CN207099377U

CN207099377U - LED drive system and constant-current control circuit

Info

Publication number: CN207099377U
Application number: CN201720879784.9U
Authority: CN
Inventors: 朱晓杰; 吴建兴
Original assignee: Hangzhou Silan Microelectronics Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd
Priority date: 2017-07-19
Filing date: 2017-07-19
Publication date: 2018-03-13
Anticipated expiration: 2027-07-19

Abstract

This application discloses a kind of LED drive system and constant-current control circuit, LED drive system includes：Rectifier bridge, its first output end provide DC voltage；Constant-current control circuit, first output end of its power port and rectifier bridge is joined directly together to receive DC voltage, constant-current control circuit includes power supply circuit, control circuit and power tube, power supply circuit is connected with power port so that DC voltage directly is converted into the first power supply signal, control circuit is connected with power supply circuit to produce switch controlling signal according to the first power supply signal, and the turn-on and turn-off of power tube are controlled by switch controlling signal；Drive circuit, for producing driving current.The utility model can directly produce stable supply voltage according to the direct current of high pressure, and prevent supply voltage to be pulled low for larger supply current, so as to ensure that the normal work of constant-current control circuit, eliminate external capacitor, LED drive system is simplified, and has saved cost.

Description

LED drive system and constant-current control circuit

Technical field

Light emitting diode actuation techniques field is the utility model is related to, more particularly, to a kind of LED drive system and perseverance Flow control circuit.

Background technology

In traditional LED drive system, current constant control chip needs to obtain from the bus of an offer high voltage direct current Power taking energy, with to current constant control chip power itself.Current constant control chip internal usually includes larger-size power tube, When switch control is carried out to power tube, it usually needs larger electric current is provided power tube.If not taking voltage stabilizing measure, this Electric current will cause supply voltage caused by current constant control chip to be pulled low, so as to influence the normal work of current constant control chip.

In the prior art, in order to realize the stabilization of supply voltage, the outside of current constant control chip is provided with a great Rong The electric capacity of value, the electric capacity is used to deposit the energy from bus, so as to ensure that current constant control chip is carried out to power tube Keep stable during switch control.

Fig. 1 shows a kind of circuit diagram of existing LED drive system.

As shown in figure 1, LED drive system include current rectifying and wave filtering circuit 1200, current constant control chip 1100 and for pair LED string 2000 produces the drive circuit 1300 of driving current.Current rectifying and wave filtering circuit 1200 is used to alternating voltage Vac being converted into High voltage direct current is simultaneously exported to bus VBUS.The energization pins VCC of current constant control chip 1100 is female from high pressure by resistance R01 Line VBUS obtains electric energy, and electric capacity C01 is connected between energization pins VCC and ground.Current constant control chip 1100 includes using In producing the control circuit 1110 of switch controlling signal and being controlled by the power tube M0 of switch controlling signal, when current constant control chip During 1100 work, power tube M0 needs very big electric current, is now directly individually unable to maintain that perseverance by the bus VBUS energy provided The normal work of flow control chip 1100 is, it is necessary to using electric capacity C01 storage energies with energization pins VCC voltage pull-down pair Energization pins VCC voltage compensates, and causes current constant control chip 1100 to prevent energization pins VCC spread of voltage Occur abnormal.

Fig. 2 shows the circuit diagram of another existing LED drive system.

Unlike the LED drive system shown in Fig. 1, the current constant control chip in LED drive system as shown in Figure 2 1100 obtain electric energy by the sustained diode 0 in drive circuit 1300 from bus VBUS, and internally utilize power supply circuit 1120 produce supply voltage for the normal work of current constant control chip 1100.Although eliminate energization pins VCC and VBUS buses Between resistance, but needed also exist between the energization pins VCC and ground of current constant control chip 1100 connect electric capacity C01, with profit The voltage stabilization at energization pins VCC is maintained with the charge-discharge principle of electric capacity.

Fig. 3 shows driving pin DRV and power supply of the LED drive system after electric capacity C01 is removed shown in Fig. 1 and Fig. 2 Pin VCC voltage waveform view.It can be seen that when driving pin DRV voltage Vdrv significantly to decline, due to not having Electric capacity C01 carries out voltage compensation to energization pins VCC, and the voltage at energization pins VCC can be pulled low and can not provide unlatching work( Electric current needed for rate pipe, the voltage on energization pins VCC can even be pulled low to the low-voltage protection of current constant control chip 1100 Point Vu and make current constant control chip be forced to restart, cause whole LED drive system operation irregularity.

Utility model content

In view of the above problems, the utility model provides a kind of LED drive system and constant-current control circuit, being capable of direct basis The direct current of high pressure produces stable supply voltage, and providing larger supply current prevents supply voltage to be pulled low, so as to protect The normal work of constant-current control circuit has been demonstrate,proved, has eliminated external capacitor, has simplified LED drive system, and saved cost.

According to one side of the present utility model, there is provided a kind of LED drive system, it is used to produce driving current to drive Light emitting diode, it is characterised in that the LED drive system includes：Rectifier bridge, between its first input end and the second input Alternating voltage is received, its first output end provides DC voltage, its second output head grounding；Constant-current control circuit, its power end First output end of mouth and the rectifier bridge is joined directly together to receive the DC voltage, and the constant-current control circuit includes power supply Circuit, control circuit and power tube, the power supply circuit are connected with the power port directly to change the DC voltage For the first power supply signal, the control circuit is connected with the power supply circuit to produce switch control according to the first power supply signal Signal, the control terminal of the power tube is connected with the control circuit so that the turn-on and turn-off of the power tube are controlled by institute State switch controlling signal；Drive circuit, itself and the first output end of the rectifier bridge and the first end of the power tube and Two ends are connected, for producing the driving current.

Preferably, the power supply circuit includes：Current source, for according to the DC voltage produce DC current, and The output end of the current source provides the DC current；Voltage regulation unit, for producing the first driving according to the DC current Voltage and the second driving voltage；And amplifying unit, for according to first driving voltage and second driving voltage production Raw first power supply signal.

Preferably, the voltage regulation unit includes voltage-regulator diode and current-limiting resistance, and the current-limiting resistance is connected on the electricity Between the negative electrode of the output end in stream source and the voltage-regulator diode, the negative electrode of the voltage-regulator diode provides stable benchmark electricity Pressure, the voltage regulation unit are used to produce the first driving electricity according to the reference voltage and the voltage at the current-limiting resistance both ends Pressure and second driving voltage.

Preferably, the current source includes FET, and the control terminal of the FET receives bias voltage, the field The first end of effect pipe is connected with the power port, and the second end of the FET provides the DC current.

Preferably, the FET is N-channel technotron, and the bias voltage is equal to 0V.

Preferably, the plus earth of the voltage-regulator diode.

Preferably, the first end of the current-limiting resistance is connected with the output end of the current source to provide second driving Voltage.

Preferably, the amplifying unit includes the first triode, and the base stage of first triode receives described first and driven Dynamic voltage, the colelctor electrode of first triode receive second driving voltage, and the emitter stage of first triode provides First power supply signal.

Preferably, the amplifying unit includes Darlington transistor, and the base stage of the Darlington transistor receives the first driving electricity Pressure, the colelctor electrode of the Darlington transistor receive second driving voltage, and the emitter stage of the Darlington transistor provides described first Power supply signal.

