阅读说明：本技术 一种led筒灯驱动控制器 (LED down lamp drive controller ) 是由 杨辉 任艳江 巩奇 李乾坤 张继哲 钮佳丽 吕国伟 于世杰 王辉 袁艳玲 李翔然 于 2021-02-01 设计创作，主要内容包括：本发明属于LED技术领域,公开了一种LED筒灯驱动控制器,本发明包括EMI滤波模块,用于抑制输入的交流市电中的共摸干扰信号和浪涌信号,将处理后的输入交流市电送入到全桥整流模块的输入端；全桥整流模块,用于将输入的交流市电整流输出为直流电,再将直流电输送到高频降压变换模块的初级绕组中；反馈控制模块,利用OB3330X芯片对高频降压变换模块的初级绕组进行反馈控制和功率因数校正,同时控制高频降压变换模块中场效应管的关断；高频降压变换模块,用于将整流后的直流电降压、稳压恒流处理后输出到LED模块。本发明具有电流峰波比低、性价比高,功率因素高,电磁兼容性好,不会对照明产生污染的优点。(The invention belongs to the technical field of LEDs and discloses an LED down lamp driving controller which comprises an EMI filtering module, a full-bridge rectifying module and an EMI filtering module, wherein the EMI filtering module is used for inhibiting common-mode interference signals and surge signals in input alternating current commercial power and sending the processed input alternating current commercial power to the input end of the full-bridge rectifying module; the full-bridge rectification module is used for rectifying the input alternating current commercial power into direct current and then transmitting the direct current to a primary winding of the high-frequency voltage-reducing conversion module; the feedback control module performs feedback control and power factor correction on a primary winding of the high-frequency buck conversion module by using an OB3330X chip and controls the turn-off of a field effect tube in the high-frequency buck conversion module; and the high-frequency voltage-reducing conversion module is used for reducing the voltage of the rectified direct current, stabilizing the voltage and performing constant current treatment and then outputting the direct current to the LED module. The invention has the advantages of low current peak-to-wave ratio, high cost performance, high power factor, good electromagnetic compatibility and no pollution to illumination.)

1. The utility model provides a LED down lamp drive controller which characterized in that includes:

the EMI filtering module (10) is used for suppressing common mode interference signals and surge signals in the input alternating current commercial power and sending the processed input alternating current commercial power to the input end of the full-bridge rectification module (20);

the full-bridge rectification module (20) is used for rectifying the input alternating current commercial power into direct current and then transmitting the direct current to a primary winding of the high-frequency voltage-reducing conversion module (40);

the feedback control module (30) utilizes an OB3330X chip to perform feedback control and power factor correction on a primary winding of the high-frequency buck conversion module (40), and simultaneously controls the turn-off of a field effect tube (Q1) in the high-frequency buck conversion module (40);

and the high-frequency voltage-reducing conversion module (40) is used for reducing the voltage of the rectified direct current, stabilizing the voltage and constant current and outputting the direct current to the LED module.

2. The LED down lamp driving controller according to claim 1, wherein the EMI filtering module (10) comprises a fuse (F1), a twentieth resistor (R20), a first inductor (L1), a third inductor (L3), a fourth inductor (L4), a first safety capacitor (CX1), a third resistor (R3), a sixth resistor (R6), a seventh resistor (R7) and a nineteenth resistor (R19), and the third inductor (L3) and the fourth inductor (L4) are both common-mode inductors;

one end of a fuse (F1) is connected with one end of alternating current mains supply, the other end of the fuse (F1) is connected with one end of a twentieth resistor (R20), the other end of the twentieth resistor (R20) is respectively connected with one end of a nineteenth resistor (R19) and the first end of a fourth inductor (L4), the other end of a nineteenth resistor (R19) and the third end of a fourth inductor (L4) are both connected with the other end of the alternating current mains supply, the second end of a fourth inductor (L4) is connected with the first end of a third inductor (L3), the fourth end of the fourth inductor (L4) is connected with the third end of a third inductor (L3), the second end of the third inductor (L3) is respectively connected with one end of a first ampere-standard capacitor (CX1), one end of a sixth resistor (R6), the other end of the sixth resistor (R6) is connected with one end of a seventh resistor (R7), the other end of the first ampere-standard capacitor (CX1) is both connected with the fourth end of the seventh inductor (CX 7), the first inductor (L1) is connected in parallel with the third resistor (R3), one end of the parallel connection is connected with the second end of the third inductor (L3), the other end of the parallel connection is connected with one input end of the full-bridge rectification module (20), and the fourth end of the third inductor (L3) is connected with the other input end of the full-bridge rectification module (20).

