M399572 « « 五、新型說明： 【新型所屬之技術領域】 本創作是有關於一種發光二極體(LED)驅動器’且特別是有關於一 種隔離型LED驅動器。 【先前技術】 • 圖1為一種現有的隔離型LED驅動器的電路圖。請參見圖丨，隔 離型LED驅動器1用於驅動可應用在大尺寸液晶顯示器背光面板場合 •的LED光源4，其中LED光源4由m個燈條41〜4m組成，每—燈條例 如由η個LED 51〜5n串聯耦接組成，m、η為正整數。隔離型led驅 動器1包括電磁干擾(EMI)濾波器11、橋式整流器12、功因修正器13、 濾波電容器14、隔離型直流至直流(DC/DC)轉換器15、升壓轉換器16 和電流平衡控制器17。90Vrms〜264Vrms市用交流電源輸入後需要經 過三級的電源轉換，分別是第一級的功因修正器13將輸入電源轉換為 400V高壓的直流電源’再經由第二級的隔離型DC/DC轉換器15將4〇叭 高壓轉換為24V〜60V較低壓的直流電源，最後經由第三級的升壓轉換 裔16將24V〜60V轉換為60V〜140V適合燈條41〜4m額定工作電壓的 直流電源。 隔離型LED驅動器1由於採用了三級的電源轉換，第一級功因修 正器13的效率約可達91%、第二級隔離型DC/DC轉換器15的效率約 ^達m、第三級升壓轉換器16的效率約可達93%，如不考慮傳輸過 程中其他裳置的損失’那麼隔離型LED驅動器i的電源轉換效率只有 TO 〇91%χ91%χ93%)。由此可知，當隔離型⑽鶴器採用越多級的 電源轉換時’其電源轉換效麵低，即電源轉換損失越多。 另外，隔離型LED驅動器i以並聯方式驅動燈條41〜細，而需要 3 M399572 電流平衡控制器17控制燈條4】〜4m的電流平衡以提供均勻亮度。現 有的電流平衡控制器17設計通常使用整合各種所需功能的專用積體 電路之LED控制H π卜在大尺寸液晶顯示器背光面板應用場合，燈 條41〜4m的數量較多或者會使用大電流的高亮度LED，電流平衡控制 器17使用的LED控制器ι71需要外接電晶體以〜咖和電阻器Rsi〜M399572 « « V. New description: [New technology field] This work is about a light-emitting diode (LED) driver' and especially related to an isolated LED driver. [Prior Art] • Fig. 1 is a circuit diagram of a conventional isolated LED driver. Referring to the figure, the isolated LED driver 1 is used to drive an LED light source 4 that can be applied to a large-size liquid crystal display backlight panel. The LED light source 4 is composed of m light bars 41 to 4 m, and each light bar is, for example, made of η. The LEDs 51~5n are coupled in series, and m and η are positive integers. The isolated type LED driver 1 includes an electromagnetic interference (EMI) filter 11, a bridge rectifier 12, a power factor corrector 13, a filter capacitor 14, an isolated direct current to direct current (DC/DC) converter 15, a boost converter 16, and Current balance controller 17. 90Vrms~264Vrms City AC power input needs to pass three levels of power conversion, respectively, the first stage power factor corrector 13 converts the input power to 400V high voltage DC power supply' and then through the second stage The isolated DC/DC converter 15 converts 4 〇 high voltage into a 24V~60V lower voltage DC power supply, and finally converts 24V~60V to 60V~140V through the third stage boost conversion 16 for the light bar 41 ~4m rated working voltage DC power supply. Since the isolated LED driver 1 adopts three-stage power conversion, the efficiency of the first-stage power factor corrector 13 is about 91%, and the efficiency of the second-stage isolated DC/DC converter 15 is about m, third. The efficiency of the stage boost converter 16 is about 93%. If the loss of other devices in the transmission process is not considered, then the power conversion efficiency of the isolated LED driver i is only TO 〇 91% χ 91% χ 93%). It can be seen that when the isolated (10) crane adopts more stages of power conversion, its power conversion effect is low, that is, the power conversion loss is more. In addition, the isolated LED driver i drives the light bar 41~ in a parallel manner, and requires 3 M399572 current balancing controller 17 to control the current balance of the light bar 4~4m to provide uniform brightness. The current current balance controller 17 is usually designed to use LED control of a dedicated integrated circuit that integrates various required functions. In the large-size liquid crystal display backlight panel application, the number of light bars 41 to 4 m is large or a large current is used. The high-brightness LED, the current balance controller 17 uses the LED controller ι71 requires an external transistor to ~ coffee and resistor Rsi ~
