CN209402765U - LED headlamp control circuit with failure protection function - Google Patents
LED headlamp control circuit with failure protection function Download PDFInfo
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- CN209402765U CN209402765U CN201821533902.1U CN201821533902U CN209402765U CN 209402765 U CN209402765 U CN 209402765U CN 201821533902 U CN201821533902 U CN 201821533902U CN 209402765 U CN209402765 U CN 209402765U
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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]
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Abstract
A kind of LED headlamp control circuit with failure protection function.LED headlamp includes the LED multi-path lamp string being connected in parallel to each other; the anode of LED multi-path lamp string is connected by the first current-limiting resistance with input voltage; wherein, LED headlamp control circuit include reference voltage circuit, overvoltage crowbar and respectively with the one-to-one multiple constant current circuit of LED multi-path lamp string.The input terminal of reference voltage circuit connects input voltage, and output end is connect with the input terminal of multiple constant current circuit respectively.Overvoltage crowbar includes that input voltage detection circuit and reference voltage adjust circuit；Input voltage detection circuit, which is used to adjust circuit to reference voltage when detecting that input voltage is more than scheduled voltage threshold, sends regulated voltage signal；Reference voltage adjusts circuit and connect with reference voltage circuit, to reduce the reference voltage of reference voltage circuit output when receiving the regulated voltage signal.The utility model can accurately control LED headlamp, have failure protection function, and safety in utilization is good.
Description
Technical field
The utility model relates to the LED headlamp control circuits with failure protection function.
Background technique
Currently, just in rapid growth, outfit is had been introduced in numerous automobile vendors for use of the LED light source on automotive lighting
The vehicle of full LED headlamp.But the characteristic of LED light source proposes increasingly higher demands, including multichannel perseverance to drive control device
Flow control, overcurrent/short-circuit protection, overvoltage protection, overheat protector etc..In addition, light is also very heavy to the driving safety of automobile
It wants, such as headlight, daytime running lamps, turn signal, brake lamp, it is indispensable to the driving safety of automobile, this requires
Headlight for vehicles will guarantee its availability as far as possible.In addition, as LED light source starts to be widely used in common low price vehicle, automobile
Manufacturer also payes attention to the cost of LED light source further.However, in the prior art, inexpensive headlight for vehicles can not have comprehensively
Defencive function has the then with high costs of comprehensive defencive function, existing furthermore when such as excess temperature, over-voltage, short circuit occurs
There is control circuit that headlight can be automatically closed, leads to the reduction of safety.
Summary of the invention
The technical problem to be solved by the utility model is to provide one kind to be accurately controlled to LED headlamp,
With the good LED headlamp control circuit of failure protection function, safety in utilization.
According to a kind of LED headlamp control circuit with failure protection function of an embodiment of the present invention, LED is big
Light lamp includes the LED multi-path lamp string being connected in parallel to each other, and the anode of LED multi-path lamp string passes through the first current-limiting resistance and input voltage phase
Even, wherein LED headlamp control circuit include reference voltage circuit, overvoltage crowbar and respectively with LED multi-path lamp string one
One corresponding multiple constant current circuit；The input terminal of reference voltage circuit is for connecting input voltage, the output of reference voltage circuit
End is connect with the input terminal of multiple constant current circuit respectively, for providing reference voltage to multiple constant current circuit；Per Constant Electric Current all the way
Road includes first switch tube, sampling resistor, feedback resistance and operational amplifier；First conduction terminal of first switch tube with it is corresponding
LED light string cathode be connected, the second conduction terminal of first switch tube is connected with one end of sampling resistor, sampling resistor it is another
End ground connection；The non-inverting input terminal of operational amplifier and the output end of reference voltage circuit connect, the anti-phase input of operational amplifier
End is connect with one end of feedback resistance, and the other end of feedback resistance is connected to the second conduction terminal and sampling resistor of first switch tube
One end total contact, the output end of operational amplifier is connected with the control terminal of first switch tube；Overvoltage crowbar includes defeated
Enter voltage detecting circuit and reference voltage adjusts circuit；The input terminal of input voltage detection circuit is for connecting input voltage, electricity
The input terminal for pressing the output end of detection circuit to adjust circuit with reference voltage is connect, and input voltage detection circuit is for detecting
Circuit, which is adjusted, to reference voltage when input voltage is more than scheduled voltage threshold sends regulated voltage signal；Reference voltage adjusts electricity
Road is connect with reference voltage circuit, and reference voltage adjusts circuit and is used to reduce reference voltage electricity when receiving regulated voltage signal
The reference voltage of road output.
