LED drive circuit and LED
Technical field
The utility model is related to electric lighting technical field, in particular to a kind of LED drive circuit and a kind of LED.
Background technology
At present, LED (Light Emitting Diode, light emitting diode) light source is as a kind of conventional alternative source of light,
Being used among the life of people increasingly, bulb lamp, ceiling lamp, Down lamp, Frame lamp etc., be widely used in household,
Corridor, building corridor, washing house etc., LED/light source is due to its high-luminous-efficiency, long service live, color true to nature, environmental protection etc.
Advantage, is gradually substituting application of traditional incandescent lamp in illumination.
However, the drive circuit of the LED in correlation technique, in the driving LED course of work, its own anti-interference
Ability so that LED is highly prone to the electromagnetic interference of interference source, influences LED normal work, there is presently no effective to this
Solution.
Utility model content
The utility model is intended at least solve one of technical problem present in prior art or correlation technique.
Therefore, a purpose of the present utility model is to propose a kind of new LED drive circuit, done with stronger resisting
Disturb the electromagnetic interference of ability, the more interference-free source of Shangdi protection LED, it is ensured that the LED driven can be normal
Work.
Another purpose of the present utility model is to propose a kind of LED.
To achieve the above object, according to the embodiment of first aspect of the present utility model, it is proposed that a kind of LED drivings electricity
Road, including:Power supply, for providing power supply for LED drive circuit;Drive module, is connected to LED light group module, for for
The LED light group module provides operating voltage and operating current;AF panel module, is connected to the power supply and is driven with described
Between dynamic model block, for being filtered to the electromagnetic interference in the LED drive circuit.The AF panel module includes:The
One electric capacity, the first end of first electric capacity is connected to the live wire of the power supply, the second end connection of first electric capacity
To the zero line of the power supply;First inductance, the first end of first inductance is connected to the first end of first resistor, described
Second end of the first inductance is connected to the second end of the first resistor;The first resistor, the first end of the first resistor
The first output end of the drive module is connected to, the second end of the first resistor is connected to the ground connection of the drive module
End.
According to the LED drive circuit of embodiment of the present utility model, by being set between power supply and drive module
AF panel module, to be filtered to the electromagnetic interference in LED drive circuit so that LED drive circuit has stronger resist
The electromagnetic interference in the interference-free source of interference performance, more Shangdi protection LED lamps, it is ensured that the LED driven can be just
Often work.
Whole AF panel modular structure is simple, and used electronic component is less, and the connection between each electronic component
Relation is also relatively simple so that while the antijamming capability of LED drive circuit is improved, will not increase considerably cost.Root
According to the LED drive circuit of above-described embodiment of the present utility model, there can also be following technical characteristic:
According to one embodiment of the present utility model, the drive module includes:Rectification module, the of the rectification circuit
One input is connected to the first end of first electric capacity, and the second input of the rectification module is connected to first electric capacity
The second end, the first input end of the rectification module as the drive module first input end, the rectification module
Second output end is connected to constant-current circuit;The constant-current circuit, the direct current for the rectification module to be exported is converted to institute
State the operating voltage and operating current needed for LED lamp group modules.
According to the LED drive circuit of embodiment of the present utility model, by rectification module to being filtered by AF panel module
Alternating current after ripple carries out rectification generation direct current, and direct current is converted by constant-current circuit, and direct current is changed
For the operating voltage and operating current needed for LED light group module, it is ensured that the stability of LED light group module work, wherein, rectification
Module includes rectifier circuit.