Rsm而以外部㈣方式進行電流平衡㈣，避免因直絲接燈條4ι〜 4m進行電流平衡控制導致接收的電流太大而過熱或燒毀。⑽控制哭 Π1的電源端VCC接收24V〜60V電源，檢測端IS1〜—通過電阻器° kl〜Rsm檢測到燈條4i〜4m的電流，並據以從驅動端CH1〜咖輸出。 信號控制電晶體Ql〜Qm和從迴授端FB輸出信號控制升壓轉換器Μ， 以完成電流平衡控制。 器需數量增加，電流平衡控制器17中的led控制 才夂r主二二燈條的專用積體電路’這樣的專用積體電路價 Ϊ:二而不利於周邊線路佈局”戈者，led控制器可採用 燈條的專用積體電路，然後通過多個⑽控制器—起驅動燈 需要同步控制 設計’若其需要外接額外的電 【新型内容】 提高嶋㈣刪，可 本創作提出一種隔離型LED驅動哭， 轉換器、-隔離賴m及至少 ^ 流至3〇A(DC/AC) ㈣轉換器用於將- M39.9572 直=電源轉換為一交流電源。隔離變壓器具有—一次側繞線和一二次 側繞隔離變壓器的一次側繞線搞接DC/AC轉換器以接收交流電 源。。。每—驅動單元具有一第一端和一第二端且包括一第一和一第二變 ^器、。—第—和一第二電容器、一第一和一第二二極體，第一和第二 變壓器均具有一一次側繞線和一二次側繞線，第一變壓器的一次側繞 線=打點端雜驅動單元的第—端’第-變壓ϋ的-次側繞線的非打 點轉接第—變壓器的一次側繞線的非打點端，第二變壓器的一次側 繞線的打點端輕接驅動單元的第二端，第—變壓器的二次側繞線的打 點端搞接第一電容器的第一端，第一電容器的第二端搞接第一二極體 的陰極％和第-燈條的輸人端’第二變塵||的二次側繞線的打點端耗 ，第二電容器的第-端，第二電容器的第二端轉接第二二極體的陰極 和第—燈條的輸入端，第一和第二變壓器的二次側繞線的非打點 知第一和第二二極體的陽極端、第一和第二燈條的輸出端均接地。 所有驅動單元通過各自的第一端和第二端串聯耦接且串聯耦接後的兩 端分別耦接隔離變壓器的二次側繞線的兩端。 在本創作的一實施例中，每一驅動單元還包括一第三和一第四二 極體、一第一和一第二電阻器，第一燈條的輸出端耦接第三二極體的 馨陽極端，第三二極體的陰極端耦接第一電阻器的第一端，第一電阻器 的第一端接地，第二燈條的輸出端耦接第四二極體的陽極端，第四二 極體的陰極端耦接第二電阻器的第一端，第二電阻器的第二端接地。 為讓本創作之上述和其他目的、特徵和優點能更明顯易懂，下文 特舉較佳貫施例，並配合所附圖式，作詳細說明如下。圖式中具有相 同或類似元件符號的裝置表示具有相同或類似結構的裝置’然其並非 用於限定本創作。 【實施方式】 M399572 圖2為本創作的隔離型LED驅動器的第一實施例的電路圖。請參 見圖2，隔離型LED驅動器2用於驅動可應用在大尺寸液晶顯示器背 光面板場合的LED光源5，其中LED光源5由4個如圖1所示的燈條 41〜44組成，這些燈條41〜44可分成第一燈條LB1和第二燈條LB2， 如燈條41和43為第一燈條LB卜燈條42和44為第二燈條LB2。隔離 型LED驅動器2包括EMI濾波器1卜橋式整流器12、功因修正器13、 濾波電容器14、DC/AC轉換器25卜隔離變壓器TO以及2個驅動單元 21 和 22。Rsm and current balance (4) in the external (four) way, to avoid the current is too large to overheat or burn out due to current balance control of the straight wire light bar 4ι ~ 4m. (10) Controlling the crying The power supply terminal VCC of the Π1 receives the 24V~60V power supply, and the detection terminal IS1~- detects the current of the light bar 4i~4m through the resistors k1~Rsm, and outputs it according to the driving terminal CH1~C. The signal control transistors Q1 to Qm and the output signal from the feedback terminal FB control the boost converter 以 to complete the current balance control. The number of devices needs to be increased, and the LED control in the current balance controller 17 is only a special integrated circuit of the main two or two light strips. The price of the special integrated circuit is not good for the surrounding circuit layout. The device can use the special integrated circuit of the light bar, and then through multiple (10) controllers - the drive lamp needs to be synchronously controlled. If it needs extra external power [new content] to improve the 嶋 (4) deletion, this creation proposes an isolated type. LED driver crying, converter, - isolation and at least ^ flow to 3 〇 A (DC / AC) (four) converter is used to convert - M39.9572 straight = power to an AC power supply. Isolation transformer has - primary winding And a primary side winding of the primary side winding isolation transformer is connected to the DC/AC converter to receive the AC power supply. Each of the driving units has a first end and a second end and includes a first and a second a first, a second capacitor, a first and a second diode, the first and second transformers each having a primary side winding and a secondary side winding, the first transformer Primary side winding = the first part of the dot drive unit 'Non-commutation of the first-transformed --secondary winding--the non-tapping end of the primary side winding of the transformer, the striking end of the primary side winding of the second transformer is lightly connected to the second end of the driving unit, The first end of the first capacitor is connected to the dot