CN104427719B - Led drive circuit - Google Patents
Led drive circuit Download PDFInfo
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- CN104427719B CN104427719B CN201410409540.5A CN201410409540A CN104427719B CN 104427719 B CN104427719 B CN 104427719B CN 201410409540 A CN201410409540 A CN 201410409540A CN 104427719 B CN104427719 B CN 104427719B
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- 239000003990 capacitor Substances 0.000 claims abstract description 33
- 238000001514 detection method Methods 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims description 20
- 230000008929 regeneration Effects 0.000 claims description 7
- 238000011069 regeneration method Methods 0.000 claims description 7
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 239000004065 semiconductor Substances 0.000 abstract description 17
- 238000007599 discharging Methods 0.000 abstract 1
- 238000004804 winding Methods 0.000 description 7
- 230000005611 electricity Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000001172 regenerating effect Effects 0.000 description 3
- 101100462365 Aspergillus niger (strain CBS 513.88 / FGSC A1513) otaA gene Proteins 0.000 description 2
- 229910002601 GaN Inorganic materials 0.000 description 2
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 2
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000000994 depressogenic effect Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
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Abstract
The invention provides an LED drive circuit which is a high-frequency buck chopper circuit using a wide bandgap semiconductor as a switch element. In the buck chopper circuit, the constant current characteristic can be maintained even input voltage fluctuates. The LED drive circuit (10a) realizes constant-current lightening of LEDs through direct current output. The direct current output is generated by charging and discharging of en electric reactor (L) based on the ON/OFF of a normally-open first switch element (Q1). The LED drive circuit (10a) comprises an average value detection circuit (a transconductance amplifier OTA and a capacitor Ccomp connected with an output terminal of the transconductance amplifier OTA) used for detecting the average value of electric reactor current flowing through the electric reactor (L) and determines the time of OFF of the first switch element (Q1) according to the average value of the electric reactor current detected by the average value detection circuit.
Description
Technical field
The present invention relates to the LED drive circuit of LED is lighted with constant current using the switch element of normal open type.
Background technology
In recent years it has been proposed that following technology：By GaAs (GaAs) used in semiconductor substrate, GaN (gallium nitride),
Low-loss wide bandgap semiconductor element of SiC (carborundum) etc. is used as the switch element of switching power circuit (referring for example to special
Sharp document 1).By using wide bandgap semiconductor element as switch element, can carry in the case where power-efficient is not reduced
Senior engineer's working frequency, can realize the miniaturization of device.
Wide bandgap semiconductor element is usually normal open type, with the Vgs as voltage between gate/source be 0V when connect,
Vgs disconnects this characteristic when being the nagative potential less than threshold value Vth (negative voltage), Patent Document 1 discloses in reactor stream
That what is crossed increases the chopper circuit of the auto-excitation type that switch element (wide bandgap semiconductor element) is disconnected when electric current has reached the value of regulation.
【Patent documentation 1】Japanese Unexamined Patent Publication 2011-199024 publications
But, in the prior art, as shown in figure 5, peak I p of reactor current is controlled to it is constant, in input voltage
In the case of changing, there is a problem of that constant-current characteristicses deteriorate.
The content of the invention
It is an object of the invention in view of the above problems, solve problem of the prior art and a kind of LED drive circuit be provided,
It is as switch element and to have carried out the buck circuit of high frequency using wide bandgap semiconductor, in the buck circuit
In, even if there is input voltage variation is also able to maintain that constant-current characteristicses.
The LED drive circuit of the present invention, it passes through direct current output and lights LED with constant current, wherein, the direct current output is profit
Generated, the LED drive circuit with the discharge and recharge of the reactor of the on-off action of the switch element based on normal open type
It is characterised by, with average detection circuit, the average detection circuit is to flowing through the reactor current of the reactor
Meansigma methodss are detected, are controlled to make institute according to the meansigma methodss of the reactor current detected by the average detection circuit
State the opportunity of switch element disconnection.