According to one embodiment of the present utility model, the constant-current circuit includes:Constant current chip, the electricity of the constant current chip
Source input is connected to the first end of second resistance, the earth terminal of the constant current chip as the drive module earth terminal;
The second resistance, the second end of the second resistance is connected to the first end of 3rd resistor;The 3rd resistor, the described 3rd
Second end of resistance is connected to the second output end of the rectification module;Second electric capacity, the first end connection of second electric capacity
To the power input of the constant current chip, the second end of second electric capacity is connected to the earth terminal of the constant current chip;The
Four resistance, the first end of the 4th resistance is connected to open-circuit-protection and the line voltage compensation end of the constant current chip, described
Second end of four resistance is connected to the first end of the 3rd resistor;5th resistance, the first end of the 5th resistance is connected to
The first end of 4th resistance, the second end of the 5th resistance is connected to the earth terminal of the constant current chip;6th resistance,
The first end of 6th resistance is connected to the current sample section of the constant current chip, and the second end of the 6th resistance is connected to
The earth terminal of the constant current chip;Diode, the anode of the diode is respectively connecting to the first output of the constant current chip
End and the second output end, the negative electrode of the diode be respectively connecting to the first end of the 3rd electric capacity, the first end of the 7th resistance and
The LED light group module;3rd electric capacity, the second end of the 3rd electric capacity is respectively connecting to the second of the 7th resistance
End, the first end of the second inductance and the LED light group module;Second inductance, the second end of second inductance is connected to
Second output end of the constant current chip.
According to the LED drive circuit of embodiment of the present utility model, constant current chip is preferably by the serial cores of MT781X
Small, drive is lost in piece, such as MT7812, MT7810, MT7811, MT7812 and MT7813S/D, the MT781X family chip long lifespans
Dynamic precision is high, it is ensured that the performance of whole LED drive circuit.
According to one embodiment of the present utility model, the constant-current circuit also includes:Current sampling circuit, the electric current is adopted
The first end of sample circuit is connected to the first control end of the constant current chip, and the second end of the current sampling circuit is connected to institute
The first output end of constant current chip is stated, the current sampling circuit is used to gather the current value for flowing through second inductance, described
First control end of constant current chip determines whether to control the high pressure in the constant current chip according to the current value of second inductance
Power tube is turned on.
According to the LED drive circuit of embodiment of the present utility model, specifically, the first control end of constant current chip is second
When the current value of inductance is less than predetermined threshold, it is determined that the high-voltage power pipe conducting in control constant current chip.
According to one embodiment of the present utility model, first current sampling circuit includes:4th electric capacity, the described 4th
One end of electric capacity is as the first end of the current sampling circuit, and the second end of the 4th electric capacity is used as current sample electricity
Second end on road.
According to one embodiment of the present utility model, the constant-current circuit also includes:Bleeder resistance, the bleeder resistance
First end is connected to the first end of second electric capacity, and the second end of the bleeder resistance is connected to the second of second electric capacity
End.
According to the LED drive circuit of embodiment of the present utility model, bleeder resistance is set to be used in whole LED drive circuit
During power down, the electricity stored in the second electric capacity is discharged by bleeder resistance, the security of whole LED drive circuit is improved.
According to one embodiment of the present utility model, in addition to:Overload protection module, is connected to the power supply and institute
State between AF panel module, overload protection module be used for the supply current of the power supply be more than first threshold and/or
When supply voltage is more than Second Threshold, the path of the power supply and the AF panel intermodule is cut off.
According to the LED drive circuit of embodiment of the present utility model, by setting overload protection module, power supply occurs
When excessively stream or overvoltage, the path of switching power supply and AF panel intermodule, protects whole LED drivings electricity in time
Road.
According to one embodiment of the present utility model, the overload protection module includes:Wire-wound resistor, the wire-wound resistor
First end be connected to the zero line of the power supply, the second end of the wire-wound resistor is connected to the AF panel mould
Block;Piezo-resistance, the first end of the piezo-resistance is connected to the second end of the wire-wound resistor, the second of the piezo-resistance
End is respectively connecting to the zero line side and the AF panel module of the power supply.
According to the embodiment of second aspect of the present utility model, it is proposed that a kind of LED, including:Appoint in above-described embodiment
LED drive circuit described in one.
Additional aspect and advantage of the present utility model will be set forth in part in the description, partly by from following description
In become obvious, or by it is of the present utility model practice recognize.