3. The LED tube light driving controller according to claim 2, wherein the output end of the full-bridge rectification module (20) is connected with one end of a third capacitor (C3), and the other end of the third capacitor (C3) is grounded.

4. The LED downlight driving controller of claim 1, wherein the OB3330X chip has a ZCD terminal, an OCP _ TH terminal, a MULT terminal, a COMP terminal, a CS terminal, a GND terminal, a GATE terminal and a VCC terminal;

the ZCD end is connected with a first end of a feedback resistor (60), a second end of the feedback resistor (60) is connected with one end of an auxiliary winding, and the other end of the auxiliary winding and a third end of the feedback resistor (60) are both grounded;

the feedback resistor (60) comprises a fourteenth resistor (R14), a seventeenth resistor (R17) and an eighteenth resistor (R18) which are sequentially connected in series;

one end of a twenty-second resistor (R22) is connected with the OCP _ TH end, and the other end of the twenty-second resistor (R22) is grounded; a twenty-third resistor (R23) is connected with a fourth capacitor (C4) in parallel, one end of the parallel connection is respectively connected with the MULT end and one end of a sixteenth resistor (R16), the other end of the parallel connection is grounded, the other end of the sixteenth resistor (R16) is connected with one end of a thirteenth resistor (R13), and the other end of the thirteenth resistor (R13) is connected with the output end of the full-bridge rectifying module (20);

one end of a fifth capacitor (C5) is connected with the COMP end, and the other end of the fifth capacitor is grounded;

one end of a sixth capacitor (C6) and one end of a fifteenth resistor (R15) are both connected with the CS end, the other end of the sixth capacitor (C6) is grounded, the CS end is also connected with one end of a twenty-fourth resistor (R24), the other end of the twenty-fourth resistor (R24) is connected with one end of a sampling resistor, a seventh capacitor (C7) is connected with the two ends of the twenty-fourth resistor (R24) in parallel, the other end of the fifteenth resistor (R15) is connected with one end of a twelfth resistor (R12), and the other end of the twelfth resistor (R12) is connected with the output end of the full-bridge rectifying module (20);

the GND end is grounded; the twenty-first resistor (R21) is connected with the fourth diode (D4) in an anti-parallel mode, one end of the anti-parallel connection is connected with the GATE end, and the other end of the anti-parallel connection is connected with the G pole of the field effect transistor (Q1);

one end of an eleventh resistor (R11) is connected with one end of the auxiliary winding, the other end of the eleventh resistor (R11) is connected with the anode of a third diode (D3), the cathode of the third diode (D3) is respectively connected with the anode of a fourth electrolytic capacitor (CE4) and the VCC end, the cathode of the fourth electrolytic capacitor (CE4) is grounded, the cathode of the third diode (D3) is also connected with one ends of an eighth resistor (R8) and a fifth resistor (R5) which are connected in series, and the other ends of the eighth resistor (R8) and the fifth resistor (R5) which are connected in series are connected with the output end of the full-bridge rectification module (20).

5. The LED tube lamp driving controller according to claim 1, wherein the high frequency step-down conversion module (40) comprises a high frequency switch transformer (T1) and a field effect transistor (Q1), the high frequency switch transformer (T1) comprises a primary winding and an auxiliary winding on one side, a secondary winding on the other side, one end of the primary winding is connected with a D pole of the field effect transistor (Q1), the other end of the primary winding is connected with an output end of the full bridge rectification module (20), an S pole of the field effect transistor (Q1) is connected with one end of a sampling resistor (70), the other end of the sampling resistor (70) is grounded, a G pole of the field effect transistor (Q1) is connected with the feedback control module (30), and the sampling resistor (70) comprises a twenty-fifth resistor (R25), a twenty-sixth resistor (R26) and a twenty-seventh resistor (R27) which are sequentially connected in parallel.

6. The LED tube lamp driving controller according to claim 5, wherein the high frequency buck conversion module (40) further comprises a first diode (D1), a first electrolytic capacitor (CE1), a second electrolytic capacitor (CE2), a third electrolytic capacitor (CE3), a ninth resistor (R9), a tenth resistor (R10) and a second inductor (L2), and the second inductor (L2) is a common mode inductor;

the anode of the first diode (D1) is connected with one end of the secondary winding, one ends of a first electrolytic capacitor (CE1), the anode of a second electrolytic capacitor (CE2) and the anode of a third electrolytic capacitor (CE3), a ninth resistor (R9) and a tenth resistor (R10) and the third end of the second inductor (L2) are all connected with the cathode of the first diode (D1), the cathodes of the first electrolytic capacitor (CE1), the second electrolytic capacitor (CE2) and the third electrolytic capacitor (CE3), the other ends of the ninth resistor (R9) and the tenth resistor (R10) and the first end of the second inductor (L2) are all connected with the other end of the secondary winding and grounded, and the second end and the fourth end of the second inductor (L2) are respectively connected with two input ends of the LED module.

