CN110049594A - A kind of load overvoltage protection circuit and protection chip - Google Patents
A kind of load overvoltage protection circuit and protection chip Download PDFInfo
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- CN110049594A CN110049594A CN201910286732.4A CN201910286732A CN110049594A CN 110049594 A CN110049594 A CN 110049594A CN 201910286732 A CN201910286732 A CN 201910286732A CN 110049594 A CN110049594 A CN 110049594A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
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- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
Abstract
The present invention provides a kind of load overvoltage protection circuit and protection chips; it is set between load and the fore-stage driver unit of the load; it is characterized in that; the protection circuit includes: the first comparing unit, and the output voltage for comparing load exports the first comparison signal when being greater than first threshold voltage；Driving unit is connect with the output end of the first comparing unit；Switching device, for dragging down the output voltage of load based on the driving signal that driving unit persistently exports；Second comparing unit exports the second comparison signal to fore-stage driver unit, the fore-stage driver unit stops working when the electric current for comparing switching device is greater than the threshold current.It can detecte the high-tension cable exported when high voltage arc occurs in load based on load overvoltage protection circuit provided by the invention; and actively drag down output voltage; and fault-signal is exported to the fore-stage driver unit of load, it is exported by fore-stage driver unit according to the signal-off prime, to reduce risk.
Description
Technical field
The present invention relates to circuit fields, more particularly to a kind of load overvoltage protection circuit and protection chip.
Background technique
Currently, load driving output is mostly high voltage-small current, especially in field of light fittings, LED is mostly used without isolation
Built-in power provides convenience for High voltage output.But under the output condition of 200-400V, open a way in case of rosin joint, LED,
Higher voltage can strike sparks in the case where being unsatisfactory for creepage distance, and then cause LED on fire or make paper base pcb board
It is carbonized on fire.In practical application, for the generation for preventing above-mentioned phenomenon, special protection mechanism is needed.Currently, common LED drives
Dynamic IC provides output over-voltage protection, but the response time is longer, can not cope with the protection in the case where short time sparking, and
Output over-voltage protection error is larger, accurately can not be judged and be controlled.
Summary of the invention
The present invention provides a kind of load overvoltage protection circuits and protection chip to overcome the above problem or at least partly
Ground solves the above problems.
According to an aspect of the invention, there is provided a kind of load overvoltage protection circuit, the load include input terminal and
Output end, the input terminal of the load be connected as it is described load provide driving power fore-stage driver unit, the load it is defeated
Outlet connects the protection circuit, which is characterized in that the protection circuit includes:
First comparing unit, including first input end, the first output end, the output end of the first input end and load
Connection, is compared for obtaining the output voltage of the load, and with preset first threshold voltage, if the load
Output voltage is greater than the first threshold voltage, then exports the first comparison signal；
Driving unit is connect with the first output end of first comparing unit, for receiving first comparing unit
First comparison signal of output is based on the first comparison signal output drive signal；
Switching device, the driving signal for persistently being exported based on the driving unit enters magnifying state, and then drags down
The output voltage of the load；
Second comparing unit, including the second input terminal and second output terminal, the second input terminal of second comparing unit
It is connect with the switching device, the second output terminal is connect with the fore-stage driver unit, for obtaining the switching device
Electric current after be compared with threshold current, if the electric current of the switching device be greater than the threshold current, to the prime
Driving unit exports the second comparison signal, and the fore-stage driver unit stops working.
Optionally, the output end of the load is additionally provided with first resistor and second resistance；
First resistor and with the concatenated second resistance of the first resistor, one end of the first resistor and described negative
The output end of load connects, while the other end of the first resistor is connect with one end of the second resistance and described first
The first input end of comparing unit connects；
The other end of the second resistance is connect with the driving unit；
First comparing unit, for obtaining the electricity of the output after the partial pressure of the first resistor and second resistance
Pressure is compared with the first threshold voltage, defeated if the output voltage after the partial pressure is greater than the first threshold voltage
First comparison signal out.