end of the secondary winding of the transformer, and the second end of the first capacitor is connected to the cathode of the first diode and the input end of the first strip The second end of the second side winding of the second dusting wire, the second end of the second capacitor, the second end of the second capacitor is connected to the cathode of the second diode and the input end of the first light bar, The non-spots of the secondary side windings of the first and second transformers are known to be grounded at the anode ends of the first and second diodes, and the output ends of the first and second light bars are all grounded. The second end is coupled in series and coupled to the two ends of the secondary winding of the isolation transformer respectively. In an embodiment of the present invention, each driving unit further includes a third and a first a quadrupole body, a first and a second resistor, the output end of the first light bar is coupled to the sweet anode of the third diode The cathode end of the third diode is coupled to the first end of the first resistor, the first end of the first resistor is grounded, and the output end of the second strip is coupled to the anode end of the fourth diode. The cathode end of the quadrupole is coupled to the first end of the second resistor, and the second end of the second resistor is grounded. To make the above and other objects, features and advantages of the present invention more apparent, the following DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) The detailed description of the embodiments, in which the same or similar elements are used in the drawings, means that the device has the same or similar structure, which is not intended to limit the present invention. M399572 Figure 2 is a circuit diagram of a first embodiment of the isolated LED driver of the present invention. Referring to Figure 2, the isolated LED driver 2 is used to drive an LED light source 5 that can be applied to a large-size LCD backlight panel, wherein the LED The light source 5 is composed of four light bars 41 to 44 as shown in FIG. 1. The light bars 41 to 44 can be divided into a first light bar LB1 and a second light bar LB2, such as the light bars 41 and 43 being the first light bar LB. The light bars 42 and 44 are the second light bar LB2. The isolated LED driver 2 includes an EMI filter 1 bridge rectifier 12, a power factor corrector 13, a filter capacitor 14, a DC/AC converter 25, an isolation transformer TO, and two drive units 21 and 22.
EMI濾波器11用於濾除EMI雜訊。橋式整流器12用於將9〇Vrm 264Vrms市用交流電源整流成脈動直流電源。功因修正器13用於必 市用交流電源的輸入電流波形跟蹤輸入電壓波形以提高功率因數。如 波，容器14用於將脈動直流電源濾波為4〇〇y的直流電源。dc/ac葬 換器251用於將400V的直流電源轉換為交流電源。隔離變壓器罚β ^次側繞線和二次舰線，隔離懸㈣的—次側繞線输°dc/a< 轉換器25Ux接收DC/AC轉換器251輸出的交流電源。The EMI filter 11 is used to filter out EMI noise. The bridge rectifier 12 is used to rectify a 9 〇 Vrm 264 Vrms commercial AC power source into a pulsating DC power source. The power factor corrector 13 is used to track the input voltage waveform of the input current waveform of the must-use AC power source to improve the power factor. For example, the vessel 14 is used to filter the pulsating DC power source to a 4 〇〇 dc power source. The dc/ac burial converter 251 is used to convert a 400V DC power source into an AC power source. The isolating transformer penalizes the β ^ secondary winding and the secondary ship, and the isolated suspension (four) - the secondary winding output °dc / a < converter 25Ux receives the AC power output of the DC / AC converter 251.
