M383241 五、新型說明： 【新型所屬之技術領域】 本創作是有關於一種電流檢測電路，且特別是有關於一種用於檢 測直流電壓源的電源輸出線中是否有過電流的過電流檢測電路。 【先前技術】 • $見的用於電源輸出的過電流檢測電路，以其屬性可分為被動式 與主動式兩種。被動式過電流檢測電路為採用保險絲、熱融開關等具 鲁有熱跳脫特性的正溫度反應元件，在檢測到流過的電流超出規範時， 通過7L件本身的跳脫來斷開電路，以達到保護效果。主動式過電流檢 測電路為_可檢測電流的元件，如霍爾⑽⑴元件、電阻等將流 過的電流t小轉換為賴大小，依據哺躺得的頓大小來判斷流 過的電流是否超出規範，以便通知後面的保護電路作出適當的保護。M383241 V. New description: [New technical field] This creation is related to a current detecting circuit, and in particular to an overcurrent detecting circuit for detecting whether there is an overcurrent in a power supply output line of a DC voltage source. [Prior Art] • The overcurrent detection circuit for power output can be divided into passive and active. The passive overcurrent detection circuit uses a positive temperature response element with a thermal tripping characteristic such as a fuse or a hot-melt switch. When it detects that the current flowing exceeds the specification, the circuit is disconnected by the jump of the 7L piece itself. Achieve protection. The active overcurrent detection circuit is a component that can detect current, such as Hall (10) (1) component, resistor, etc., which converts the current t flowing through into a small size, and determines whether the current flowing exceeds the specification according to the size of the feeding. In order to inform the subsequent protection circuit to make appropriate protection.
A被動式過電流檢測電路雜架構相當簡單、安裝方便但卻存在 相當大的誤差’對不同的削過電流峰值所需的反麟間均不相等， 如此將會造成保護點飄移。舉例來說，假設總負載電流額定為舰， 癱所6又疋的保4點為在電流A 15A時斷開魏進行保護’那麼如果使用 ’被動式過電流檢測電路，顺法絲在紐為15A _來跳脫的元件 會發生跳脫’而必須取決於電流流過元件所產生的熱損耗大小。主動 式過電檢測電路具有較精準的保護點控制、不受貞載糊峰值影響 等特性，但所需的成本通常高於被動式過電流檢測電路。 B 因此’如何在精準的保護點控制與低成本設計考量下取得相對性 的平衡點是本領域技術人員所一直努力的課題。 【新型内容】 本創作的目的就是在提出一種主動式過電流檢測電路，用於檢測 3 M383241 直流電壓_電輯出射是时過，並在精 低成本兩者間取得相對性的平衡點。 ’、4點控制與 出線中疋否有過仏，其中電源輸出線具有輸人端及輸 檢測電路包括檢測電阻、設定電阻、定電流源以 t 7 電阻具有第-端及第二端，檢測電阻的第一端 t ^測 ς端，檢:電阻的第二端祕至電源輸出線的輸出端。設;電;= =第二端’設定電阻的第-端柄接至電源輸出線的2= ΐ 接至紅電阻的第二端，用於從設定電_第二端吸取定電 机。電壓比較益輕接至檢測電阻的第二端及設定電阻的第二端用於 ===電壓小於設定電阻的第二端的電壓時輸出錯誤 仏说表不仏測到電源輸出線中有過電流。 在-實施例中，定電流源包括參考電流源以及電流鏡電路。 電流源用於產生狱的參考電m鏡祕_至 : 於根據參考電流輸出定電流。 电l原用 在一實施例中’電壓比較器包括第-運算放大器'第二運管放大 器以及^納二極體。第一運算放大器具有非反相輸入端、反相^入端 及輸出端，運算放A||的非反相輸人輪接至檢測電阻的第二 ，，第運算放大器的反相輸入端輕接至設定電阻的第二端。第二運 异放大Θ具有非反相輸人端、反她人端及輸出端，第二運算放大器 的非反相輸人端耦接至參考電壓，第二運算放大器的反相輸入端輛接 至第-運异放大器的輸出端。齊納二極體具有陰極端及陽極端，齊納 二極體的陰極端祕至第二運算放大器的輸出端，齊納二極體的陽極 端f檢測電阻的第二端的碰小於設定電阻的第二端的雜時輸出錯 誤信號。 M383241 本創個顧找麵獅駄絲奴賴點而 準的保遵點設定，其中定電流源還可採用 ς、月 ，電流來產生定電流，利用電流鏡電路中具有正』 溫度健的設定電阻進行溫賴償而使保護點不受二-響，另外電壓比較器還可採用運算放大器及 的： :護點設定、不受外界溫度變化影響、抗雜訊干擾且架構簡ί: 特兴之上述和其他目的、特徵和優點能更_易懂，下文 特舉#嫌貫_ ’並配合所關式，作詳細說明如下。 【實施方式】 灸日=為rtf作一較佳實施例的過電流檢測電路的電路圖。請 及2 2通過電源輸出線20輸出穩定的直流電壓： =負載雙化的直流電流u、當負載發生變化時，輸 電直流電壓源2及/或負载造成傷害。因此二過在 ^ 2ΐ vT且::出電二值極低，輸出端22的電壓v。接近於輸入端二ΐί 轉換ΐ Γίΐϊ = ’可為常見的具有隔離形式的升降壓 ^如返驰式⑴ybaek)、順向式(fQrward)、半橋 中是否 過電流檢測電路1用於檢測直流電壓源2的電源輸出線2〇 5 M383241 有過電流，其中電源輸出線20具有輸入端21及輸出端22。過電流檢 =電路1包括檢測電阻R卜設定電阻R2、定電流源u以及電壓比較 益12。檢測電HRR1具有第一端及第二端，檢測電阻R1的第一端耗接 至電源輸出線2G的輸人端21，檢測電阻_第二端雛至電源輸出 線20的輸出端22。設定電阻R2具有第一端及第二端，設定電阻R2 的第-端祕至電源輸出線2G的輸人端2卜定電流源n祕至設定 電阻R2的第二端，用於從設定電阻R2的第二端吸取定電流！2。電壓 比‘較器12具有第-輸入端（其標示為‘‘+，，）、帛二輸人端（其標示為 -)及輸出端’第一輸入端耦接至檢測電阻R1的第二端，第二輸入 端搞接至設^電阻R2的第二端。電壓比較器12用於在第一輸入端的 電壓v卜j、於第二輸人端的電壓V2時，即在檢測電阻ri的第二端的電 壓一VI小於設定電阻R2的第二端的電壓V2日夺，輸出錯誤信號Ε· 表示檢測到電;稀&線20巾有過電流。