Optionally, the switching device is triode；
The base stage of the switching device is connect with the output end of the driving unit, the collector of the switching device with
The output end of the load connects, and the emitter of the switching device is connect with the second input terminal of second comparing unit.
Optionally, the protection circuit further includes 3rd resistor and the 4th resistance in parallel；
One end of the 3rd resistor and the 4th resistor coupled in parallel connects the emitter of the switching device, the other end simultaneously
The output end of the load is connected simultaneously.
Optionally, the protection circuit further includes third comparing unit and SCR structure unit；
The third comparing unit, for detecting the voltage of the 3rd resistor and the 4th resistance, when the 3rd resistor
When being greater than preset second threshold voltage with the voltage of the 4th resistance, Xiang Suoshu driving unit exports third comparison signal, by institute
It states driving unit and closes the switching device, and then make electric current by the SCR structure unit, drive the silicon-controlled knot
Structure cell operation；
Wherein, the third comparing unit includes third input terminal and third output end, and the of the third comparing unit
Three input terminals are connect with one end of the 3rd resistor and the 4th resistor coupled in parallel, the third output end and the driving unit
Connection.
Optionally, the SCR structure unit includes: the first triode and the second triode；
The emitter of first triode connects the output end of the load, first transistor collector and institute
It states the base stage of the second triode while connecting the third output end of the third comparing unit, first transistor base connects
Connect the collector of second triode；
The emitter of second triode connects the second input terminal of second comparing unit.
Optionally, the protection circuit further include:
First lead-edge-blanking unit is set between the third comparing unit and the switching device, for filtering out
State the interference signal in third input unit in input voltage.
Optionally, the protection circuit further include:
Signal output unit, the signal output unit include the 4th input terminal, the 5th input terminal and the 4th output end,
4th input terminal is connect with the second output terminal of second comparing unit；4th output end and the prime are driven
Moving cell connection.
Optionally, the protection circuit further include:
Temperature protection unit is connect with the 5th input terminal of the signal output unit, is become for detecting ambient temperature
Change, when the temperature that the temperature protection unit detects is greater than assigned temperature threshold value, by the signal output unit to institute
State fore-stage driver unit output signal.
Optionally, the protection circuit further include:
Second lead-edge-blanking unit is set between the output end of the load and first comparing unit, for filtering
Except the interference signal in the output voltage of the load.
According to another aspect of the present invention, a kind of protection chip is additionally provided, is packaged with described in any of the above embodiments negative
Carry overvoltage crowbar.
The present invention provides a kind of load overvoltage protection circuit, it can detecte what exporting when high voltage arc occurred in load
High-voltage signal, and output voltage is actively dragged down, while exporting fault-signal to the fore-stage driver unit of load, it is driven by prime
Unit is exported according to the signal-off prime, to reduce risk, protects the reliability of product-laden.
The above description is only an overview of the technical scheme of the present invention, in order to better understand the technical means of the present invention,
And it can be implemented in accordance with the contents of the specification, and in order to allow above and other objects of the present invention, feature and advantage can
It is clearer and more comprehensible, the followings are specific embodiments of the present invention.
According to the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will be more
The above and other objects, advantages and features of the present invention is illustrated.
Detailed description of the invention
By reading the following detailed description of the preferred embodiment, various other advantages and benefits are general for this field
Logical technical staff will become clear.The drawings are only for the purpose of illustrating a preferred embodiment, and is not considered as to this hair
Bright limitation.And throughout the drawings, the same reference numbers will be used to refer to the same parts.In the accompanying drawings:
Fig. 1 is load light source protection electrical block diagram according to an embodiment of the present invention；
Fig. 2 is load light source protection electrical block diagram according to the preferred embodiment of the invention；
Voltage change V-T curve when Fig. 3 is load light source protection circuit work according to the preferred embodiment of the invention shows
It is intended to；
Curent change I-T curve when Fig. 4 is load light source protection circuit work according to the preferred embodiment of the invention shows
It is intended to；
Fig. 5 is protection chip structure schematic diagram according to an embodiment of the present invention.