According to the present invention, using wide bandgap semiconductor is as switch element and has carried out the buck circuit of high frequency
In, according to the meansigma methodss of the reactor current detected by average detection circuit control make the 1st switch element Q1 disconnect when
Carve, the meansigma methodss thus, it is possible to equally carry out LED current are controlled, even if there is input voltage variation is also able to maintain that constant current is special
Property, thereby serve to that the effect of the correspondence LED drive device that the whole world is input into can be provided.
Description of the drawings
Fig. 1 is the circuit structure diagram of the 1st embodiment structure of the LED drive circuit for illustrating the present invention.
Fig. 2 is the oscillogram for illustrating the reactor current flow through in the reactor shown in Fig. 1.
Fig. 3 is the circuit structure diagram of the 2nd embodiment structure of the LED drive circuit for illustrating the present invention.
Fig. 4 is the circuit structure diagram of the 3rd embodiment structure of the LED drive circuit for illustrating the present invention.
Fig. 5 is the oscillogram for illustrating the reactor current that the reactor in conventional LED drive circuit flows through.
Label declaration
10a：LED drive circuit (the 1st embodiment)；10b：LED drive circuit (the 2nd embodiment)；10c：LED drives
Circuit (the 3rd embodiment)；BF：Buffer circuit；C1：Bypass capacitor；C2：Output capacitor；C3、C4：Coupled capacitor device；
Ccomp：Capacitor；D1：Regeneration diode；D2、D3、D4：Diode；L：Reactor；LD：LED array；OP：Operational amplifier；
OTA：Trsanscondutance amplifier；OSC：Triangular wave oscillator；Q1：Switch element (the 1st switch element)；Q2：Switch element (the 2nd switch
Element)；R1、R2、R3：Resistance；Rs：Current sense resistor；Ta：Control circuit (the 1st embodiment)；Tb：Control circuit (the 2nd,
3rd embodiment)；Ton：Comparator；ZD1、ZD2：Zener diode.
Specific embodiment
Then, embodiments of the present invention are specifically described referring to the drawings.In addition, in the various figures, identical structure is marked
Identical label and clipped explanation.
(the 1st embodiment)
With reference to Fig. 1, the LED drive circuit 10a of the 1st embodiment is the use of the wide bandgap semiconductor element of normal open type
Auto-excitation type buck circuit, with rectification circuit DB, as normal open type wide bandgap semiconductor element switch element Q1,
Q2, control circuit Ta that current constant control is carried out to switch element Q2, bypass capacitor C1, reactor L, winding AW, two poles of regeneration
Pipe D1, output capacitor C2, Zener diode ZD1, resistance R1, R2, R3, diode D2, current sense resistor Rs and capacitor
Ccomp, is driven using constant current to the LED array LD as load circuit.Hereinafter, it is first in order to distinguish switch element Q1 and switch
Part Q2, is referred to as switch element Q1 the 1st switch element Q1, switch element Q2 is referred to as into the 2nd switch element Q2.
It is connected on the input terminal V+ and input terminal V0 of LED drive circuit 10a and is made up of diode bridge
Rectification circuit DB rectification output cathode terminal, ground connection rectification output negative pole terminal.It is input in the exchange of rectification circuit DB
Commercial ac power source AC1 is connected with terminal ACin1, ACin2, the ac input voltage from commercial ac power source AC1 is through complete
Export from rectification circuit DB after ripple rectification.
In the rectification output cathode terminal and input terminal V0 of input terminal V+, i.e. rectification circuit DB, i.e. rectification circuit DB
Rectification output negative pole terminal between, be connected in parallel to bypass capacitor C1 and following series circuit, the series circuit is by the 1st
Switch element Q1, the 2nd switch element Q2, reactor L, output capacitor C2, current sense resistor Rs are constituted.In input terminal V+
On be connected with the drain terminal of the 1st switch element Q1, be connected with the 2nd switch element on the source terminal of the 1st switch element Q1
The drain terminal of Q2, and a terminal of reactor L is connected with the source terminal of the 2nd switch element Q2.In reactor L
Another terminal on be connected with the anelectrode of output capacitor C2, negative electrode and the current sense resistor Rs of output capacitor C2
A terminal connection.