7. The LED tube lamp driving controller according to claim 6, wherein a first resistor (R1), a second resistor (R2) and a first capacitor (C1) which are connected in series in sequence are connected in parallel at two ends of the first diode (D1), the cathode of the first diode (D1) is further connected with one end of a second safety-regulation capacitor (CY1), and the other end of the second safety-regulation capacitor (CY1) is connected with the other end of the primary winding.

8. The LED tube lamp driving controller according to claim 7, wherein an RCD absorption module (50) is further connected to one end of the primary winding, the RCD absorption module (50) comprises a second diode (D2), a fourth resistor (R4) and a second capacitor (C2), an anode of the second diode (D2) is connected to one end of the primary winding, a cathode of the second diode (D2) is connected to one end of the fourth resistor (R4) and one end of the second capacitor (C2), and the other ends of the fourth resistor (R4) and the second capacitor (C2) are connected to the other end of the primary winding.

9. The LED down lamp driving controller according to claim 1, wherein the type of the field effect transistor (Q1) is SMK0465F, the type of the magnetic core of the high-frequency switching transformer (T1) is EE28, and the material of the magnetic core is P40.

10. The LED tube light driving controller according to claim 1, wherein the type of the full-bridge rectification module (20) is ABS 210.

Technical Field

The invention relates to the technical field of LEDs, in particular to a drive controller of an LED down lamp.

Background

Along with the requirement to green energy-conserving, the lamp that more and more places were used all is the hoist and mount down lamp of LED light source, however the LED that uses now often appears not bright or stroboscopic situation because the problem of driver, and the frequency of damage of driver is high, needs maintenance personal to change often, and the spare parts spare part that needs is many, difficult the maintenance.

However, most of the inductive ballast drivers in the market have the characteristics of simple structure and long service life, but frequently generate a stroboscopic phenomenon, and have the defects of low power factor, poor performance during low-voltage starting, high energy consumption and the like, so that the electronic ballast driving power source for outputting voltage-stabilizing constant current is particularly important for the development of the LED lamp.

Disclosure of Invention

The invention aims to provide an LED down lamp driving controller which can solve the problems of low power factor, poor performance during low-voltage starting and poor electromagnetic performance of the existing LED driver.

In order to solve the technical problems, the technical scheme of the invention is as follows:

an LED downlight drive controller, comprising:

the EMI filtering module is used for suppressing a common mode interference signal and a surge signal in the input alternating current commercial power and sending the processed input alternating current commercial power to the input end of the full-bridge rectification module;

the full-bridge rectification module is used for rectifying the input alternating current commercial power into direct current and then transmitting the direct current to a primary winding of the high-frequency voltage-reducing conversion module;

the feedback control module performs feedback control and power factor correction on a primary winding of the high-frequency buck conversion module by using an OB3330X chip and controls the turn-off of a field effect tube in the high-frequency buck conversion module;

and the high-frequency voltage-reducing conversion module is used for reducing the voltage of the rectified direct current, stabilizing the voltage and performing constant current treatment and then outputting the direct current to the LED module.

Further, the EMI filter module includes a fuse, a twentieth resistor, a first inductor, a third inductor, a fourth inductor, a first safety capacitor, a third resistor, a sixth resistor, a seventh resistor, and a nineteenth resistor, where the third inductor and the fourth inductor are both common-mode inductors;

one end of the fuse is connected with one end of an alternating current commercial power, the other end of the fuse is connected with one end of a twentieth resistor, the other end of the twentieth resistor is respectively connected with one end of a nineteenth resistor and the first end of a fourth inductor, the other end of the nineteenth resistor and the third end of the fourth inductor are both connected with the other end of the alternating current commercial power, the second end of the fourth inductor is connected with the first end of a third inductor, the fourth end of the fourth inductor is connected with the third end of a third inductor, the second end of the third inductor is respectively connected with one end of a first safety capacitor and one end of a sixth resistor, the other end of the sixth resistor is connected with one end of a seventh resistor, the other end of the first safety capacitor and the other end of the seventh resistor are both connected with the fourth end of the third inductor, the first inductor is connected with the third resistor in parallel, the parallel end is connected with the second end of the third inductor, and the parallel other end is connected, and the fourth end of the third inductor is connected with the other input end of the full-bridge rectification module.

Further, the output end of the full-bridge rectification module is connected with one end of a third capacitor, and the other end of the third capacitor is grounded.

