CN104780682A - Over-voltage protection circuit, driver chip and power module - Google Patents

Over-voltage protection circuit, driver chip and power module Download PDF

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Publication number
CN104780682A
CN104780682A CN201510177238.6A CN201510177238A CN104780682A CN 104780682 A CN104780682 A CN 104780682A CN 201510177238 A CN201510177238 A CN 201510177238A CN 104780682 A CN104780682 A CN 104780682A
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overvoltage
voltage
reference voltage
driving chip
unit
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CN104780682B (en
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宋利军
许煌樟
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Microelectronics Co Ltd Of Shenzhen City First Stable
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Microelectronics Co Ltd Of Shenzhen City First Stable
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40Control techniques providing energy savings, e.g. smart controller or presence detection

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Abstract

The invention discloses an over-voltage protection circuit, a driver chip and a power module, wherein the over-voltage protection circuit is connected with an overvoltage regulating resistor, the over-voltage protection circuit comprises a reference voltage generating unit, a slope generating unit and a voltage comparing unit, and the reference voltage generating unit, the slope generating unit and the voltage comparing unit are connected in sequence; the reference voltage generating unit is externally connected with the overvoltage regulating resistor, and is used for generating first reference voltage according to the overvoltage regulating resistor, and rising the voltage value of the first reference voltage according to sneak-out current; the slope generating unit is used for generating a slope signal, and the initial voltage of the slope signal equals to the first reference voltage; the rising of the first reference voltage enables the initial voltage to rise; the voltage comparing unit is used for comparing the slope signal with an internal second reference voltage; the rising of the initial voltage enables the time for rising the slope signal to be in the second reference voltage to be shortened. Therefore, the over-voltage protection time is shorted, and the phenomena of electric leakage and lighting off are avoided.