這個錯誤信號EiTQr可直接應 用來π令直流電壓源2強制關閉，或是傳送到微控制器㈤⑽c〇ntr〇1The passive structure of the A passive overcurrent detection circuit is quite simple and easy to install, but there is a considerable error. The reverse phase required for different current peaks is not equal, which will cause the protection point to drift. For example, suppose the total load current is rated as a ship, and the 4 points of the 瘫 瘫 为 为 为 为 为 为 在 在 电流 电流 电流 电流 电流 电流 电流 电流 电流 电流 电流 电流 电流 电流 那么 那么 那么 那么 那么 那么 那么 那么 那么 那么 那么 那么 那么 那么 那么 那么 那么The component that is tripped will trip, and must depend on the amount of heat loss generated by the current flowing through the component. The active over-voltage detection circuit has more precise protection point control and is not affected by the peak value of the load, but the cost is usually higher than the passive over-current detection circuit. B Therefore, how to achieve a relative balance between precise protection point control and low-cost design considerations is a problem that those skilled in the art have been working on. [New content] The purpose of this creation is to propose an active overcurrent detection circuit for detecting 3 M383241 DC voltage_Electronic series emission is over time, and the relative balance between the two is achieved. ', 4 points control and out of the line have no flaws, wherein the power output line has an input terminal and a transmission detection circuit including a sense resistor, a set resistor, a constant current source with a t 7 resistor having a first end and a second end, The first end of the sense resistor is measured, and the second end of the resistor is secreted to the output end of the power output line. Set; electric; = = second end 'set the first end of the resistor to the power output line 2 = 接 to the second end of the red resistor, used to draw the constant motor from the set power _ second end. The voltage comparison is lightly connected to the second end of the detecting resistor and the second end of the set resistor for outputting an error when the voltage of the second end of the set resistor is lower than the voltage of the second end of the set resistor, and the meter indicates that there is an overcurrent in the power output line. . In an embodiment, the constant current source includes a reference current source and a current mirror circuit. The current source is used to generate the reference voltage of the prison. _To: The current is output according to the reference current. In the embodiment, the 'voltage comparator includes a second operational amplifier' and a second transistor. The first operational amplifier has a non-inverting input terminal, an inverting input terminal and an output terminal, and the non-inverting input wheel of the operational amplifier A|| is connected to the second of the detecting resistor, and the inverting input terminal of the operational amplifier is light. Connect to the second end of the set resistor. The second operational amplifier has a non-inverting input terminal, an anti-her terminal, and an output terminal. The non-inverting input terminal of the second operational amplifier is coupled to the reference voltage, and the inverting input terminal of the second operational amplifier is connected. To the output of the first-differential amplifier. The Zener diode has a cathode end and an anode end, the cathode end of the Zener diode is secreted to the output end of the second operational amplifier, and the anode end of the Zener diode f is less than the set resistance of the second end of the sense resistor The second end of the timing outputs an error signal. M383241 This is a set of guards to meet the requirements of the lion's silk slaves. The constant current source can also use