Preferably, the Darlington transistor includes the second triode and the 3rd triode, second triode and described Three triodes are NPN type, the base stage of the base stage of second triode as the Darlington transistor, the hair of second triode Emitter-base bandgap grading is connected with the base stage of the 3rd triode, the transmitting of the emitter stage of the 3rd triode as the Darlington transistor Pole, the colelctor electrode of second triode are connected using the current collection as the Darlington transistor with the colelctor electrode of the 3rd triode Pole.

Preferably, the second end of the current-limiting resistance is connected with the negative electrode of the voltage-regulator diode with by the reference voltage As first driving voltage.

Preferably, the voltage regulation unit also includes the first diode, anode and the current limliting electricity of first diode Second end of resistance, the negative electrode of the voltage-regulator diode are connected, and the negative electrode of first diode provides first driving voltage.

Preferably, the amplifying unit also includes the 4th triode, base stage and the Darlington of the 4th triode The base stage of pipe is connected, and the emitter stage of the 4th triode provides the second power supply signal to the control circuit, and the described 4th 3 The colelctor electrode of pole pipe is connected with the colelctor electrode of the Darlington transistor.

Preferably, the amplifying unit also includes the 4th triode and the 5th triode, the base stage of the 4th triode It is connected with colelctor electrode and is connected with the base stage of the Darlington transistor, emitter stage and the 5th triode of the 4th triode Base stage be connected, the emitter stage of the 5th triode provides the second power supply signal, the colelctor electrode of the 5th triode and institute The colelctor electrode for stating Darlington transistor is connected.

Preferably, the voltage regulation unit produces the 3rd driving voltage, the amplifying unit root always according to the reference voltage The second power supply signal is produced to the control circuit according to the 3rd driving voltage.

Preferably, the voltage regulation unit also includes the 6th triode, and the base stage of the 6th triode is connected with colelctor electrode And it is connected with the second end of the current-limiting resistance and first driving voltage, the emitter stage of the 6th triode and institute is provided The negative electrode for stating voltage-regulator diode is connected and provides the 3rd driving voltage.

Preferably, the voltage regulation unit also includes the 6th triode, the second diode and the 3rd diode, and the described 6th 3 The base stage and colelctor electrode of pole pipe, the second end of the current-limiting resistance are connected with the anode of second diode, and the described 2nd 2 The negative electrode of pole pipe provides first driving voltage, the emitter stage of the 6th triode, the negative electrode of the voltage-regulator diode with The anode of 6th diode is connected, and the negative electrode of the 3rd diode provides the 3rd driving voltage.

Preferably, the amplifying unit also includes the 7th triode, and the base stage of the 7th triode receives the described 3rd Driving voltage, the emitter stage of the 7th triode provide second power supply signal, the colelctor electrode of the 7th triode with The colelctor electrode of the Darlington transistor is connected.

Preferably, the control circuit includes drive control circuit and logic control circuit, and the logic control circuit connects Second power supply signal is received to carry out logical operation, the drive control circuit receives first power supply signal and according to institute The operation result for stating logic control circuit produces the switch controlling signal.

Preferably, the drive circuit has the first output end and the second output end, and first output end is used for and LED The anode of lamp string is connected, and second output end is used to be connected with the negative electrode of the LED string, and the drive circuit includes electricity Sense, output resistance, sampling resistor, the first electric capacity and fly-wheel diode, the output resistance are parallel to first electric capacity Between first output end and second output end, the first end of the inductance and the second output end of the drive circuit It is connected, the second end of the inductance and the anode of the fly-wheel diode are connected with the first end of the power tube, described continuous The negative electrode of stream diode is connected with the first output end of the drive circuit to receive the DC voltage, the sampling resistor First end is connected with the second end of the power tube, the second end ground connection of the sampling resistor.

Preferably, the LED drive system also includes the second electric capacity, second capacitance connection in the rectifier bridge To be filtered to the DC voltage between one output end and the second output end.

Preferably, the power supply circuit in the constant-current control circuit, the control circuit and the power tube collection Into in same chip.

According to another aspect of the present utility model, a kind of constant-current control circuit is additionally provided, it is characterised in that the constant current Control circuit has the driving port for being used to provide control electric current, the sample port for receiving sampled signal, for ground connection Grounding ports and power port, the power port directly receive DC voltage, and the constant-current control circuit includes：Power supply electricity Road, it is connected with the power port so that the DC voltage directly is converted into the first power supply signal；Control circuit, with the confession Circuit is connected to produce switch controlling signal according to the first power supply signal；And power tube, its first end and the second end point It is not connected with the driving port and the sample port, its control terminal is connected with the control circuit, and the power tube is led Logical and shut-off is controlled by the switch controlling signal.

Preferably, the voltage regulation unit voltage-regulator diode and current-limiting resistance, the current-limiting resistance are connected on the current source Output end and the voltage-regulator diode negative electrode between, the negative electrode of the voltage-regulator diode provides stable reference voltage, institute State voltage regulation unit be used for according to the reference voltage and the voltage at the current-limiting resistance both ends produce first driving voltage and Second driving voltage.

Preferably, the plus earth of the voltage-regulator diode.

According to the constant-current control circuit of the utility model embodiment and LED drive system without the electricity in constant-current control circuit The electric capacity of the external big capacitance of source port can produce stable supply voltage without being opened by power tube according to the direct current of high pressure The influence of pass action, so as to ensure that the normal work of constant-current control circuit, eliminates external capacitor, simplifies LED drivetrains System, and saved cost.In some preferred embodiments, power supply circuit can produce two magnitude of voltage identicals first and power Signal and the second power supply signal, so as to stronger to the drive control circuit output in constant-current control circuit using the first power supply signal Supply current and using the second power supply signal to the normal power supply electricity of logic control circuit output in constant-current control circuit Stream, can prevent drive control circuit caused power supply signal of influence of fluctuations second on the first power supply signal, be further ensured that The stable power-supplying of constant-current control circuit.

Brief description of the drawings

By the description to the utility model embodiment referring to the drawings, of the present utility model above-mentioned and other mesh , feature and advantage will be apparent from.

Fig. 1 shows a kind of circuit diagram of existing LED drive system.

Fig. 2 shows the circuit diagram of another existing LED drive system.

Fig. 3 shows driving pin DRV and power supply of the LED drive system after electric capacity C01 is removed shown in Fig. 1 and Fig. 2 Pin VCC voltage waveform view.

Fig. 4 shows the electrical block diagram of the LED drive system of the utility model embodiment.

Fig. 5 shows the structural representation of the first embodiment of power supply circuit in Fig. 4.

Fig. 6 a show a kind of circuit diagram of specific embodiment of the power supply circuit shown in Fig. 5.

Fig. 6 b show the circuit diagram of another specific embodiment of the power supply circuit shown in Fig. 5.

Fig. 7 shows the structural representation of the second embodiment of power supply circuit in Fig. 4.

Fig. 8 a show a kind of circuit diagram of specific embodiment of the power supply circuit shown in Fig. 7.

Fig. 8 b show the circuit diagram of another specific embodiment of the power supply circuit shown in Fig. 7.

Fig. 8 c show the circuit diagram of another specific embodiment of the power supply circuit shown in Fig. 7.

Fig. 9 shows the structural representation of the 3rd embodiment of power supply circuit in Fig. 4.