The two ends of output capacitor C2 for LED drive circuit 10a output, the positive electricity extremely outfan of output capacitor C2
The negative electricity extremely output terminal Vout of sub- Vout+, output capacitor C2-.The output terminal Vout+, on Vout-, with sun
Mode of the pole in output terminal Vout+side is connected with the LED array LD as load.
A terminal of source terminal and the reactor L of the 2nd switch element Q2 junction point and input terminal V0 it
Between, it is connected with regeneration diode D1.On the source terminal of the 2nd switch element Q2 with the junction point of a terminal of reactor L
The negative electrode of regeneration diode D1 is connected with, the anode of regeneration diode D1 is connected with input terminal V0.Thus, open the 1st
When closing element Q1 and the 2nd switch element Q2 two side connection, to reactor L and LED array LD applied voltages, so as in reactor L
Middle accumulation electric power.If also, any one party in the 1st switch element Q1 and the 2nd switch element Q2 is when disconnecting, reactor L
The electric power accumulated is fed into LED array LD.
1st switch element Q1 of high side is carried out using the negative voltage induced in winding AW magnetic-coupled with reactor L
Disconnect control.One end of winding AW magnetic-coupled with reactor L and the company of the source terminal of reactor L and the 2nd switch element Q2
Contact connects, and the other end is connected via coupled capacitor device C3 with the gate terminal of the 1st switch element Q1.Thus, when reactor L's
When polarity of voltage is inverted, induce in winding AW so that the gate terminal of the 1st switch element Q1 is changed into the voltage of nagative potential, from
And the 1st switch element Q1 is maintained to off-state.Additionally, gate terminal and the input terminal V0 of the 1st switch element Q1 it
Between be connected with diode D2.The negative electrode of diode D2 is connected with the gate terminal of the 1st switch element Q1, in input terminal V0
On be connected with the anode of diode D2.Thus, the gate terminal by the forward voltage VF of diode D2 to the 1st switch element Q1
Carry out voltage clamp.
Between the gate terminal and source terminal of the 2nd switch element Q2 of downside, Zener diode ZD1 is connected in parallel to
With resistance R1.The anode of Zener diode ZD1 is connected with the gate terminal of the 2nd switch element Q2, negative electrode and the 2nd switch element Q2
Source terminal connection.
Control circuit Ta is the IC circuits for carrying out current constant control to the 2nd switch element Q2, with trsanscondutance amplifier (electricity
Piezo-electric stream switching amplifier) OTA, operational amplifier OP, reference voltage V ref1, Vref2, bipolar transistor Q3, diode D3,
Public terminal COM, current feedback terminal Isense, external phase compensation terminal COMP, drive signal lead-out terminal OUT and starting
Current input terminal ST.
The public terminal COM of control circuit Ta with ground connection input terminal V0 be connected, current feedback terminal Isense with it is defeated
Go out the junction point connection of terminal Vout-, i.e. LED array LD and detection resistance Rs, external phase compensates terminal COMP via electric capacity
Device Ccomp is connected with ground terminal, drive signal lead-out terminal OUT via resistance R2 and the 2nd switch element Q2 of downside grid
Extreme son connection, starting current input terminal ST is connected via resistance R3 with input terminal V+.
In control circuit Ta, current feedback terminal Isense is connected with the inversing input terminal of trsanscondutance amplifier OTA, across
Lead the non-inverting input terminal of amplifier OTA1 to be connected with the positive terminal of reference voltage V ref1, the negative pole of reference voltage V ref1
Terminal is connected with public terminal COM.Additionally, the lead-out terminal of trsanscondutance amplifier OTA is connected with external phase compensation terminal COMP.