Further, the OB33 3330X chip has a ZCD terminal, an OCP _ TH terminal, a MULT terminal, a COMP terminal, a CS terminal, a GND terminal, a GATE terminal, and a VCC terminal;

the ZCD end is connected with the first end of the feedback resistor, the second end of the feedback resistor is connected with one end of the auxiliary winding, and the other end of the auxiliary winding and the third end of the feedback resistor are both grounded;

the feedback resistor comprises a fourteenth resistor, a seventeenth resistor and an eighteenth resistor which are sequentially connected in series;

one end of the twenty-second resistor is connected with the OCP _ TH end, and the other end of the twenty-second resistor is grounded; the twenty-third resistor is connected with the fourth capacitor in parallel, one end of the parallel connection is respectively connected with the MULT end and one end of the sixteenth resistor, the other end of the parallel connection is grounded, the other end of the sixteenth resistor is connected with one end of the thirteenth resistor, and the other end of the thirteenth resistor is connected with the output end of the full-bridge rectifier module;

one end of the fifth capacitor is connected with the COMP end, and the other end of the fifth capacitor is grounded;

one end of a sixth capacitor and one end of a fifteenth resistor are both connected with the CS end, the other end of the sixth capacitor is grounded, the CS end is also connected with one end of a twenty-fourth resistor, the other end of the twenty-fourth resistor is connected with one end of a sampling resistor, the seventh capacitor is connected in parallel with the two ends of the twenty-fourth resistor, the other end of the fifteenth resistor is connected with one end of a twelfth resistor, and the other end of the twelfth resistor is connected with the output end of the full-bridge rectification module;

the GND end is grounded; the twenty-first resistor is connected with the fourth diode in an anti-parallel mode, one end of the anti-parallel connection is connected with the GATE end, and the other end of the anti-parallel connection is connected with the G pole of the field effect transistor;

one end of an eleventh resistor is connected with one end of the auxiliary winding, the other end of the eleventh resistor is connected with the anode of a third diode, the cathode of the third diode is respectively connected with the anode of a fourth electrolytic capacitor and the VCC end, the cathode of the fourth electrolytic capacitor is grounded, the cathode of the third diode is also connected with one end of an eighth resistor and one end of a fifth resistor which are connected in series, and the other end of the eighth resistor and the fifth resistor which are connected in series is connected with the output end of the full-bridge rectification module.

Further, high frequency step-down transform module includes high frequency switch transformer and field effect transistor, high frequency switch transformer includes primary winding and auxiliary winding in one side, opposite side secondary, the one end of primary winding is connected with the D utmost point of field effect transistor, and the other end of primary winding is connected with the output of full-bridge rectifier module, and the S utmost point of field effect transistor is connected with sampling resistor' S one end, sampling resistor other end ground connection, the G utmost point and the feedback control module of field effect transistor are connected, sampling resistor is including twenty fifth resistance, twenty sixth resistance and the twenty seventh resistance that connect in parallel in proper order.

Further, the high-frequency buck conversion module further comprises a first diode, a first electrolytic capacitor, a second electrolytic capacitor, a third electrolytic capacitor, a ninth resistor, a tenth resistor and a second inductor, wherein the second inductor is a common-mode inductor;

the anode of the first diode is connected with one end of the secondary winding, the anodes of the first electrolytic capacitor, the second electrolytic capacitor and the third electrolytic capacitor, one ends of the ninth resistor and the tenth resistor are connected with the third end of the second inductor, the cathodes of the first electrolytic capacitor, the second electrolytic capacitor and the third electrolytic capacitor, the other ends of the ninth resistor and the tenth resistor and the first end of the second inductor are connected with the other end of the secondary winding and grounded, and the second end and the fourth end of the second inductor are connected with two input ends of the LED module respectively.

Furthermore, a first resistor, a second resistor and a first capacitor which are sequentially connected in series are connected in parallel at two ends of the first diode, the cathode of the first diode is further connected with one end of a second safety-regulation capacitor, and the other end of the second safety-regulation capacitor is connected with the other end of the primary winding.

Furthermore, one end of the primary winding is further connected with an RCD absorption module, the RCD absorption module comprises a second diode, a fourth resistor and a second capacitor, the anode of the second diode is connected with one end of the primary winding, the cathode of the second diode is respectively connected with one ends of the fourth resistor and the second capacitor, and the other ends of the fourth resistor and the second capacitor are connected with the other end of the primary winding.

Furthermore, the type of the field effect transistor is SMK0465F, the type of the magnetic core of the high-frequency switching transformer is EE28, and the material of the magnetic core is P40.

Further, the full-bridge rectification module is of the type ABS 210.