Figure 10 a show a kind of circuit diagram of specific embodiment of the power supply circuit shown in Fig. 9.

Figure 10 b show the circuit diagram of another specific embodiment of the power supply circuit shown in Fig. 9.

Figure 11 shows the electricity at the supply voltage of constant-current control circuit and driving port in LED drive system shown in Fig. 4 The waveform diagram of pressure.

Embodiment

Various embodiments of the present utility model are more fully described hereinafter with reference to accompanying drawing.In various figures, identical Element is represented using same or similar reference.For the sake of clarity, the various pieces in accompanying drawing are not drawn to paint System.

As shown in figure 4, the LED drive system 3000 of the utility model embodiment includes constant-current control circuit 3100, rectification Filter circuit 3200 and drive circuit 3300.Wherein, current rectifying and wave filtering circuit 3200 is used to carry out rectification filter to alternating voltage Vac Ripple is to produce DC voltage Vin；Constant-current control circuit 3100 is used to produce control electric current Idrv according to DC voltage Vin；Driving Circuit 3300 is used for the storage and release that energy is carried out according to DC voltage Vin and control electric current Idrv, is used to drive to produce The driving current ILED of LED string 2000.

Current rectifying and wave filtering circuit 3200 includes rectifier bridge, resistance R2 and the electric capacity C2 for filtering.Wherein, rectifier bridge includes Diode D11 to D14, diode D11 anode, diode D12 negative electrode are connected using the first input end as rectifier bridge, and two Pole pipe D12 anode is connected using the second output end as rectifier bridge with diode D14 anode and is grounded gnd, diode D13 Anode be connected with diode D14 negative electrode using the second input as rectifier bridge, diode D13 negative electrode and diode D11 negative electrode is connected using the first output end as rectifier bridge and provides DC voltage Vin；Resistance R2 first end and rectifier bridge First input end be connected, alternating voltage Vac is received between resistance R2 the second end and the second input of rectifier bridge；Electric capacity C2 First end and the second end be connected respectively with the first output end of rectifier bridge and the second output end, with to DC voltage Vin carry out Filtering.

Constant-current control circuit 3100 has power port HV, grounding ports GND, driving port DRV and sample port CS, Wherein power port HV directly receives DC voltage Vin by bus VBUS, and power port HV is without external capacitor, grounding ports GND is grounded gnd, and sample port CS receives sampled signal S2, and driving port DRV provide control electric current Idrv.

Constant-current control circuit 3100 includes power tube M1, control circuit 3110 and the power supply that can be integrated in same chip Circuit 3120.Wherein, power supply circuit 3120 is connected with power port HV to receive supply voltage Vhv (in the present embodiment, power supplys Voltage Vhv is equal to the DC voltage Vin that current rectifying and wave filtering circuit 3200 provides), the first power supply signal is produced according to supply voltage Vhv VCC1；Control circuit 3110 receives the first power supply signal VCC1 and is connected with the grounding ports GND of constant-current control circuit 3100, controls Circuit 3110 processed is used to provide switch controlling signal S1；Power tube M1 control terminal receives switch controlling signal S1, power tube M1 First end be connected with the driving port DRV of constant-current control circuit 3100, power tube M1 the second end and constant-current control circuit 3100 sample port CS is connected.Specifically, power tube M1 is, for example, N-channel metal-oxide-semiconductor field effect t.

In some alternative embodiments, power supply circuit 3120 not only produces the first power supply signal VCC1, also produces second Power supply signal VCC2, wherein the first power supply signal VCC1 driving force is higher than the second power supply signal VCC2 power supply capacity, the One power supply signal VCC1 is used to be powered the drive control circuit in control circuit 3110, and the second power supply signal VCC2 is used for Logic control circuit in control circuit 3110 is powered, ensures the first power supply signal in a manner of by powering respectively Voltage pulsation caused by the upper drive control circuits due in control circuit 3110 of VCC1 is not interfered with control circuit 3110 The normal work of logic control circuit.

Drive circuit 3300 includes diode D5, inductance L1, resistance R1 (output resistance), sampling resistor Rcs and electric capacity C1.Inductance L1 first end is connected with the driving port DRV of constant-current control circuit 3100, and inductance L1 the second end is with electric capacity C1's First end is connected receives DC voltage Vin, electricity using the second output end LED- as drive circuit 3300, electric capacity C1 the second end Resistance R1 is in parallel with electric capacity C1, and diode D5 anode is connected with inductance L1 first end, and diode D5 negative electrode is with electric capacity C1's Second end is connected using the first output end LED+ as drive circuit 3300.Sampling resistor Rcs first end and current constant control electricity The sample port CS on road 3100 is connected to provide sampled signal S2, sampling resistor Rcs the second end ground connection gnd.Drive circuit 3300 the first output end LED+ connects the anode of LED string 2000, and the second output end LED- of drive circuit 3300 connects LED string 2000 negative electrode.

When the power tube M1 in constant-current control circuit 3100 is turned under switch controlling signal S1 control, sampling resistor Rcs, power tube M1, inductance L1, with LED string 2000 loop is formed to provide driving current ILED, in inductance L1 and electric capacity C1 Storage energy；When the power tube M1 in constant-current control circuit 3100 is turned off under switch controlling signal S1 control, diode D5, inductance L1 and LED string form loop, and inductance L1 and electric capacity C1 release energy to maintain driving current ILED, so as to pass through Controlling switch control signal S1, LED string 2000 can be driven by constant driving current ILED, realize current constant control.

Illustrated below for above-mentioned power supply circuit.

As shown in figure 5, power supply circuit 3120 includes current source 3121, voltage regulation unit 3122 and amplifying unit 3123.Electricity Stream source 3121 is used to produce electric current Iin according to supply voltage Vhv, and the output end of current source 3121 provides electric current Iin.Voltage regulation unit 3122 are used to provide the first driving voltage V1 and the second driving voltage V2 according to electric current Iin.Amplifying unit 3123 drives according to first Dynamic voltage V1 and the second driving voltage V2 produces the first power supply signal VCC1.

Fig. 6 a show a kind of circuit diagram of specific embodiment of the power supply circuit shown in Fig. 5.Fig. 6 b are shown shown in Fig. 5 Power supply circuit another specific embodiment circuit diagram.

As a kind of specific embodiment of power supply circuit 3120, as shown in Figure 6 a, current source 3121 includes FET J1. Because supply voltage Vhv voltage is generally higher, therefore specifically, imitated using the junction type field of the N-channel with high pressure resistant property Should pipe voltage-controlled current source 3121 is realized as FET J1.FET J1 is by source electrode, drain electrode and PN junction gate Pole is formed, and raceway groove be present under 0V grid bias, its operation principle is the electric current in the electric field controls raceway groove on PN junction. FET J1 control terminal (grid) ground connection gnd, its first end (one of source electrode and drain electrode) pass through constant-current control circuit 3100 Power port HV be connected with bus VBUS to regard DC voltage Vin as supply voltage Vhv, its second end (source electrode and drain electrode In another) provide electric current Iin (DC current).In certain embodiments, FET J1 can also be the junction type of P-channel FET, its control terminal (grid) ground connection gnd, its first end (one of source electrode and drain electrode) pass through constant-current control circuit 3100 Power port HV is connected with bus VBUS so that by DC voltage Vin, as supply voltage Vhv, its second end is (in source electrode and drain electrode Another) electric current Iin is provided.It should be noted that FET J1 control terminal is not limited to be grounded gnd, can also basis Actual circuit receives other voltages to meet the requirement of current control.

