201247014 六、發明說明： 【發明所▲之技術領域】 本發明係有關一種LED驅動電路。 【先前技術】 美國專利號6989807提出一種LED驅動電路，將一個串 式LED陣列分成幾個LED群組，每—個LED群組的輪 ，連接一個電流單元，根據電源電壓的大小從該多個電故 早το選擇一個致能，以最大化點亮LED = 電路需要多個電流單元，整體電路較大，成本較高種^201247014 VI. Description of the Invention: [Technical Field of Invention] The present invention relates to an LED driving circuit. [Prior Art] U.S. Patent No. 6,989,807 proposes an LED driving circuit that divides a string LED array into several LED groups, each of which is connected to a current unit according to the magnitude of the power supply voltage. Electric το early select an enable to maximize the LED = circuit requires multiple current units, the overall circuit is larger, the cost is higher ^
因為該多個電流單元彼此之間不匹配，導致驅動電流 定，影響LED的亮度和色溫。 LBecause the plurality of current cells do not match each other, the drive current is set, affecting the brightness and color temperature of the LED. L
此外，上述的驅動電路係根據電源電壓的大小決定要致 哪-個電流單元，造成應用上缺乏適應性。美國專利 案公開號2011084618將控制方式改為根據第二個LE ίί!Ϊ後—個LED群組的輸出端電壓，決定是否要致能該 輸出端連接的電流單元及禁能其他電流單元，因而改盖了 驅動電路在應用上的適應性。但是上述多個電流單元&致 的缺點依然存在。 我國專利申請案公開號撕刚奶使用旁通開關來改變 LED組態，其驅動電路如圖丨所示，為了簡潔之故，僅綸 示與本發明相關的電路。在圖丨中，橋式整 ^ 電源Vac整流產生輸入電壓給第一個電源連接端 一個電源連接端GND，連接第一個電源連接端Vin的串列 式LED陣列被分成LED群組G卜G2、G3及G4，LED 群、’且G2 G3及G4各並聯一個旁通開關swi、SW2及 分別受控於比較器12、14及16，參考電壓源18提In addition, the above-mentioned driving circuit determines which one of the current units is to be caused according to the magnitude of the power supply voltage, resulting in a lack of adaptability in application. U.S. Patent Publication No. 2011084618 changes the control mode to determine the current unit connected to the output terminal and disable other current units according to the output voltage of the second LE ί ί — 个 LED group. Adapted to the adaptability of the drive circuit in application. However, the disadvantages of the above multiple current units & still exist. China's patent application publication No. Tearing uses a bypass switch to change the LED configuration, and its driving circuit is as shown in the figure. For the sake of brevity, only the circuit related to the present invention is shown. In the figure, the bridge type power supply Vac rectifies the input voltage to the first power connection end of a power connection terminal GND, and the tandem LED array connected to the first power connection end Vin is divided into LED groups Gb G2 , G3 and G4, LED group, 'and G2 G3 and G4 are each connected in parallel with a bypass switch swi, SW2 and controlled by comparators 12, 14 and 16, respectively, reference voltage source 18
3 J巧壓Vref給比較器12、14及16。當輪入電壓％ 較低打，旁通開關SW1、SW2及SW3全部閉合，口有LED 受驅動；在㈣群組G1導通後，ΐ輸出端的電 垄Ik耆輸入電壓Vin上升，當此電壓超過參考電壓Vref， 201247014 比較器12切斷開關SW1，因此LED群組G2加入串聯到 群組G1 ’ 一起受驅動；如此，在輸入電壓％上升的 過私中，會有越來越多的LED群組加入串聯的LED組態； 反之’、在輸入電壓Vin下降的過程中，會有越來越多的lED 群組被旁通而失能。然而旁通開關SWb SW2及SW3在 實際上會有跨壓’因此造成壓降損失，影響LED輸 工率。例如，在旁通開關SW1、SW2及SW3全部閉合 a，，:要更南的輸入電壓vin才足以驅動LED群組Q1， 群組gi串聯而被浪費掉。 曰導致文此降低’而且在串列 < ㈣陣列被分成 ΪίΪΐ時’問題越嚴重。旁通開關讓、SW2及SW3 ^ if 2耗功率，越多串聯的開關就會浪費越多的 會ί制此.UHHi6，關_參考電壓— ㈣群組的串聯LED 二:曰^咸二中某個 累加起來的切入㈣姻雷變異，各led群組 A於士歸ί )電財同，參考電M Vref必須設定 旁^門關t導ί部分功率被浪f掉。在圖1t，全部的 另方二及SW3都是浮接的設計，電路會比 使用恆定雷、* ’為了穩定驅動電流，圖1的驅動電路 【發明内容】 二月列驅:電路具有多個LED連接端供 個LED群组，夢切換二，將該串列<LED陣列分成多 個電源連接端及第二個電& 電流單元串聯在第- 態皆串聯到該共用電接。由於每一種LED組 且電路較小。在每—#L 維持穩定_動電流， 隹母種LED組態下，只有一個路徑開 201247014 跨壓損失，或甚至沒有路徑開關的跨壓損失，因此提高 能。. 