The invention has the beneficial effects that:

1. the LED tube lamp driving controller provided by the invention has high cost performance, adopts the flyback high-frequency buck converter, utilizes the OB3330X primary side feedback control chip to drive the field effect transistor, realizes the primary side feedback control of the transformer through the design of the peripheral circuit of the chip, ensures the stable output and the loading capacity of the circuit, provides a comprehensive protection function for the whole driving controller, and ensures that the power supply current provided by the driver for the LED has low peak-to-wave ratio, high power factor and good electromagnetic compatibility, and does not pollute the illumination.

2. The EMI filtering module provided by the invention can play a role in lightning protection and surge prevention, can effectively inhibit common-mode interference signals in alternating current mains supply transmitted by a power grid, suppress interference radiation, improve the anti-electromagnetic interference capability of the system, and cannot cause power grid fluctuation to interfere normal work of other instruments and equipment.

3. The RCD absorption module is arranged on the primary winding and used for absorbing the peak voltage of the field effect tube, the high-frequency peak wave absorption loop is arranged on the diode of the secondary winding loop, and the safety capacitor is arranged between the primary winding and the secondary winding to form the high-frequency loop for filtering and isolating, so that the stability of the device is enhanced.

Drawings

Fig. 1 is a block diagram of a driving controller of an LED tube light provided by the present invention;

fig. 2 is a detailed circuit configuration diagram of fig. 1.

The labels in the figure are: 10-EMI filtering module; 20-full bridge rectification module; 30-a feedback control module; 40-high frequency buck conversion module; a 50-RCD absorber module; 60-feedback resistance; 70-sampling resistance.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and examples.

Example 1

As shown in fig. 1, an LED tube lamp driving controller includes:

the EMI filter module 10 is configured to suppress common mode interference signals and surge signals in the input ac mains supply, and send the processed input ac mains supply to an input end of the full-bridge rectifier module 20;

the full-bridge rectification module 20 is used for rectifying the input alternating current commercial power into direct current and then transmitting the direct current to a primary winding of the high-frequency voltage-reducing conversion module 40;

the feedback control module 30 performs feedback control and power factor correction on the primary winding of the high-frequency buck conversion module 40 by using an OB3330X chip, and controls the turn-off of a field effect transistor Q1 in the high-frequency buck conversion module 40;

and the high-frequency voltage-reducing conversion module 40 is used for reducing the voltage of the rectified direct current, stabilizing the voltage and constant current and outputting the direct current to the LED module.

When the device works, alternating current commercial power is firstly subjected to electromagnetic interference filtering, common-mode interference suppression of power grid input and the like through the EMI filtering module 10, then is sent to the full-bridge rectification module 20 to be converted into direct current, and the rectified direct current is too high in voltage and is not suitable for being used as a driving power supply of an LED lamp, so that high-voltage direct current obtained through arrangement is converted through the high-frequency voltage-reducing conversion module 40, meanwhile, feedback control driving is carried out through the feedback control module 30, and the high-voltage direct current is processed through the voltage-stabilizing filtering circuit in the high-frequency voltage-reducing conversion module 40 to obtain the driving power supply. The driving controller provided by the invention has the advantages of low current peak-to-wave ratio, high cost performance, high power factor, good electromagnetic compatibility, no pollution to illumination and no interference of power grid fluctuation on normal operation of other instruments and equipment.

Example 2

Based on embodiment 1, a specific circuit structure of the apparatus is as shown in fig. 2, the EMI filter module 10 includes a fuse F1, a twentieth resistor R20, a first inductor L1, a third inductor L3, a fourth inductor L4, a first safety capacitor CX1, a third resistor R3, a sixth resistor R6, a seventh resistor R7, and a nineteenth resistor R19, and both the third inductor L3 and the fourth inductor L4 are common mode inductors. The EMI filtering module can play the roles of lightning protection and surge prevention, can effectively suppress common-mode interference signals in alternating current mains supply transmitted by a power grid, suppress interference radiation, improve the anti-electromagnetic interference capability of the system, and cannot cause power grid fluctuation to interfere normal work of other instruments and equipment.