Optionally, LED headlamp control circuit includes thermal-shutdown circuit, and thermal-shutdown circuit includes the first field-effect
Pipe, the second field-effect tube, third field-effect tube, the 4th field-effect tube, the 5th field-effect tube, NPN triode, the first phase inverter and
Second phase inverter；The grid of first field-effect tube, the second field-effect tube and third field-effect tube is all connected to bias voltage
The drain electrode of Vbias, first field-effect tube are connect with the drain electrode of the second field-effect tube and the drain electrode of third field-effect tube respectively,
The total contact of the drain electrode of first field-effect tube, the drain electrode of the second field-effect tube and the drain electrode of third field-effect tube is limited by third
Leakage resistance connects input voltage；The drain electrode of 4th field-effect tube is connect with the source electrode of the second field-effect tube, the 4th field-effect tube
Source electrode is connected with the source electrode of the first field-effect tube, and the grid of the 4th field-effect tube is connect with the output end of the first phase inverter；5th
The grid of field-effect tube is connected to the total contact and NPN of the source electrode of the first field-effect tube and the source electrode of the 4th field-effect tube
The collector of triode, the drain electrode of the 5th field-effect tube be connected to third field-effect tube source electrode and the first phase inverter it is defeated
Enter end, the source electrode ground connection of the 5th field-effect tube；The base stage of NPN triode is connect with a reference voltage Vref, the hair of NPN triode
Emitter grounding；The input terminal of second phase inverter is connect with the output end of the first phase inverter, the output end and voltage of the second phase inverter
The output end of detection circuit connects.
The utility model is at least up to one of beneficial effect below:
1, the LED headlamp control circuit of the utility model embodiment has multiple constant current circuit, can multiple groups LED in parallel
Lamp string, every group of LED light string can choose different power or color, realize that high-power or Multifunctional LED shines；Furthermore when certain
When open circuit occurs for one group of LED light string, will not influence remaining LED light string, still ensure that it is basic shine, ensure that row
Vehicle safety；
2, every group of LED light string has independent constant-current circuit, can be independently controlled for every paths of LEDs lamp string, mutually not
Interference, improves versatility, stability and the accuracy of control；Furthermore when constant-current circuit breaks down all the way, Bu Huiying
The control to another way LED light string is rung, the stability of light is ensure that, improves traffic safety；
3, the LED headlamp control circuit of the utility model embodiment is joined when over-voltage excess temperature situation occurs by reducing
The mode for examining voltage output value reduces electric current and indirect breaking circuit, so that circuit can be protected not cross crushing because of excess temperature
It is bad, but accident will not be led to because light is closed；
4, the circuit temperature of crossing of the LED headlamp control circuit of the utility model embodiment has hysteresis defencive function, makes
The circuit is obtained after excess temperature generation, need to be cooled to lower temperature could restore normally, therefore avoids the circuit in excess temperature and facing
Concussion near boundary's temperature, improves circuit stability.
Detailed description of the invention
It, below will be to required in embodiment description in order to illustrate more clearly of the technical scheme in the embodiment of the utility model
Attached drawing to be used is briefly introduced, it should be apparent that, the accompanying drawings in the following description is only some implementations of the utility model
Example, for those of ordinary skill in the art, without any creative labor, can also be attached according to these
Figure obtains other attached drawings.
Fig. 1 shows the LED headlamp control circuit with failure protection function according to an embodiment of the present invention
Circuit diagram.
Fig. 2 shows control electricity according to the LED headlamp with failure protection function of another embodiment of the utility model
The circuit diagram on road.
Specific embodiment
Further explanation is made to the utility model with reference to the accompanying drawing.
Fig. 1 shows the LED headlamp control circuit with failure protection function according to an embodiment of the present invention
Circuit diagram.Please refer to Fig. 1.LED headlamp includes the LED multi-path lamp string being connected in parallel to each other, the anode of the LED multi-path lamp string
It is connected by the first current-limiting resistance RIN with input voltage vin.In example in figure, two paths of LED lamp string 11,12 is shown, often
Paths of LEDs lamp string is connected in series by 3 LED, but not limited to this, the quantity of LED light string can be increased or decreased according to actual needs
To provide the lamp group of bigger luminous power or more, also in adjustable every paths of LEDs lamp string LED quantity.