ς, 月, current to generate constant current, and the current mirror circuit has a positive temperature setting. The resistor is temperature compensated so that the protection point is not affected by the second sound. In addition, the voltage comparator can also be used with an operational amplifier and: : protection point setting, not affected by external temperature changes, anti-noise interference and simple structure: The above and other objects, features and advantages can be more easily understood. The following is a detailed description of the following. [Embodiment] Moxibustion Day = circuit diagram of an overcurrent detecting circuit which is a preferred embodiment of rtf. Please output a stable DC voltage through the power output line 20: = Load DC current u, when the load changes, the input DC voltage source 2 and / or load damage. Therefore, the second pass is ^ 2 ΐ vT and the power-off binary value is extremely low, and the voltage at the output terminal 22 is v. Close to the input terminal ΐ ΐ ΐϊ ΐϊ ΐϊ = ' can be used for the common type of lift voltage with isolation type ^ such as flyback (1) ybaek), forward (fQrward), half bridge, whether the overcurrent detection circuit 1 is used to detect DC voltage The power supply output line 2〇5 M383241 of the source 2 has an overcurrent, wherein the power output line 20 has an input terminal 21 and an output terminal 22. Overcurrent detection = Circuit 1 includes a sense resistor R, a set resistor R2, a constant current source u, and a voltage comparator 12. The detecting power HRR1 has a first end and a second end, the first end of the detecting resistor R1 is connected to the input end 21 of the power output line 2G, and the detecting resistor _ second end is connected to the output end 22 of the power output line 20. The setting resistor R2 has a first end and a second end, and the first end of the set resistor R2 is connected to the input end of the power output line 2G, and the current source n is fixed to the second end of the set resistor R2 for setting the resistor. The second end of R2 draws constant current! 2. The voltage ratio 'the comparator 12 has a first input terminal (which is labeled as ''+,)), a second input terminal (which is labeled as -), and an output terminal 'the first input terminal is coupled to the second detection resistor R1. The second input terminal is connected to the second end of the resistor R2. The voltage comparator 12 is used for the voltage Vb at the first input terminal and the voltage V2 at the second input terminal, that is, the voltage VI of the second terminal of the detecting resistor ri is smaller than the voltage V2 of the second terminal of the setting resistor R2. The output error signal Ε· indicates that the power is detected; the thin & line 20 has an overcurrent. This error signal EiTQr can be directly applied to π to force the DC voltage source 2 to be forcibly turned off, or to the microcontroller (5) (10) c〇ntr〇1
