CN104955205A - Field effect transistor step-down LED drive circuit with power correction - Google Patents

Field effect transistor step-down LED drive circuit with power correction Download PDF

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Publication number
CN104955205A
CN104955205A CN201410125624.6A CN201410125624A CN104955205A CN 104955205 A CN104955205 A CN 104955205A CN 201410125624 A CN201410125624 A CN 201410125624A CN 104955205 A CN104955205 A CN 104955205A
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CN
China
Prior art keywords
described
resistor
effect transistor
end
bridge rectifier
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Application number
CN201410125624.6A
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Chinese (zh)
Inventor
郑榕彬
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郑榕彬
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Priority to CN201410125624.6A priority Critical patent/CN104955205A/en
Publication of CN104955205A publication Critical patent/CN104955205A/en

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Abstract

The invention relates to a field effect transistor step-down LED drive circuit with power correction. The field effect transistor step-down LED drive circuit is composed of a full-bridge rectification circuit (1), a voltage detection circuit (2) and an output control circuit (3). According to the drive circuit, output current control is performed via a voltage reference chip, output current is corrected by detecting input voltage and input power is automatically corrected so that a problem that power of a non-switch type LED drive circuit changes along with change of input voltage can be effectively solved.

Description

A kind of field-effect transistor step-down LED drive circuit with power correction

Technical field

The present invention relates in general to LED illumination circuit field, particularly non-switch formula LED drive circuit.

Background technology

Current non-switch formula LED drive circuit generally has capacitor step-down, resistance buck, current regulator diode buck, field-effect transistor buck etc.When these modes all exist input voltage change, input power follows the problem of change.Non-linear due to LED, input voltage change causes the change of power larger, impacts the useful life of LED.

Summary of the invention

The invention provides a kind of field-effect transistor step-down LED drive circuit with power correction, it comprises full bridge rectifier, voltage detecting circuit and output control circuit, input voltage is converted to all positive half cycles and exports by wherein said full bridge rectifier, and the input voltage after rectification is provided to described output control circuit and described voltage detecting circuit, wherein said voltage detecting circuit detects the variable quantity of the input voltage after described rectification, and this variable quantity is provided to described output control circuit, and wherein said output control circuit detects output feedack electric current, and adjust output current according to described output feedack electric current with from the described variable quantity that described voltage detecting circuit receives, to keep the constant of input power.

This LED drive circuit realizes input power auto modification, effectively solves the problem that input voltage change causes changed power, makes the work of LED more stable, ensure LED useful life.

Accompanying drawing explanation

Fig. 1 is schematic block circuit diagram according to one example embodiment.

Fig. 2 is more detailed circuit theory diagrams according to one example embodiment.

Embodiment

Fig. 1 is schematic block circuit diagram according to one example embodiment.As shown in Figure 1, in an example embodiment, LED drive circuit comprises 3 parts: full bridge rectifier 1, voltage detecting circuit 2 and output control circuit 3.Full bridge rectifier 1 is connected to input AC electricity, is whole positive half cycles by input AC electric rectification, and service voltage testing circuit 2 and output control circuit 3.Voltage detecting circuit 2 detects the input voltage after rectification, and the variable quantity produced passes to output control circuit 3.Output control circuit 3 detects output feedack electric current and receives the input voltage variable quantity from voltage detecting circuit 2, automatically controls adjustment output current, realizes the constant of input power.

Fig. 2 is more detailed circuit theory diagrams according to one example embodiment.In an example embodiment, full bridge rectifier 1 comprises fuse F1 and bridge rectifier (bridgediode) BD1.One end of fuse F1 is connected to the live wire of input AC electricity, the other end of fuse F1 is connected with an input of bridge rectifier BD1, another input of bridge rectifier BD1 is connected to the zero line of input AC electricity, the anode of bridge rectifier BD1 is as the positive output of full bridge rectifier 1, and the negative terminal of bridge rectifier BD1 is as the negative output of full bridge rectifier 1.

In an example embodiment, voltage detecting circuit 2 comprises resistor R1, resistor R2 and Zener diode ZD1.One end of resistor R1 is connected to the positive output of full bridge rectifier 1, and the other end of resistor R1 is connected with one end of the negative electrode of Zener diode ZD1 and resistor R2, and the other end of resistor R2 is connected to the negative output of full bridge rectifier 1.The anode of Zener diode ZD1 as the output of voltage detecting circuit 2, and is connected to the power correction input of output control circuit 3.Resistor R1 and resistor R2 carries out dividing potential drop to the input voltage after rectification.When input voltage increases, when making the partial pressure value of resistor R1 and resistor R2 be greater than the voltage stabilizing value of Zener diode ZD1, just there is electric current to flow through Zener diode ZD1 and be transferred to output control circuit 3.The voltage stabilizing value that partial pressure value is greater than Zener diode ZD1 is more, and the electric current flowing through Zener diode ZD1 is larger, and the correction being transferred to output control circuit 3 is larger.