Specific embodiment
The exemplary embodiment that the present invention will be described in more detail below with reference to accompanying drawings.Although showing this hair in attached drawing
Bright exemplary embodiment, it being understood, however, that may be realized in various forms the implementation of the invention without that should be illustrated here
Example is limited.On the contrary, providing these embodiments is to be able to thoroughly understand the present invention, and can will be of the invention
Range is fully disclosed to those skilled in the art.
The embodiment of the invention provides a kind of load overvoltage protection circuit, it is set to load and provides driving to the load
Between the fore-stage driver unit 1 of power supply, as shown in Figure 1, load 2 includes input terminal X21 and output end Y22,2 input is loaded
End X21 is connected as load 2 and provides the fore-stage driver unit 1 of driving power, loads 1 output end Y22 connection protection circuit.This
The load overvoltage protection circuit that inventive embodiments provide may include: sequentially connected first comparing unit 10, driving unit 20
And second comparing unit 30.
Wherein, the first comparing unit 10, including first input end X11, the first output end Y12, first input end X11 with
The output end Y22 connection of load 2 for obtaining the output voltage of load 2, and is compared with preset first threshold voltage,
If the output voltage of load 2 is greater than first threshold voltage, the first comparison signal is exported；Driving unit 20, it is single compared with first
First output end Y12 connection of member 10, for receiving the first comparison signal of the first comparing unit 10 output, based on the first ratio
It may include driving circuit compared with signal output drive signal；Switching device SW, the drive persistently exported based on driving unit 20
Enter magnifying state after dynamic signal, and then drags down the output voltage of load 2.Second comparing unit 30 includes the second input terminal
X31 and second output terminal Y32, the second input terminal X31 of the second comparing unit 30 are connect with driving unit 20, second output terminal
Y32 is connect with fore-stage driver unit 1, is compared after the electric current for obtaining switch triode SW with threshold current, if switch
The electric current of triode SW is greater than threshold current, then exports the second comparison signal to fore-stage driver unit 1, and fore-stage driver unit 1 is stopped
It only works, and then stops providing driving power to load 2.
The embodiment of the invention provides a kind of load overvoltage protection circuit, when can detecte load 2 and high voltage arc occur
The high-voltage signal of output, and output voltage is actively dragged down, and export fault-signal to the fore-stage driver unit 1 of load 2, by preceding
Grade driving unit 1 is exported according to the signal-off prime, to reduce risk, protects the reliability of product-laden.Especially when
When plurality of LEDs is used in series, in the event of under LED open circuit situation, since LED internal structure spacing is smaller, pin envelope
Dress distance is smaller, causes creepage distance smaller and unbearable high voltage, and then the phenomenon that climbing the sparking of electric gap occurs.It is based on
Protection circuit provided in an embodiment of the present invention, which can be quickly detected, carrys out self-supported high-voltage signal, and is efficiently treated through.Separately
Outside, during triggering abnormal protection, driving unit 20 will be slow unlatching and opens protection circuit provided in an embodiment of the present invention
Device SW is closed, linear amplification region is subjected to, the energy in being electrolysed can be gone out with slow release, moment is avoided to drag down output voltage,
It causes big surge current and damages circuit.When load is LED, the fore-stage driver unit in the embodiment of the present invention be can be
The devices such as LED constant-current driver or other can to load provide driving power device.
Wherein, switching device SW is preferably triode；The base stage of switching device SW and the output end of driving unit 20 connect
It connects, the collector of switching device SW is connect with the output end Y22 of load 2, the emitter of switching device SW and the second comparing unit
30 the second input terminal X31 connection, switching device SW can be set in load overvoltage protection circuit based on variable current source,
Or be configured by other means, the present invention is without limitation.