According to the LED headlamp control circuit with failure protection function of an embodiment of the present invention, including reference
Potential circuit 3, overvoltage crowbar and respectively with the one-to-one multiple constant current circuit of the LED multi-path lamp string.Fig. 1's
In example, LED headlamp control circuit have respectively with two paths of LED lamp string 11,12 one-to-one two-way constant-current circuits 21,
22。
The input terminal of reference voltage circuit 3 for connecting input voltage vin, the output end of reference voltage circuit 3 respectively with
The input terminal of multiple constant current circuit connects, for providing reference voltage V1 to multiple constant current circuit.In the present embodiment, with reference to electricity
Volt circuit 3 includes the first divider resistance R41, the second divider resistance R42 and the third divider resistance R43 being sequentially connected in series.First point
One end of piezoresistance R41 is for connecting input voltage vin, the total contact structure of the second divider resistance R42 and third divider resistance R43
At the output end of reference voltage circuit 3.One end of third divider resistance R43 is connect with the second divider resistance R42, third partial pressure electricity
Hinder the other end ground connection of R43.
In the present embodiment, input voltage vin is output to reference voltage after anti-reverse and filter circuit 6 processing
Circuit 3.Anti-reverse and filter circuit 6 includes counnter attack diode D9 and three filter capacitor C91, C92 and C93 in parallel.
It include first switch tube, sampling resistor, feedback resistance and operational amplifier per constant-current circuit all the way.With first via perseverance
For current circuit 21, the first conduction terminal of first switch tube Q1 is connected with the cathode of corresponding LED light string 11, first switch tube
The second conduction terminal of Q1 is connected with one end of sampling resistor R11, the other end ground connection of sampling resistor R11.Operational amplifier U1's
Power end is connected to input voltage vin by resistance R3, to obtain the operating current of operational amplifier.Operational amplifier U1's
Non-inverting input terminal is connect with the output end of reference voltage circuit 3, and the inverting input terminal of operational amplifier U1 is with feedback resistance R13's
One end connection, the other end of feedback resistance R13 are connected to the second conduction terminal of first switch tube Q1 and one end of sampling resistor R11
Total contact.Further, capacitor C11 is parallel to the series arm of feedback resistance R13 and sampling resistor R11 composition, to defeated
The voltage signal entered to the reverse side of operational amplifier U1 is filtered.The circuit structure and the first via of No. second constant-current circuit 22
The circuit structure of constant-current circuit 21 is identical, and details are not described herein.
First switch tube Q1, Q2 can be can be used as using NMOS tube or pliotron when it works in linear zone
The one adjustable resistance of dynamic is to control output.When the electric current flowed through in LED light string becomes smaller, on sampling resistor R11, R21
Voltage become smaller, the input of the inverting input terminal of operational amplifier U1, U2 becomes smaller, then operational amplifier U1, U2 makes first switch
The dynamic electric resistor of pipe Q1, Q2 become smaller, so as to increase the voltage and current in LED light string.Conversely, being flowed through when in LED light string
Electric current it is bigger than normal when, the voltage on sampling resistor R11, R21 is bigger than normal, and the inverting input terminal input of operational amplifier U1, U2 become larger,
Then operational amplifier U1, U2 increases the dynamic electric resistor of first switch tube Q1, Q2, so as to reduce the electricity in LED light string
Pressure and electric current.Therefore, by above-mentioned constant-current circuit, the constant current hold passed through in LED light string can be made, and may be implemented pair
The overcurrent and short-circuit protection of LED light string.The size of reference voltage V1 determines the size of current of corresponding LED light string, first via LED
The size of current flowed through in lamp string 11 is Iled1=V1/R11, the size of current flowed through in first via LED light string 12 be Iled2=
V1/R21, if there is more LED light strings, then and so on.The resistance value size for adjusting sampling resistor can control required perseverance
Flow size.