As shown in Figure 6 a, voltage regulation unit 3122 includes voltage-regulator diode (also known as Zener diode) DZ and current-limiting resistance R11, current-limiting resistance R11 first end are connected with voltage-regulator diode DZ negative electrode, voltage-regulator diode DZ plus earth gnd, limit Leakage resistance R11 the second end is connected with FET J1 the second end to receive electric current Iin.Therefore, in the work of current source 3121 There is the reverse current Ir that anode is flowed to by negative electrode under, in voltage-regulator diode DZ, voltage-regulator diode DZ is reverse current Ir's Reverse breakdown area is operated under effect, therefore stable reference voltage V ref can be produced at voltage-regulator diode DZ negative electrode to make For the first driving voltage V1.Acting on the electric current on current-limiting resistance R11 can be on the basis of reference voltage V ref in current limliting electricity Hinder and the second driving voltage V2 is produced at R11 the second end, and the second driving voltage V2 magnitude of voltage is higher than the first driving voltage V1. Current-limiting resistance R11 is used for the reverse current Ir for limiting voltage-regulator diode DZ simultaneously, to ensure the first of voltage-regulator diode DZ offers Driving voltage V1 stabilization.

As shown in Figure 6 a, amplifying unit 3123 includes the Darlington transistor being made up of triode Q1 and triode Q2.Wherein, three Base stage of the pole pipe Q1 base stage as Darlington transistor, triode Q1 emitter stage are connected with triode Q2 base stage, triode Q1 Colelctor electrode be connected with triode Q2 colelctor electrode using the colelctor electrode as Darlington transistor, triode Q2 emitter stage is as reaching woods Pipe emitter stage pause to provide the first power supply signal VCC1.Wherein, the multiplication factor of Darlington transistor is equal to triode Q1 and triode The product of Q2 multiplication factor, therefore Darlington transistor can export larger supply current, i.e. the first power supply signal VCC1 has Stronger driving force；And the faster response speed that Darlington transistor has, therefore constant-current control circuit 3100 is (permanent when opening Flow control circuit is for example switched on and off circuit unlatching), amplifying unit 3123 can export larger supply current, so as to ensure first Power supply signal VCC1 fluctuation is small, that is, avoids the work caused by the first power supply signal VCC1 fluctuation of constant-current control circuit 3100 Make abnormal.

Specifically, as shown in Figure 6 a, the base stage of Darlington transistor is connected with voltage-regulator diode DZ negative electrode is driven with receiving first Dynamic voltage V1, the colelctor electrode of Darlington transistor are connected with FET J1 the second end to receive the second driving voltage V2, Darlington Pipe is operated in amplification region.

In the case where the first power supply signal VCC1 magnitude of voltage is higher, as a kind of alternative embodiment, such as Fig. 6 b institutes Show, diode D01 is also included in voltage regulation unit 3122, and diode D01 anode is connected with voltage-regulator diode DZ negative electrode to connect Reference voltage V ref is received, diode D01 negative electrode provides the first driving voltage V1, the collection of Darlington transistor to the base stage of Darlington transistor Electrode is connected with FET J1 the second end to receive the second driving voltage V2.Diode D01 is as reverse resistance to voltage device work Make in forward conduction area, therefore when the first power supply signal VCC1 exceedes supply voltage Vhv voltage, diode D01 can be to prevent Only electric current pours in down a chimney the first end being connected into FET J1 with bus VBUS by the emitter stage of Darlington transistor, so as to prevent electric current Operation irregularity caused by pouring in down a chimney phenomenon.

It should supplement, in other less demanding embodiments of driving force to the first power supply signal VCC1, Amplifying unit 3123 can also be the amplifying circuit of other structures, such as single triode etc..

The course of work of power supply circuit 3120 as shown in figures 6 a and 6b is：When power supply circuit 3120 receives power supply electricity After pressing Vhv, current source 3121 provides electric current Iin, therefore reversely electricity is formed in the voltage-regulator diode DZ to be connected with current source 3121 Stream Ir causes voltage-regulator diode DZ to be operated in reverse breakdown area, and stable reference voltage is provided so as to voltage-regulator diode DZ negative electrode Vref, and provided surely by reference voltage V ref directly as the first driving voltage V1 (as shown in Figure 6 a) or by diode D01 The first fixed driving voltage V1 (as shown in Figure 6 b).Current-limiting resistance R11 limitations reverse current Ir size is to ensure the first driving Voltage V1 stabilization, and be used to provide the second driving voltage V2 higher than the first driving voltage V1 to ensure amplifying unit 3123 In Darlington transistor be operated in amplification region, the triode Q1 and Q2 that the first driving voltage V1 passes through in Darlington transistor form first and supplied Electric signal VCC1, then the first power supply signal VCC1=V1-VBE1-VBE2, wherein VBE1 are triode Q1 base stages and emitter stage Between voltage, VBE2 is the voltage between triode Q2 base stage and emitter stage.

As shown in fig. 7, unlike the first embodiment of above-mentioned power supply circuit, the power supply circuit 3120 of power supply circuit 3120 To needing the drive control circuit of large driven current density and logic control circuit without large driven current density in control circuit 3110 It is powered respectively.Specifically, power supply circuit 3120 is respectively to the drive control circuit in control circuit 3110 and logic control Circuit provides the first power supply signal VCC1 and the second power supply signal VCC2, wherein, the first power supply signal VCC1 has stronger drive Kinetic force, i.e., can provide larger supply current, and the second power supply signal VCC2 only needs have normal driving force.

Power supply circuit 3120 as shown in Figure 7 equally includes current source 3121, voltage regulation unit 3122 and amplifying unit 3123. Wherein, current source 3121 is used to produce electric current Iin according to supply voltage Vhv, and the output end of current source 3121 provides electric current Iin； Voltage regulation unit 3122 is used to provide the first driving voltage V1 and the second driving voltage V2 according to electric current Iin；Amplifying unit 3123 The first power supply signal VCC1 and the second power supply signal VCC2 is produced according to the first driving voltage V1 and the second driving voltage V2.

Fig. 8 a show a kind of circuit diagram of specific embodiment of the power supply circuit shown in Fig. 7.Fig. 8 b are shown shown in Fig. 7 Power supply circuit another specific embodiment circuit diagram.Fig. 8 c show another tool of the power supply circuit shown in Fig. 7 The circuit diagram of body embodiment.

As a kind of specific embodiment of power supply circuit 3120, as shown in Figure 8 a, current source 3121 includes FET J1. Because supply voltage Vhv voltage is generally higher, therefore specifically, imitated using the junction type field of the N-channel with high pressure resistant property Should pipe voltage-controlled current source 3121 is realized as FET J1.FET J1 is by source electrode, drain electrode and PN junction gate Pole is formed, and raceway groove be present under 0V grid bias, its operation principle is the electric current in the electric field controls raceway groove on PN junction. FET J1 control terminal (grid) ground connection gnd, its first end (one of source electrode and drain electrode) pass through constant-current control circuit 3100 Power port HV be connected with bus VBUS to regard DC voltage Vin as supply voltage Vhv, its second end (source electrode and drain electrode In another) electric current Iin is provided.In certain embodiments, FET J1 can also be the technotron of P-channel, Its control terminal (grid) is grounded gnd, and its first end (one of source electrode and drain electrode) passes through the power port of constant-current control circuit 3100 HV be connected with bus VBUS using by DC voltage Vin as supply voltage Vhv, its second end (in source electrode and drain electrode another) Electric current Iin is provided.It should be noted that FET J1 control terminal is not limited to be grounded gnd, can also be connect according to actual circuit Other voltages are received to meet the requirement of current control.

