CN104470095B - Ripple rejection LED drive circuit - Google Patents
Ripple rejection LED drive circuit Download PDFInfo
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- CN104470095B CN104470095B CN201410686190.7A CN201410686190A CN104470095B CN 104470095 B CN104470095 B CN 104470095B CN 201410686190 A CN201410686190 A CN 201410686190A CN 104470095 B CN104470095 B CN 104470095B
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Abstract
A ripple rejection LED drive circuit comprises an output end, an output voltage feedback end, a control loop for controlling the duty cycle of switching of a power tube according to the output voltage feedback end, and the power tube connected with the control loop. The ripple rejection LED drive circuit further comprises a first reference voltage, an LDO and a pass transistor connected between the power tube and a load LED, wherein the control end of the pass transistor is connected with the output end of the LDO; the two input ends of the LDO are connected with the common end of the pass transistor and a CS sampling resistor and the first reference voltage respectively. The ripple rejection LED drive circuit further comprises an output capacitor connected with the output end, and the common end of the pass transistor and the load LED serves as the output voltage feedback end. By the adoption of the control mode of the LDO and the pass transistor, pressure-drop fluctuation on the load LED caused by output voltage fluctuation is eliminated, output current of the LED is more stable, the output voltage feedback end voltage input to the internal control loop is constant, and power loss of the control loop is reduced.
Description
Technical field
The invention belongs to IC design field, is related to Switching Power Supply, particularly a kind of Ripple Suppression LED drives electricity
Road.
Background technology
With the more and more harsh requirement of the development and LED drive power of high-voltage LED lamp bead to cost and volume, it is low into
This high voltage and constant current Linear Driving method obtains certain technology innovation and application in the past few years.But current Linear Driving side
All the time there is low reliability in method, have high demands matching to input voltage and output lamp bead, it is impossible to bear input with output voltage significantly
The shortcomings of fluctuation, hinder Linear Driving method and be really applied in the production in enormous quantities and safety applications of LED illumination.
Fig. 1 provides at present on the market common without the linear driving method of stroboscopic.20 is the linear driving chip of constant current, chip
Power supply is provided by VDD, one high pressure LDO of chip internal（Linear voltage regulator）, the electric current of CS pins outer meeting resistance setting LED.This
In be 300mV/15ohm=20mA.The method requires that input voltage must be highly stable, and the voltage for exporting LED is connect with Vbus voltages
Closely.In this example, Vbus average voltages are about 220V*1.414-5V=306V, then the loss of chip LDO is then (306V-250V) *
20mA=1.12W, this loss heating will be very big challenge to chip.If putting into, hot environment is aging to be easy to generation
Failure.Along with power network fluctuation and the rational change range of LED lamp bead, these extra pressure reduction can also produce on LDO bigger again
Loss.Some linear chips increased overpower and over-temperature protection etc. at present, and its principle is all the output by reducing LED
Electric current is also result in and exports luminous dimmed or flicker etc. to realize the protection to chip.So this simple Linear Driving side
Method does not possess practical feasibility.
The content of the invention
To overcome the shortcomings of that existing LED drive chip is existing using linear voltage regulator blood pressure lowering control, the invention discloses
A kind of Ripple Suppression LED drive circuit.
Ripple Suppression LED drive circuit of the present invention, including ac voltage input, drive circuit outfan, output
Pressure feedback port, the control loop that power tube duty cycle of switching is controlled according to output voltage feedback end and it is connected with control loop
Power tube；The adjustment pipe for also including the first reference voltage, LDO and being connected between power tube and load LED, and it is connected to power
CS sampling resistors between pipe and adjustment pipe, the control end of the adjustment pipe are connected with LDO outfans, and two of the LDO are defeated
Common port and the first reference voltage with CS sampling resistors are managed in connection adjustment respectively to enter end；The power tube and CS sampling resistors
Common port also includes the output capacitance being connected with drive circuit outfan, the output electricity as the drive circuit outfan
The common port of the other end ground connection of appearance, the adjustment pipe and load LED is used as output voltage feedback end.