Brief description of the drawings
Of the present utility model above-mentioned and/or additional aspect and advantage will from description of the accompanying drawings below to embodiment is combined
Become substantially and be readily appreciated that, wherein:
Fig. 1 shows the structural schematic block diagram of the LED drive circuit according to embodiment of the present utility model;
Fig. 2 shows the structural representation of the LED drive circuit according to one embodiment of the present utility model;
Fig. 3 shows the structural representation of the LED drive circuit according to another embodiment of the present utility model;
Fig. 4 shows the current waveform figure of the second inductance in Fig. 2 and Fig. 3;
Fig. 5 shows the schematic block diagram of the LED according to embodiment of the present utility model.
Embodiment
In order to be more clearly understood that above-mentioned purpose of the present utility model, feature and advantage, below in conjunction with the accompanying drawings and tool
The utility model is further described in detail body embodiment.It should be noted that in the case where not conflicting, this Shen
The feature in embodiment and embodiment please can be mutually combined.
Many details are elaborated in the following description to fully understand the utility model, still, this practicality
New to be different from other modes described here to implement using other, therefore, protection domain of the present utility model is simultaneously
Do not limited by following public specific embodiment.
Fig. 1 shows the structural schematic block diagram of the LED drive circuit according to one embodiment of the present utility model.
As shown in figure 1, according to the LED drive circuit 100 of embodiment of the present utility model, including:Including:Power supply
102, for providing power supply for LED drive circuit 100;Drive module 104, is connected to LED light group module 108, for be described
LED light group module 108 provides operating voltage and operating current;AF panel module 106, be connected to the power supply 102 with
Between the drive module 104, for being filtered to the electromagnetic interference in the LED drive circuit 100.
By setting AF panel module between power supply and drive module, with to the electromagnetism in LED drive circuit
Interference is filtered so that LED drive circuit has stronger antijamming capability, and more Shangdi protects LED not by dry
Disturb the electromagnetic interference in source, it is ensured that the LED driven being capable of normal work.
Embodiment one:As shown in Fig. 2 specifically, the AF panel module 106 includes:First electric capacity 1062, described
The first end of one electric capacity 1062 is connected to the live wire of the power supply 102, and the second end of first electric capacity 1062 is connected to
The zero line of the power supply 102;First inductance 1064, the first end of first inductance 1064 is connected to first resistor 1066
First end, the second end of first inductance 1064 is connected to the second end of the first resistor 1066;The first resistor
1066, the first end of the first resistor 1066 is connected to the first output end of the drive module 104, the first resistor
1066 the second end is connected to the earth terminal of the drive module 104.Whole AF panel modular structure is simple, used electricity
Subcomponent is less, and the annexation between each electronic component is also relatively simple so that improving the anti-interference of LED drive circuit
While ability, cost will not be increased considerably.
The drive module 104 includes:Rectification module 1042, the first input end of the rectification circuit 1042 is connected to institute
The first end of the first electric capacity 1062 is stated, the second input of the rectification module 1042 is connected to the of first electric capacity 1062
Two ends, the first input end of the rectification module 1042 is used as the first input end of the drive module 104, the rectification module
1042 the second output end is connected to constant-current circuit 1044;The constant-current circuit 1044, for the rectification module 1044 is defeated
The direct current gone out is converted to the operating voltage and operating current needed for the LED light group module 108.
Rectification is carried out to the alternating current after AF panel module filtered by rectification module and generates direct current, and is passed through
Constant-current circuit is converted to direct current, and direct current is converted to operating voltage and operating current needed for LED light group module,
The stability of LED light group module work is ensure that, wherein, rectification module includes rectifier circuit.