Unit ’簡稱MGU)而由其對直流電壓源2做出適當祕護，如切除電源、 關閉負載、關閉顯示等。 由於電壓比較器12為高輸入阻抗的元件，電壓比較器12的第〆 輸入端及第二輸人端的輸人電流幾乎為零，輸出電流n幾乎全流過檢 測電阻R1，定電流12幾乎全流過設定電阻貶，另外，丨丨，=u + i2， 其中il’、il和i2分別為輸出電、u和定電流12的電流值。 因此’電壓比較器12的第一輸入端的電壓Vl=vi —小且第二輸 入端的電壓V2 = Vl-如2，其中rl和r2分別為檢測電阻R1和設定 電阻R2的電阻值。在電壓比較器12的第—輸入端的電壓νι大於第二 輸入端的電壓V2時，il<i2的/r卜此時輸出電流n的電流值U 尚未超出規範’表示尚未檢測到電源輸出線2〇中有過電流。在電壓比 較器12的第-輸入端的電壓V1小於第二輪入端的電壓v2時，il>i2 M383241 xr2/rl此l·]·輸出電流ii的電流值ii超出規範，表示檢測到電源輸 出線20中有過電流’電壓比較器12因此輸出錯誤信號Err〇r。所以， 在檢測電阻R1的電阻值r丨、設定電阻R2的電阻值r2及定電流丨2的 電流值i2設定後，輸出電流n的電流值丨〗的保護點即被設定為（i2Unit ‘MGU for short) is used to make appropriate protection for DC voltage source 2, such as cutting off the power, turning off the load, turning off the display, and so on. Since the voltage comparator 12 is a component with a high input impedance, the input current of the second input terminal and the second input terminal of the voltage comparator 12 is almost zero, and the output current n flows almost completely through the detecting resistor R1, and the constant current 12 is almost complete. The set resistance 贬 flows, in addition, 丨丨, =u + i2, where il', il, and i2 are the current values of the output power, u, and constant current 12, respectively. Therefore, the voltage V1 of the first input terminal of the voltage comparator 12 = vi - and the voltage of the second input terminal V2 = V1 - such as 2, where rl and r2 are the resistance values of the sense resistor R1 and the set resistor R2, respectively. When the voltage νι at the first input terminal of the voltage comparator 12 is greater than the voltage V2 at the second input terminal, the current value U of the output current n of il<i2 at this time has not exceeded the specification' indicating that the power output line 2 has not been detected yet. There is an over current in it. When the voltage V1 at the first input terminal of the voltage comparator 12 is smaller than the voltage v2 at the second wheel terminal, il > i2 M383241 xr2 / rl. The current value ii of the output current ii is out of specification, indicating that the power output line is detected. There is an overcurrent 'voltage comparator 12 in 20 thus outputting an error signal Err〇r. Therefore, after the resistance value r丨 of the detecting resistor R1, the resistance value r2 of the setting resistor R2, and the current value i2 of the constant current 丨2 are set, the protection point of the current value 输出 of the output current n is set to (i2).
Xr2/rl)，一旦電流值il大於保護點則立刻輸出錯誤信號Error通知 後面的保護電路以做出適當的保護。 * 在本貫施例中，過電流檢測電路1還包括電容C1，電容C1具有 =一端及第二端，電容C1的第一端耦接至檢測電阻R1的第二端電 鲁=C1的，二端耦接至設定電阻R2的第二端。電容C1可用於電壓比較 器12的第輸入、及第一輸入端間的雜訊遽波器，同時也對輸入信號 轉態提供緩衝的效果。 —圖2為圖1所示定電流源I〗的一實施方式的電路圖。請參照圖 定電流源1,1包括參考電流源ηι以及電流鏡電路112。參考電流源⑴ =產生穩定的參考電流Ire卜電流鏡電路112触至參考電流源 ，用於根據參考電流Iref輸出定電流12。 在本實婦,丨巾，參考紐源lu包括參考賴源113以及轉換電 /、申參考電壓源U3用於產生穩定的參考電麼v ^，而轉換 =4用於將參考電㈣爾換為參考電流㈣電參考電壓^ 電阻奶以及並聯穩壓S TU。輸入電^ R3具有第一端及第 拖-9认電阻Μ的第一端搞接以接收直流電壓VCC。由於DC/DC轉 成触多個敎且具林同賴雜職流電源，例如 ϋ電路/Γ通Ϊ 24V/5A _電源’而過電流 南十對电源輸出線（如12V/1A)進行過電流檢測， 2^!?(如議伽可用來提供直流電壓Vcc。並聯穩壓器 等，陽梅嫂Λ ^ A、陰極端K及參考端R，可採用市售積體電路TL431 k A輕接至接地端，陰極端κ输至參考端r及輸人電阻⑹ 7 M383241 一端及第-踹Mi輸出t的參考電壓。轉換電阻R4且有第 鈿及弟—^，轉換電M4的第1耦接至陰極端K Vref，轉換電阻R4的第二雜 按以接收參考電壓 一鈿輸出參考電流Iref至電流鏡電路112。 〇2 t ’電流鏡電路112包括第一電晶體以、第二電晶體 第—電晶體集極端、基極端一及二端 至參考電流源111以接收參考電流一 ί-ί: 電曰體02的=。第—電晶體Q2具有集極端、基極端及射極端，第二 ，第二電晶體Q2的基極端祕至第 R5的第二山土極端。退化電阻肪具有第一端及第二端 ，退化電阻 I至第二射極端，退化電阻R5的第二端耦接至接地端。 诉1 =不^參考電流源111輸㈣參考電流1 ref直接作為定電流 來產^ ^疋電流12 ’而是彻電流鏡電路112複製參考電流Iref 第ΐΐ，12’這是為了利用電流鏡電路112中具有正溫度係數的 Q2來對具有負溫度係數的設定電阻R2進行溫度補償，使 上、=不^1卜界溫度變化的影響。下面將對此做進一步說明：當溫度 4 ¥ β.°又疋電阻似因為是負溫度係數元件，其電阻值r2會下降， a塑電【匕較^ 12的第二輸入端的電壓V2偏高，因此保護點受溫度 节^飄矛夕，但疋第一電晶體Q2因為是正溫度係數元件，其輸出電 ί V2的電流Ϊ 12會上升’因此可將電壓比較$ 12的第二輸入端的電 回正常，使保護點不受溫度的影響。另外，由於電壓V2會接 晶h，如果不加入退化電阻R5，則電壓V2將會全部由第二電 Q2承叉，造成第二電晶體Q2工作時會有溫度偏高的現象，因此 、退化電阻R5驗分擔電壓V2落在第二電晶體如的跨壓。 圖3為圖1所示電壓比較器12的一實施方式的電路圖。請參照圖 8 jj383241 3 ’電壓比較器12包括第一運算放大器0PA卜第二運算放大器〇pA2 以及齊納二極體ZDl。第一運算放大器opAi具有非反相輸入端、反相 輸入端及輸出端，第-運算放大器GPA1的非反相輸人端_至檢測電 阻R1，第二端，第一運算放大器〇PA1的反相輸入端耦接至設定電阻 R2的第=端。