Description

A kind of overvoltage crowbar, driving chip and power module
Technical field
The present invention relates to output over-voltage protection technical field, in particular a kind of overvoltage crowbar, driving chip and power module.
Background technology
Along with LED drives the development in market, the type of the protection mechanism of LED drive scheme also gets more and more.Wherein, LED output over-voltage protection is exactly wherein a kind of.In order to meet different system requirements, namely different load LED lamp string numbers, chip dedicated pin outer meeting resistance can be set to adjustable mode, be carried out the overvoltage protection threshold of regulating system by this resistance.
Such as, Fig. 1 is the circuit diagram of the adjustable non-isolation type LED information display system of existing typical overvoltage protection threshold.Driving chip regulates LED overvoltage protection threshold by the connection on its ROVP pin to earth resistance R01.In Fig. 1, the dotted line (long dotted line) on the left side illustrates in the application of system complete machine, deposits the parasitic leakage paths of on-Line Voltage to ROVP pin, and it causes the electric current I 0 flowing through resistance R01 to be made up of chip current I1 and parasite current I2.
See also Fig. 2, it is the circuit diagram of the overvoltage crowbar in Fig. 1.Parasite current I2 in Fig. 1 can cause the chip current I1 flowing out driving chip to reduce; the electric current I 3 of charging for electric capacity C01 is caused to reduce; cause when PFM signal is low further, the OVP signal demand longer time is just turning is high, and namely the overvoltage protection time is longer.The longer overvoltage protection time means lower overvoltage protection threshold, therefore in normal LED application, the parasite current I2 of system can reduce overvoltage protection threshold, cannot normally open when causing LED number fixing.
Visible, the overvoltage crowbar of existing LED drive chip is adjustable overvoltage protection threshold has yet to be improved and developed.
Summary of the invention
The technical problem to be solved in the present invention is; for the above-mentioned defect of prior art; a kind of overvoltage crowbar, driving chip and power module are provided, are intended to solve the problem that in existing overvoltage crowbar, the LED that causes is gone out because parasitic leakage flows into overvoltage regulating circuit.
The technical scheme that technical solution problem of the present invention adopts is as follows:
A kind of overvoltage crowbar, be connected with overvoltage regulating resistance, it comprises reference voltage generation unit, slope generation unit and voltage comparison unit, and described reference voltage generation unit, slope generation unit, voltage comparison unit connect successively; The external overvoltage regulating resistance of described reference voltage generation unit, for producing the first reference voltage according to overvoltage regulating resistance, raises the magnitude of voltage of the first reference voltage according to parasite current; Described slope generation unit is for generation of ramp signal, and the starting voltage of described ramp signal equals the first reference voltage; Ramp signal and the second built-in reference voltage are compared acquisition overvoltage protection signal by described voltage comparison unit.
In described overvoltage crowbar, described reference voltage generation unit comprises the first current source and operational amplifier; The input in the same way of described operational amplifier connect the first current source one end, also by overvoltage regulating resistance ground connection, the output of operational amplifier connects its reverse input end and slope generation unit, the other end of described first current source connects power end.
In described overvoltage crowbar, described slope generation unit comprises the second current source, switching tube and electric capacity; The grid of described switching tube inputs the control signal of this overvoltage crowbar inside; the output of the source electrode concatenation operation amplifier of switching tube; the drain electrode of switching tube connects the positive pole of electric capacity, one end of the second current source and voltage comparison unit; the minus earth of described electric capacity, the other end of described second current source connects power end.
In described overvoltage crowbar, described switching tube is NMOS tube.
In described overvoltage crowbar, described voltage comparison unit comprises the 3rd current source, comparator and the second resistance; The reverse input end of described comparator connects the drain electrode of one end of the second current source, the positive pole of electric capacity and switching tube, and the input in the same way of comparator connects one end of the 3rd current source, also by the second grounding through resistance, the output of comparator connects drive circuit.
A kind of driving chip, be connected with overvoltage regulating resistance, comprise drive circuit and high-voltage power pipe, it also comprises described overvoltage crowbar, and described overvoltage crowbar, drive circuit, high-voltage power pipe connect successively; 1st end of described overvoltage crowbar is the VCC pin of driving chip, and the 2nd end of overvoltage crowbar connects drive circuit, and the 3rd end of overvoltage crowbar is the ROVP pin of driving chip, and the external overvoltage regulating resistance of described ROVP pin is to ground.
A kind of power module, comprise rectification unit, power supply unit, load unit and overvoltage regulating resistance, it also comprises described driving chip, described power supply unit connects rectification unit and load unit, the VCC pin of driving chip connects power supply unit, and the Drain pin of driving chip connects load unit, and the ROVP pin of driving chip is by overvoltage regulating resistance ground connection, the GND pin ground connection of driving chip, the CS pin of driving chip is by sampling resistor ground connection.
Compared to prior art, overvoltage crowbar provided by the invention, driving chip and power module, described overvoltage crowbar is connected with overvoltage regulating resistance, comprises the reference voltage generation unit, slope generation unit and the voltage comparison unit that connect successively; The external overvoltage regulating resistance of described reference voltage generation unit, for producing the first reference voltage according to overvoltage regulating resistance; The magnitude of voltage of the first reference voltage is raised according to parasite current; Described slope generation unit is for generation of ramp signal, and the starting voltage of described ramp signal equals the first reference voltage; Ramp signal and built-in second reference voltage are compared acquisition overvoltage protection signal by described voltage comparison unit; First reference voltage raises and starting voltage is raised; starting voltage raises and shortens the time that ramp signal rises to the second reference voltage; that is to say and shorten the overvoltage protection time, improve output loading overvoltage protection threshold, and then avoid the phenomenon of leaking electricity and turning off the light.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of the adjustable non-isolation type LED information display system of existing typical overvoltage protection threshold.
Fig. 2 is the circuit diagram of the overvoltage crowbar in Fig. 1.
Fig. 3 is the structured flowchart of overvoltage crowbar Application Example provided by the invention.
Fig. 4 is the circuit diagram of overvoltage crowbar provided by the invention.
Fig. 5 is the simulation waveform figure of overvoltage crowbar provided by the invention.
Fig. 6 is the circuit diagram of power module provided by the invention.
Embodiment
The invention provides a kind of overvoltage crowbar, driving chip and power module, can avoid LED information display system due to complete machine electric leakage the LED that causes to go out phenomenon.For making object of the present invention, technical scheme and advantage clearly, clearly, developing simultaneously referring to accompanying drawing, the present invention is described in more detail for embodiment.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
Please refer to Fig. 3 and Fig. 4; overvoltage crowbar 100 provided by the invention is connected with overvoltage regulating resistance Rext; it comprises reference voltage generation unit 110, slope generation unit 120 and voltage comparison unit 130, and described reference voltage generation unit 110, slope generation unit 120, voltage comparison unit 130 connect successively.Described reference voltage generation unit 110 external overvoltage regulating resistance Rext, for producing the first reference voltage VA1 with larger current ability according to overvoltage regulating resistance Rext; When having parasite current to flow through overvoltage regulating resistance Rext, the first reference voltage VA1 that output voltage values raises.Described slope generation unit 120 is for generation of ramp signal VC1, and the starting voltage of ramp signal VC1 equals the first reference voltage VA1; First reference voltage VA1 raises and starting voltage is raised.Ramp signal VC1 and the second built-in reference voltage Vref compare and obtain overvoltage protection signal OVP by described voltage comparison unit 130; Starting voltage raises and shortens the time that ramp signal VC1 rises to the second reference voltage Vref, that is to say and shortens the overvoltage protection time, improve output loading overvoltage protection threshold, and then avoids the phenomenon of leaking electricity and turning off the light.
