1、創(chuàng)新的節(jié)能技術(shù)(NCP4303)有關(guān)能效問(wèn)題Source: Energy Information Administration能源統(tǒng)計(jì)1990 2005Demandup +59%Productionup +40%更多電廠和更多污染能效: 采用高科技消耗更少的能源達(dá)到相同的任務(wù)節(jié)制: 改變生活方式用更少的能源:選擇?Source: Energy Star全球能效標(biāo)準(zhǔn)China CNIS,China CSC (ex-CECP)Japan Top RunnerJapanEco MarkAustralian Greenhouse OfficeCalifornia EnergyCommissionEur

2、opeCode of Conduct,EuP Ecodesign,Eco-LabelENERGY STARKorea e-StandbyCanada OE, CE, & more Europe: Code of Conduct EuP Ecodesign,Eco-LabelUS ENERGY STAR OE, EPS CA Energy Commission South Korea EPS Japan China CNIS OE EPS Taiwan OE Australia OE, CE, EPS New Zealand OE, CE EPS: External Power Supplies

3、OE: Office EquipmentCE: Consumer Electronics不同功率的拓?fù)浣Y(jié)構(gòu)Increasing Power Levelsforwardflyback2-transistor forwardLLC HB resonant topology擁有豐富的產(chǎn)品軟開(kāi)關(guān)拓?fù)浞独?）準(zhǔn)諧振MOSFET turns on when VDS(t) reaches its minimum value.Minimizes switching lossesImproves the EMI signatureMOSFET turns on in first valleyMOSFET tu

4、rns on in second valleyvalley軟開(kāi)關(guān)拓?fù)浞独?）正激有源鉗位Active clamp forward topology operationSwitching losses (turn-on)Valley Switching to reduce switching lossesSeries Resonant LLC Half BridgeSwitching losses = 0 ZVSLmagLrCrBFlux Density (T)HMagnetic FieldStrength (A.t/m) BFlux Density (T)HMagnetic FieldStr

5、ength (A.t/m)Better utilization of magnetics軟開(kāi)關(guān)拓?fù)浞独?）半橋諧振半橋諧振的優(yōu)點(diǎn)Series type of resonant converter that allows operation over relatively wide input voltage and output load rangesLimited number of components: resonant tank can be partially or fully integrated into main transformerZero Voltage Switchi

6、ng (ZVS) condition for the primary switches under all load conditionsZero Current Switching (ZCS) for secondary rectifier under all load conditionsSimple synchronous rectification (SR) implementation性?xún)r(jià)比高，高效且低EMI同步整流基本原理Sprim VDRV(t)Ssync Vsync(t)負(fù)載tdelay輸出電容(Cout)Ssync體二極管(Body diode)MOSFET通道Sprim開(kāi)關(guān)

7、電源次級(jí)端同步整流(SR)原理及NCP4303 SR驅(qū)動(dòng)器應(yīng)用設(shè)計(jì)The NCP4303 is a versatile full featured controller and drive for synchronous rectification in switch mode power supplies with high efficiency requirements.Externally adjustable min. on and min. off timesLow turn off delay and high sink currentTrue secondary zero cur

8、rent detectionFights ringing and dropouts induced by PCBExcellent use of switching cycle for high efficiencyWide Vcc range up to 30 V allows use with 24V outputs40ns turn off delay from current sense input to driverInterface to external signal for CCM modeTrigger input to enter standby, low consumpt

9、ion mode5 A / 2.5 A peak sink / source drive capabilityParasitic Induction Compensation500 kHz maximum operating frequency Notebook AdaptersHigh Power AC/DC AdaptersUltra Slim Flat TVGaming ConsolesATX power suppliesNCP4303A/B 次級(jí)端同步整流驅(qū)動(dòng)器NCP4303ADR2G, NCP4303BDR2GSOIC-8Diver Clamp Voltage: A = 12 V,

10、B = 6 V電源段選擇 應(yīng)用同步整流(SR)的理?yè)?jù)高于特定輸出功率時(shí)，同步整流能夠大幅提升能效計(jì)算出來(lái)的1個(gè)肖特基二極管的損耗計(jì)算出來(lái)的1個(gè)同步整流MOSFET(含驅(qū)動(dòng))的損耗輸出功率的1.4 %(注1)輸出功率的2.17 %(注1)輸出功率的2.33 %(注1)此時(shí)應(yīng)當(dāng)關(guān)閉同步整流注1：計(jì)算針對(duì)的是2個(gè)SR整流器- 支持在連續(xù)導(dǎo)電模式(CCM)和不連續(xù)導(dǎo)電模式(DCM)應(yīng)用中工作- 真正的次級(jí)零電流檢測(cè)(ZCD)，帶可調(diào)節(jié)閾值- 自動(dòng)寄生電感補(bǔ)償- 從電流感測(cè)(CS)電阻到驅(qū)動(dòng)器有40 ns的關(guān)閉延遲- 在CCM模式下提供至外部信號(hào)的接口- 以觸發(fā)器輸入進(jìn)入待機(jī)模式- 可調(diào)節(jié)最小導(dǎo)通時(shí)間，