每—驅動單元(如21或22)具有第-端P1和第二端p2且 -變壓器τ卜第二變壓器T2、第一電容器α、第二電容哭c2、^ 二極體D1和第二二極體D2，其中第一變壓器T1和第二變壓器❿ 具有:次側繞線和二次側繞線。在每—驅動單元(如21或 ^ 一=壓fT1的—次側繞線的打點端祕驅動單元21的第-端P卜f 壓器T1的一次側繞線的非打點端耦 線的非打點端，篦一轡壓涔 文全时μ的-人側每 Μ Μ ^ # Τ2的—次側繞線的打點端_驅動單ϋ 21的红端Ρ2，第一變壓器T1的 動:: 和第- ^ ΐ 的第二端相接第一二極體的陰細 :條LB1的輸入知，第二變壓器Τ2的二次側繞線的打 第一電谷器C2的第一端，第二電衮51 n?吐‘，鸲耦去Each drive unit (such as 21 or 22) has a first end P1 and a second end p2 and - a transformer τ a second transformer T2, a first capacitor α, a second capacitor cry c2, ^ diode D1 and a second two The pole body D2, wherein the first transformer T1 and the second transformer ❿ have a secondary side winding and a secondary side winding. In each of the drive units (such as 21 or ^==================================================================================================== Dot end, 篦 辔 辔 全 全 全 - 人 人 人 人 # # # # # # # # # # # # # # # # # # # # # # # # # # # 的 的 的 的 的 的 的 的 的 的 的 的 的 的 的 的The second end of the first - ^ 相 is connected to the cathode of the first diode: the input of the strip LB1 is known, the second end of the second transformer Τ2 is wound with the first end of the first electric grid C2, and the second Electric 衮 51 n? 吐', 鸲 coupling
电谷态C2的第二端耦接第二二極體D 6 =陰極端=第—燈條LB2的輸 τ2 Γ==打點端、第—：極體^ 的陽極端、 第-燈條LB_二燈條LB2的輪出端均接地。 接，二有通過各自的第一端ρι和第二端p2串聯耦 时- π 、兩端（在本例中為驅動單元21的第一端？1和驅動 、 一端Ρ2)分別耦接隔離變壓器TO的二次側繞線的兩端。 、口居說所有帛賴器T1和第二變麼器T2的一次側繞線串聯耦 且串聯麵接後的兩端（在本财為驅動單元2丨的第—變壓器T1 的人側、，凡線的打點端和驅動單元22的第二變墨器的一次側繞線 的打點端）分職接隔離變壓器TO的二次側繞線的兩端。因此，只要 設計所有第—變壓⑽㈣二賴ϋ 了2具有相_-次側繞線阻抗 和^比，則隔離變壓器刊的二次側繞線感應出的交流電源的電壓將 平^洛於所有第-魏器T1和第二變壓器Τ2的—次側繞線上，進而 可完成所有第-燈串LB1和第二燈串LB2的電流平衡控制^ _為了控制流過第一燈φ LB1和第二燈串⑽的電流，每一驅動單 疋(如21或22)還包括第三二極體D3、第四二極體M、第一電阻器们 和第二電阻器R2。此時，第—燈條LB1的輸出端墟第三二極體⑽ 的陽極端，第三二極體D3着極端祕第—電阻器R1的第一端，第 一電阻器R1的第二端接地；第二燈條LB2的輸出端減第四二極體 Μ的陽極端，第四二極體D4 極端搞接第二電阻器R2力第一端， 第-電阻器R2的第二端接地。這部分後面會有進—步的描述。 在隔離型IXD驅動器2中，DC/AC轉換器251、隔離變壓器τ〇、 第一變壓器Τ1和第二變壓器Τ2組成隔離型DC/AC轉換電路25。在本 實施例中’ DC/AC轉換器251例如是半橋式或全橋式開關電路而可將 ^流電源髓為交流方波，隔__ TQ可通過改魏數比來決 疋升壓或降壓’或者紐數比設定為1 : 1僅作為安規隔離使用，這時 M399572 祕4不#要保留_祕來進行能 高的能量轉換效率。由於隔離則叩純。使仔交心具有絕對 換，第-級雜二 動器2僅採用了二級的電源轉 換第、.及力因t正$13的效率約可達91% 換電路25賴軸可達_，如不相频過財裝ΐ的損 1 =隔驅動器2的電源轉換效率將提升至84·6% (儀 93/。），因此本創作可提高電源轉換_，即減少電源轉換損失。The second end of the electric valley state C2 is coupled to the second diode D 6 = the cathode end = the first light strip LB2 of the input τ2 Γ == the dot end, the first: the anode end of the pole body ^, the first light bar LB The wheel end of the _2 bar LB2 is grounded. Connected, two through the respective first end ρι and the second end p2 coupled in series - π, both ends (in this example, the first end of the driving unit 21? 