Thus, trsanscondutance amplifier OTA is electric using the go-and-retum of detected detection resistance Rs as the reactor current for flowing through reactor L
The potential difference of pressure and reference voltage V ref1 is converted to electric current and exports.Therefore, compensate what terminal COMP was connected with external phase
Capacitor Ccomp carries out discharge and recharge by the output current from trsanscondutance amplifier OTA, therefore in reactor current less than predetermined
It is electrically charged in the case of current value, is discharged in the case where reactor current is higher than predetermined current value.
Additionally, the lead-out terminal of trsanscondutance amplifier OTA is connected with the non-inverting input terminal of operational amplifier OP, computing is put
The inversing input terminal of big device OP is connected with the positive terminal of reference voltage V ref2, negative terminal and the public affairs of reference voltage V ref2
Terminal COM connections altogether.Also, the lead-out terminal of operational amplifier OP is connected with the base stage of bipolar transistor Q3, bipolar transistor
The colelctor electrode of Q3 is connected via diode D3 with drive signal lead-out terminal OUT, the emitter stage and common port of bipolar transistor Q3
Sub- COM connections.In addition, the negative electrode of diode D3 is connected with the colelctor electrode of bipolar transistor Q3, anode and drive signal outfan
Sub- OUT connections.
Thus, the collector current of bipolar transistor Q3 becomes the capacitor being connected with external phase compensation terminal COMP
The corresponding value of meansigma methodss of the charge volume of Ccomp, i.e. reactor current.Therefore, in the wide bandgap semiconductor unit as normal open type
In the case that switch element Q1, Q2 of part are on-state, by gate terminal and source terminal with the 2nd switch element Q2
Between connect resistance R1 voltage drop, be determined as the Vgs of voltage between the gate/source of the 2nd switch element Q2, therefore, it is possible to
Vgs is controlled into into nagative potential corresponding with the charge volume of the capacitor Ccomp of external phase compensation terminal COMP connections.By inciting somebody to action
The Vgs of so control is set to and wide bandgap semiconductor element is carried out in the range of action as constant flow element, the 2nd switch element
Q2 plays a role as the constant flow element of constant current value corresponding with the meansigma methodss of reactor current.
Then, the action of the LED drive circuit 10a of the 1st embodiment is described in detail with reference to Fig. 2.
When DC source is connected, switch element Q1, Q2 are connected, therefore as shown in Fig. 2 reactor current flows out and linear
Increase.Thus, electric power is accumulated in reactor L, and couple capacitor Ccomp being connected with external phase compensation terminal COMP enters
Row charges.Even if also, to be increasedd reactor current has reached and has compensated the capacitor that terminal COMP is connected with external phase
The constant current value of the corresponding 2nd switch element Q2 of meansigma methodss of the charge volume of Ccomp, i.e. reactor current, due to reactor current
Further to increase, therefore the drain terminal of switch element Q1, the i.e. voltage of the source terminal of switch element Q1 steeply rise.By
This, the Vgs of switch element Q1 becomes the nagative potential less than threshold value Vth (negative voltage), and switch element Q1 disconnects.
When switch element Q1 disconnects, the polarity of voltage reversion of reactor L is induced so that the 1st switch in winding AW
The gate terminal of element Q1 is changed into the voltage of nagative potential, so as to the 1st switch element Q1 is maintained to off-state, becomes reactor
During the regeneration that the electric power that L is accumulated is released.Also, when middle reactor current is changed into 0 during regenerating, do not induce so that
The gate terminal of switch element Q1 is changed into the voltage of nagative potential, and switch element Q1, Q2 are again switched on, afterwards repeatedly with above-mentioned action
Identical action.
In the 1st embodiment, perseverances of the 2nd switch element Q2 as constant current value corresponding with the meansigma methodss of reactor current
Fluid element plays a role, therefore as shown in Fig. 2 the peak value of reactor current is changed according to input voltage.Therefore, equally into
Meansigma methodss for LED current are controlled, and LED current is not affected by the duty cycle of switching that input voltage variation causes, forms
For constant LED current, even if therefore there is input voltage variation and be also able to maintain that constant-current characteristicses.