【實施方式】 圖2係本發明的第一實施例，一種LED驅動電路包括多個 LED連接端OUT1、OUT2及OUT3分別連接各個LED群 組Gl、G2及G3的輸出端，配置器22從LED連接端 OUT1、OUT2及OUT3 #情擇-個連接纟彳制電流單元 24。配置器22包含路徑開關SW連接共用電流單元24, 以及控制器26連接第一個電源連接端vin，根據輸入電壓 Vin的大小切換路徑開關sw以切換LED連接端〇υτι、 OUT2及OUT3到共用電流單元24。控制器26將輸入電壓 Vin與參考電壓vrl及Vr2比較，以決定信號sw。藉著切 換路徑開關Sw’在輸入電壓Vin上升的過程中逐漸增加 串聯的LED群組’在輸入電μ yin下降的過程中逐漸減少 =聯的LED群組，不論在哪—種LED組態下，驅動電流 皆維持不變，而且只有一個路徑開關sw的壓降損失。如 同本技術領，具有通常知識者已知的，這種LED驅動電路 使用的電流單元可以用電流源或限流器來實現，限流器可 電阻來實現。控制器26切換路徑開關SW所需的參考 面f 3及％2係彼此獨立的，不會互相影響，因此不需 ί ^ ㈤LED群組含有補數量㈣聯LED，而且每 麻的夂去^組的LED數量可以任意增減’只要修改其對 雷、踗I 口古^的大小。即使有更多的LED群組，這種驅動 低。址用、電、、Π共用電流單元24 ’整體電路較小，成本較 用雷:/011•早凡24連接在低壓端’路徑開關SW連接共 24，因此電路比較簡單。上述偵測輸入電壓 oim的^=文為_第一個㈣群組G1的輸出端 她nTm 4^1，路徑開關SW預設為切換到LED連接 Ϊ 電壓Vrl及似的設定值比上述實施例低。 田 呀’路徑開關SW將LED連接端OUT1連接到 201247014 共用電流單元24 ;在LED群組G1導通期間，電壓V1隨 著輸入電壓Vin變動，因此偵測電壓V1等同於偵測輸入 電壓Vin。 ' ，f的LED驅動電路可以改成圖3的實施例，將共用電流 單元24改為連接在第一個電源連接端Vin和串列式lED 陣列的巧入端Vs之間，控制器26偵測串列式[ED陣列的 輸入電壓Vs或第一個LED群組⑴的輸出端〇UT1的電 壓vi，據以切換路徑開關sw而將LED連接端0UT1、 OUT2或OUT3接地。在此實施例中，路徑開關sw係連 接在地端，因此沒有高壓的問題。 圖4係本發明的第三實施例，其配置器22使用更多的路徑 開關。在LED連接端0UT1與共用電流單元24之間係路 徑開關SW1’在LED連接端0UT2與共用電流單元24之 ，係路徑開關SW2’LED連接端〇UT3直接連接共用電流 單兀24。控制器26偵測LED群組G1及G2的輸出端〇UT1 及OUT2❾電壓VI及V2，據以切換路徑開關SW1及SW2 而將LED連接端0UT1或〇UT2連接到共用電流單元％ 在輸入電壓Vin上升的過程中，在電壓V1上升到參考 ，Vrl以前，路徑開關SW1導通，路徑開關sw2切斷； ，電壓VI上升到超過參考電壓Vrl時，路握開關簡切 辦’路㈣關SW2導通；當電壓V2上升到超 Γ，t電=斷。在輸入_ Vin下降的過程 、s .二ί〗下降到參考電壓Vr2時，路徑開關SW2導 ，，當電壓Vi下降到參考電壓Vrl時，路徑開關_ ^ ^ ’路徑開關SW2崎。任一個LED群組在導通後，直 輸出端的電壓會反映其輸人端的電壓，因此，經過上^ ，方法的教導，本技術領域具有通常知識者當知 | 法可以用來控制路徑開關SW1及SW2。此實施例 ^猎制LED群_輸出端來控觀 ^ 於個別的LED群組具有適應性。此外，如同圖3的實施2 201247014 一般’圖4的LED驅動電路也可以改成將共用電流單元 24連接在第一個電源連接端Vin和串列式LED陣列的輸 入端之間，路徑開關SW1及SW2都接地。 如圖5所示，圖4的LED驅動電路可以改成在最後一個 LED群組G3的輸出端〇UT3與共用電流單元24之間增加 一個路徑開關SW3,受控制器26切換以連接輸出端〇UT3 到共用電流單元24，或切斷該連接。如果需要的話’增加 一個參考電壓Vr3用來控制路徑開關SW3。 圖6係本發明的第五實施例，配置器22包含MOS電晶體 M1、M2及M3各連接在LED連接端〇UTl、OUT2及OUT3 與共用電流單元24之間，以及運算放大器28、3〇及32 刀別控制MOS電晶體Ml、M2及M3。運算放大器28、 30及32的負輸入端分別連接到M〇s電晶體及 M3的源極，以各自建立負回授路徑。運算放大器π、如 及32的正輸入端分別接受參考電壓Vrl、Vr2及ye，且 Vrl<Vr2<Vr3。在輸入電壓Vin上升的過程中，當LED群 組G1導通，因為負回授的緣故，共節點Vx的電壓會被限 制在Vrl，電壓V1隨著Vin上升；當電壓V1上升到某個 位準，LED群組G2導通’造成共節點Vx的電壓快速拉升 到Vr2，因而導致運算放大器28關閉m〇s電晶體Ml ;同 樣的，輸入電壓Vin繼續上升到LED群組G3導通，導致 運算放大器30關閉MOS電晶體M2 ;然後，當輸入電壓 Vm下降到不足以驅動lED群組g3時，M〇s電晶體M3 ΓΙί算放大器30導通则電晶體M2;當輸入電壓 Vm繼績下降到不足以驅動LED群組G2時，M〇s3 J presses Vref to comparators 12, 14 and 16. When the wheeling voltage % is lower, the bypass switches SW1, SW2 and SW3 are all closed, and the LEDs are driven by the port; after the (4) group G1 is turned on, the electric ridge Ik耆 of the output terminal of the ΐ output voltage Vin rises, when the voltage exceeds Reference voltage Vref, 201247014 Comparator 12 cuts off switch SW1, so LED group G2 is connected in series to group G1' to be driven together; thus, in the excessive increase of input voltage %, there will be more and more LED groups The group joins the LED configuration in series; otherwise, in the process of the input voltage Vin falling, more and more lED groups are disabled by the bypass. However, the bypass switches SWb SW2 and SW3 actually have a voltage across them, thus causing a voltage drop loss, which affects the LED power transmission rate. For example, when the bypass switches SW1, SW2, and SW3 are all closed a,, the input voltage vin to be more south is sufficient to drive the LED group Q1, and the group gi is connected in series and wasted.