第二運算放大器〇PA2具有非反相輸入端、反相輸入端 及輸出第二運算放大器QPA2的非反相輸人雜接至參考電壓 yf ’第二運算放大器〇PA2的反相輸入端通過電阻肋耦接至第一運 算放大器0PA1的輸出端。齊納二極體ZD1具有陰極端及陽極端，齊納 二極體ZD\的陰極端耦接至第二運算放大器〇pA2的輸出端齊納二極 體ZD1的陽極端在檢測電阻R1的第二端的電壓Vl小於 的第二端的電壓V2時輸出錯誤信號Error。 本創作除了採用第—運算放大器_比較電壓比較器12的第一 3第二輸入端的電壓V2之外，還加人第：運算放大 〇。〇Pf將第一運鼻放大器_的比較結果進行反相，同時第 放大器0PA2舰供阻抗匹配的效果。在這裡，參 電壓源⑴所提供。另外，串接的齊納二極體观 ^到^ 面電路的電壓準位，而且除非第 :低傳达到後 確，否則㈣輸出的電壓足夠明 定俨樂Γ Γ 會進入崩潰區，如此將形同另一個準位判 疋私準，提尚抗雜訊能力。 干’ 阻R7 電的第二端她至第二運算放大器QPA2的輸出端。 :，的第，至接地端。 過RC時間常數提供信號轉態的緩衝效果 成RC 4波 ’不上所述’本創作因採収電流源輸出敎的定電流來設定保護 9 M383241 護點設定’其中定電流源還可採用電流鏡電路複製 數的生定電流，_電流鏡電路中具有正溫度係 不無外=慎有貞溫度錄的奴電崎行溫度補償而使保護點 二溫ί變化影響，另外電壓崎11還可_運算放大器及齊納 雖然本創作已以較佳實施例揭露如上，然其並非用於限定 ’任何熟習此技藝者，在不脫離本創作之精神和範_，當可作些 潤飾’因此本創作之保護範圍當視後附之申請專利範圍戶; 【圖式簡單說明】 圖1為依照本創作一較佳實施例的過電流檢測電路的電路圖。 圖2為圖1所示定電流源的一實施方式的電路圖。 圖3為圖1所示電壓比較器的一實施方式的電路圖。 【主要元件符號說明】 11 :定電流源 112 :電流鏡電路 12 :電壓比較器 20 :電源輸出線 22 :電源輸出線的輸出端 ΟΡΑ1 :第一運算放大器 Q1 :第一雙極性電晶體 1 :過電流檢測電路 111 :參考電流源 113 :參考電壓源 2 :直流至直流(dc/DC)轉換器 21 :電源輸出線的輸入端Xr2/rl), once the current value il is greater than the protection point, immediately outputs an error signal Error notification to the subsequent protection circuit to make appropriate protection. In the present embodiment, the overcurrent detecting circuit 1 further includes a capacitor C1 having a first end and a second end. The first end of the capacitor C1 is coupled to the second end of the detecting resistor R1. The two ends are coupled to the second end of the set resistor R2. Capacitor C1 can be used for the first input of voltage comparator 12 and the noise chopper between the first input, and also provides a buffering effect on the input signal transition. - Figure 2 is a circuit diagram of an embodiment of the constant current source I of Figure 1. Referring to the figure, the current source 1, 1 includes a reference current source ηι and a current mirror circuit 112. Reference Current Source (1) = Generate a stable reference current Ire The current mirror circuit 112 touches the reference current source for outputting the constant current 12 according to the reference current Iref. In this real woman, the towel, the reference source source lu includes the reference Lai source 113 and the conversion electric /, the reference voltage source U3 is used to generate a stable reference power v ^, and the conversion = 4 is used to convert the reference electric (four) For the reference current (four) electrical reference voltage ^ resistance milk and shunt regulator S TU. The input terminal ^R3 has a first end and a first end of the first-side -9 resistor Μ to receive the DC voltage VCC. Since the DC/DC is turned into a multi-turn and has a power supply with the same flow, such as ϋ circuit / Γ Ϊ 24V/5A _ power supply' and over current south ten pairs of power output lines (such as 12V/1A) Current detection, 2^!? (If the gamma can be used to provide DC voltage Vcc. Shunt regulator, etc., Yangmei 嫂Λ ^ A, cathode terminal K and reference terminal R, can be used as a commercial integrated circuit TL431 k A light Connected to the ground terminal, the cathode terminal κ is input to the reference terminal r and the input resistor (6) 7 M383241 one end and the first - 踹Mi output t reference voltage. The conversion resistor R4 has the third and the younger, ^, the first of the conversion M4 Coupling to the cathode terminal K Vref , the second impurity of the conversion resistor R4 receives the reference voltage - the output reference current Iref to the current mirror circuit 112. 