According to one embodiment of the present utility model, the constant-current circuit 1044 includes:Constant current chip 1044A, the perseverance
Stream chip 1044A power input (" VCC " end of chip as shown in Figure 2) is connected to second resistance 1044B first end, institute
Constant current chip 1044A earth terminal (" GND " end of chip as shown in Figure 2) is stated as the earth terminal of the drive module 104;
The second resistance 1044B, the second resistance 1044B the second end are connected to 3rd resistor 1044C first end;It is described
3rd resistor 1044C, the second end of the 3rd resistor 1044C is connected to the second output end of the rectification module 1042;The
Two electric capacity 1044D, the second electric capacity 1044D first end is connected to the power input of the constant current chip 1044A, institute
The second end for stating the second electric capacity 1044D is connected to the earth terminal of the constant current chip 1044A;4th resistance 1044E, described
Four resistance 1044E first end be connected to the constant current chip 1044A open-circuit-protection and line voltage compensation end (as shown in Figure 2
" VOVP " end of chip), the second end of the 4th resistance 1044E is connected to the first end of the 3rd resistor 1044C;5th
Resistance 1044F, the 5th resistance 1044F first end are connected to the first end of the 4th resistance 1044E, the described 5th
Resistance 1044F the second end is connected to the earth terminal of the constant current chip 1044A;6th resistance 1044G, the 6th resistance
1044G first end is connected to the current sample section (" CS " end of chip as shown in Figure 2) of the constant current chip 1044A, described
6th resistance 1044G the second end is connected to the earth terminal of the constant current chip;Diode 1044H, the diode 1044H's
Anode is respectively connecting to the first output end (the 5th pin " DRAIN " end of chip as shown in Figure 2) of the constant current chip 1044A
With the second output end (the 6th pin " DRAIN " end of chip as shown in Figure 2), the negative electrode of the diode 1044H is respectively connecting to
3rd electric capacity 1044I first end, the 7th resistance 1044J first end and the LED light group module 108;3rd electric capacity
1044I, the second end of the 3rd electric capacity 1044I is respectively connecting to the second end of the 7th resistance 1044J, the second inductance
1044K first end and the LED light group module 108;The second inductance 1044K, the second of the second inductance 1044K
End is connected to the second output end of the constant current chip 1044A.
Constant current chip is preferably by MT781X family chips, such as MT7812, MT7810, MT7811, MT7812 and
Small, driving precision is lost high, it is ensured that the property of whole LED drive circuit in MT7813S/D, the MT781X family chip long lifespans
Energy.
LED drive circuit 100 also includes:Overload protection module 110, is connected to the power supply 102 and the interference
Between suppression module 106, overload protection module 110 be used for the power supply 102 supply current be more than first threshold and/
Or supply voltage is when being more than Second Threshold, the path between the power supply 102 and the AF panel module 106 is cut off.
By setting overload protection module, power supply occurs when excessively stream or overvoltage, switches power supply in time
With the path of AF panel intermodule, whole LED drive circuit is protected.
According to one embodiment of the present utility model, the overload protection module 110 includes:Wire-wound resistor 1102, it is described
The first end of wire-wound resistor 1102 is connected to the zero line of the power supply 102, and the second end of the wire-wound resistor 1102 connects
It is connected to the AF panel module 106;Piezo-resistance 1104, the first end of the piezo-resistance 1104 is connected to the line around electricity
Second end of resistance 1102, the second end of the piezo-resistance 1104 is respectively connecting to zero line side and the institute of the power supply 102
State AF panel module 106.
Embodiment two:As shown in figure 3, on the basis of Fig. 2, the constant-current circuit 1044 in LED drive circuit 100 is also wrapped
Include:Current sampling circuit, the first end of the current sampling circuit is connected to the first control end of the constant current chip, the electricity
Second end of stream sample circuit is connected to the first output end (" SW " of chip as shown in Figures 2 and 3 of the constant current chip
End), the current sampling circuit is used to gather the current value for flowing through the second inductance 1044K, the first of the constant current chip
Control end determines whether to control the high-voltage power in the constant current chip 1044 according to the current value of the second inductance 1044K
Pipe is turned on.
Specifically, the first control end of constant current chip is when the current value of the second inductance is less than predetermined threshold, it is determined that control
High-voltage power pipe conducting in constant current chip.