曰 causes this to decrease' and the more serious the problem is when the tandem < (4) array is divided into ΪίΪΐ. Bypass switch let, SW2 and SW3 ^ if 2 consume power, the more switches connected in series will waste more of this. UHHi6, off _ reference voltage - (four) group of LEDs in series 2: 曰 ^ salt two A certain cumulative cut-in (four) marriage variability, each led group A Yu Shigui ί) electricity, the reference electricity M Vref must be set next to the door close t guide ί part of the power is waved off. In Figure 1t, all the other two and SW3 are floating design, the circuit will be more than the use of constant lightning, * 'To stabilize the drive current, the drive circuit of Figure 1 [invention] February column drive: circuit has multiple The LED connection end is provided with an LED group, and the dream switch 2 is divided into a plurality of power connection terminals and a second electric current unit. The current units are connected in series to the common electric connection in series. Because of each LED group and the circuit is small. In each -#L maintains a stable _ dynamic current, 隹 mother-type LED configuration, only one path to open 201247014 cross-voltage loss, or even no cross-circuit loss of the path switch, thus improving energy. [Embodiment] FIG. 2 is a first embodiment of the present invention. An LED driving circuit includes a plurality of LED terminals OUT1, OUT2, and OUT3 connected to respective LED groups G1, G2, and G3. The configurator 22 The LED terminals OUT1, OUT2, and OUT3 are connected to the current unit 24. The configurator 22 includes a path switch SW connected to the common current unit 24, and the controller 26 is connected to the first power connection terminal vin, and switches the path switch sw according to the magnitude of the input voltage Vin to switch the LED connection terminals 〇υτι, OUT2 and OUT3 to the common current. Unit 24. The controller 26 compares the input voltage Vin with the reference voltages vrl and Vr2 to determine the signal sw. By switching the path switch Sw' gradually increases the series of LED groups in the process of increasing the input voltage Vin' gradually decreases in the process of the input power μ yin falling = the associated LED group, no matter where - the LED configuration The drive current remains unchanged, and there is only one path switch sw with a voltage drop loss. As is known in the art, the current unit used in such an LED driving circuit can be realized by a current source or a current limiter, and the current limiter can be implemented by a resistor. The reference planes f 3 and %2 required by the controller 26 to switch the path switch SW are independent of each other and do not affect each other, so there is no need for ί ^ (5) LED groups contain a complementary number (four) of LEDs, and each numb The number of LEDs can be increased or decreased arbitrarily as long as the size of the lightning and 踗I ports is modified. This drive is low even with more LED groups. Address, power, and Π shared current unit 24 ′ overall circuit is small, the cost is better than mine: / 011 • early 24 connected to the low-voltage end of the path switch SW connected a total of 24, so the circuit is relatively simple. The above-mentioned detection input voltage oim ^= text is _ the first (four) group G1 output terminal her nTm 4^1, the path switch SW is preset to switch to the LED connection 电压 voltage