As described above, according to the 1st embodiment, driven with the LED that LED is lighted in constant current by direct current output
Circuit 10a, the direct current output is the reactor L of the on-off action using the 1st switch element Q1 based on normal open type
Discharge and recharge and generate, LED drive circuit 10a is configured to that there are meansigma methodss to flowing through the reactor current of reactor L to carry out
Average detection circuit (trsanscondutance amplifier OTA and the capacitor being connected with the lead-out terminal of trsanscondutance amplifier OTA of detection
Ccomp), and according to the control of the meansigma methodss of the reactor current detected by average detection circuit the 1st switch element Q1 is made to break
The opportunity opened.Specifically, with the 1st switch element Q1 and the 2nd switch element Q2 being connected in series, and have：Control circuit
Ta, the 2nd switch element Q2 of downside is driven to the meansigma methodss with the reactor current detected by average detection circuit for it
The constant flow element of corresponding constant current value；And holding circuit (winding AW, coupled capacitor device C3) is disconnected, during it is during regenerating,
1st switch element of high side is maintained into into off-state.
Using the structure, using wide bandgap semiconductor is as switch element and has carried out the buck circuit of high frequency
In, the meansigma methodss control of LED current can be equally carried out, even if there is input voltage variation is also able to maintain that constant-current characteristicses,
Therefore, it is possible to provide the microminiature LED drive device of correspondence whole world input.No matter additionally, using as the electric current of current measuring element
Detection resistance Rs is installed to the where regenerated as reactor L- in the loop of diode D1-LED array LD, can obtain
The meansigma methodss of reactor current, therefore also have the advantages that the installation site degree of freedom of current measuring element is high.
(the 2nd embodiment)
With reference to Fig. 3, the LED drive circuit 10b of the 2nd embodiment is the use of the wide bandgap semiconductor element of normal open type
Separated exciting buck circuit.In the LED drive circuit 10 of the 1st embodiment, the 2nd switch element Q2 of downside is used as into perseverance
Fluid element, and in the LED drive circuit 10b of the 2nd embodiment, by 2nd switch element Q2 of control circuit Tb to downside
Carry out on-off control.
Between the gate terminal and source terminal of the 2nd switch element Q2 of downside, Zener diode ZD2 is connected with.Together
The anode of diode ZD2 received is connected with the gate terminal of the 2nd switch element Q2, the source terminal of negative electrode and the 2nd switch element Q2
Connection.Additionally, between the gate terminal and input terminal V0 of the 2nd switch element Q2, being connected with resistance R2 high-resistance enough.
In a period of Zener diode ZD2 and resistance R2 are before control circuit Tb carries out action, as according to the 2nd switch element Q2's
The current potential of source terminal, makes the autobias circuit that the 2nd switch element Q2 turns off action play a role.That is, it is connected in series
1st switch element Q1 and the 2nd switch element Q2 disconnects this characteristic with Vgs=0V when connection, Vgs=nagative potentials
Normal open type, therefore in a period of control circuit Tb is carried out before action when to power on etc., the 1st switch element Q1 and the 2nd
When the grid voltage of switch element Q2 becomes with source potential identical current potential, it is turned on, flows through high current.Therefore,
High-resistance resistance R2 is connected between gate terminal and input terminal V0 (ground terminal) so that the 2nd switch element Q2's
Grid voltage is depressed into the Zener diode ZD2's being connected between gate terminal and source terminal by abundant self-bias by negative voltage
Till Zener voltage Vz, so as to the 2nd switch element Q2 is disconnected.Thus, even if control circuit Tb does not carry out action, it is also possible to
Make the 2nd switch element Q2 turn off action during power on, therefore before control circuit Tb carries out action, the 2nd can be opened
Pass element Q2 is stably used as the semiconductor element of nomal closed type and is processed.