According to one embodiment of the present utility model, first current sampling circuit includes:4th electric capacity 1044L, institute
The 4th electric capacity 1044L one end is stated as the first end of the current sampling circuit, the second end of the 4th electric capacity 1044L is made
For the second end of the current sampling circuit.
According to one embodiment of the present utility model, the constant-current circuit 1044 also includes:Bleeder resistance 1044M, it is described
Bleeder resistance 1044M first end is connected to the first end of the second electric capacity 1044D, the second of the bleeder resistance 1044M
End is connected to the second end of the second electric capacity 1044D.Set bleeder resistance to be used in whole LED drive circuit power down, lead to
Cross bleeder resistance and discharge the electricity stored in the second electric capacity, improve the security of whole LED drive circuit.
In figs. 2 and 3, constant current chip 1044 is preferably by MT781X family chips, below using MT7812 chips as
Example, is described further to the technical solution of the utility model.
Wherein, chip MT7812 each pin is described as follows shown in table 1:
Pin title |
Number of pins |
Description |
GND |
1 |
Chip |
VOVP |
2 |
Open-circuit-protection sets pin and line voltage compensation |
VCC |
3 |
Chip power, internal pressure limiting 15.5V |
SW |
4 |
Internal high pressure power MOS pipe source electrode |
DRAIN |
5/6 |
Internal high pressure power MOS pipe drains |
NC |
7 |
The unsettled pin |
CS |
8 |
Current sample end, connects sampling resistor to ground |
Table 1
MT7812 is a high-precision LED perseverances for working in zero current passing, the critical conduction mode of peak point current shut-off
Flow control chip, is mainly used in non-isolated voltage-dropping type LED power system, and its critical conduction mode ensure that MT7812 can be controlled
Power switch processed inductive current be zero moment open, reduce the switching loss of power tube, it is ensured that system have 95% with
On peak efficiencies.The critical conduction mode that inductive current valley is zero combines the electricity of the peak value after inlet highway voltage compensation
Inducing current, it is ensured that the high accuracy of output LED current, and with good line regulation and load regulation.To inductance
Amount change is insensitive, can use I-shaped inductance.
High using the LED drive circuit constant current accuracy of MT7812 chips, peripheral component is few, and cost is low.In start-up course
When electric, the VCC ends of chip be connected to the startup resistance of inlet highway second resistance 1044B (R4 as shown in Figures 2 and 3) and
3rd resistor 1044C (R3 as shown in Figures 2 and 3) charges, and when VCC reaches 12V, control logic begins to work, internal
Switch starts switch motion, if VCC is increased to 15.5V, is clamped, if VCC is less than 5.5V, MT7812 will be closed
Close.
A), critical conduction mode control is set with output current:
MT7812 flows through peak point current (the inductance peak value electricity of internal switch pipe by monitoring CS terminal voltages, Cycle by Cycle detection
Stream), when CS terminal voltages reach 400mV threshold values, the shut-off of internal power pipe;When inductive current is reduced to zero, circuit will be opened again
Open power tube.The expression formula of inductance peak point current is:
Wherein, R in formula (1)CS(i.e. R8 shown in the 6th resistance 1044G, Fig. 2 and Fig. 3) is current sampling resistor,
Unit is also to include a CS comparators in ohm, MT7812 chips, when CS comparators also include 500nS lead-edge-blanking
Between with filter out CS ends conducting moment noise.
B), the calculation formula of LED output currents is:
Wherein in formula (2), ILPKFor inductance peak point current, output LED current is only by current sampling resistor RCSAnd inside
400mV reference voltages are determined, unrelated with inductance value.