1 and the driving, one end Ρ 2) respectively coupled to the isolation transformer Both ends of the secondary side of the TO are wound. The port says that the primary side windings of all the device T1 and the second transformer T2 are coupled in series and are connected in series at both ends (in the case of the front side of the transformer unit T1 of the driving unit 2丨, The dot end of the wire and the dot end of the primary winding of the second ink changer of the driving unit 22 are separately connected to both ends of the secondary winding of the isolation transformer TO. Therefore, as long as all the first-transformed voltages (10) and (4) are designed to have 2 phase-to-side winding impedances and ratios, the voltage of the AC power source induced by the secondary winding of the isolation transformer will be flat. All the first-vessels T1 and the second-side windings of the second transformer Τ2, and thus the current balance control of all the first-light strings LB1 and the second light-string LB2 can be completed to control the flow of the first lamps φ LB1 and The current of the two strings (10), each driving unit (such as 21 or 22) further includes a third diode D3, a fourth diode M, a first resistor, and a second resistor R2. At this time, the output end of the first light bar LB1 is at the anode end of the third diode (10), the third diode D3 is at the first end of the extreme secret-resistor R1, and the second end of the first resistor R1 Grounding; the output end of the second light bar LB2 is reduced from the anode end of the fourth diode body, the fourth diode D4 is connected to the first end of the second resistor R2, and the second end of the first resistor R2 is grounded. . There will be a description of the steps in this section. In the isolated type LCD driver 2, the DC/AC converter 251, the isolation transformer τ, the first transformer Τ1, and the second transformer Τ2 constitute an isolated DC/AC conversion circuit 25. In the present embodiment, the DC/AC converter 251 is, for example, a half-bridge or full-bridge switching circuit, and the power supply core can be an AC square wave, and the __TQ can be adjusted by changing the Wei number ratio. Or buck' or the new-to-digital ratio is set to 1:1. It is only used as a safety isolation. At this time, M399572 is not allowed to perform high energy conversion efficiency. Because the isolation is pure. The eccentricity of the nucleus has an absolute change, the first-stage hybrid two-actuator 2 only uses the secondary power conversion, and the force due to the positive energy of $13 is about 91%, and the circuit 25 can reach the _, if not The loss of the phase frequency over the financial package 1 = the power conversion efficiency of the drive 2 will be increased to 84.6% (instrument 93 /.), so this creation can improve the power conversion _, that is, reduce the power conversion loss.