Specifically, the control loop includes logic drive circuit, PWM comparators, error amplifier, the second reference voltage
And triangular-wave generator, two inputs of the error amplifier connect the second reference voltage and output voltage feedback respectively
End, two inputs of the PWM comparators connect the outfan of error amplifier and triangular-wave generator, the triangle respectively
Wave producer be connected to the ac voltage input outfan and relatively between divider resistance string, partial pressure electricity
Outfan of the common port of two resistance as the triangular-wave generator in resistance string, the outfan connection of the PWM comparators are patrolled
Collect drive circuit, the outfan connection power tube control end of the logic drive circuit.
Preferably, the outfan of the error amplifier and relatively between be connected with compensating electric capacity.
Further, the adjustment pipe is PMOS or PNP pipe.
Further, first reference voltage and the second reference voltage are produced by bandgap voltage reference output voltage partial pressure
It is raw.
Using Ripple Suppression LED drive circuit of the present invention, by with reference to switched-capacitor circuit and linear constant current
LDO, rechargeable energy path turn-on and turn-off of the switching capacity control input to output capacitance, LDO and adjustment pipe absorb output electricity
Embossing ripple, realizes the ripple-free constant current output to LED, and realizes transmission energy supplying on demand.
Description of the drawings
Fig. 1 is current existing high-voltage linear drive scheme structural representation；
Fig. 2 illustrates a kind of specific embodiment structural representation of the present invention.
Specific embodiment
Below in conjunction with the accompanying drawings, the specific embodiment of the present invention is described in further detail.
Ripple Suppression LED drive circuit of the present invention, including ac voltage input, drive circuit outfan, output
Pressure feedback port, driving loop control and the power tube being connected with driving loop control, also including the first reference voltage, LDO and
The adjustment pipe being connected between power tube and load LED, and the CS sampling resistors being connected between power tube and adjustment pipe, it is described
The control end of adjustment pipe is connected with LDO outfans, and two inputs of the LDO connect adjustment pipe and CS sampling resistors respectively
Common port and the first reference voltage.The common port of the power tube and CS sampling resistors is gone back as the drive circuit outfan
Including the output capacitance being connected with drive circuit outfan, the other end of the output capacitance is grounded, and the adjustment is managed and load
The common port of LED is used as output voltage feedback end.
As shown in Fig. 2 system is divided into two large divisions, high-voltage circuit breaker pipe MN1 and output capacitance COUT form switch electricity
Hold the turn-on and turn-off that control VBUS is transferred to Cout energy pathways.LDO and adjustment pipe MP1 is control LED output currents, it with
The string series connection of output LED, the energy of LDO and LED conductings is from COUT.The anode LED+ of the drain terminal connection load LED strip of MP1,
LED+ can reflect the size of energy on COUT electric capacity in real time, and the positive input of LDO is connected with the first reference voltage.Adjustment pipe can
Think PMOS or PNP pipe.
Using above-mentioned LDO and the control mode of adjustment pipe, eliminate on the load LED caused due to output voltage fluctuation
Fluctuation of pressure drop, makes LED output currents more stable, while making the output voltage feedback terminal voltage for being input to Inner Control Loop permanent
It is fixed, reduce the power attenuation of control loop.
Specifically, the control loop includes logic drive circuit, PWM comparators, error amplifier, the second reference voltage
And triangular-wave generator, two inputs of the error amplifier connect the second reference voltage and output voltage feedback respectively
End, the triangular-wave generator be connected to the ac voltage input outfan and relatively between divider resistance
String, outfan of the common port of two resistance as the triangular-wave generator in the divider resistance string, the PWM comparators
Two inputs connect the outfan of error amplifier and triangular-wave generator, the outfan connection of the PWM comparators respectively
Logic drive circuit, the outfan connection power tube control end of the logic drive circuit.Wherein the first reference voltage V REF1 and
Second reference voltage V REF2 is produced by bandgap voltage reference output voltage partial pressure, and partial pressure can adopt conventional electric resistance partial pressure
Form.