Overvoltage crowbar includes that input voltage detection circuit 41 and reference voltage adjust circuit 42.Input voltage measurement electricity
The input terminal on road 41 adjusts circuit 42 for connecting input voltage vin, the output end and reference voltage of voltage detecting circuit 41
Input terminal connection, input voltage detection circuit 41 is for detecting that input voltage vin is more than scheduled voltage threshold Shi Xiangcan
It examines voltage regulator circuit 42 and sends regulated voltage signal.Reference voltage adjusts the output end of circuit 42 and reference voltage circuit 3 connects
It connects, reference voltage adjusts circuit 42 for reducing the reference electricity that reference voltage circuit 3 exports when receiving regulated voltage signal
Press V1.
In the present embodiment, it includes the second current-limiting resistance R51 and second switch Q5 that reference voltage, which adjusts circuit 42,.Second
One end of current-limiting resistance R51 is connected to the total contact of the second divider resistance R42 and third divider resistance R43, the second current-limiting resistance
The other end of R42 is connected with the drain electrode of second switch Q5, the source electrode ground connection of second switch Q5, the grid of second switch Q5
It is connect with the output end of input voltage detection circuit 31.Input voltage detection circuit 41 includes the 4th divider resistance being sequentially connected in series
R61, the 5th divider resistance R62 and diode D6.One end of 4th divider resistance R61 is for connecting input voltage vin, and the 4th point
The output end of the total contact of piezoresistance R61 and the 5th divider resistance R62 composition voltage detecting circuit 41；Diode D6 anode with
5th divider resistance R62 connection, the cathode ground connection of diode D6.Diode D6 can play temperature-compensating to second switch Q5
Effect.
When input voltage vin is in normal range (NR), the partial pressure on the 5th divider resistance R62 is insufficient to allow second switch Q5
Conducting, when over-voltage (i.e. input voltage vin is more than scheduled voltage threshold) occurs for input voltage vin, the 5th divider resistance R62
On voltage will increase so that second switch Q5 is connected, then, the second current-limiting resistance R51 and third divider resistance R43
Parallel connection is formed, to reduce the output voltage V1 of reference voltage output circuit 3, thereby reduces operational amplifier U1, U2
The voltage and the electric current in LED light string of non-inverting input terminal, have the function that protection.
In the present embodiment, second switch Q5 is NMOS tube；Grid, drain electrode and the source electrode of NMOS tube respectively constitute second
The control terminal of switching tube, the first conduction terminal and the second conduction terminal.Similarly, when first switch tube Q1, Q2 is NMOS tube,
Grid, drain electrode and the source electrode of NMOS tube respectively constitute the control terminal of first switch tube, the first conduction terminal and the second conduction terminal.
It optionally, further include thermal-shutdown circuit 5 according to the LED headlamp control circuit of an embodiment of the present invention,
Thermal-shutdown circuit 5 includes the first field-effect tube Q71, the second field-effect tube Q72, third field-effect tube Q73, the 4th field-effect tube
Q74, the 5th field-effect tube Q75, NPN triode Q76, the first phase inverter U71 and the second phase inverter U72.
The grid of first field-effect tube Q71, the second field-effect tube Q72 and third field-effect tube Q73 are all connected to biased electrical
Press Vbias, the drain electrode leakage with the drain electrode of the second field-effect tube Q72 and third field-effect tube Q73 respectively of the first field-effect tube Q71
Pole connection, the drain electrode of the first field-effect tube Q71, the drain electrode of the second field-effect tube Q72 and the drain electrode of third field-effect tube Q73
Contact passes through third current-limiting resistance R7 connection input voltage vin altogether；The drain electrode and the second field-effect tube of 4th field-effect tube Q74
The source electrode of Q72 connects, and the source electrode of the 4th field-effect tube Q74 is connected with the source electrode of the first field-effect tube Q71, the 4th field-effect tube
The grid of Q74 is connect with the output end of the first phase inverter U71；The grid of 5th field-effect tube Q75 is connected to first effect
Should pipe Q71 source electrode and the 4th field-effect tube Q74 source electrode total contact and NPN triode Q76 collector, the 5th effect
Should the drain electrode of pipe Q75 be connected to the source electrode of third field-effect tube Q73 and the input terminal of the first phase inverter U71, the 5th effect
Should pipe Q75 source electrode ground connection.
The base stage of NPN triode Q76 is connect with a reference voltage Vref, the emitter ground connection of NPN triode Q76.Second
The input terminal of phase inverter U72 is connect with the output end of the first phase inverter U71, the output end and voltage detecting of the second phase inverter U71
The output end of circuit 41 connects.