C), the working frequency of LED drive circuit:
MT7812 works in critical current mode conduction mode, when inductive current is reduced to zero, and detection circuit will be led again
Logical internal switch pipe, the SW ends of high-voltage power pipe are pulled low, and power MOS pipe is also switched on, and inductive current is started from scratch rising, power
Pipe conducting time be:
Wherein, in formula (3), L is the sensibility reciprocal of inductance, ILPKIt is the current peak for flowing through inductance; VINIt is that input is received
Input direct voltage after the rectifier bridge rectification arrived, VLEDIt is the forward voltage drop in load LED lamp group.Voltage on CS pins
The 400mV peak values limitation of setting is reached, internal switch pipe be will be off, and SW terminal voltages rise, power MOS pipe is also turned off, electricity
Sense will be by fly-wheel diode to load LED electric discharges, and when inductive current drops to zero, chip will be again turned on internal switch
Pipe, wherein, the turn-off time of power tube is:
Therefore the working frequency of system is calculated as:
As shown in figure 4, flowing through the second inductance 1044K (i.e. inductance L shown in Fig. 2 and Fig. 32) current waveform figure, from
As can be seen that MT7812 system operating frequency and system input voltage V in formula (5)IN, load LED forward voltage drop VLED,
And the sensibility reciprocal L of inductance is related.System input voltage VINHigher, the working frequency of system is higher.In order to take into account AF panel mould
Block and efficiency, the operating frequency range of system are generally located between 30kHz-80kHz, so should be in the minimum input voltage of system
Under, suitable inductance value is selected, system frequency is met the requirement of design.MT7812 is provided with the maximum deadline of system
For TOFF_MAX=400uS, minimum deadline is TOFF_MIN=1.5uS.From formula (4), if inductance value is very big, TOFF
T may be exceededOFF_MAX, inductive current is not dropped to zero also and start next cycle charging, if continuous more than five times
There is TOFF_MAX, system will enter hiccup-rebooting status;, whereas if inductance value very little, TOFFT may be less thanOFF_MIN,
At the time of inductive current occur be zero, inductive current enters discontinuous mode, so actual load LED current is set less than target
Evaluation.
D), overcurrent protection:
When CS pin voltage more than 400mV, MT7812 will immediately turn off internal switch pipe, so that switch-off power metal-oxide-semiconductor, this
The mode of each cycle over-current detection protects the component of correlation from damaging, such as power MOS pipe, transformer etc..MT7812 is complete
Kind defencive function also includes LED short-circuit protections, current sampling resistor open-circuit-protection and current sampling resistor short-circuit protection, and
Overheat protector etc..Automatic monitoring state can be entered during chip operation, if there is LED short circuits or current sampling resistor short circuit,
Chip can immediately enter short-circuit protection state, shutdown switch signal, while discharging VCC, and system, which enters, has the hiccups-restart
State, system only consumes slight power, it is ensured that system safety.After short-circuit state is released, chip automatically restores to normal work
Make state.Internal thermal-shutdown circuit can monitor the PN junction temperature of chip, and when temperature exceedes overheat protector threshold value, chip enters
Guard mode, shutdown switch action, chip temperature declines after 30 DEG C, can just exit overheat protector state, be restored to just
Normal working condition.
By above-described embodiment, it can effectively eliminate the lotus root between interference source and disturbed equipment and close and radiate, and improve LED drives
Dynamic circuit antijamming capability in itself and performance, AF panel modular structure are simple, can effectively pass through GB17743, GB/T
The requirement of 18595 pairs of LEDs.
Fig. 5 shows the schematic block diagram of the LED according to embodiment of the present utility model.
As shown in figure 5, according to the LED 500 of embodiment of the present utility model, including:As shown in Figure 1, Figure 2 or shown in Fig. 3
LED drive circuit 100.
The technical solution of the utility model is described in detail above in association with accompanying drawing, the utility model proposes a kind of new
LED drive circuit, the electromagnetic interference with stronger antijamming capability, the more interference-free source of Shangdi protection LED,
It ensure that driven LED being capable of normal work.
Preferred embodiment of the present utility model is the foregoing is only, the utility model is not limited to, for this
For the technical staff in field, the utility model can have various modifications and variations.It is all it is of the present utility model spirit and principle
Within, any modification, equivalent substitution and improvements made etc. should be included within protection domain of the present utility model.