One end of a fuse F1 in the EMI filter module is connected with one end of an alternating current mains supply, the other end of the fuse F1 is connected with one end of a twentieth resistor R20, the other end of the twentieth resistor R20 is respectively connected with one end of a nineteenth resistor R19 and a first end of a fourth inductor L4, the other end of the nineteenth resistor R19 and a third end of a fourth inductor L4 are both connected with the other end of the alternating current mains supply, a second end of the fourth inductor L4 is connected with a first end of a third inductor L3, a fourth end of a fourth inductor L4 is connected with a third end of a third inductor L3, a second end of the third inductor L3 is respectively connected with one end of a first safety regulation capacitor CX1 and one end of a sixth resistor R6, the other end of the sixth resistor R6 is connected with one end of a seventh resistor R7, the other end of the first safety regulation capacitor CX1 and the other end of the seventh resistor 7 are both connected with a fourth end of a third inductor L5, and the first inductor 58L 57324 are connected in parallel, one end of the parallel connection is connected to the second end of the third inductor L3, the other end of the parallel connection is connected to one input end of the full-bridge rectification module 20, and the fourth end of the third inductor L3 is connected to the other input end of the full-bridge rectification module 20. The fuse F1 is used for lightning protection and surge impact prevention, and the third inductor L3 and the fourth inductor L4 adopt common mode inductors, so that common mode interference signals can be effectively inhibited in a balanced circuit, and the EMC of the system is improved.

After the input alternating current is filtered and the like, the alternating current is converted into direct current through a full-bridge rectifier module, and the direct current is output, for example, the direct current of 310V is obtained by rectifying 220V alternating current after EMI filtering. In order to ensure that the rectified output voltage with small ripple content is output, the output end of the full-bridge rectification module 20 is connected with one end of the third capacitor C3, and the other end of the third capacitor C3 is grounded. Preferably, the full bridge rectifier module 20 is of the type ABS 210.

In order to ensure that the LED down lamp works normally, the arranged high-frequency voltage reduction conversion module 40 is used for voltage reduction conversion. The high-frequency step-down transformer 40 constitutes a flyback transformer, and performs energy storage conversion by controlling the field effect transistor Q1 to realize step-down. The high-frequency step-down conversion module 40 comprises a high-frequency switching transformer T1 and a field effect transistor Q1, wherein the high-frequency switching transformer T1 comprises a primary winding and an auxiliary winding on one side, a secondary winding on the other side forms a flyback winding by the primary winding and the secondary winding, and the auxiliary winding supplies power for an OB3330X chip. One end of the primary winding is connected with the D pole of the field effect transistor Q1, the other end of the primary winding is connected with the output end of the full-bridge rectification module 20, the S pole of the field effect transistor Q1 is connected with one end of the sampling resistor 70, the other end of the sampling resistor 70 is grounded, and the G pole of the field effect transistor Q1 is connected with the feedback control module 30.

It is worth mentioning that the model of the field effect transistor Q1 is preferably SMK0465F, the model of the magnetic core of the high-frequency switching transformer T1 is preferably EE28, and the magnetic core material is preferably P40, so that the device has good working effect.

The working principle of the flyback transformer circuit is as follows: when the MOSFET is switched on, the current of the primary winding rises to store magnetic energy, the polarity of the voltage of the secondary winding is negative, positive and negative, and the diode D1 is cut off; when the MOSFET is turned off, the magnetic energy stored in the coupling winding is released, the polarity of the voltage of the secondary winding is positive, negative, and positive, the diode D1 is turned on, and the capacitors CE1, CE2, and CE3 are charged.

It is further illustrated that the high-frequency buck conversion module 40 further includes a first diode D1, a first electrolytic capacitor CE1, a second electrolytic capacitor CE2, a third electrolytic capacitor CE3, a ninth resistor R9, a tenth resistor R10, and a second inductor L2, and the second inductor L2 is a common-mode inductor. The electrolytic capacitors CE1, CE2 and CE3 play a role in filtering, stabilizing and storing energy, and can ensure that stable driving voltage is obtained.

The anode of the first diode D1 is connected to one end of the secondary winding, the anodes of the first electrolytic capacitor CE1, the second electrolytic capacitor CE2 and the third electrolytic capacitor CE3, and one end of the ninth resistor R9 and the tenth resistor R10 and the third end of the second inductor L2 are all connected to the cathode of the first diode D1, the cathodes of the first electrolytic capacitor CE1, the second electrolytic capacitor CE2 and the third electrolytic capacitor CE3, and the other ends of the ninth resistor R9 and the tenth resistor R10 and the first end of the second inductor L35 2 are all connected to the other end of the secondary winding and grounded, and the second end and the fourth end of the second inductor L2 are connected to two input ends of the LED module.

In order to absorb high-frequency spike voltage in the device and inhibit electromagnetic interference, a first resistor R1, a second resistor R2 and a first capacitor C1 which are sequentially connected in series are connected in parallel at two ends of a first diode D1, the cathode of the first diode D1 is further connected with one end of a second safety capacitor CY1, and the other end of the second safety capacitor CY1 is connected with the other end of the primary winding.