Bias voltage Vbias can mention for the first field-effect tube Q71, the second field-effect tube Q72 and third field-effect tube Q73
For constant bias voltage, to generate constant bias current.It is defeated that bandgap voltage reference preferably can be used in reference voltage Vref
The output voltage of circuit out, the voltage value is not with the voltage of power supply and temperature change.
In the present embodiment, the first field-effect tube Q71, the second field-effect tube Q72, third field-effect tube Q73, the 4th effect
Should pipe Q74 and the 5th field-effect tube Q75 be NMOS tube.Optionally, thermal-shutdown circuit further includes filter capacitor C7, filtered electrical
The one end for holding C7 is connected to drain electrode and the input terminal of the first phase inverter U71 of the 5th field-effect tube Q75, filter capacitor C7's
The other end is connect with the source electrode of the 5th field-effect tube Q75.
Under room temperature, since reference voltage Vref is less than the conducting voltage of NPN triode Q76, so NPN triode Q76 is cut
Only, flow through the first field-effect tube Q71 and the second field-effect tube Q72 electric current be zero, A point current potential be high level.At this time the 5th
Field-effect tube Q75 conducting, leading to the current potential of B point is low level, is exported after the first phase inverter U71, the second phase inverter U72 low
Level, therefore second switch Q5 is disconnected, circuit is in normal operating conditions.C point voltage is high level, the 4th field-effect at this time
Pipe Q74 conducting.Reference voltage Vref can guarantee to flow through the first field-effect tube Q71 and second in sizable temperature range
The circuit of effect pipe Q72 is zero, reduces circuit power consumption.Since the Vbe of NPN triode Q76 has negative temperature coefficient, so
The conducting voltage of NPN triode Q76 is constantly reduced with the raising of temperature.As the temperature rises, when Vref is greater than tri- pole NPN
When the conducting voltage of pipe Q76, NPN triode Q76 conducting.When temperature continues to rise, the collector current of NPN triode Q76 will
It is gradually increased.When temperature is increased to Thermal shutdown threshold point Th, the collector current of NPN triode Q76 increases to first effect
Should pipe Q71 and the second field-effect tube Q72 electric current and.If temperature continues to rise, the current potential of A point will sharply decline, so that the
Five field-effect tube Q75 shutdown, makes B point reach high potential, high level is exported by two phase inverters, to trigger second switch
Overheat protector is realized in the conducting of Q5.At this point, C point current potential is low level, NPN triode is flowed through in the 4th field-effect tube Q74 cut-off
The electric current of Q76 only has the electric current on the first field-effect tube Q71.At this point, only when temperature drops to sluggish point TL more lower than TH
When, it so that the electric current for flowing through NPN triode Q76 is equal to the electric current on the first field-effect tube Q71, the temperature for realizing circuit is slow
Stagnant characteristic.
As the scheme for reducing cost, Fig. 2 shows have error protection function according to another embodiment of the utility model
The circuit diagram of the LED headlamp control circuit of energy.The main distinction of another embodiment and previous embodiment is to provide
A kind of generation circuit of simple and practical bias voltage Vbias and reference voltage Vref.In another embodiment, LED is big
Light lamp control circuit includes the 6th divider resistance R81 being sequentially connected in series, the 7th divider resistance R82, the 8th divider resistance R83,
Nine divider resistance R84, the tenth divider resistance R85 and the 11st divider resistance R86.The partial pressure electricity of 6th divider resistance R81 and the 7th
Resistance R82 is respectively provided with opposite temperature-coefficient of electrical resistance, and the 8th divider resistance R83 is respectively provided with opposite with the 9th divider resistance R84
Temperature-coefficient of electrical resistance, the tenth divider resistance R85 is respectively provided with opposite temperature-coefficient of electrical resistance with the 11st divider resistance R86,
Due to opposite the sum of the resistance of two temperatures coefficient vary with temperature it is suppressed, by inhibit resistance variation with temperature, therefore
It can inhibit bias voltage and reference voltage variation with temperature.By taking R81 and R82 as an example, R81=R0* (1+ α * Δ T), R82=
R0* (1+ β * Δ T), wherein R0 is the resistance value of resistance R81, R82 under temperature T0, and α, β are respectively the resistance temperature of resistance R81, R82
Coefficient, Δ T be deviate temperature T0 size, if the temperature-coefficient of electrical resistance of R81, R82 on the contrary, i.e. alpha+beta be at or about 0,
The sum of the resistance value of R81 and R82 variation with temperature is suppressed.