In the present embodiment, described reference voltage generation unit 110 comprises the first current source Is1 and operational amplifier A 1; The input in the same way of described operational amplifier A 1 connect the first current source Is1 one end, also by overvoltage regulating resistance Rext ground connection, the output of operational amplifier A 1 connects its reverse input end and slope generation unit, and the other end of described first current source Is1 connects power end VCC.
The electric current of described first current source Is1, by overvoltage regulating resistance Rext, produces and detects voltage VREF1; Detect voltage VREF1 after described operational amplifier A 1 cushions, obtain identical but the first reference voltage VA1 that current driving ability is larger of magnitude of voltage.When parasite current I2 flows into overvoltage regulating resistance Rext, can cause detecting voltage VREF1 and uprise, thus the first reference voltage VA1 is uprised.
Described slope generation unit 120 comprises the second current source Is2, switching tube M1 and electric capacity C1; The grid of described switching tube M1 inputs the control signal PFM of this overvoltage crowbar inside; the output of the source electrode concatenation operation amplifier A1 of switching tube M1; the drain electrode of switching tube M1 connects the positive pole of electric capacity C1, one end of the second current source Is2 and voltage comparison unit 130; the minus earth of described electric capacity C1, the other end of described second current source Is2 connects power end VCC.
Wherein, described switching tube M1 is NMOS tube.When control signal PFM is high level, described switching tube M1 opens, and described electric capacity C1 starts electric discharge until the magnitude of voltage of ramp signal VC1 equals the output of the first reference voltage VA1(and reference voltage generation unit 110).When PFM signal is low level, described switching tube M1 turns off, and described second current source Is2 charges to electric capacity C1 immediately, magnitude of voltage linear rising from the voltage of the first reference voltage VA1 of ramp signal VC1.Material is thus formed with the ramp signal VC1 of the magnitude of voltage of the first reference voltage VA1 for starting point (that is to say each voltage minimum point in ramp signal VC1).
Described voltage comparison unit 130 comprises the 3rd current source Is3, comparator A2 and the second resistance R2; The reverse input end of described comparator A2 connects the drain electrode of one end of the second current source Is2, the positive pole of electric capacity C1 and switching tube M1, the input in the same way of comparator A2 connect the 3rd current source Is3 one end, also by the second resistance R2 ground connection, the output of comparator A2 connects drive circuit.
The electric current of described 3rd current source Is3 is by described second resistance R2, thus inner generation the second reference voltage Vref.Described ramp signal VC1 and the second reference voltage Vref compare by described comparator A2, obtain overvoltage protection signal OVP.
See also Fig. 5, from control signal PFM from high step-down, from electric capacity C1, be namely charged to overvoltage protection signal OVP that described comparator A2 exports the is LED information display system overvoltage protection time from high step-down, required time.Adopt above-mentioned overvoltage crowbar, when parasite current I2 flows into described overvoltage regulating resistance Rext, cause the first reference voltage VA1 to raise (for VA1_H).First reference voltage VA1 raises the starting voltage causing ramp signal VC1 to charge further and raises (for VC1_H); so that the time that ramp signal VC1 rises to the second reference voltage Vref reduces; finally cause the overvoltage protection time to diminish, as shown in Figure 5 become tOVP_H from tOVP.The overvoltage protection time that tOVP is the first reference voltage VA1 when being low, the overvoltage protection time that tOVP_H is the first reference voltage VA1 when being high, tOVP_H is less than tOVP.The starting voltage during charging of electric capacity C1 described in visible Fig. 4 is higher (that is to say that in Fig. 5, the first reference voltage VA1 is higher; the overvoltage protection time of LED information display system is shorter; the shorter overvoltage protection time means higher system protection voltage; higher system protection voltage means that output can bear larger load, namely can drive more LED number.
As can be seen here; adopt the overvoltage crowbar that the present embodiment provides; by utilizing operational amplifier A 1; the starting voltage that the first reference voltage VA1 that overvoltage regulating resistance Rext and the first current source Is1 produces charges as electric capacity C1; there is leakage path and namely there is parasite current I2 even if achieve to overvoltage regulating resistance Rext(); also the time that ramp signal VC1 rises to built-in second reference voltage Vref can be shortened; reduce the overvoltage protection time; improve output loading overvoltage protection threshold, and then avoid the phenomenon of leaking electricity and turning off the light.
Based on above-mentioned overvoltage crowbar, the embodiment of the present invention also provides a kind of driving chip 10, and please refer to Fig. 3, Fig. 4 and Fig. 6, described driving chip 10 comprises above-mentioned overvoltage crowbar 100, drive circuit 200 and high-voltage power pipe Q.Overvoltage crowbar 100, drive circuit 200, high-voltage power pipe Q connect successively.Wherein, the VCC pin that 1st end (the power end VCC namely in Fig. 4) of described overvoltage crowbar is driving chip 10; 2nd end of the overvoltage crowbar output of comparator A2 (namely in Fig. 4) connects drive circuit 200; the ROVP pin that 3rd end of the overvoltage crowbar input in the same way of operational amplifier A 1 (namely in Fig. 4) is driving chip 10, described ROVP pin external overvoltage regulating resistance Rext is to ground.
When there being parasite current I2 to flow into overvoltage regulating resistance Rext, described overvoltage crowbar reduces the overvoltage protection time, thus avoids the LED caused due to complete machine electric leakage in LED information display system and to go out phenomenon.
It is to be appreciated that drive circuit 200 and high-voltage power pipe Q are prior art, its internal structure, annexation and with the pin relation of driving chip 10 as shown in Figure 6, be not described further herein.
Based on above-mentioned driving chip 10, the embodiment of the present invention also provides a kind of power module, and described power module comprises driving chip 10, rectification unit 20, power supply unit 30, load unit 40, sampling resistor Rcs and overvoltage regulating resistance Rext.Described power supply unit 30 connects rectification unit 20 and load unit 40, the VCC pin of driving chip 10 connects power supply unit 30, the Drain pin of driving chip 10 connects load unit 40, the ROVP pin of driving chip 10 is by overvoltage regulating resistance Rext ground connection, the GND pin ground connection of driving chip 10, the CS pin of driving chip 10 is by sampling resistor Rcs ground connection.
Described alternating current AC powers to driving chip 10 by power supply unit 30 after rectification unit 20 rectification.Driving chip 10 drives load unit 40.
It is to be appreciated that above-mentioned rectification unit, power supply unit, load unit are prior art, its internal circuit structure and annexation are not described further herein.
In sum; overvoltage crowbar provided by the invention, driving chip and power module; described overvoltage crowbar is by utilizing operational amplifier; the first reference voltage that overvoltage regulating resistance and the first current source produce is as the starting voltage of capacitor charging; there is parasite current and also can shorten even if achieve the time that ramp signal rises to built-in second reference voltage; reduce the overvoltage protection time, improve output loading overvoltage protection threshold, and then avoid the phenomenon of leaking electricity and turning off the light.
Should be understood that, application of the present invention is not limited to above-mentioned citing, for those of ordinary skills, can be improved according to the above description or convert, and all these improve and convert the protection range that all should belong to claims of the present invention.