Fig. 2 shows load overvoltage protection circuits according to the preferred embodiment of the invention, referring to fig. 2 it is found that shown in Fig. 2
Load be LED, the output end Y22 of load be also provided with first resistor R1 and with first resistor R1 concatenated second
One end of resistance R2, first resistor R1 and the output end Y22 connection of load, the other end and second resistance R2 of first resistor R1
One end connection while connect with the first input end X11 of the first comparing unit 10；The other end of second resistance R2 and driving
Unit 20 connects；First comparing unit 10 can also obtain the output after the partial pressure of first resistor R1 and second resistance R2
Voltage is compared with first threshold voltage, if the output voltage after partial pressure is greater than first threshold voltage, the first ratio of output
Compared with signal.The input voltage Vo of voltage value and first resistor R1, second resistance R2 and load 2 for first threshold voltage
It is related, it is assumed that first threshold voltage V30(if Vo*R2)/(R1+R2) > V30, then the first comparing unit 10 has signal output.
In practical application, when the output voltage of load increases, the branch pressure voltage of first resistor R1 and second resistance R2
It can increase, method provided in an embodiment of the present invention can be compared using non-essential resistance with first threshold voltage, and load power source is worked as
When output voltage is more than this threshold value, so that it may export corresponding comparison signal by the first comparing unit 10.
With continued reference to Fig. 2 it is found that load overvoltage protection circuit provided in an embodiment of the present invention can also include in parallel the
Three resistance R3 and the 4th resistance R4；The hair of one end of 3rd resistor R3 and the 4th resistance R4 parallel connection while connection switch device SW
Emitter-base bandgap grading, the other end connect the output end Y22 of load simultaneously.
In addition, load overvoltage protection circuit can also include: third comparing unit 40 and SCR structure unit 50；The
Three comparing units 40, for detecting the voltage of 3rd resistor R3 and the 4th resistance R4, when 3rd resistor R3's and the 4th resistance R4
When voltage is greater than preset second threshold voltage, third comparison signal is exported to driving unit 20, is opened by the closing of driving unit 20
Device SW is closed, and then makes electric current by SCR structure unit 50, driving SCR structure unit 50 works；Wherein, third ratio
It include third input terminal X41 and third output end Y42, the third input terminal X41 and third of third comparing unit 40 compared with unit 40
The connection of one end of resistance R3 and the 4th resistance R4 parallel connection, the third output end Y42 and driving unit 20 of third comparing unit 40
Connection.When route is in malfunction, overvoltage crowbar provided in an embodiment of the present invention can not only be divided by periphery
Resistance is detected, and detection judgement can also be carried out by the electric current of switching device, and export a fault-signal, the signal
It can be transferred to the fore-stage driver unit 1 of load, fore-stage driver unit 1 is made to stop working, and then load is made to stop working.
Second threshold voltage can be set based on the resistance value of 3rd resistor R3 and the 4th resistance R4, it is assumed that second threshold
Voltage is V40, the electric current for flowing through switching device SW is Isw, if Isw*R3*R4/ (R3+R4) > V40, then third comparing unit 40
There is signal output.
For the second comparing unit 30, can also resistance value first based on 3rd resistor R3 and the 4th resistance R4 into
Row setting reference voltage V30, threshold current I30=V30* (R3+R4)/(R3*R4), as Isw*R3*R4/ (R3+R4) > V30When,
Then the second comparing unit 30 has signal output.
Optionally, referring to fig. 2 it is found that SCR structure unit 50 may include: the first triode Q1 and the second triode
Q2；The collector and the second triode of the output end Y22, the first triode Q1 of the emitter connection load of first triode Q1
The base stage that the base stage of Q2 connects third the output end Y42, the first triode Q1 of third comparing unit 40 simultaneously connects the two or three pole
The collector of pipe Q2；The emitter of second triode Q2 connects the second input terminal X31 of the second comparing unit 30.The present invention is real
Example is applied by setting SCR structure unit 50, carrying out self-supported over-voltage signal only need to once trigger, without lasting driving
So that load overvoltage protection circuit enters protective program.