One end of 6th divider resistance R81 is for connecting input voltage vin, the partial pressure electricity of the 7th divider resistance R82 and the 8th
The voltage for hindering the total contact of R83 constitutes bias voltage Vbias, the total contact of the 9th divider resistance R84 and the tenth divider resistance R85
Voltage constitute reference voltage Vref, one end of the 11st divider resistance R86 connect with the tenth divider resistance R85, the 11st point
The other end of piezoresistance R86 is grounded.
Obviously, it is practical without departing from this can to carry out various modification and variations to the utility model by those skilled in the art
Novel spirit and scope.If in this way, these modifications and variations of the present invention belong to the utility model claims and
Within the scope of its equivalent technologies, then the utility model is also intended to include these modifications and variations.
Claims (9)
1. a kind of LED headlamp control circuit with failure protection function, the LED headlamp includes the multichannel being connected in parallel to each other
The anode of LED light string, the LED multi-path lamp string is connected by the first current-limiting resistance with input voltage, which is characterized in that described
LED headlamp control circuit includes reference voltage circuit, overvoltage crowbar and right one by one with the LED multi-path lamp string respectively
The multiple constant current circuit answered；
The input terminal of the reference voltage circuit is for connecting the input voltage, the output end difference of the reference voltage circuit
It is connect with the input terminal of the multiple constant current circuit, for providing reference voltage to the multiple constant current circuit；
It include first switch tube, sampling resistor, feedback resistance and operational amplifier per the constant-current circuit described all the way；Described first opens
The first conduction terminal and the cathode of corresponding LED light string for closing pipe are connected, the second conduction terminal of the first switch tube with it is described
One end of sampling resistor is connected, the other end ground connection of sampling resistor；The non-inverting input terminal of the operational amplifier and the reference
The output end of potential circuit connects, and the inverting input terminal of the operational amplifier and one end of feedback resistance connect, feedback resistance
The other end be connected to the total contact of the second conduction terminal of first switch tube and one end of sampling resistor, the output of operational amplifier
End is connected with the control terminal of first switch tube；
The overvoltage crowbar includes that input voltage detection circuit and reference voltage adjust circuit；The input voltage measurement electricity
The input terminal on road is adjusted for connecting the input voltage, the output end of the input voltage detection circuit and the reference voltage
The input terminal of circuit connects, and the input voltage detection circuit is used for when detecting that input voltage is more than scheduled voltage threshold
Circuit, which is adjusted, to the reference voltage sends regulated voltage signal；The reference voltage adjusts circuit and the reference voltage circuit
Connection, it is defeated for reducing the reference voltage circuit when receiving the regulated voltage signal that the reference voltage adjusts circuit
The reference voltage out.
2. as described in claim 1 with the LED headlamp control circuit of failure protection function, which is characterized in that the ginseng
Examining potential circuit includes the first divider resistance, the second divider resistance and third divider resistance being sequentially connected in series；First partial pressure
One end of resistance is for connecting input voltage, the total contact composition reference of second divider resistance and third divider resistance
The output end of potential circuit；One end of the third divider resistance is connect with the second divider resistance, the third divider resistance
Other end ground connection.
3. as claimed in claim 2 with the LED headlamp control circuit of failure protection function, which is characterized in that the ginseng
Examining voltage regulator circuit includes the second current-limiting resistance and second switch；One end of second current-limiting resistance is connected to described
The of the total contact of two divider resistances and third divider resistance, the other end of second current-limiting resistance and the second switch
One conduction terminal is connected, the second conduction terminal ground connection of the second switch, the control terminal of second switch and the input voltage
The output end of detection circuit connects.
4. the LED headlamp control circuit as claimed in claim 1 or 3 with failure protection function, which is characterized in that described
Input voltage detection circuit includes the 4th divider resistance, the 5th divider resistance and the diode being sequentially connected in series；4th partial pressure
One end of resistance is for connecting input voltage, the total contact composition voltage of the 4th divider resistance and the 5th divider resistance
The output end of detection circuit；The anode of the diode is connect with the 5th divider resistance, the cathode ground connection of the diode.