Claims (7)

1. an overvoltage crowbar, is connected with overvoltage regulating resistance, it is characterized in that, comprises reference voltage generation unit, slope generation unit and voltage comparison unit, and described reference voltage generation unit, slope generation unit, voltage comparison unit connect successively; The external overvoltage regulating resistance of described reference voltage generation unit, for producing the first reference voltage according to overvoltage regulating resistance, raises the magnitude of voltage of the first reference voltage according to parasite current; Described slope generation unit is for generation of ramp signal, and the starting voltage of described ramp signal equals the first reference voltage; Ramp signal and the second built-in reference voltage are compared acquisition overvoltage protection signal by described voltage comparison unit.
2. overvoltage crowbar according to claim 1, is characterized in that, described reference voltage generation unit comprises the first current source and operational amplifier; The input in the same way of described operational amplifier connect the first current source one end, also by overvoltage regulating resistance ground connection, the output of operational amplifier connects its reverse input end and slope generation unit, the other end of described first current source connects power end.
3. overvoltage crowbar according to claim 2, is characterized in that, described slope generation unit comprises the second current source, switching tube and electric capacity; The grid of described switching tube inputs the control signal of this overvoltage crowbar inside; the output of the source electrode concatenation operation amplifier of switching tube; the drain electrode of switching tube connects the positive pole of electric capacity, one end of the second current source and voltage comparison unit; the minus earth of described electric capacity, the other end of described second current source connects power end.
4. overvoltage crowbar according to claim 3, is characterized in that, described switching tube is NMOS tube.
5. overvoltage crowbar according to claim 3, is characterized in that, described voltage comparison unit comprises the 3rd current source, comparator and the second resistance; The reverse input end of described comparator connects the drain electrode of one end of the second current source, the positive pole of electric capacity and switching tube, and the input in the same way of comparator connects one end of the 3rd current source, also by the second grounding through resistance, the output of comparator connects drive circuit.
6. a driving chip, be connected with overvoltage regulating resistance, comprise drive circuit and high-voltage power pipe, it is characterized in that, also comprise as arbitrary in claim 1-5 as described in overvoltage crowbar, described overvoltage crowbar, drive circuit, high-voltage power pipe connect successively; 1st end of described overvoltage crowbar is the VCC pin of driving chip, and the 2nd end of overvoltage crowbar connects drive circuit, and the 3rd end of overvoltage crowbar is the ROVP pin of driving chip, and the external overvoltage regulating resistance of described ROVP pin is to ground.
7. a power module, comprise rectification unit, power supply unit, load unit, sampling resistor and overvoltage regulating resistance, it is characterized in that, also comprise driving chip as claimed in claim 6, described power supply unit connects rectification unit and load unit, the VCC pin of driving chip connects power supply unit, the Drain pin of driving chip connects load unit, the ROVP pin of driving chip is by overvoltage regulating resistance ground connection, the GND pin ground connection of driving chip, the CS pin of driving chip is by sampling resistor ground connection.
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Cited By (8)