In an example embodiment, output control circuit 3 comprises voltage reference chip U1(such as, voltage reference chip 431 or 432 etc.), field-effect transistor Q1, resistor R3, R4, R5, R6 and capacitor C1, C2.One end of resistor R3 is connected with the positive pole of capacitor C1 and is connected to the positive output of full bridge rectifier 1, as the positive input terminal of LED load.One end of the other end of resistor R3 and the grid of field-effect transistor Q1, the negative electrode of voltage reference chip U1, one end of resistor R4 and capacitor C2 is connected.The other end of resistor R4 is connected with the negative pole of the drain electrode of field-effect transistor Q1, capacitor C1, as the negative input end of LED load.The other end of capacitor C2 is connected with the benchmark pin of voltage reference chip U1 and one end of resistor R5, is connected as the output of power correction input with voltage detecting circuit 2.The other end of resistor R5 is connected with one end of the source electrode of field-effect transistor Q1, resistor R6.The other end of resistor R6 is connected to the negative output of full bridge rectifier 1.Resistor R3, R4 form current supply circuit, provide driving voltage to field-effect transistor Q1.Resistor R5 transfers the current signal that voltage detecting circuit 2 transmits to voltage signal.Output current becomes voltage signal through resistor R6 sampling, is added to the benchmark pin of voltage reference chip U1 together with the detection signal from voltage detecting circuit 2.Voltage reference chip U1 is by the driving voltage of the signal intensity controlling filed effect transistor Q1 of benchmark pin, thus the conducting resistance of controlling filed effect transistor, reach the electric current that control flow check crosses field-effect transistor, complete the control of output current and the auto modification of input power.Capacitor C1, as output filter capacitor, is used for level and smooth output current, reduces current ripples.Capacitor C2 does negative feedback, makes the work of voltage reference chip U1 more stable.

Although describe the present invention for specific embodiment, it will be appreciated by those skilled in the art that when not departing from protection scope of the present invention, can modify to the embodiment shown in these and change.

Claims (5)

1. the field-effect transistor step-down LED drive circuit with power correction, is characterized in that, comprises full bridge rectifier (1), voltage detecting circuit (2) and output control circuit (3),
Input voltage is converted to all positive half cycles and exports by wherein said full bridge rectifier (1), and the input voltage after rectification is provided to described output control circuit (3) and described voltage detecting circuit (2),
Wherein said voltage detecting circuit (2) detects the variable quantity of the input voltage after described rectification, and this variable quantity is provided to described output control circuit (3), and
Wherein said output control circuit (3) detects output feedack electric current, and adjusts output current, to keep the constant of input power according to described output feedack electric current with from the described variable quantity that described voltage detecting circuit (2) receives.
2. the field-effect transistor step-down LED drive circuit of band power correction according to claim 1, it is characterized in that, wherein said output control circuit (3) comprises voltage reference chip (U1) and field-effect transistor (Q1), described field-effect transistor (Q1) detects described output feedack electric current, described output feedack electric current is converted to magnitude of voltage via sampling resistor, this magnitude of voltage is provided to the benchmark pin of described voltage reference chip (U1) after being added with the described variable quantity detected, described voltage reference chip (U1) adjusts the driving voltage of described field-effect transistor according to the change in voltage of its benchmark pin, thus control the conducting resistance of described field-effect transistor, then the electric current flowing through described field-effect transistor is controlled.
3. the field-effect transistor step-down LED drive circuit of band power correction according to claim 2, it is characterized in that, described output control circuit (3) also comprises the 3rd resistor (R3), the 4th resistor (R4), the 5th resistor (R5), the 6th resistor (R6), the first capacitor (C1) and the second capacitor (C2)
One end of wherein said 3rd resistor (R3) is connected with the positive pole of described first capacitor (C1) and is connected to the positive output of described full bridge rectifier (1), as the positive input terminal of LED load, the described other end of the 3rd resistor (R3) and the grid of described field-effect transistor (Q1), the negative electrode of described voltage reference chip (U1), one end of described 4th resistor (R4) and one end of described second capacitor (C2) are connected, the described other end of the 4th resistor (R4) is connected with the negative pole of the drain electrode of described field-effect transistor (Q1) and described first capacitor (C1), as the negative input end of LED load, the other end of described second capacitor (C2) is connected with one end of the benchmark pin of described voltage reference chip (U1) and described 5th resistor (R5), be connected as the output of power correction input with described voltage detecting circuit (2), the described other end of the 5th resistor (R5) is connected with one end of the source electrode of described field-effect transistor (Q1) and described 6th resistor (R6), the other end of described 6th resistor (R6) is connected to the negative output of described full bridge rectifier (1).
4. the field-effect transistor step-down LED drive circuit of band power correction according to claim 1, it is characterized in that, described voltage detecting circuit (2) comprises the first resistor (R1), second resistor (R2) and Zener diode (ZD1), one end of described first resistor (R1) is connected to the positive output of described full bridge rectifier (1), the other end of described first resistor (R1) is connected with one end of the negative electrode of described Zener diode (ZD1) and described second resistor (R2), the other end of described second resistor (R2) is connected to the negative output of described full bridge rectifier (1), the anode of described Zener diode (ZD1) as voltage detecting circuit (2) output and be connected to the power correction input of described output control circuit (3).
5. the field-effect transistor step-down LED drive circuit of band power correction according to claim 1, it is characterized in that, described full bridge rectifier (1) comprises fuse (F1) and bridge rectifier (BD1), one end of described fuse (F1) is connected to the live wire of input AC electricity, the other end of described fuse (F1) is connected with an input of described bridge rectifier (BD1), another input of described bridge rectifier (BD1) is connected to the zero line of input AC electricity, the anode of described bridge rectifier (BD1) is as the positive output of described full bridge rectifier (1), the negative terminal of described bridge rectifier (BD1) is as the negative output of described full bridge rectifier (1).
CN201410125624.6A 2014-03-31 2014-03-31 Field effect transistor step-down LED drive circuit with power correction CN104955205A (en)