Load overvoltage protection circuit provided in an embodiment of the present invention can also include: the first lead-edge-blanking unit 60, setting
Interference letter between third comparing unit 40 and switching device SW, in the input voltage for filtering out third comparing unit 40
Number.In addition, can be with setting signal output unit 70 at the second output terminal Y32 of the second comparing unit 30, signal output is single
Member 70 includes the 4th input terminal X71, the 5th input terminal X72 and the 4th output end Y73, and the 4th input terminal X71 is compared with second
The second output terminal Y32 connection of unit 30；4th output end 73 of signal output unit 70 is connect with fore-stage driver unit 1.
5th input terminal X72 of signal output unit 70 can connect temperature protection unit 80, and temperature protection unit 80 is used
It is defeated by signal when the temperature that temperature protection unit 80 detects is greater than assigned temperature threshold value in detection ambient temperature variation
Unit 70 is to 1 output signal of fore-stage driver unit out.
In circuit based on the embodiment of the present invention, if higher by 30 electric current of the second comparing unit, temperature rises
Also can be larger, letter can be passed through when its neighbouring temperature anomaly by detecting its ambient temperature by setting temperature protection unit 80
Number output unit 70 equally plays the function of abnormal signal output to 1 output signal of fore-stage driver unit.
It optionally, as shown in Figure 2, can also include the second forward position in load overvoltage protection circuit provided in this embodiment
Blanker unit 90 is set between the output end Y22 of load and the first comparing unit 10, for filtering out the output voltage of load
In interference signal.
After above-mentioned introduction, load overvoltage protection circuit shown in Fig. 2 can also include the power supply mould inside circuit
Block, the work for entire circuit provide power supply, and the linear stable connecting with power supply module can also be arranged.
Referring to fig. 2 it is found that being provided with LED1~LENn in figure, n concatenated LED use LED constant current as load
Driving is used as LED1~LENnFore-stage driver unit 1, the course of work is as follows:
1, when LED light string is opened a way, Vo voltage can be increased, and the output voltage of LED is V1, due to LED2Open circuit, is climbed
Electrical distance is smaller, will cause spark phenomenon, and the peak voltage V3 for occurring in schematic diagram 3 at t0, this voltage V3 is caused to break through
When the protection voltage V2 that one resistance R1 and second resistance R2 are set, triggering LED overvoltage crowbar work enters protection mechanism.
2、VoRaising causes the branch pressure voltage of the junction first resistor R1 and second resistance R2 also to increase, i.e. A point voltage,
It is filtered out by the second lead-edge-blanking unit 90 and is compared after a part is interfered in the first comparing unit 10, when A point voltage is higher than
When benchmark (i.e. the first threshold voltage) of the first comparing unit 10, driving unit 20 is just output signals to, on driving signal is slow
It rises, makes switching device SW pipe in magnifying state, the electric current flowed it through slowly becomes larger, and current direction is LED output → LED1
The port → B → the port SW → C/E → LEDn → GND.T1- in curent change process reference view 4 in I-T curve at this time
T2, V-T is similarly t1-t2 in voltage change schematic diagram 3.
T1 moment, overvoltage crowbar work, driving switch device SW enter amplification region, decline output voltage slowly,
Slow release exports the energy inside filter point solution, and the amplification region duration is t1-t2.T2 moment, overvoltage crowbar will be defeated
Voltage clamping prevents spark phenomenon to a lower level out.
3, by the 3rd resistor R3 being set at the E of port, the second comparing unit 30 is configured, is switched when flowing through
The electric current of device SW, that is, when flowing through R3, R4 electric current and reaching certain value, the second comparing unit 30 and its benchmark (threshold current) into
Row compares, and can export a high level signal by the port D, show currently to be likely to be at malfunction, can be believed by this
Number control whether fore-stage driver unit 1 needs to close.The threshold current can be configured based on 3rd resistor R3.