〇 2 t 'the current mirror circuit 112 includes the first transistor, the second The crystal first-transistor sets the extreme, the base terminal one and the two ends to the reference current source 111 to receive the reference current, and the first transistor Q2 has a set terminal, a base terminal, and an emitter terminal. Second, the base of the second transistor Q2 is extremely secreted to the second mountain extreme of the R5. The degenerate resistor has a first end and a End, degenerate resistor I to the second emitter, the second end of the degeneration resistor R5 is coupled to the ground. ???1 = no reference current source 111 input (four) reference current 1 ref directly as a constant current to produce ^ ^ 疋 current 12 'Although the current mirror circuit 112 replicates the reference current Iref, ' 12' is to use the Q2 with a positive temperature coefficient in the current mirror circuit 112 to temperature compensate the set resistor R2 with a negative temperature coefficient, so that The effect of temperature change is not ^1. This will be further explained below: when the temperature is 4 ¥β.° and the resistance is similar because it is a negative temperature coefficient component, its resistance value r2 will decrease, a plastic electricity [匕^ The voltage V2 of the second input terminal of 12 is high, so the protection point is affected by the temperature node, but the first transistor Q2 is a positive temperature coefficient component, and the current Ϊ 12 of the output voltage ί V2 rises. The voltage is compared to the normal input of the second input terminal of $12, so that the protection point is not affected by the temperature. In addition, since the voltage V2 will be connected to the crystal h, if the degeneration resistor R5 is not added, the voltage V2 will be all the second electric Q2. Fork, resulting in the second transistor Q 2 There is a phenomenon that the temperature is high during operation. Therefore, the degeneration resistor R5 detects that the voltage V2 falls across the voltage across the second transistor. Fig. 3 is a circuit diagram of an embodiment of the voltage comparator 12 shown in Fig. 1. Referring to FIG. 8 jj383241 3 'The voltage comparator 12 includes a first operational amplifier 0PA, a second operational amplifier 〇pA2, and a Zener diode ZD1. The first operational amplifier opAi has a non-inverting input, an inverting input, and an output. The non-inverting input terminal of the first operational amplifier GPA1 is connected to the detection resistor R1, and the second terminal is coupled to the inverting input terminal of the set resistor R2. The second operational amplifier 〇PA2 has a non-inverting input terminal, an inverting input terminal, and a non-inverting input of the output second operational amplifier QPA2, which is connected to the reference voltage yf. The inverting input terminal of the second operational amplifier 〇PA2 passes through the resistor. The rib is coupled to the output of the first operational amplifier OPA1. The Zener diode ZD1 has a cathode end and an anode end, and the cathode end of the Zener diode ZD\ is coupled to the output terminal of the second operational amplifier 〇pA2 at the anode end of the Zener diode ZD1 at the detecting resistor R1 When the voltage V1 of the second terminal is smaller than the voltage V2 of the second terminal, an error signal Error is output. In addition to the voltage V2 of the first 3rd second input terminal of the first operational amplifier_comparison voltage comparator 12, the present invention adds a third operation amplification 〇. 