As shown in Fig. 2 being output voltage feedback end feed back input to error amplifier and the first reference voltage ratio by LED+
Output voltage error amplifier COMP is produced relatively；A kind of error amplifier of crest constant pressure, the i.e. mistake are used in present case
The function of difference amplifier is that the crest of constant LED+ triangular waves is stable near a steady state value.COMP voltages and triangular-wave generator
The constant frequency triangle wave voltage of output is compared the ON time Ton for producing power tube MN1.COMP is higher, and the Ton times are longer,
The energy for being transferred to output capacitance COUT is more, and the time of power tube MN1 conductings is only led when VBUS and COUT voltages are close
It is logical.Whole system forms closed loop control, and the energy according to needed for LED outputs realizes the real-time of the ON time to COUT transmission energies
Control.
This closed loop energy hole realize the loss of control circuit no longer with input voltage, output voltage is relevant, with defeated
Enter voltage for 220V civil powers, output voltage is used to drive 28-60 LED light emitting diode, change of the output voltage in 80-200V
Scope build-in test, the loss of control loop only change 0.2W or so.It is considered that loss is substantially unrelated with output voltage.
Preferably, the outfan of the error amplifier and relatively between be connected with compensating electric capacity, can be control ring
Road provides a dominant pole, the stability of reinforcing feedback control.The default relatively low electricity of control circuit itself is represented relatively
Position, can be with the current potential being utterly directly connected to, or other are stable.
Compared with prior art, the present invention can produce following beneficial effect：
Using above-mentioned LDO and the control mode of adjustment pipe, no matter it is input into or how output voltage changes, make the electricity on LED+
Pressure is constant all the time to be equal to the first reference voltage, eliminates the fluctuation of pressure drop on the load LED caused due to output voltage fluctuation, makes
LED output currents are more stable, while making to be input to the output voltage feedback end voltage constant of Inner Control Loop, reduce control
The power attenuation of loop processed.
The present invention finally realizes a kind of linear LED illumination drive circuit, make loss in control loop no longer with input
Voltage and output voltage have strong connection, it is no longer necessary to which LED output voltages are matched with input voltage.This also causes this framework to claim
The linear LED illumination drive scheme of low cost really to can be universally used in various different high-voltage LED lamp beads.
Previously described each preferred embodiment for the present invention, if the preferred implementation in each preferred embodiment
It is not substantially contradictory or premised on a certain preferred implementation, each preferred implementation can any stack combinations
Use, the design parameter in the embodiment and embodiment merely to clearly state inventor invention proof procedure, and
It is not used to limit the scope of patent protection of the present invention, the scope of patent protection of the present invention is still defined by its claims, all
It is the equivalent structure change made with the description and accompanying drawing content of the present invention, should be included in the protection model of the present invention in the same manner
In enclosing.
Claims (3)
1. Ripple Suppression LED drive circuit, including ac voltage input, drive circuit outfan, output voltage feedback end, root
The power tube being connected according to the control loop of output voltage feedback end control power tube duty cycle of switching and with control loop；
Characterized in that, also including the first reference voltage, LDO and being connected to power tube and load the adjustment pipe between LED and company
The CS sampling resistors being connected between power tube and adjustment pipe, the control end of the adjustment pipe are connected with LDO outfans, the LDO
Two inputs connect adjustment pipe and the common port of CS sampling resistors and the first reference voltage respectively；The power tube is adopted with CS
The common port of sample resistance also includes the output capacitance being connected with drive circuit outfan, institute as the drive circuit outfan
The common port of the other end ground connection of output capacitance, the adjustment pipe and load LED is stated as output voltage feedback end；
The control loop includes that logic drive circuit, PWM comparators, error amplifier, the second reference voltage and triangular wave are sent out
Raw device, two inputs of the error amplifier connect the second reference voltage and output voltage feedback end, the triangle respectively
Wave producer be connected to the ac voltage input outfan and relatively between divider resistance string, partial pressure electricity
Outfan of the common port of two resistance as the triangular-wave generator in resistance string, two inputs point of the PWM comparators
Not Lian Jie error amplifier and triangular-wave generator outfan, the outfan connection logic drive circuit of the PWM comparators,
The outfan connection power tube control end of the logic drive circuit；
The outfan of the error amplifier and relatively between be connected with compensating electric capacity.