Because circuit thus can flow through high current, if higher because flowing through electric current, temperature rise is larger or peripheral temperature
When higher, the function of abnormal signal output can equally be played from the end D output signal by temperature protection unit 80.
4, third comparing unit 40 also can detecte the voltage of 3rd resistor R3 and the 4th resistance R4, silicon-controlled to control
Structural unit 50 is connected, because after SCR structure unit 50 is connected, without lasting driving, even if current circuit power supply is very low
It stops working, can be maintained as long as flowing through the electric current of SCR structure unit 50, SCR structure unit 50 can persistently be led
It is logical, until external circuit is cut off.
SCR structure unit 50 is connected, and available lower conduction voltage drop further decreases loss, can refer to signal
In the t3-t4 stage in V-T curve in Fig. 3, overvoltage crowbar can further decrease loss without additional power supply at this time.Work as third
When comparing unit 40 has signal output, synchronous signal can also be output to the driving of SW, close SW, and electric current is made to pass through silicon-controlled knot
Structure unit 50.
5, RESET reset unit can also be arranged in circuit shown in Fig. 2, when the peripheral circuit of load overvoltage protection circuit falls
When electricity re-powers, it can reset and restart, and then re-start monitoring abnormal state.
Based on the same inventive concept, the embodiment of the invention also provides a kind of protection chip, it is packaged with any of the above-described implementation
Load overvoltage protection circuit described in example.Fig. 5 shows the structural schematic diagram of protection chip according to an embodiment of the present invention, ginseng
Fig. 5 is seen it is found that the protection chip may include 7 pins, is pin C (1), pin D (2), pin NC (3), pin A respectively
(4), pin E (7), pin F (6), pin B (5).Wherein, pin C expression GND: chip reference；Pin D indicates EN: enabled
Signal controls pin；Pin NC indicates empty (nonfunctional definition)；Pin A indicates FB: voltage sense pin；Pin E is indicated
CS: current sample pin；Pin F indicates VCC: chip energization pins；Pin B indicates that HV: high input voltage pin, Fig. 5 are
The structure chart of protection chip is schematically shown, can be adjusted according to different needs in practical application, the present invention is not done
It limits.
Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention., rather than its limitations；
Although present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that:
Within the spirit and principles in the present invention, it is still possible to modify the technical solutions described in the foregoing embodiments, or
Equivalent substitution of some or all of the technical features；And these are modified or replaceed, and do not make corresponding technical solution
It is detached from protection scope of the present invention.
Claims (11)
1. a kind of load overvoltage protection circuit, the load includes input terminal and output end, and the input terminal of the load is connected as
The load provides the fore-stage driver unit of driving power, and the output end of the load connects the protection circuit, and feature exists
In the protection circuit includes:
The output end of first comparing unit, including first input end, the first output end, the first input end and load connects,
It is compared for obtaining the output voltage of the load, and with preset first threshold voltage, if the output electricity of the load
Pressure is greater than the first threshold voltage, then exports the first comparison signal；
Driving unit is connect with the first output end of first comparing unit, for receiving the first comparing unit output
The first comparison signal, be based on the first comparison signal output drive signal；
Switching device, the driving signal for persistently being exported based on the driving unit enter magnifying state, and then drag down described
The output voltage of load；
Second comparing unit, including the second input terminal and second output terminal, the second input terminal of second comparing unit and institute
Switching device connection is stated, the second output terminal is connect with the fore-stage driver unit, for obtaining the electricity of the switching device
It is compared after stream with threshold current, if the electric current of the switching device is greater than the threshold current, is driven to the prime
Unit exports the second comparison signal, and the fore-stage driver unit stops working.