As shown in Figure 8 a, voltage regulation unit 3122 includes voltage-regulator diode DZ and current-limiting resistance R11, and the of current-limiting resistance R11 One end is connected with voltage-regulator diode DZ negative electrode, voltage-regulator diode DZ plus earth gnd, current-limiting resistance R11 the second end with FET J1 the second end is connected to receive electric current Iin.Therefore, in the presence of current source 3121, in voltage-regulator diode DZ With the reverse current Ir that anode is flowed to by negative electrode, voltage-regulator diode DZ is operated in reverse breakdown in the presence of reverse current Ir Area, therefore stable reference voltage V ref can be produced at voltage-regulator diode DZ negative electrode to be used as the first driving voltage V1.Make It can be produced with the electric current on current-limiting resistance R11 at the second end on the basis of the first driving voltage V1 in current-limiting resistance R11 Raw second driving voltage V2, and the second driving voltage V2 magnitude of voltage is higher than the first driving voltage V1.Current-limiting resistance R11 is used simultaneously In limitation voltage-regulator diode DZ reverse current Ir, to ensure the reference voltage V ref of voltage-regulator diode DZ offers stabilization.

As shown in Figure 8 a, amplifying unit 3123 is included by triode Q1 and triode the Q2 Darlington transistor formed and three poles Pipe Q3.Wherein, base stage of the triode Q1 base stage as Darlington transistor, triode Q1 emitter stage and triode Q2 base stage phase Even, triode Q1 colelctor electrode is connected with triode Q2 colelctor electrode using the colelctor electrode as Darlington transistor, triode Q2 hair Emitter-base bandgap grading is as Darlington transistor emitter stage to provide the first power supply signal VCC1；Triode Q3 base stage and the base stage phase of Darlington transistor Even to receive the first driving voltage V1, triode Q3 colelctor electrode is connected with the colelctor electrode of Darlington transistor to receive the second driving electricity V2 is pressed, triode Q3 emitter stage provides the second power supply signal VCC2.The multiplication factor of Darlington transistor is equal to triode Q1 and three The product of pole pipe Q2 multiplication factor, therefore Darlington transistor can export larger supply current, i.e. the first power supply signal VCC1 With stronger driving force, and the faster response speed that Darlington transistor has, therefore the first power supply signal VCC1 is used for pair Drive control circuit power supply in control circuit 3110 so that constant-current control circuit 3100 is when opening, in control circuit 3110 Drive control circuit can quickly obtain larger supply current, to prevent excessive ripple occur in the first power supply signal VCC1 It is dynamic, that is, avoid the operation irregularity caused by the first power supply signal VCC1 fluctuation of constant-current control circuit 3100.And control circuit Logic control circuit in 3110 can be powered using the second power supply signal VCC2, because logic control circuit need not be big Supply current, therefore only need the amplifying circuit i.e. achievable power supply to logical gate using triode Q3 or other structures.

Specifically, as shown in Figure 8 a, the base stage of Darlington transistor is connected with voltage-regulator diode DZ negative electrode is driven with receiving first Dynamic voltage V1, the colelctor electrode of Darlington transistor are connected with FET J1 the second end to receive the second driving voltage V2, Darlington Pipe is operated in amplification region.

In the case where the first power supply signal VCC1 magnitude of voltage is higher, as a kind of alternative embodiment, such as Fig. 8 b institutes Show, diode D01 is also included in voltage regulation unit 3122, and diode D01 anode is connected with voltage-regulator diode DZ negative electrode to connect Reference voltage V ref is received, diode D01 negative electrode provides the first driving voltage V1, the collection of Darlington transistor to the base stage of Darlington transistor Electrode is connected with FET J1 the second end to receive the second driving voltage V2.Diode D01 is as reverse resistance to voltage device work Make in forward conduction area, therefore when the first power supply signal VCC1 exceedes supply voltage Vhv voltage, diode D01 can be to prevent Only electric current pours in down a chimney the first end being connected into FET J1 with bus VBUS by the emitter stage of Darlington transistor, so as to prevent electric current Operation irregularity caused by pouring in down a chimney phenomenon.

The course of work of power supply circuit 3120 as figures 8 a and 8 b show is：When power supply circuit 3120 receives power supply electricity After pressing Vhv, current source 3121 provides electric current Iin, therefore reversely electricity is formed in the voltage-regulator diode DZ to be connected with current source 3121 Stream Ir causes voltage-regulator diode DZ to be operated in reverse breakdown area, and stable reference voltage is provided so as to voltage-regulator diode DZ negative electrode Vref, and provided surely by reference voltage V ref directly as the first driving voltage V1 (as shown in Figure 8 a) or by diode D01 The first fixed driving voltage V1 (as shown in Figure 8 b).Current-limiting resistance R11 limitations reverse current Ir size is to ensure the first driving Voltage V1 stabilization, and be used to provide the second driving voltage V2 higher than the first driving voltage V1 to ensure amplifying unit 3123 In Darlington transistor be operated in amplification region, the triode Q1 and Q2 that the first driving voltage V1 passes through in Darlington transistor form first and supplied Electric signal VCC1, then the first power supply signal VCC1=V1-VBE1-VBE2, wherein VBE1 are triode Q1 base stages and emitter stage Between voltage, VBE2 is the voltage between triode Q2 base stage and emitter stage.First driving voltage V1 passes through triode Q3 Form the second power supply signal VCC2, then the second power supply signal VCC2=V1-VBE3, wherein, during VBE3 triode Q3 base stage with Voltage between emitter stage.

It was found from above-mentioned analysis, there is voltage difference in the first power supply signal VCC1 and the second power supply signal VCC2, therefore, in order to The voltage difference between the first power supply signal VCC1 and the second power supply signal VCC2 is reduced or eliminated, as amplifying unit in Fig. 7 A kind of 3123 alternative embodiment, as shown in Figure 8 c, amplifying unit 3123 also include triode Q5, triode Q5 base stage and Colelctor electrode is connected together to diode structure, and triode Q5 base stage is connected with the base stage of Darlington transistor, triode Q5 transmitting Pole is connected with triode Q3 base stage, now, the second power supply signal VCC2=V1-VBE5-VBE3, when triode Q1, Q2, Q3, When Q5 uses identical size and technique, the first power supply signal VCC1 and the second power supply signal VCC2 are of substantially equal, i.e. VCC1= V1-VBE1-VBE2=V1-VBE5-VBE3=VCC2.