圖3Α和圖3Β分別為圖2所示本創作的隔離型LED驅動器2在正 +週時和在負半週時的功示意圖。請參 3A，當隔離變壓器仰 的-次側繞線接㈣交流獅在正麵時，隔離變㈣tq的二次側繞 線的電流流人第-㈣H T1的—次側繞線的打點端韻出第二變壓 器T2^一次側繞線的打點端，根據打點原則（dot convention)，第一 變壓器T1的二次側繞線的電流從其打點端流出，而第二變壓器Τ2的 二次側繞線的電流從其打點端流入。此時，第一變壓器T1的二次側繞 線的電流從其打點端流出經由第一電容器C1、第一燈串LB1、第三二 極體D3和第一電阻器扪到地，再從地回到第一變壓器T1的二次側繞 線的非打點端形成一個迴路，而第二變壓器T2的二次側繞線的電流從 其非打點端流出到地，再從地經由第二二極體D2和第二電容器C2回 到第二變壓器T2的二次側繞線的打點端形成另一個迴路。第一燈串 LB1有電流流過而會發光，而第二燈串[Β2沒有電流流過而不會發光。 請參見圖3B，當隔離變壓器TO的一次側繞線接收的交流電源在 負半週時，隔離變壓器TO的二次側繞線的電流流出第一變壓器丁1的 一次側繞線的打點端且流入第二變壓器T2的一次側繞線的打點端，根 據打點原則，第一變壓器T1的二次側繞線的電流從其打點端流入，而 第一變壓為T2的二次側繞線的電流從其打點端流出。此時，第·~~變壓 器Ή的二次側繞線的電流從其非打點端流出到地，再從地經由第—二 極體D1和第一電容器C1回到第一變壓器Τ1的二次側繞線的打點端形 8 M399572 -辦慰哭/述本，作因採用DC/AC轉換器、隔離變壓器、至少-第 正=二:!二_器組成的隔離型dc/ac轉換器，其接收功 電源並在^換w ί電源或接收橋式整流11和遽波電容器輸出的直流 數而提高電源二和第，:串，因此減少電源轉換級 -次側繞線阶純奴$外料所有第—和第二變㈣具有相同的 均落於戶ί有第二第二二，，壓器二次側繞線感應出的電壓平 一欠側缺绩m 的—次側繞線上，第—和第二變壓器的 =U線再通過—些線路即可完成第―和第二燈串的電流 制，因此間化電流平衡控制設計。 、二 雖…、:本創作已以較佳實施例揭露如上，然其並非用於限定本創 作任何热習此技藝者，在不麟本創作之精神和範圍内，當可作些 許^更動與潤飾，因此本_之健細當視_之中料利範圍戶; 界定者為準。 【圖式簡單說明】 圖1為一種現有的隔離型LED驅動器的電路圖。 圖2為本創作的隔離型LED驅動器的第一實施例的電路圖。 圖3A為本創作的隔離型led驅動器在正半週時的工作示意圖。 圖3B為本創作的隔離型LED驅動器在負半週時的工作示意圖。 圖4為本創作的隔離型LED驅動器中迴授和調光的一實施例的電 路圖。 圖5為本創作的隔離型LED驅動器的第二實施例的電路圖。 【主要元件符號說明】 1 :現有的隔離型LE1D驅動器 11 : EMI濾波器 M399572 12 :橋式整流器 14 :濾波電容器 16 :升壓轉換器 171 : LED控制器 IS1〜ISm : LED控制器的檢測端 VCC : LED控制器的電源端 21、22 :驅動單元 P2 :驅動單元的第二端 251 :DC/AC轉換器 FB ·· DC/AC轉換器的迴授端 261 ·誤差放大益的第—輪入端 263 :誤差放大器的輸出端 28 :隔離電路 41〜4m :燈條 C1 :第一電容器 D1 :第一二極體 D3 :第三二極體 LB1 :第一燈條 Q1〜Qm :電晶體 R1 :第一電阻器 13 :功因修正器 15 :隔離型DC/DC轉換器 17 :電流平衡控制器 CH1〜CHm : LED控制器的驅動端 FB : LED控制器的迴授端 2、3 :本創作的隔離型led驅動器 P1 :驅動單元的第一端 25 :隔離型DC/AC轉換器 EN : DC/AC轉換器的致能端 26 :誤差放大器 262 :誤差放大器的第二輸入端 27 :隔離電路 4〜6 : LED光源 51〜5n : LED C2 :第二電容器 D2 :第二二極體 D4 :第四二極體 LB2 :第二燈條 Rsl〜Rsm :電阻器 R2 :第二電阻器 12 M399572 TO :隔離變壓器 T2 :第二變壓器 Vfb :回授信號 T1 :第一變壓器 Vdim :調光信號 Vref :參考電壓3A and 3B are diagrams showing the work of the isolated LED driver 2 of the present invention shown in FIG. 2 at positive + week and negative half cycle, respectively. Please refer to 3A. When the isolation transformer is turned upside down - the secondary side is connected (4), the AC lion is on the front side, and the isolation is changed. (4) The secondary side winding current of the tq is the current - (4) H T1 - the secondary side winding The second transformer T2^ is tapped at the primary side winding. According to the dot convention, the current of the secondary winding of the first transformer T1 flows out from the tapping end thereof, and the secondary side of the second transformer Τ2 is wound. The current of the line flows in from its dot end. At this time, the current of the secondary side winding of the first transformer T1 flows out from the tapping end thereof via the first capacitor C1, the first lamp string LB1, the third diode D3, and the first resistor to the ground, and then from the ground. Returning to the non-tapping end of the secondary side winding of the first transformer T1 to form a loop, and the current of the secondary side winding of the second transformer T2 flows out from its non-tapping end to the ground, and then from the ground to the second pole The body D2 and the second capacitor C2 return to the dot end of the secondary side winding of the second transformer T2 to form another loop. The first string LB1 has a current flowing to emit light, and the second string [Β2 has no current flowing without emitting light. Referring to FIG. 3B, when the AC power received by the primary side winding of the isolation transformer TO is in the negative half cycle, the current of the secondary winding of the isolation transformer TO flows out of the check end of the primary winding of the first transformer D1 and Flowing into