resistance of described filter unit and the 3rd electric capacity, the cathode terminal of the second diode, the 12 resistance of filter unit and the other end ground connection of the 3rd electric capacity.
Wherein, the resistance of described the 12 resistance is much larger than the 8th to the 11 resistance.
Another scheme that the utility model adopts provides a kind of power module, is applied on the liquid crystal display product, comprises described excess voltage protection, also comprises an energy-saving control circuit;
Described excess voltage protection comprises the first main power voltage and the second main power voltage, the first main power voltage is used for the power supply input terminal voltage as the led drive circuit of the LED fluorescent tube of liquid crystal panel, and the second main power voltage is used to liquid crystal display product to provide internal circuit required power supply; Described excess voltage protection is used to the first main power voltage and the second main power voltage that overvoltage protection is provided; Described energy-saving control circuit is used to the more energy saving under standby mode of described liquid crystal display product.
The overvoltage determination methods of described power module comprises the steps:
Whether the digital-to-analogue conversion port of judging image processor detects the output voltage of excess voltage protection greater than the reference voltage of software inner setting;
If, the signal output part output low level of image processor then;
If not, then the signal output part of image processor is exported high level.
The beneficial effects of the utility model are:
Whether the digital-to-analogue conversion port in the image processor of employing mainboard control circuit is detected the main circuit output end voltage accurately overvoltage problem, when detecting by the overvoltage protection signal, output end signal output low level by software judgement and image processor is turned off the 3rd transistor of energy-saving control circuit, thereby stops to provide required power supply for internal power source voltage; What described excess voltage protection had overcome prior art has caused the problem of protective circuit misoperation under hot and humid condition because of voltage stabilizing diode and diode reverse leakage current; and the protective circuit set point that is is more accurate, greatly reduces simultaneously the difficulty of this protective circuit setting parameter.
Description of drawings
Fig. 1 is the system block diagram of the power module of conventional solution of the present utility model;
Fig. 2 A is the structural representation of the energy-saving control circuit of conventional solution of the present utility model;
Fig. 2 B is the structural representation of the excess voltage protection of conventional solution of the present utility model;
Fig. 3 A is the structural representation of the energy-saving control circuit of certain execution mode of the present utility model;
Fig. 3 B is the structural representation of the excess voltage protection of certain execution mode of the present utility model;
Fig. 4 is the flow chart of over-voltage protection method of the present utility model.
Embodiment
By describing technology contents of the present utility model, structural feature in detail, being realized purpose and effect, below in conjunction with execution mode and cooperate accompanying drawing to give in detail explanation.
Fig. 1 is a kind of calcspar of power module of existing high-power liquid crystal display product.See also Fig. 1; power module 1 comprises electromagnetic interference (Electro Magnetic Interference; EMI) filter circuit 11, bridge rectifier 12, power factor correction (Power Factor Correction; PFC) circuit 13, main power conversion circuit 14, light-emitting diode (Light-Emitting Diode, LED) drive circuit 15, standby power change-over circuit 16, energy-saving control circuit 17 and excess voltage protection 18.Electric main (as 90～264Vac) through the bus voltage Vbus(of generation direct current after EMI filter circuits 11 filtering Conducted EMI noises, bridge rectifier 12 full-wave rectifications, pfc circuit 13 correcting current waveforms and the filtering as: about 400V).
Consult Fig. 3 B, the utility model provides a kind of voltage protection circuit, be applied to image processor, described image processor is inner integrated microcontroller (MCU:Micro Control Unit), comprise digital-to-analogue conversion port (ADC:Analog to Digital Converter), this ADC port often is set to input detecting port by the engineer by software, be used for detecting accurately the inner various electric signals of liquid crystal display product, described circuit comprises filter unit, the the 8th to the 11 resistance, the first diode D1, the second diode D2, the first main power voltage Vm1 and the second main power voltage Vm2; The 8th resistance R 8 and the 9th resistance R 9 coupled in series are between the first main power source Vm1 and ground, and the common node of the 8th resistance R 8 and the 9th resistance R 9 connects the anode of the first diode D1, and the negative electrode of the first diode D1 is connected to digital-to-analogue conversion port ADC; The tenth resistance R 10 and the 11 resistance R 11 coupled in series are between the second main power source Vm2 and ground, and the common node of the tenth resistance R 10 and the 11 resistance R 11 connects the anode of the second diode D2, and the cathode terminal of the second diode D2 connects the negative electrode of the first diode D1; One end ground connection of described filter unit, the cathode terminal of another termination the first diode D1, the second diode D2.Concrete, described filter unit comprises the 12 resistance D12 and the 3rd capacitor C 3 composition filter units parallel with one another, one termination, the first diode D1 of the 12 resistance of described filter unit and the 3rd electric capacity, cathode terminal, the 12 resistance of filter unit and the other end ground connection of the 3rd electric capacity of the second diode D2.The RC filter circuit that described the 12 resistance R 12 and the 3rd capacitor C 3 form is used for filtering and is coupled to high-frequency noise in the circuit; with prevent the higher high-frequency noise of level enter image processor 190 digital-to-analogue conversion ADC port 1901; be the overvoltage protection signal and be mistaken for by software, the resistance of described the 12 resistance R 12 needs that (resistance value of R8 ~ R11) is to avoid having influence on the sampling of the first main power voltage Vm1 and the second main power voltage Vm2 much larger than the 8th to the 11 resistance.