5. as claimed in claim 3 with the LED headlamp control circuit of failure protection function, which is characterized in that described the
One switching tube is NPN triode or NMOS tube, and the second switch is NMOS tube；The first switch tube is NPN triode
When, the base stage of the NPN triode, collector, emitter respectively constitute the control terminal of first switch tube, the first conduction terminal and
Two conduction terminals；When the first switch tube and/or second switch are NMOS tube, grid, drain electrode and the source electrode of the NMOS tube
Respectively constitute the control terminal, the first conduction terminal and the second conduction terminal of switching tube.
6. as described in claim 1 with the LED headlamp control circuit of failure protection function, which is characterized in that the LED
Headlamp control circuit includes thermal-shutdown circuit, the thermal-shutdown circuit include the first field-effect tube, the second field-effect tube,
Third field-effect tube, the 4th field-effect tube, the 5th field-effect tube, NPN triode, the first phase inverter and the second phase inverter；
The grid of first field-effect tube, the second field-effect tube and third field-effect tube is all connected to bias voltage Vbias, institute
The drain electrode for stating the first field-effect tube is connect with the drain electrode of the second field-effect tube and the drain electrode of third field-effect tube respectively, first effect
Should the total contact of the drain electrode of pipe, the drain electrode of the second field-effect tube and the drain electrode of third field-effect tube connected by third current-limiting resistance
Connect the input voltage；The drain electrode of 4th field-effect tube is connect with the source electrode of the second field-effect tube, the 4th field-effect tube
Source electrode be connected with the source electrode of first field-effect tube, the output end of the grid of the 4th field-effect tube and the first phase inverter connects
It connects；The grid of 5th field-effect tube is connected to the total contact of the source electrode of the first field-effect tube and the source electrode of the 4th field-effect tube
And the collector of the NPN triode, the drain electrode of the 5th field-effect tube are connected to the source electrode and of third field-effect tube
The input terminal of one phase inverter, the source electrode ground connection of the 5th field-effect tube；
The base stage of the NPN triode is connect with a reference voltage Vref, the emitter ground connection of the NPN triode；
The input terminal of second phase inverter is connect with the output end of first phase inverter, the output end of second phase inverter
It is connect with the output end of the voltage detecting circuit.
7. as claimed in claim 6 with the LED headlamp control circuit of failure protection function, which is characterized in that described
First field-effect tube, the second field-effect tube, third field-effect tube, the 4th field-effect tube and the 5th field-effect tube are NMOS tube；
The thermal-shutdown circuit includes filter capacitor, and one end of the filter capacitor is connected to the leakage of the 5th field-effect tube
The input terminal of pole and the first phase inverter, the other end of the filter capacitor are connect with the source electrode of the 5th field-effect tube.
8. as claimed in claim 6 with the LED headlamp control circuit of failure protection function, which is characterized in that the LED
Headlamp control circuit includes the 6th divider resistance being sequentially connected in series, the 7th divider resistance, the 8th divider resistance, the 9th partial pressure electricity
Resistance, the tenth divider resistance and the 11st divider resistance；
For connecting input voltage, the 7th divider resistance and the 8th divider resistance are total to for one end of 6th divider resistance
The voltage of the total contact of the voltage composition bias voltage Vbias of contact, the 9th divider resistance and the tenth divider resistance
The reference voltage Vref is constituted, one end of the 11st divider resistance is connect with the tenth divider resistance, and the described tenth
The other end of one divider resistance is grounded.
9. as claimed in claim 8 with the LED headlamp control circuit of failure protection function, which is characterized in that the 6th point
Piezoresistance is respectively provided with opposite temperature-coefficient of electrical resistance with the 7th divider resistance, and the 8th divider resistance and the 9th divider resistance are distinguished
With opposite temperature-coefficient of electrical resistance, the tenth divider resistance is respectively provided with opposite resistance temperature system with the 11st divider resistance
Number.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113823229A (en) * | 2021-09-03 | 2021-12-21 | 惠州视维新技术有限公司 | Driving circuit, fault detection method thereof, backlight module and display device |
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2018
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113823229A (en) * | 2021-09-03 | 2021-12-21 | 惠州视维新技术有限公司 | Driving circuit, fault detection method thereof, backlight module and display device |
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