Vrl and similar set values than the above embodiment low. The field switch SW connects the LED connection terminal OUT1 to the 201247014 shared current unit 24; during the conduction of the LED group G1, the voltage V1 varies with the input voltage Vin, so the detection voltage V1 is equivalent to the detection input voltage Vin. The LED driving circuit of 'f can be changed to the embodiment of FIG. 3, and the common current unit 24 is connected between the first power connection terminal Vin and the in-line Vs of the serial lED array, and the controller 26 detects The serial input voltage Vs of the ED array or the voltage vi of the output terminal 〇UT1 of the first LED group (1) is measured, and the LED connection terminal OUT1, OUT2 or OUT3 is grounded accordingly by switching the path switch sw. In this embodiment, the path switch sw is connected to the ground end, so there is no problem of high voltage. Figure 4 is a third embodiment of the invention with configurator 22 using more path switches. The LED switch SW1' is connected between the LED connection terminal OUT1 and the common current unit 24 at the LED connection terminal OUT2 and the common current unit 24, and the path switch SW2' LED connection terminal 〇UT3 is directly connected to the common current unit 兀24. The controller 26 detects the output terminals 〇UT1 and OUT2 of the LED groups G1 and G2, voltages VI and V2, and switches the path switches SW1 and SW2 to connect the LED terminals 0UT1 or 〇UT2 to the common current unit % at the input voltage Vin. During the rising process, before the voltage V1 rises to the reference, before the Vrl, the path switch SW1 is turned on, and the path switch sw2 is turned off; when the voltage VI rises above the reference voltage Vrl, the road grip switch simply cuts the 'road (four) off SW2 conduction; When the voltage V2 rises to over Γ, t = = off. When the input _ Vin falling process, s. 2 ί is lowered to the reference voltage Vr2, the path switch SW2 is turned on, and when the voltage Vi falls to the reference voltage Vrl, the path switch _ ^ ^ ' path switch SW2 is slug. After any LED group is turned on, the voltage at the direct output will reflect the voltage at the input end. Therefore, after the teaching of the method, the person skilled in the art knows that the method can be used to control the path switch SW1 and SW2. This embodiment ^ Hunting LED group_output to control the individual LED groups are adaptable. In addition, as in the implementation of FIG. 3 2 201247014, generally, the LED driving circuit of FIG. 4 can also be changed to connect the common current unit 24 between the first power connection terminal Vin and the input end of the tandem LED array, and the path switch SW1 And SW2 are grounded. As shown in FIG. 5, the LED driving circuit of FIG. 4 can be modified to add a path switch SW3 between the output terminal 〇UT3 of the last LED group G3 and the common current unit 24, and is switched by the controller 26 to connect the output terminal. UT3 to the shared current unit 24, or cut the connection. Add a reference voltage Vr3 to control the path switch SW3 if necessary. 