Control circuit Tb is the IC circuits for carrying out on-off control to the 2nd switch element Q2, is amplified with mutual conductance
Device (Voltage-current conversion amplifier) OTA, reference voltage V ref1, triangular wave oscillator OSC, comparator Ton, buffer BF,
Public terminal COM, current feedback terminal Isense, external phase compensation terminal COMP, drive signal lead-out terminal OUT and starting
Current input terminal ST.
In the LED drive circuit 10b of the 2nd embodiment, the source terminal of detection resistance Rs and the 2nd switch element Q2 and
Connect between the junction point of reactor L, public terminal COM and detection resistance Rs and the junction point of reactor L of control circuit Tb
Connection, current feedback terminal Isense is connected with the source terminal of the 2nd switch element Q2 and the junction point of detection resistance Rs.And
And, external phase compensation terminal COMP is connected via capacitor Ccomp with the junction point of detection resistance Rs and reactor L, drives
Signal output terminal OUT is connected via coupled capacitor device C4 with the gate terminal of the 2nd switch element Q2 of downside, and starting current is defeated
Enter terminal ST to be connected with input terminal V+ via resistance R3.
In control circuit Tb, current feedback terminal Isense is connected with the inversing input terminal of trsanscondutance amplifier OTA, across
Lead the non-inverting input terminal of amplifier OTA1 to be connected with the positive terminal of reference voltage V ref1, the negative pole of reference voltage V ref1
Terminal is connected with public terminal COM.Additionally, the lead-out terminal of trsanscondutance amplifier OTA is connected with external phase compensation terminal COMP.
Thus, trsanscondutance amplifier OTA is electric using the go-and-retum of detected detection resistance Rs as the reactor current for flowing through reactor L
The potential difference of pressure and reference voltage V ref1 is converted to electric current and exports.Therefore, compensate what terminal COMP was connected with external phase
Capacitor Ccomp carries out discharge and recharge by the output current from trsanscondutance amplifier OTA, therefore in reactor current less than predetermined
It is electrically charged in the case of current value, is discharged in the case where reactor current is higher than predetermined current value.
Additionally, the lead-out terminal of trsanscondutance amplifier OTA is connected with the non-inverting input terminal of comparator Ton, comparator Ton
Inversing input terminal be connected with the lead-out terminal of triangular wave oscillator OSC.Also, the lead-out terminal of comparator Ton is via slow
Rush device BF to be connected with drive signal lead-out terminal OUT.In addition, triangular wave oscillator OSC becomes anode-side Jing from LED array LD
The structure of critical action signal is transfused to by the diode D4 for countercurrently preventing, middle reactor current L becomes for 0 during regenerating
Afterwards, triangular wave rises.
The capacitor that terminal COMP is connected is compensated when the triangular wave exported from triangular wave oscillator OSC exceedes with external phase
During the corresponding voltage of the meansigma methodss of the charge volume of Ccomp, i.e. reactor current, the output of comparator Ton is reversed to low level.By
This, from buffer circuit BF rectangular wave is output into, and the output from buffer circuit BF is being entered by coupled capacitor device C4
When row capacitor is coupled, the positive voltage after the area to original waveform is split up and down and negative voltage are converted into.Therefore, exist
Apply negative voltage drastically to the gate terminal of the 2nd switch element Q2 during shut-off, therefore, it is possible to make the 2nd switch element Q2 break rapidly
Open, and maintained off-state.That is, coupled capacitor device C2 plays a role as pulse signal change-over circuit, and it will postpone
The pulse signal for rushing circuit BF outputs is converted to negative waveform from common potential, and by the output of pulse signal after conversion to the 2nd
The gate terminal of switch element Q2.In addition, positive voltage is pressure more than the grid of the 2nd switch element Q2, but by Zener diode
The forward voltage VF of ZD2 carries out voltage clamp, therefore, it is possible to make the 2nd in the case where the damage of the 2nd switch element Q2 is not caused
Switch element Q2 is connected.