the striking end of the primary side winding of the second transformer T2, according to the striking principle, the current of the secondary side winding of the first transformer T1 flows from the striking end thereof, and the first variable voltage is the secondary side winding of the T2 The current flows from its dot end. At this time, the current of the secondary winding of the first to fourth transformers flows from the non-input terminal to the ground, and then returns to the second transformer Τ1 from the ground via the first diode D1 and the first capacitor C1. The side winding of the side winding 8 M399572 - to do the crying / description, due to the use of DC / AC converter, isolation transformer, at least - the positive = two: ! two _ device composed of isolated dc / ac converter, It receives the power supply and increases the power supply of the power supply and the DC output of the bridge rectifier 11 and the chopper capacitor to increase the power supply of the second and the first: string, thus reducing the power conversion level - the secondary side winding line pure slave All the first and second variants (four) have the same uniformity, and the second and second turns, the voltage induced by the secondary winding of the press is equal to the short side of the underside m. - The current line of the first and second strings can be completed by the -U line of the second transformer and then through the lines, thus the current balance control design. 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 Retouching, therefore, the _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a circuit diagram of a conventional isolated LED driver. 2 is a circuit diagram of a first embodiment of the isolated LED driver of the present invention. FIG. 3A is a schematic view showing the operation of the isolated LED driver of the present invention in the positive half cycle. FIG. 3B is a schematic view showing the operation of the isolated LED driver of the present invention in the negative half cycle. 4 is a circuit diagram of an embodiment of feedback and dimming in the isolated LED driver of the present invention. Figure 5 is a circuit diagram of a second embodiment of the isolated LED driver of the present invention. [Main component symbol description] 1 : Existing isolated LE1D driver 11 : EMI filter M399572 12 : Bridge rectifier 14 : Filter capacitor 16 : Boost converter 171 : LED controller IS1 ~ ISm : Detection terminal of LED controller VCC: power supply terminal 21, 22 of LED controller: drive unit P2: second end 251 of drive unit: DC/AC converter FB · · feedback terminal of DC/AC converter 261 · Error-amplification of the first wheel Inverter 263: Output terminal 28 of error amplifier: Isolation circuit 41~4m: Light bar C1: First capacitor D1: First diode D3: Third diode LB1: First light bar Q1~Qm: Transistor R1: first resistor 13: power factor corrector 15: isolated DC/DC converter 17: current balance controller CH1~CHm: drive terminal FB of LED controller: feedback terminal 2, 3 of LED controller: The isolated LED driver P1 of the present invention: the first end 25 of the driving unit: the isolated DC/AC converter EN: the enabling end 26 of the DC/AC converter: the error amplifier 262: the second input 27 of the error amplifier: Isolation circuits 4 to 6: LED light sources 51 to 5n: LED C2: second capacitor D2: second diode D4: fourth Polar body LB2: second light bar Rsl~Rsm: resistor R2: second resistor 12 M399572 TO: isolation transformer T2: second transformer Vfb: feedback signal T1: first transformer Vdim: dimming signal Vref: reference voltage
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