6 is a fifth embodiment of the present invention, in which the configurator 22 includes MOS transistors M1, M2, and M3 connected between the LED terminals UT1, OUT2, and OUT3 and the common current unit 24, and the operational amplifiers 28, 3A. And 32 knives control MOS transistors Ml, M2 and M3. The negative inputs of operational amplifiers 28, 30 and 32 are connected to the M〇s transistors and the sources of M3, respectively, to establish a negative feedback path, respectively. The positive input terminals of the operational amplifiers π, such as and 32 receive the reference voltages Vrl, Vr2, and ye, respectively, and Vrl < Vr2 < Vr3. During the rise of the input voltage Vin, when the LED group G1 is turned on, the voltage of the common node Vx is limited to Vrl due to the negative feedback, and the voltage V1 rises with Vin; when the voltage V1 rises to a certain level , LED group G2 turns on 'causes the voltage of the common node Vx to rapidly rise to Vr2, thus causing the operational amplifier 28 to turn off the m〇s transistor M1; likewise, the input voltage Vin continues to rise until the LED group G3 turns on, resulting in an operational amplifier 30 turns off the MOS transistor M2; then, when the input voltage Vm falls below enough to drive the lED group g3, the M〇s transistor M3 算 算 the amplifier 30 is turned on and the transistor M2; when the input voltage Vm falls below enough When driving LED group G2, M〇s
=2關閉，運算放大器28導通M〇s電晶體Μι。m〇BsB 及M3也可以改用其他種類的電晶體，例如 接面電3日日體。在不_實施例中，也可以把運算放 士盗28、3〇及32以等效元件取代，例如一個多輸出 放大器，這是本技術領域具有通常知識者已知之事。 201247014 從以上各實施例的展示可知，本發明的LED驅動電路切換 路徑開關以改變LED組態，在每一種LED組態下，都是 串聯到共用電流單元24，因此維持穩定的驅動電流，而且 電路較小。此外，在每一種LED組態下，只有一個路徑開 關的跨壓損失，或甚至沒有路徑開關的跨壓損失，因此提 面效能。本發明的LED驅動電路也釋放了對LED群組的 限制，因此更具應用彈性。 【圖式簡單說明】 圖1係習知的LED驅動電路； 圖2係本發明的第一實施例； 圖3係本發明的第二實施例； 圖4係本發明的第三實施例； 圖5係本發明的第四實施例；以及 圖6係本發明的第五實施例。 【主要元件符號說明】 10 橋式整流器 12 比較器 14 比較器 16 比較器 18 參考電壓源 20 恆定電流源 22 配置器 24 共用電流單元 26 控制器 28 運算放大器 30 運算放大器 運算放大器 32=2 is off, and the operational amplifier 28 turns on the M〇s transistor Μι. m〇BsB and M3 can also be used with other types of transistors, such as 3 days of junction. In the non-embodiment, it is also possible to replace the operational thieves 28, 3, and 32 with equivalent elements, such as a multi-output amplifier, as is known to those of ordinary skill in the art. 201247014 It can be seen from the above embodiments that the LED driving circuit of the present invention switches the path switch to change the LED configuration. In each LED configuration, it is connected in series to the common current unit 24, thereby maintaining a stable driving current, and The circuit is small. In addition, in each LED configuration, there is only one path switch cross-voltage loss, or even no path switch cross-voltage loss, so the performance is improved. The LED driver circuit of the present invention also releases the restrictions on the LED group and is therefore more flexible. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conventional LED driving circuit; FIG. 2 is a first embodiment of the present invention; FIG. 3 is a second embodiment of the present invention; 5 is a fourth embodiment of the present invention; and Fig. 6 is a fifth embodiment of the present invention. [Main component symbol description] 10 Bridge rectifier 12 Comparator 14 Comparator 16 Comparator 18 Reference voltage source 20 Constant current source 22 Configurator 24 Common current unit 26 Controller 28 Operational amplifier 30 Operational amplifier Operational amplifier 32