In addition, in LED drive circuit 10b, the 1st switch element Q1 and the 2nd switch element Q2 have carried out cascade company
Connect, therefore low pressure element is set to by the way that the 1st switch element Q1 is set to into high withstand voltage element, the 2nd switch element Q2, by the 2nd
The on-off of switch element Q2 is controlled and had using the 1st switch element Q1 pressure.Therefore, in action, additionally it is possible to by the 2nd
Switch element Q2 is replaced into low pressure SiMOSFET etc..
As described above, according to the 2nd embodiment, have：Pulse-generating circuit (comparator Ton), its output
Pulse signal, the pulse signal has what is determined according to the meansigma methodss of the reactor current detected by average detection circuit
Dutycycle；And pulse signal change-over circuit (coupled capacitor device C4), its by the pulse signal exported from pulse-generating circuit from
Common potential is converted to negative waveform, and by the gate terminal of the output of pulse signal after conversion to the 2nd switch element Q2.
Using the structure, switch element Q1, Q2 can be used as the wide bandgap semiconductor of normal open type, carry out separate excitation control
System, can be in the case where deteriorating switching characteristic by frequency of oscillation high frequency.
Also, according to the 2nd embodiment, the electricity with the source terminal (lead-out terminal) corresponding to the 2nd switch element Q2
Position, makes the 2nd switch element Q2 turn off the autobias circuit (Zener diode ZD2, resistance R2) of action.
Using the structure, when can prevent power activation by autobias circuit without control action, in control circuit Tb
Before carrying out action, the 2nd switch element Q2 can be processed as the semiconductor element of nomal closed type.
(the 3rd embodiment)
With reference to Fig. 4, the LED drive circuit 10c of the 3rd embodiment is from the LED drive circuit 10b of the 2nd embodiment
Except the 1st switch element Q1, the winding AW and capacitor C3 of high side, only the 2nd switch element Q2 is connect by control circuit Tb
Break-make opens control, thus generates direct current output.So, the 2nd switch element Q2 is controlled by separated exciting, it is not necessary to make other
Switch element and constant-current circuit are connected in series with the 2nd switch element Q2, therefore, it is possible to simplify circuit structure.
In addition, the present invention is not limited to the respective embodiments described above, it is known that in the range of the technological thought of the present invention, can
Each embodiment is suitably changed.In addition, the quantity of said structure part, position, shape etc. are not limited to above-mentioned enforcement
Mode, can become and be suitable for carrying out quantity, position, shape of the invention etc..In addition, in the various figures, to identical structural element mark
Note identical label.
Claims (4)
1. a kind of LED drive circuit, it passes through direct current output and lights LED with constant current, wherein, the direct current output is to utilize reactor
Discharge and recharge and generate, the discharge and recharge of the reactor is the connection of the switch element based on the normal open type being connected with rectification circuit
Disconnection action and perform, the LED drive circuit is characterised by,
The switch element and following circuit unit have been connected in series to the rectification circuit：The circuit unit is by diode
The reactor and the series circuit of the LED are connected in parallel in,
The anode of the diode is connected with the negative output terminals of the rectification circuit, and the negative electrode of the diode is connected to institute
The junction point of switch element and the reactor is stated,
The switch element is made up of the 1st switch element and the 2nd switch element that are connected in series, the 1st switch element and institute
The positive output terminals connection of rectification circuit is stated, the 2nd switch element is connected with the reactor,
The LED drive circuit has：
Average detection circuit, the average detection circuit is examined to the meansigma methodss for flowing through the reactor current of the reactor
Survey；
Control circuit, it is driven to the 2nd switch element and the reactance detected by the average detection circuit
The constant flow element of the corresponding constant current value of meansigma methodss of device electric current；And
Holding circuit is disconnected, during it is during the regeneration that the electric power that the reactor is accumulated is released, by the described 1st switch unit
Part maintains into off-state,
The switch element is made according to the control of the meansigma methodss of the reactor current detected by the average detection circuit
The opportunity of disconnection.