As shown in figure 9, power supply circuit 3120 is to the drive control circuit for needing large driven current density in control circuit 3110 It is powered respectively with the logic control circuit without large driven current density.Specifically, power supply circuit 3120 is respectively to control circuit Drive control circuit and logic control circuit in 3110 provide the first power supply signal VCC1 and the second power supply signal VCC2, its In, the first power supply signal VCC1 has stronger driving force, i.e., can provide larger supply current, the second power supply signal VCC2 only needs have normal driving force.In the second embodiment of above-mentioned power supply circuit, due to the first driving voltage V1 generates the first power supply signal VCC1 by two triodes Q1 and Q2, but the first driving voltage V1 is merely through three poles Pipe Q3 produces the second power supply signal VCC2, therefore the first power supply signal VCC1 and the second power supply signal VCC2 can be slightly different. In the 3rd embodiment of power supply circuit as shown in Figure 9, by the structure for improving voltage regulation unit, it is possible to achieve the first power supply is believed The regulation of voltage difference number between VCC1 and the second power supply signal VCC2.

Power supply circuit 3120 as shown in Figure 9 equally includes current source 3121, voltage regulation unit 3122 and amplifying unit 3123. Wherein, current source 3121 is used to produce electric current Iin according to supply voltage Vhv, and the output end of current source 3121 provides electric current Iin； Voltage regulation unit 3122 is used to provide the first driving voltage V1, the second driving voltage V2 and the 3rd driving voltage V3 according to electric current Iin； Amplifying unit 3123 produces the first power supply signal according to the first driving voltage V1, the second driving voltage V2 and the 3rd driving voltage V3 VCC1 and the second power supply signal VCC2.

Figure 10 a show a kind of circuit diagram of specific embodiment of the power supply circuit shown in Fig. 9.Figure 10 b show Fig. 9 institutes The circuit diagram of another specific embodiment of the power supply circuit shown.

As a kind of specific embodiment of power supply circuit 3120, as shown in Figure 10 a, current source 3121 and above-mentioned power supply unit Second embodiment in current source structure it is identical, will not be repeated here.

As shown in Figure 10 a, voltage regulation unit 3122 includes voltage-regulator diode DZ, current-limiting resistance R11 and triode Q4, current limliting Resistance R11 first end is connected with triode Q4 base stage and colelctor electrode, and triode Q4 emitter stage is with voltage-regulator diode DZ's Negative electrode is connected, voltage-regulator diode DZ plus earth gnd, current-limiting resistance R11 the second end and FET J1 the second end phase Connect to receive electric current Iin.Therefore, have in the presence of current source 3121, in voltage-regulator diode DZ and anode is flowed to by negative electrode Reverse current Ir, voltage-regulator diode DZ are operated in reverse breakdown area, therefore voltage-regulator diode DZ in the presence of reverse current Ir Negative electrode at can produce stable reference voltage V ref to be used as the 3rd driving voltage V3.The electric current acted on triode Q4 Colelctor electrode that can be in triode Q4 on the basis of reference voltage V ref produces the first driving voltage V1=Vref+VBE4, its Middle VBE4 is the voltage between the base stage of triode and emitter stage；The electric current acted on current-limiting resistance R11 can drive first Produce the second driving voltage V2 on the basis of dynamic voltage V1 at current-limiting resistance R11 the second end, and the second driving voltage V2 Magnitude of voltage is higher than the first driving voltage V1.Current-limiting resistance R11 is used for the reverse current Ir for limiting voltage-regulator diode DZ simultaneously, to protect Demonstrate,prove the stabilization for the reference voltage V ref that voltage-regulator diode DZ is provided.

As shown in Figure 10 a, amplifying unit 3123 includes the Darlington transistor and three being made up of triode Q1 and triode Q2 Pole pipe Q3.In the present embodiment, amplifying unit 3123 substantially with the amplifying unit phase in the second embodiment of above-mentioned power supply circuit Together, difference is：The base stage of Darlington transistor receives the first driving voltage V1, and triode Q3 base stage receives the 3rd driving electricity V3 is pressed, therefore, the first power supply signal VCC1=V1-VBE1-VBE2=Vref+VBE4-VBE1-VBE2, the second power supply signal VCC2=V3-VBE3=Vref-VBE3, therefore the triode Q4 in voltage regulation unit 3122 can reduce the first power supply signal VCC1 With the difference between the second power supply signal VCC2.When triode Q1 to Q4 technique is identical with size, VBE1=VBE2= VBE3=VBE4, therefore the first power supply signal VCC1 magnitude of voltage is equal to the second power supply signal VCC2 magnitude of voltage, so as to power Power supply of the circuit 3120 to control circuit 3110 is unanimously and stably.In certain embodiments, triode Q4 can also be replaced directly For diode.

In the case where the first power supply signal VCC1 and the second power supply signal VCC2 magnitude of voltage are higher, substituted as one kind Embodiment, as shown in fig. lob, diode D02 and D03, diode D03 anode and voltage stabilizing are also included in voltage regulation unit 3122 Diode DZ negative electrode is connected, and diode D03 negative electrode provides the 3rd driving voltage V3, diode to triode Q3 base stage D02 anode is connected with triode Q4 colelctor electrode and base stage, and diode D02 negative electrode provides the first driving voltage V1 and extremely reaches woods The base stage of pipe.Here diode D02 and D03 is operated in forward conduction area as reverse resistance to voltage device, therefore when the first power supply When signal VCC1 and the second power supply signal VCC2 exceedes supply voltage Vhv, diode D02 and D03 can prevent electric current by three poles The emitter stage of pipe and Darlington transistor pours in down a chimney the first end being connected into FET J1 with bus VBUS, so as to prevent electric current from pouring in down a chimney Operation irregularity caused by phenomenon.

As shown in Figure 11 and Fig. 4, the voltage Vdrv at the driving port DRV of constant-current control circuit 3100 occurs significantly During decline, less ripple only occurs in first power supply signal VCC1 caused by the power supply circuit 3120 in constant-current control circuit 3100 It is dynamic, so as to which control circuit 3110 can provide enough firing currents to power tube M1, so as to ensure that constant-current control circuit 3100 normal work, and restarting for constant-current control circuit 3100 will not be caused because of low-voltage protection.

It should be noted that the various embodiments described above only describe the LED drive system with buck topology structure, but In further embodiments, LED drive system provided by the utility model can have other kinds of topological structure, such as rise Buck topology structure.In the various embodiments described above, power supply circuit 3120, control circuit 3110 and power tube can be integrated in In one current constant control chip, the electric capacity without external big capacitance.In the embodiment of above-mentioned each power supply unit, diode To be substituted by the triode of base stage and colelctor electrode short circuit, the base stage of the triode equivalent to diode anode, the triode Negative electrode of the emitter stage equivalent to diode.

According to above-mentioned various embodiments, power supply circuit provided by the utility model employs voltage-regulator diode, Neng Gouzhi Connect and stable supply voltage is produced according to the direct current of high pressure, and as a result of Darlington transistor, therefore can provide larger Supply current to prevent supply voltage to be pulled low；Constant-current control circuit provided by the utility model and LED drive system need not Stable power supply electricity can be produced according to the direct current of high pressure in the electric capacity of the external big capacitance of the power port of constant-current control circuit Pressure is influenceed without the switch motion by power tube, so as to ensure that the normal work of constant-current control circuit, eliminates external electricity Hold, simplify LED drive system, and saved cost.In some preferred embodiments, power supply circuit can produce two electricity The first power supply signal of pressure value identical and the second power supply signal, so as to utilize the first power supply signal to the drive in constant-current control circuit The stronger supply current of dynamic control circuit output simultaneously utilizes the second power supply signal to the logic control circuit in constant-current control circuit Normal supply current is exported, can prevent the caused influence of fluctuations second on the first power supply signal of drive control circuit from powering Signal, further ensure the stable power-supplying of constant-current control circuit.