Above-described excess voltage protection is applied to power module, and described power module generally is applied to consult Fig. 1 on the liquid crystal display product, and described power module also comprises an energy-saving control circuit; Described excess voltage protection comprises the first main power voltage Vm1 and the second main power voltage Vm2, the first main power voltage Vm1 is used for the power supply input terminal voltage as the led drive circuit of the LED fluorescent tube of liquid crystal panel, and the second main power voltage Vm2 is used to liquid crystal display product to provide internal circuit required power supply; Described excess voltage protection is used to the first main power voltage Vm1 and the second main power voltage Vm2 that overvoltage protection is provided; Described energy-saving control circuit is used to the more energy saving under standby mode of described liquid crystal display product.See also Fig. 3 A and Fig. 3 B, energy-saving control circuit 27 of the present utility model is applied to power module 1 shown in Fig. 1 and Fig. 2 A, the 2B to replace energy-saving control circuit 17 and excess voltage protection 18 with excess voltage protection 28.The utility model energy-saving control circuit 27 is that with the difference of existing energy-saving control circuit 17 the described energy-saving control circuit of the technical program need not adopt diode D1.Diode D1 in the existing energy-saving control circuit 17 is for when the first main power voltage Vm1 or the second main power voltage Vm2 have overvoltage; the pressure drop (being Vf4+Vce5-Vf1=0.7V+0.2V-0.7V=0.2V) of guaranteeing the LED that drops to optical coupler OC1 input side that excess voltage protection 18 causes can not allow the LED conducting and make the LED of optical coupler OC1 input side not have electric current to pass through; wherein; Vf4 and Vf1 are respectively the forward conduction voltage drop of diode D4 and D1, and collector terminal was to the emitter-base bandgap grading terminal voltage when Vce5 was transistor Q5 saturation conduction.But the protection mechanism of excess voltage protection 28 of the present utility model is not so that energy-saving control circuit 27 needs diode D1.
The over-voltage protection method of described power module comprises the steps:
Whether the digital-to-analogue conversion port of judging image processor detects the output voltage OVP of excess voltage protection greater than the reference voltage Vref of software inner setting; If, then the PS_ON signal of 1902 ports of image processor output is low level, that is: turn off pfc circuit 13 and main power conversion circuit 14 by the PS_ON low level signal, make main power conversion circuit 14 stop to export the first main power voltage and the second main power voltage; If not, then the PS_ON signal of 1902 ports of image processor output be during with normal operation phase one to high level, that is: pfc circuit 13 and main power conversion circuit 14 normal operations, main power conversion circuit 14 normal output the first main power voltage and the second main power voltages.
Concrete, consult Fig. 4, and by reference to the accompanying drawings 1, Fig. 3 A and Fig. 3 B describe in detail, Fig. 4 is that this software OVP signal is judged sequential chart, when the first main power voltage Vm1 surpasses the value of the first main power source overvoltage protection point of (Vref+Vf1) * (R8+ R9)/R9, and when the second main power voltage Vm2 surpasses the value of the second main power source overvoltage protection point of (Vref+Vf2) * (R10+R11)/R11, when the digital-to-analogue conversion of presentation video processor 190 (ADC) port one 901 detects signal Vovp less than the reference voltage Vref of software inner setting, the PS_ON signal port 1902 of image processor 190 just will be exported originally as continuing high level signal (High) so that pfc circuit 13 and main power conversion circuit 14 normal operations; When the first main power voltage Vm1 surpasses the value of the first main power source overvoltage protection point of (Vref+Vf1) * (R8+ R9)/R9; and when the second main power voltage Vm2 surpasses the value of the second main power source overvoltage protection point of (Vref+Vf2) * (R10+R11)/R11; when the digital-to-analogue conversion of presentation video processor 190 (ADC) port one 901 detects signal Vovp greater than the Vref reference voltage of software inner setting, the PS_ON signal port 1902 of image processor 190 will be exported and continue low level signal (Low) so that pfc circuit 13 and main power conversion circuit 14 are stopped action.Wherein: Vf1, Vf2-------D1, the pressure drop when the D2 diode forward imports, the comparison reference voltage that the Vref---------software arranges.