In order to absorb the spike voltage of the fet, an RCD absorption module 50 is further connected to one end of the primary winding, the RCD absorption module 50 includes a second diode D2, a fourth resistor R4 and a second capacitor C2, an anode of the second diode D2 is connected to one end of the primary winding, a cathode of the second diode D2 is connected to one end of a fourth resistor R4 and one end of a second capacitor C2, and the other end of the fourth resistor R4 and the other end of the second capacitor C2 are both connected to the other end of the primary winding.

In the above device, the feedback control module 30 uses OB3330X chip to design peripheral circuits to perform feedback control on the high-frequency buck conversion module 40, and the OB3330X chip has ZCD terminal, OCP _ TH terminal, MULT terminal, COMP terminal, CS terminal, GND terminal, GATE terminal and VCC terminal.

It is worth proposing that OB33 3330X is an LED constant current driving controller that employs a primary feedback control technique and implements high power factor correction, providing a variety of characteristic functions, including soft start function, power factor correction, constant current control, zero current detection, built-in leading edge blanking of a current sampling comparator, and totem-pole output driving. Meanwhile, OB3330X can provide comprehensive protection functions including LED open-circuit and short-circuit protection, VCC overvoltage and undervoltage protection, output load overvoltage protection, cycle-by-cycle peak current limit for a threshold value which can be set by a user, over-temperature protection, and output drive clamping to protect a power MOSFET.

The following describes some functions of the OB3330X chip:

starting: the LED constant-current controller for realizing high-power correction by adopting primary side feedback is applied to flyback isolated LED illumination, and TL431 and optocoupler secondary side components are not needed. The chip works in a critical mode, so that the switching loss is reduced to the maximum extent, and the efficiency is improved.

VCC undervoltage protection: the VCC undervoltage protection function has hysteresis control, and when VCC voltage exceeded 15.2V threshold, the chip started normal work, and when VCC voltage was less than 9V threshold, the chip stopped working, recovered to 15.2V threshold again when VCC, the chip worked again.

LED constant current control: OB3330X adopts constant current control technology of primary side feedback, and can realize high-precision LED constant current output.

Current sampling: OB3330X provides cycle-by-cycle current limitation, the switch current connected to the sampling resistor Rcs is detected through the CS pin, the reverse recovery characteristic of the Snubber diode causes the MOSFET to generate a peak voltage on the sampling resistor at the turn-on moment, and the built-in leading edge blanking circuit of the chip can shield the peak voltage, so that an external RC filter circuit is not needed at the current detection input end, and the current limitation comparator cannot work in the shielding time, so that the external MOSFET cannot be turned off. The input voltage of the current sample and the COMP voltage determine the PWM duty cycle.

Setting an OCP threshold value: the OCP _ TH pin voltage determines the OCP threshold. The OCP _ TH pin of OB3330X provides approximately 28uA of charging current, and in order to generate the voltage required at the OCP _ TH pin, OCP _ TH needs to connect an appropriate resistor to ground. When the OCP _ TH pin is connected with the 33K omega resistor to the ground, the OCP threshold value is about 1.8V; when the OCP _ TH pin is connected with the 110K omega resistor to the ground, the OCP threshold value is about 1.5V; when the OCP _ TH pin is grounded, the OCP threshold is about 2.1V.

Zero current detection: the ZCD pin of OB3330X is connected to the resistance voltage-dividing node of the auxiliary winding, and the voltage of the auxiliary winding is monitored to realize zero current detection. The ZCD pin reflects the change in polarity of the flyback transformer. When the energy stored in the flyback transformer is transmitted to the output and completely released, the voltage on the corresponding ZCD pin drops. When the voltage on the ZCD pin drops to the 0.3V threshold, the internal ZCD comparator is triggered and a new PWM switching cycle is generated.

Maximum frequency clamping: based on the critical mode operating principle, the switching frequency is inversely proportional to the output power. Therefore, when the output power decreases, the switching frequency increases, and if the switching frequency is not limited, the switching frequency is very high. The internal maximum switching frequency limited by 0B3330X is about 300 kHz.

The multiplier realizes power factor correction: by detecting the AC half-wave rectified input voltage, an analog multiplier built in the chip outputs to limit the peak current of the primary winding. High power factor is achieved by controlling the threshold of the CS comparator as a voltage at which the AC input voltage varies sinusoidally from zero to a peak value.

Output overvoltage protection: the ZCD pin independently monitors the output overvoltage condition. In normal operation, when the voltage on the ZCD pin exceeds the 4.0V threshold, the overvoltage protection function is triggered, and the GATE is immediately closed.

VCC overvoltage protection: the system supplies power to the chip VCC through the output of the transformer auxiliary winding. When the VCC voltage is higher than 30V, overvoltage protection is triggered, the chip closes the GATE output, and meanwhile, the system enters a restart state.