Priority Applications (1)

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CN201410125624.6A CN104955205A (en) 2014-03-31 2014-03-31 Field effect transistor step-down LED drive circuit with power correction

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Application Number Priority Date Filing Date Title
CN201410125624.6A CN104955205A (en) 2014-03-31 2014-03-31 Field effect transistor step-down LED drive circuit with power correction

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109212348A (en) * 2018-08-31 2019-01-15 郑州正方科技有限公司 Condenser type pulse consumption detection system for low-power consumption electrical equipment

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2912187Y (en) * 2006-05-29 2007-06-13 刘世安 Semiconductor LED driving circuit of a.c. 220V
US20080074909A1 (en) * 2006-09-27 2008-03-27 Osram Sylvania, Inc. Power Supply and Electronic Ballast with Voltage Clamping Circuit
US20080238331A1 (en) * 2007-03-30 2008-10-02 Hon Hai Precision Industry Co., Ltd. Energy saving power supply circuit
CN202424498U (en) * 2012-01-04 2012-09-05 深圳可立克科技股份有限公司 Protection circuit applicable to PWM (pulse-width modulation) power control circuit
JP2012221561A (en) * 2011-04-04 2012-11-12 Iwasaki Electric Co Ltd Led lighting device and led bulb
CN203435180U (en) * 2013-06-18 2014-02-12 苏州市职业大学 Low-cost LED lamp self-adaptive dimming control circuit
CN203942666U (en) * 2014-03-31 2014-11-12 郑榕彬 A kind of field-effect transistor step-down LED drive circuit with power correction

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2912187Y (en) * 2006-05-29 2007-06-13 刘世安 Semiconductor LED driving circuit of a.c. 220V
US20080074909A1 (en) * 2006-09-27 2008-03-27 Osram Sylvania, Inc. Power Supply and Electronic Ballast with Voltage Clamping Circuit
US20080238331A1 (en) * 2007-03-30 2008-10-02 Hon Hai Precision Industry Co., Ltd. Energy saving power supply circuit
JP2012221561A (en) * 2011-04-04 2012-11-12 Iwasaki Electric Co Ltd Led lighting device and led bulb
CN202424498U (en) * 2012-01-04 2012-09-05 深圳可立克科技股份有限公司 Protection circuit applicable to PWM (pulse-width modulation) power control circuit
CN203435180U (en) * 2013-06-18 2014-02-12 苏州市职业大学 Low-cost LED lamp self-adaptive dimming control circuit
CN203942666U (en) * 2014-03-31 2014-11-12 郑榕彬 A kind of field-effect transistor step-down LED drive circuit with power correction

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109212348A (en) * 2018-08-31 2019-01-15 郑州正方科技有限公司 Condenser type pulse consumption detection system for low-power consumption electrical equipment

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Application publication date: 20150930