Whether the ADC port in the image processor 190 of employing mainboard control circuit 19 is detected the main circuit output end voltage accurately overvoltage problem, when having detected the overvoltage protection signal, turn off the 3rd transistor Q3 by software judgement and control PS_ON signal output low level and stop to provide internal power source voltage Vcc to controller 131 and 141 required power supplys in pfc circuit 13 and the main power conversion circuit 14; This circuit has overcome existing overvoltage protection and has caused protective circuit misoperation problem under hot and humid condition because of voltage stabilizing diode and two plate body reverse leakage currents; and so that the protective circuit set point is more accurate, greatly reduce simultaneously the difficulty of this protective circuit setting parameter.
The above only is embodiment of the present utility model; be not so limit claim of the present utility model; every equivalent structure or equivalent flow process conversion that utilizes the utility model specification and accompanying drawing content to do; or directly or indirectly be used in other relevant technical fields, all in like manner be included in the scope of patent protection of the present utility model.
Claims (4)
1. excess voltage protection, be applied to image processor, described image processor comprises the digital-to-analogue conversion port, it is characterized in that: described circuit comprises filter unit, the 8th to the 11 resistance, the first diode, the second diode, the first main power voltage and the second main power voltage;
The 8th resistance is connected with the 9th resistance and is coupled between the first main power source and the ground, and the common node of the 8th resistance and the 9th resistance connects the anode of the first diode, and the negative electrode of the first diode is connected to the digital-to-analogue conversion port;
The tenth resistance is connected with the 11 resistance and is coupled between the second main power source and the ground, and the common node of the tenth resistance and the 11 resistance connects the anode of the second diode, and the cathode terminal of the second diode connects the negative electrode of the first diode;
One end ground connection of described filter unit, the cathode terminal of another termination first diode, the second diode.
2. excess voltage protection according to claim 1; it is characterized in that: described filter unit comprises the 12 resistance and the 3rd electric capacity composition filter unit parallel with one another; one termination, first diode of the 12 resistance of described filter unit and the 3rd electric capacity, the cathode terminal of the second diode, the 12 resistance of filter unit and the other end ground connection of the 3rd electric capacity.
3. excess voltage protection according to claim 2, it is characterized in that: the resistance of described the 12 resistance is much larger than the 8th to the 11 resistance.
4. a power module is applied to it is characterized in that on the liquid crystal display product: comprise the described excess voltage protection of claims 1 to 3 any one, also comprise an energy-saving control circuit;
Described excess voltage protection comprises the first main power voltage and the second main power voltage, the first main power voltage is used for the power supply input terminal voltage as the led drive circuit of the LED fluorescent tube of liquid crystal panel, and the second main power voltage is used to liquid crystal display product to provide internal circuit required power supply;
Described excess voltage protection is used to the first main power voltage and the second main power voltage that overvoltage protection is provided;
Described energy-saving control circuit is used to the more energy saving under standby mode of described liquid crystal display product.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220353948 CN202737435U (en) | 2012-07-20 | 2012-07-20 | Overvoltage protection circuit and power supply module |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220353948 CN202737435U (en) | 2012-07-20 | 2012-07-20 | Overvoltage protection circuit and power supply module |
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| Publication Number | Publication Date |
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| CN202737435U true CN202737435U (en) | 2013-02-13 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201220353948 Expired - Fee Related CN202737435U (en) | 2012-07-20 | 2012-07-20 | Overvoltage protection circuit and power supply module |
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| CN (1) | CN202737435U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102751698A (en) * | 2012-07-20 | 2012-10-24 | 冠捷显示科技（厦门）有限公司 | Overvoltage protection circuit, power module and overvoltage protection method |
| CN104184110A (en) * | 2013-05-28 | 2014-12-03 | 海洋王（东莞）照明科技有限公司 | Overvoltage protection circuit |
-
2012
- 2012-07-20 CN CN 201220353948 patent/CN202737435U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102751698A (en) * | 2012-07-20 | 2012-10-24 | 冠捷显示科技（厦门）有限公司 | Overvoltage protection circuit, power module and overvoltage protection method |
| CN102751698B (en) * | 2012-07-20 | 2015-09-30 | 冠捷显示科技（厦门）有限公司 | Excess voltage protection, power module and over-voltage protection method |
| CN104184110A (en) * | 2013-05-28 | 2014-12-03 | 海洋王（东莞）照明科技有限公司 | Overvoltage protection circuit |
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| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130213 Termination date: 20180720 |