2. protection circuit according to claim 1, which is characterized in that the output end of the load is additionally provided with first resistor
And second resistance；
First resistor and with the concatenated second resistance of the first resistor, one end of the first resistor is defeated with the load
Outlet connection, while the other end of the first resistor is connect with one end of the second resistance and first comparing unit
First input end connection；
The other end of the second resistance is connect with the driving unit；
First comparing unit, for obtaining output voltage and institute after the partial pressure of the first resistor and second resistance
It states first threshold voltage to be compared, if the output voltage after the partial pressure is greater than the first threshold voltage, exports first
Comparison signal.
3. protection circuit according to claim 1, which is characterized in that the switching device is triode；
The base stage of the switching device is connect with the output end of the driving unit, and the collector of the switching device is born with described
The output end of load connects, and the emitter of the switching device is connect with the second input terminal of second comparing unit.
4. protection circuit according to claim 1, which is characterized in that the protection circuit further includes 3rd resistor in parallel
With the 4th resistance；
One end of the 3rd resistor and the 4th resistor coupled in parallel connects the emitter of the switching device simultaneously, and the other end connects simultaneously
Connect the output end of the load.
5. protection circuit according to claim 3, which is characterized in that the protection circuit further include third comparing unit and
SCR structure unit；
The third comparing unit, for detecting the voltage of the 3rd resistor and the 4th resistance, when the 3rd resistor and
When the voltage of four resistance is greater than preset second threshold voltage, Xiang Suoshu driving unit exports third comparison signal, by the drive
Moving cell closes the switching device, and then makes electric current by the SCR structure unit, drives the SCR structure list
Member work；
Wherein, the third comparing unit includes third input terminal and third output end, and the third of the third comparing unit is defeated
Enter end to connect with one end of the 3rd resistor and the 4th resistor coupled in parallel, the third output end is connect with the driving unit.
6. protection circuit according to claim 5, which is characterized in that the SCR structure unit includes: the one or three pole
Pipe and the second triode；
The emitter of first triode connects the output end of the load, first transistor collector and described second
The base stage of triode connects the third output end of the third comparing unit simultaneously, the first transistor base connection described the
The collector of two triodes；
The emitter of second triode connects the second input terminal of second comparing unit.
7. protection circuit according to claim 5, which is characterized in that the protection circuit further include:
First lead-edge-blanking unit is set between the third comparing unit and the switching device, for filtering out described
Interference signal in the input voltage of three comparing units.
8. protection circuit according to claim 1, which is characterized in that the protection circuit further include:
Signal output unit, the signal output unit include the 4th input terminal, the 5th input terminal and the 4th output end, and described the
Four input terminals are connect with the second output terminal of second comparing unit；
4th output end is connect with the fore-stage driver unit.
9. protection circuit according to claim 8, which is characterized in that the protection circuit further include:
Temperature protection unit is connect with the 5th input terminal of the signal output unit, for detecting ambient temperature variation, works as institute
When stating temperature that temperature protection unit detects and being greater than assigned temperature threshold value, driven by the signal output unit to the prime
Moving cell output signal.
10. -9 described in any item protection circuits according to claim 1, which is characterized in that further include:
Second lead-edge-blanking unit is set between the output end of the load and first comparing unit, for filtering out
State the interference signal in the output voltage of load.
11. a kind of protection chip is packaged with the described in any item load overvoltage protection circuits of claim 1-10.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910286732.4A CN110049594A (en) | 2019-04-10 | 2019-04-10 | A kind of load overvoltage protection circuit and protection chip |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910286732.4A CN110049594A (en) | 2019-04-10 | 2019-04-10 | A kind of load overvoltage protection circuit and protection chip |
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| CN110049594A true CN110049594A (en) | 2019-07-23 |
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| CN201910286732.4A Pending CN110049594A (en) | 2019-04-10 | 2019-04-10 | A kind of load overvoltage protection circuit and protection chip |
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Cited By (1)
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