LED short-circuit protection: when the LED output is short-circuited, the forward voltage of the auxiliary winding is close to zero, and the corresponding ZCD voltage is low level. When the ZCD pin voltage is lower than the 0.9V threshold and maintains 10mS, the chip turns off the GATE output, and the system enters a restart state.

LED open circuit protection: when the LED output is open-circuited, the forward voltage of the auxiliary winding is increased, and the corresponding ZCD voltage is at a high level. When the ZCD pin voltage is higher than the 4V threshold value, the chip closes the GATE output, and meanwhile, the system enters a restart state.

The over-temperature protection function: OB3330X provides a built-in over-temperature protection function. When the temperature of the chip exceeds 145 ℃ of the temperature protection threshold, the chip turns off the GATE output.

GATE drive output: OB3330X drives external power MOSFETs with an optimally designed drive circuit. Too weak a driving capability results in high switching losses, while too strong a driving capability results in poor EMI-a good compromise between built-in totem-pole driving and proper control of the driving output capability is achieved. GATE drives a built-in 11V high clamp protecting the MOSFET GATE.

In the feedback control module 30, the ZCD terminal is connected to a first terminal of the feedback resistor 60, a second terminal of the feedback resistor 60 is connected to one terminal of the auxiliary winding, and the other terminal of the auxiliary winding and a third terminal of the feedback resistor 60 are both grounded.

One end of the twenty-second resistor R22 is connected to the OCP _ TH end, and the other end of the twenty-second resistor R22 is grounded. The twenty-second resistor R22 is used to define the voltage threshold at OCP _ TH.

The twenty-third resistor R23 is connected in parallel with the fourth capacitor C4, one end of the parallel connection is connected to the MULT terminal and one end of the sixteenth resistor R16, the other end of the parallel connection is grounded, the other end of the sixteenth resistor R16 is connected to one end of the thirteenth resistor R13, and the other end of the thirteenth resistor R13 is connected to the output end of the full-bridge rectifier module 20. R13, R14 and R23 are used for detecting the rectified voltage and limiting the peak current of the primary winding through a chip.

One end of the fifth capacitor C5 is connected to the COMP end, and the other end is grounded; one end of a sixth capacitor C6 and one end of a fifteenth resistor R15 are both connected to the CS end, the other end of the sixth capacitor C6 is grounded, the CS end is further connected to one end of a twenty-fourth resistor R24, the other end of the twenty-fourth resistor R24 is connected to one end of a sampling resistor, a seventh capacitor C7 is connected to two ends of the twenty-fourth resistor R24 in parallel, the other end of the fifteenth resistor R15 is connected to one end of a twelfth resistor R12, and the other end of the twelfth resistor R12 is connected to the output end of the full-bridge rectification module 20.

Meanwhile, the GND end is grounded; the twenty-first resistor R21 is connected with the fourth diode D4 in an anti-parallel mode, one end of the anti-parallel connection is connected with the GATE end, and the other end of the anti-parallel connection is connected with the G pole of the field effect transistor Q1; one end of an eleventh resistor R11 is connected to one end of the auxiliary winding, the other end of the eleventh resistor R11 is connected to the anode of the third diode D3, the cathode of the third diode D3 is connected to the anode and VCC of the fourth electrolytic capacitor CE4, the cathode of the fourth electrolytic capacitor CE4 is grounded, the cathode of the third diode D3 is further connected to one ends of an eighth resistor R8 and a fifth resistor R5 which are connected in series, and the other end of the eighth resistor R8 and the fifth resistor R5 which are connected in series is connected to the output end of the full-bridge rectifier module 20. The auxiliary winding is rectified by a third diode D3 and then filtered by a capacitor CE4 to supply power to the chip, and a fifth resistor R5 and an eighth resistor R8 mainly provide initial working voltage when the chip is powered on.

It is further illustrated that the sampling resistor 70 includes a twenty-fifth resistor R25, a twenty-sixth resistor R26, and a twenty-seventh resistor R27 connected in parallel in sequence, and information collected by the sampling resistor is fed back to the chip by the R4. The feedback resistor 60 comprises a fourteenth resistor R14, a seventeenth resistor R17 and an eighteenth resistor R18 which are sequentially connected in series, and primary side feedback control is realized.

Example 3

On the basis of the embodiment 1 and the embodiment 2, a 60 Ω/25W resistor is adopted as a load for testing, corresponding technical parameters are adjusted according to actual conditions, and measured related data are obtained, so that the LED down lamp driving controller provided by the embodiment can output constant current within an error allowable range when the alternating current input is 100-240V, the maximum output voltage is 45V, the LED down lamp driving controller has a constant current characteristic, has a protection effect on an LED lamp, and is good in electromagnetic compatibility.