The utility model discloses a kind of power supply circuit, constant-current control circuit and LED drive system, and retouch referring to the drawings Specific embodiment of the present utility model and effect are stated.It is to be understood that above-described embodiment is simply to the utility model Explanation, rather than to limitation of the present utility model.According to embodiment of the present utility model as described above, these embodiments are simultaneously There is no the details that detailed descriptionthe is all, it is only described specific embodiment also not limit the utility model.Obviously, retouched more than State, can make many modifications and variations.This specification is chosen and specifically describes these embodiments, is to preferably explain this reality With new principle and practical application so that skilled artisan can well using the utility model and Modification on the basis of the utility model uses.Therefore, any utility model without departing from the utility model in essence scope Create, modification including but not limited to peripheral structure building form, the change to the local structure of circuit, the class to component The replacement of type or model, and the replacement or modification etc. of other unsubstantialities, each fall within scope of protection of the utility model.

Claims

1. a kind of LED drive system, it is used to produce driving current to drive light emitting diode, it is characterised in that the LED drives Dynamic system includes：

Rectifier bridge, alternating voltage being received between its first input end and the second input, its first output end provides DC voltage, Its second output head grounding；

Constant-current control circuit, first output end of its power port and the rectifier bridge are joined directly together to receive the direct current Pressure, the constant-current control circuit include power supply circuit, control circuit and power tube, the power supply circuit and the power port phase Even so that the DC voltage directly is converted into the first power supply signal, the control circuit is connected with root with the power supply circuit Switch controlling signal is produced according to the first power supply signal, the control terminal of the power tube is connected with the control circuit so that described The turn-on and turn-off of power tube are controlled by the switch controlling signal；

Drive circuit, it is connected with the first output end of the rectifier bridge and the first end of the power tube and the second end, uses In the generation driving current.

2. LED drive system according to claim 1, it is characterised in that the power supply circuit includes：

Current source, for producing DC current according to the DC voltage, and it is described straight in the output end offer of the current source Flow electric current；

Voltage regulation unit, for producing the first driving voltage and the second driving voltage according to the DC current；And

Amplifying unit, for producing first power supply signal according to first driving voltage and second driving voltage.

3. LED drive system according to claim 2, it is characterised in that the voltage regulation unit include voltage-regulator diode and Current-limiting resistance, the current-limiting resistance is connected between the output end of the current source and the negative electrode of the voltage-regulator diode, described The negative electrode of voltage-regulator diode provides stable reference voltage, and the voltage regulation unit is used for according to the reference voltage and the current limliting The voltage at resistance both ends produces first driving voltage and second driving voltage.

4. LED drive system according to claim 2, it is characterised in that the current source includes FET, the field The control terminal of effect pipe receives bias voltage, and the first end of the FET is connected with the power port, the field-effect Second end of pipe provides the DC current.

5. LED drive system according to claim 4, it is characterised in that the FET is N-channel junction field Pipe, the bias voltage are equal to 0V.

6. LED drive system according to claim 3, it is characterised in that the plus earth of the voltage-regulator diode.

7. LED drive system according to claim 3, it is characterised in that the first end of the current-limiting resistance and the electricity The output end in stream source is connected to provide second driving voltage.

8. LED drive system according to claim 7, it is characterised in that the amplifying unit includes the first triode, institute The base stage for stating the first triode receives first driving voltage, and the colelctor electrode of first triode receives second driving Voltage, the emitter stage of first triode provide first power supply signal.

9. LED drive system according to claim 7, it is characterised in that the amplifying unit includes Darlington transistor, described The base stage of Darlington transistor receives first driving voltage, and the colelctor electrode of the Darlington transistor receives second driving voltage, The emitter stage of the Darlington transistor provides first power supply signal.

10. LED drive system according to claim 9, it is characterised in that the Darlington transistor include the second triode and 3rd triode, second triode and the 3rd triode are NPN type, described in the base stage conduct of second triode The base stage of Darlington transistor, the emitter stage of second triode are connected with the base stage of the 3rd triode, the three or three pole Emitter stage of the emitter stage of pipe as the Darlington transistor, the collection of the colelctor electrode of second triode and the 3rd triode Electrode is connected using the colelctor electrode as the Darlington transistor.

11. LED drive system according to claim 7, it is characterised in that the second end of the current-limiting resistance with it is described steady The negative electrode of diode is pressed to be connected to regard the reference voltage as first driving voltage.

12. LED drive system according to claim 7, it is characterised in that the voltage regulation unit also includes the one or two pole Pipe, the anode of first diode is connected with the negative electrode of the second end of the current-limiting resistance, the voltage-regulator diode, and described the The negative electrode of one diode provides first driving voltage.

13. LED drive system according to claim 9, it is characterised in that the amplifying unit also includes the four or three pole Pipe, the base stage of the 4th triode is connected with the base stage of the Darlington transistor, the emitter stage offer of the 4th triode the Two power supply signals to the control circuit, the colelctor electrode of the 4th triode is connected with the colelctor electrode of the Darlington transistor.

14. LED drive system according to claim 9, it is characterised in that the amplifying unit also includes the 4th triode With the 5th triode, the base stage and colelctor electrode of the 4th triode are connected and are connected with the base stage of the Darlington transistor, described The emitter stage of 4th triode is connected with the base stage of the 5th triode, and the emitter stage of the 5th triode provides second and supplied Electric signal, the colelctor electrode of the 5th triode are connected with the colelctor electrode of the Darlington transistor.

15. LED drive system according to claim 9, it is characterised in that the voltage regulation unit is always according to benchmark electricity Pressure produces the 3rd driving voltage, and the amplifying unit produces the second power supply signal to the control according to the 3rd driving voltage Circuit.

16. LED drive system according to claim 15, it is characterised in that the voltage regulation unit also includes the six or three pole Pipe, the base stage of the 6th triode are connected with colelctor electrode and are connected with the second end of the current-limiting resistance and provide described first Driving voltage, the emitter stage of the 6th triode, which is connected with the negative electrode of the voltage-regulator diode and provides the described 3rd, drives electricity Pressure.

17. LED drive system according to claim 15, it is characterised in that the voltage regulation unit also includes the six or three pole Pipe, the second diode and the 3rd diode, the base stage and colelctor electrode of the 6th triode, the second end of the current-limiting resistance with The anode of second diode is connected, negative electrode offer first driving voltage of second diode, and the described 6th 3 The emitter stage of pole pipe, the negative electrode of the voltage-regulator diode are connected with the anode of the 6th triode, the 3rd diode Negative electrode provides the 3rd driving voltage.

18. LED drive system according to claim 15, it is characterised in that the amplifying unit also includes the seven or three pole Pipe, the base stage of the 7th triode receive the 3rd driving voltage, and the emitter stage of the 7th triode provides described the Two power supply signals, the colelctor electrode of the 7th triode are connected with the colelctor electrode of the Darlington transistor.

19. according to the LED drive system described in any one of claim 13 to 18, it is characterised in that the control circuit includes Drive control circuit and logic control circuit, the logic control circuit receive second power supply signal to carry out logic fortune Calculate, the drive control circuit receives first power supply signal and produces institute according to the operation result of the logic control circuit State switch controlling signal.