2. Ripple Suppression LED drive circuit as claimed in claim 1, it is characterised in that the adjustment pipe is PMOS or PNP
Pipe.
3. Ripple Suppression LED drive circuit as claimed in claim 1, it is characterised in that first reference voltage and second
Reference voltage is produced by bandgap voltage reference output voltage partial pressure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410686190.7A CN104470095B (en) | 2014-11-26 | 2014-11-26 | Ripple rejection LED drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410686190.7A CN104470095B (en) | 2014-11-26 | 2014-11-26 | Ripple rejection LED drive circuit |
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| Publication Number | Publication Date |
|---|---|
| CN104470095A CN104470095A (en) | 2015-03-25 |
| CN104470095B true CN104470095B (en) | 2017-04-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410686190.7A Active CN104470095B (en) | 2014-11-26 | 2014-11-26 | Ripple rejection LED drive circuit |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104780684A (en) * | 2015-04-20 | 2015-07-15 | 成都岷创科技有限公司 | DC conversion LED drive circuit |
| CN107911907B (en) * | 2017-12-11 | 2020-03-06 | 矽力杰半导体技术(杭州)有限公司 | LED drive circuit, power converter and control method |
| CN109947163B (en) | 2018-09-04 | 2020-08-07 | 合肥鑫晟光电科技有限公司 | Digital voltage stabilizer and voltage stabilizing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8334662B2 (en) * | 2009-09-11 | 2012-12-18 | Iwatt Inc. | Adaptive switch mode LED driver |
| CN101707837B (en) * | 2009-11-27 | 2014-01-22 | 上海晶丰明源半导体有限公司 | LED drive circuit of source driver with change of output voltage and induction quantity keeping constant current |
| CN102223741B (en) * | 2010-04-14 | 2015-01-21 | 日隆电子股份有限公司 | Control circuit and control method applied in light-emitting diode (LED) driver |
| CN102655706B (en) * | 2012-05-04 | 2015-03-11 | 成都芯源系统有限公司 | Light emitting element driver, control circuit and control method thereof |
| CN204392623U (en) * | 2014-11-26 | 2015-06-10 | 成都岷创科技有限公司 | Ripple suppression led driver |
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| CN104470095A (en) | 2015-03-25 |
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| TA01 | Transfer of patent application right |
Effective date of registration: 20160420 Address after: 201204 Zhang Heng road Shanghai, Pudong New Area Zhangjiang hi tech Park Lane 666 No. 2 floor 504-511 room 5 Applicant after: Shanghai Bright Power Semiconductor Co.,Ltd. Address before: West high tech Zone Fucheng Road in Chengdu city of Sichuan province 610000 399 No. 6 Building 1 unit 10 floor No. 2 Applicant before: Chengdu Minchuang Science & Technology Co., Ltd. |
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Address after: 5 room 504-511, room 2, Lane 666, Zhang Heng Road, Pudong New Area, China (Shanghai) free trade zone, Shanghai, China () Applicant after: Shanghai semiconducto Limited by Share Ltd Address before: 201204 Zhang Heng road Shanghai, Pudong New Area Zhangjiang hi tech Park Lane 666 No. 2 floor 504-511 room 5 Applicant before: Shanghai Bright Power Semiconductor Co.,Ltd. |
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