2. LED drive circuit according to claim 1, it is characterised in that the LED drive circuit has：
Pulse-generating circuit, its output pulse signal, the dutycycle of the pulse signal is according to by the average detection circuit
What the meansigma methodss of the reactor current for detecting determined, the public terminal of the pulse-generating circuit is connected to the described 2nd
The junction point of switch element and the diode；And
Pulse signal change-over circuit, it is by the public affairs from the pulse signal of pulse-generating circuit output from the public terminal
Common-battery position is converted to negative waveform, and by conversion after the output of pulse signal to the switch element control terminal.
3. LED drive circuit according to claim 2, it is characterised in that
The LED drive circuit has autobias circuit, the current potential of the autobias circuit and the lead-out terminal of the switch element
The switch element is accordingly set to turn off action,
The autobias circuit is made up of Zener diode and resistance, and the anode of the Zener diode and the described 2nd switch are first
The gate terminal connection of part, the negative electrode of the Zener diode is connected with the source terminal of the 2nd switch element,
One terminal of the resistance is connected with the gate terminal of the 2nd switch element, another terminal of the resistance with
The negative output terminals connection of the rectification circuit.
4. the LED drive circuit according to Claims 2 or 3, it is characterised in that
The pulse signal change-over circuit is coupled capacitor device.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013179469A JP6206000B2 (en) | 2013-08-30 | 2013-08-30 | LED drive circuit |
| JP2013-179469 | 2013-08-30 | ||
| JPJP2013-179469 | 2013-08-30 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104427719A CN104427719A (en) | 2015-03-18 |
| CN104427719B true CN104427719B (en) | 2017-04-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410409540.5A Expired - Fee Related CN104427719B (en) | 2013-08-30 | 2014-08-19 | Led drive circuit |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP6206000B2 (en) |
| CN (1) | CN104427719B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111867176B (en) * | 2019-04-08 | 2023-01-03 | 华润微集成电路(无锡)有限公司 | LED drive circuit and silicon controlled rectifier dimming circuit |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102735906A (en) * | 2012-07-05 | 2012-10-17 | 矽力杰半导体技术(杭州)有限公司 | Inductive current detecting circuit and LED (light emitting diode) driving circuit using inductive current detecting circuit |
| CN103079321A (en) * | 2013-01-25 | 2013-05-01 | 深圳市富满电子有限公司 | Non-auxiliary LED (Light Emitting Diode) driving circuit with self power supply |
| CN103219884A (en) * | 2012-01-19 | 2013-07-24 | 美芯晟科技（北京）有限公司 | Control circuit and control method of primary side feedback constant current |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5592613B2 (en) * | 2009-01-22 | 2014-09-17 | パナソニック株式会社 | Power supply device and lighting apparatus using the same |
| JP5648413B2 (en) * | 2009-11-09 | 2015-01-07 | 東芝ライテック株式会社 | Lighting device |
| JP5751483B2 (en) * | 2010-06-28 | 2015-07-22 | 東芝ライテック株式会社 | Switching power supply device, switching power supply circuit, and electrical equipment |
| JP5835663B2 (en) * | 2011-11-10 | 2015-12-24 | 東芝ライテック株式会社 | Lighting power supply and lighting device |
-
2013
- 2013-08-30 JP JP2013179469A patent/JP6206000B2/en not_active Expired - Fee Related
-
2014
- 2014-08-19 CN CN201410409540.5A patent/CN104427719B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103219884A (en) * | 2012-01-19 | 2013-07-24 | 美芯晟科技（北京）有限公司 | Control circuit and control method of primary side feedback constant current |
| CN102735906A (en) * | 2012-07-05 | 2012-10-17 | 矽力杰半导体技术(杭州)有限公司 | Inductive current detecting circuit and LED (light emitting diode) driving circuit using inductive current detecting circuit |
| CN103079321A (en) * | 2013-01-25 | 2013-05-01 | 深圳市富满电子有限公司 | Non-auxiliary LED (Light Emitting Diode) driving circuit with self power supply |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2015050239A (en) | 2015-03-16 |
| CN104427719A (en) | 2015-03-18 |
| JP6206000B2 (en) | 2017-10-04 |
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