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CN106793363A (en) * 2015-11-20 2017-05-31 华润矽威科技(上海)有限公司 LED drive circuit and its open-circuit-protection method
CN106793242A (en) * 2015-11-24 2017-05-31 英飞凌科技奥地利有限公司 Self adaptation open-circuited load overvoltage control method and circuit
CN108123418A (en) * 2016-11-29 2018-06-05 无锡华润矽科微电子有限公司 LED drives overvoltage crowbar
CN109152142A (en) * 2018-09-25 2019-01-04 杰华特微电子(杭州)有限公司 Switching Power Supply and LED drive circuit
US10283958B2 (en) 2016-11-08 2019-05-07 Teradyne, Inc. Protection circuit
CN109997303A (en) * 2017-11-03 2019-07-09 戴洛格半导体(英国)有限公司 Switch driver
CN111010155A (en) * 2019-12-31 2020-04-14 北京轩宇空间科技有限公司 Comparator and electronic device
CN111629159A (en) * 2019-02-27 2020-09-04 豪威科技股份有限公司 Ramp signal stabilization reduction circuit

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CN102045911A (en) * 2009-10-09 2011-05-04 财团法人工业技术研究院 Light source regulation circuit for alternating current light-emitting diode
CN103458579A (en) * 2013-08-29 2013-12-18 矽力杰半导体技术(杭州)有限公司 Load driving circuit and method

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US20060006811A1 (en) * 2004-07-12 2006-01-12 International Rectifier Corporation Fluorescent ballast controller IC
CN102045911A (en) * 2009-10-09 2011-05-04 财团法人工业技术研究院 Light source regulation circuit for alternating current light-emitting diode
CN103458579A (en) * 2013-08-29 2013-12-18 矽力杰半导体技术(杭州)有限公司 Load driving circuit and method

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106793363A (en) * 2015-11-20 2017-05-31 华润矽威科技(上海)有限公司 LED drive circuit and its open-circuit-protection method
CN106793363B (en) * 2015-11-20 2019-04-16 华润矽威科技(上海)有限公司 LED drive circuit and its open-circuit-protection method
CN106793242A (en) * 2015-11-24 2017-05-31 英飞凌科技奥地利有限公司 Self adaptation open-circuited load overvoltage control method and circuit
US10283958B2 (en) 2016-11-08 2019-05-07 Teradyne, Inc. Protection circuit
CN108123418A (en) * 2016-11-29 2018-06-05 无锡华润矽科微电子有限公司 LED drives overvoltage crowbar
CN108123418B (en) * 2016-11-29 2021-04-16 华润微集成电路(无锡)有限公司 LED drive overvoltage protection circuit
CN109997303A (en) * 2017-11-03 2019-07-09 戴洛格半导体(英国)有限公司 Switch driver
CN109997303B (en) * 2017-11-03 2021-02-12 戴洛格半导体(英国)有限公司 Switch driver
CN109152142A (en) * 2018-09-25 2019-01-04 杰华特微电子(杭州)有限公司 Switching Power Supply and LED drive circuit
CN111629159A (en) * 2019-02-27 2020-09-04 豪威科技股份有限公司 Ramp signal stabilization reduction circuit
CN111010155A (en) * 2019-12-31 2020-04-14 北京轩宇空间科技有限公司 Comparator and electronic device
CN111010155B (en) * 2019-12-31 2023-10-24 北京轩宇空间科技有限公司 Comparator and electronic device

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