20. LED drive system according to claim 1, it is characterised in that the drive circuit have the first output end and Second output end, first output end are used to be connected with the anode of LED string, and second output end is used for and the LED The negative electrode of lamp string is connected, and the drive circuit includes inductance, output resistance, sampling resistor, the first electric capacity and fly-wheel diode,

The output resistance and first electric capacity are parallel between first output end and second output end, the electricity The first end of sense is connected with the second output end of the drive circuit, the second end of the inductance and the fly-wheel diode Anode is connected with the first end of the power tube, the first output end phase of the negative electrode of the fly-wheel diode and the drive circuit Even to receive the DC voltage, the first end of the sampling resistor is connected with the second end of the power tube, the sampling electricity The second end ground connection of resistance.

21. LED drive system according to claim 1, it is characterised in that the LED drive system also includes the second electricity Hold, second capacitance connection is between the first output end and the second output end of the rectifier bridge to be pressed into the direct current Row filtering.

22. LED drive system according to claim 1, it is characterised in that the power supply in the constant-current control circuit Circuit, the control circuit and the power tube are integrated in same chip.

23. a kind of constant-current control circuit, it is characterised in that the constant-current control circuit has the driving for being used for providing control electric current Port, the sample port for receiving sampled signal, grounding ports and power port for ground connection, the power port are straight Reception DC voltage, the constant-current control circuit include：

Power supply circuit, it is connected with the power port so that the DC voltage directly is converted into the first power supply signal；

Control circuit, it is connected with the power supply circuit to produce switch controlling signal according to the first power supply signal；And

Power tube, its first end and the second end are connected with the driving port and the sample port respectively, its control terminal and institute State control circuit to be connected, the turn-on and turn-off of the power tube are controlled by the switch controlling signal.

24. constant-current control circuit according to claim 23, it is characterised in that the power supply circuit includes：

25. constant-current control circuit according to claim 24, it is characterised in that the voltage regulation unit includes voltage-regulator diode And current-limiting resistance, the current-limiting resistance are connected between the output end of the current source and the negative electrode of the voltage-regulator diode, institute The negative electrode for stating voltage-regulator diode provides stable reference voltage, and the voltage regulation unit is used for according to the reference voltage and the limit The voltage at leakage resistance both ends produces first driving voltage and second driving voltage.

26. constant-current control circuit according to claim 24, it is characterised in that the current source includes FET, institute The control terminal for stating FET receives bias voltage, and the first end of the FET is connected with the power port, the field Second end of effect pipe provides the DC current.

27. constant-current control circuit according to claim 26, it is characterised in that the FET is N-channel junction type field Effect pipe, the bias voltage are equal to 0V.

28. constant-current control circuit according to claim 25, it is characterised in that the plus earth of the voltage-regulator diode.

29. constant-current control circuit according to claim 25, it is characterised in that the first end of the current-limiting resistance with it is described The output end of current source is connected to provide second driving voltage.

30. constant-current control circuit according to claim 29, it is characterised in that the amplifying unit includes the one or three pole Pipe, the base stage of first triode receive first driving voltage, and the colelctor electrode of first triode receives described the Two driving voltages, the emitter stage of first triode provide first power supply signal.

31. constant-current control circuit according to claim 29, it is characterised in that the amplifying unit includes Darlington transistor, The base stage of the Darlington transistor receives first driving voltage, and the colelctor electrode of the Darlington transistor receives the second driving electricity Pressure, the emitter stage of the Darlington transistor provide first power supply signal.

32. constant-current control circuit according to claim 31, it is characterised in that the Darlington transistor includes the second triode With the 3rd triode, second triode and the 3rd triode are NPN type, and the base stage of second triode is as institute The base stage of Darlington transistor is stated, the emitter stage of second triode is connected with the base stage of the 3rd triode, and the described 3rd 3 Emitter stage of the emitter stage of pole pipe as the Darlington transistor, the colelctor electrode of second triode and the 3rd triode Colelctor electrode is connected using the colelctor electrode as the Darlington transistor.

33. constant-current control circuit according to claim 29, it is characterised in that the second end of the current-limiting resistance with it is described The negative electrode of voltage-regulator diode is connected to regard the reference voltage as first driving voltage.

34. constant-current control circuit according to claim 29, it is characterised in that the voltage regulation unit also includes the one or two pole Pipe, the anode of first diode is connected with the negative electrode of the second end of the current-limiting resistance, the voltage-regulator diode, and described the The negative electrode of one diode provides first driving voltage.

35. constant-current control circuit according to claim 31, it is characterised in that the amplifying unit also includes the four or three pole Pipe, the base stage of the 4th triode is connected with the base stage of the Darlington transistor, the emitter stage offer of the 4th triode the Two power supply signals to the control circuit, the colelctor electrode of the 4th triode is connected with the colelctor electrode of the Darlington transistor.

36. constant-current control circuit according to claim 31, it is characterised in that the amplifying unit also includes the four or three pole Pipe and the 5th triode, the base stage and colelctor electrode of the 4th triode are connected and are connected with the base stage of the Darlington transistor, institute The emitter stage for stating the 4th triode is connected with the base stage of the 5th triode, and the emitter stage of the 5th triode provides second Power supply signal, the colelctor electrode of the 5th triode are connected with the colelctor electrode of the Darlington transistor.

37. constant-current control circuit according to claim 31, it is characterised in that the voltage regulation unit is always according to the benchmark Voltage produces the 3rd driving voltage, and the amplifying unit produces the second power supply signal to the control according to the 3rd driving voltage Circuit processed.

38. the constant-current control circuit according to claim 37, it is characterised in that the voltage regulation unit also includes the six or three pole Pipe, the base stage of the 6th triode are connected with colelctor electrode and are connected with the second end of the current-limiting resistance and provide described first Driving voltage, the emitter stage of the 6th triode, which is connected with the negative electrode of the voltage-regulator diode and provides the described 3rd, drives electricity Pressure.

39. the constant-current control circuit according to claim 37, it is characterised in that the voltage regulation unit also includes the six or three pole Pipe, the second diode and the 3rd diode, the base stage and colelctor electrode of the 6th triode, the second end of the current-limiting resistance with The anode of second diode is connected, negative electrode offer first driving voltage of second diode, and the described 6th 3 The emitter stage of pole pipe, the negative electrode of the voltage-regulator diode are connected with the anode of the 6th triode, the 3rd diode Negative electrode provides the 3rd driving voltage.

40. the constant-current control circuit according to claim 37, it is characterised in that the amplifying unit also includes the seven or three pole Pipe, the base stage of the 7th triode receive the 3rd driving voltage, and the emitter stage of the 7th triode provides described the Two power supply signals, the colelctor electrode of the 7th triode are connected with the colelctor electrode of the Darlington transistor.

41. according to the constant-current control circuit described in any one of claim 35 to 40, it is characterised in that the control circuit includes Drive control circuit and logic control circuit, the logic control circuit receive second power supply signal to carry out logic fortune Calculate, the drive control circuit receives first power supply signal and produces institute according to the operation result of the logic control circuit State switch controlling signal.

42. the constant-current control circuit according to claim 23, it is characterised in that the power supply in the constant-current control circuit Circuit, the control circuit and the power tube are integrated in same chip.