〇Pf inverts the comparison result of the first nose amplifier _, while the first amplifier 0PA2 ship provides the effect of impedance matching. Here, the reference voltage source (1) is provided. In addition, the Zener diodes connected in series are connected to the voltage level of the circuit, and unless the first: low is communicated to the latter, the voltage of the output (4) is sufficient to determine that the music will enter the collapse zone. With another standard, it is judged to be private and to provide anti-noise ability. The second end of the R' resistor is blocked to the output of the second operational amplifier QPA2. :, the first, to the ground. The RC time constant provides the buffering effect of the signal transition state into the RC 4 wave 'not above'. This creation is set by the constant current of the output current source output. 9 M383241 Protection point setting 'The fixed current source can also use current Mirror circuit copy number of the set current, _ current mirror circuit has a positive temperature system is not without the outside = caution 贞 temperature recorded the slave electric wave temperature compensation and the protection point two temperature ί change, in addition, the voltage can also be 11 _Operational Amplifier and Zener Although the present invention has been disclosed above in the preferred embodiment, it is not intended to limit the 'anyone skilled in the art, without departing from the spirit and scope of this creation, when it can be retouched', therefore this creation The scope of protection is described in the attached patent application; [Schematic Description of the Drawings] FIG. 1 is a circuit diagram of an overcurrent detecting circuit in accordance with a preferred embodiment of the present invention. 2 is a circuit diagram of an embodiment of the constant current source of FIG. 1. 3 is a circuit diagram of an embodiment of the voltage comparator of FIG. 1. [Main component symbol description] 11 : Constant current source 112 : Current mirror circuit 12 : Voltage comparator 20 : Power output line 22 : Output end of power supply output line ΟΡΑ 1 : First operational amplifier Q1 : First bipolar transistor 1 : Overcurrent detection circuit 111: reference current source 113: reference voltage source 2: DC to DC converter (DC/DC) converter 21: input terminal of the power supply output line
Cl ' C2、C3 :電容 0ΡΑ2 :第二運算放大器 M383241 Q2 :第二雙極性電晶體 R2 :設定電阻 R4 :轉換電阻 R6、R7 :電阻 A :陽極端 R :參考端 II、11’ ：輸出電流Cl ' C2, C3 : Capacitance 0ΡΑ2 : Second operational amplifier M383241 Q2 : Second bipolar transistor R2 : Set resistor R4 : Conversion resistor R6, R7 : Resistor A : Anode R R: Reference terminal II, 11' : Output current
Iref :參考電流 V2 :設定電阻的第二端的電壓 R1:檢測電阻 R3 :輸入電阻 R5 :退化電阻 TL1 :並聯穩壓器 K :陰極端 ZD1 :齊納二極體 12 :定電流 VI :檢測電阻的第二端的電壓 Vi:電源輸出線的輸入端的電壓Iref : Reference current V2 : Set the voltage at the second end of the resistor R1 : Sense resistor R3 : Input resistor R5 : Degeneration resistor TL1 : Shunt regulator K : Cathode terminal ZD1 : Zener diode 12 : Constant current VI : Sense resistor Voltage at the second end Vi: voltage at the input of the power supply output line
Vo:電源輸出線的輸出端的電壓Vcc:直流電壓 Vref :參考電壓 Error :錯誤信號Vo: Voltage at the output of the power output line Vcc: DC voltage Vref : Reference voltage Error : Error signal