11、與Vcc電平無(wú)關(guān)- 可調(diào)節(jié)最小關(guān)閉時(shí)間，與Vcc電平無(wú)關(guān)- 5 A / 2.5 A峰值電流驅(qū)動(dòng)能力- 電壓范圍高達(dá)30 V12 V或6 V的門(mén)驅(qū)動(dòng)鉗位電壓- 低啟動(dòng)電流消耗和低待機(jī)電流消耗- 最大工作頻率可達(dá)500 kHzNCP4303同步整流控制器關(guān)鍵持性NCP4303引腳功能說(shuō)明引腳編號(hào)引腳名稱(chēng)功能引腳功能說(shuō)明1VccSupplies the driverVcc supply terminal of the controller. 2Min_toffMinimum off time adjustAdjust the minimum off time 3Min_tonMinimum on t

12、ime adjustAdjust the minimum on time 4TRIG/DisableForced reset inputThis input turns off the SR MOSFET. Activates sleep mode if pulled up for more than 100 us.5CSCurrent sense of the SR MOSFETThis pin detects if the current flows through the SR MOSFET and/or its body diode. Resistor in series with t

13、his pin adjusts the turn-off current level threshold.6COMPIC analog groundUse as a Kelvin connection to auxiliary compensation inductance. If SR MOSFET package parasitic inductance compensation is not use, connect this pin to GND.7GNDIC groundGround connection for the SR MOSFET driver and Vcc decoup

14、ling capacitor. Connection ground for minimum ton, toff adjust resistors and trigger input 8DRVGate driver outputDriver output for the SR MOSFET. NCP4303: 器件框圖及關(guān)鍵功能說(shuō)明最小導(dǎo)通(ON)和關(guān)閉(OFF)時(shí)間調(diào)節(jié)精確的零電流檢測(cè)，帶可調(diào)節(jié)閾值自動(dòng)寄生電感補(bǔ)償在CCM模式下提供至外部信號(hào)的接口或關(guān)閉工作NCP4303: 應(yīng)用NCP4303能用于連續(xù)導(dǎo)電模式(CCM)、不連續(xù)導(dǎo)電模式(DCM)、準(zhǔn)諧振(QR)模式，及反激、正激和其它拓?fù)浣Y(jié)構(gòu)

15、。以PCB走線搭接(trace strap)創(chuàng)建補(bǔ)償電感最小導(dǎo)通/關(guān)閉時(shí)間調(diào)節(jié)NCP4303: 應(yīng)用NCP4303: 應(yīng)用源自初級(jí)端驅(qū)動(dòng)器的觸發(fā)器信號(hào)需要最小導(dǎo)通/關(guān)閉時(shí)間會(huì)導(dǎo)致控制器關(guān)閉會(huì)導(dǎo)通控制器導(dǎo)通NCP4303可編程最小導(dǎo)通及關(guān)閉時(shí)間功能提供消隱特性(blanking)，防止 振鈴期間開(kāi)關(guān)MOSFET漏極振鈴會(huì)導(dǎo)致同步整流控制器出現(xiàn)不需要的開(kāi)關(guān)典型MOSFET開(kāi)關(guān)特性最小導(dǎo)通/關(guān)閉時(shí)間計(jì)算在出現(xiàn)最小導(dǎo)通時(shí)間和/或最小關(guān)閉時(shí)間偶然對(duì)地短路的情況下，絕對(duì)最小導(dǎo)電時(shí)間時(shí)長(zhǎng)內(nèi)部鉗位為300 ns，最小關(guān)閉時(shí)間時(shí)長(zhǎng)內(nèi)部鉗位為620 ns最大關(guān)閉時(shí)間和最大導(dǎo)通時(shí)間為4.8 sTon_min = 1

16、00*10-12 *RT_on_min Toff_min = 100*10-12 *RT_off_min NCP4303零電流檢測(cè)(ZCD)1) 次級(jí)電壓繞組反相。二極管D1導(dǎo)電，MOSFET M1的漏電壓降至-1 V2) SYNC/CS引腳輸出100 A電流，這電流在Rshift_cs電阻兩端產(chǎn)生電壓導(dǎo)通/關(guān)閉閾值可調(diào)節(jié)3) SYNC/CS引腳上的電壓低于 Vth_cs時(shí)，DRV導(dǎo)通4) 電流降低時(shí)，漏電壓增加到高于Vth_cs閾值，MOSFET關(guān)閉- 1V +Vcs Vth_csVcs 能效降低頻率或dIsec(t)/dt越高，能效下降得越多寄生電感效應(yīng)使用了極低導(dǎo)通阻抗(Rds_on)的

17、MOSFET時(shí)，這個(gè)問(wèn)題變得很?chē)?yán)重Vth_zcd= 0 mV的SR控制器Vth_zcd= -5 mV的SR控制器ZCD閾值電壓為0 mV的SR控制器為SR MOSFET提供更長(zhǎng)的導(dǎo)電周期NCP4303寄生電感補(bǔ)償特意在電路板上增加補(bǔ)償電感， Lcomp = Ldrain + Lsource兩個(gè)感測(cè)端子產(chǎn)生補(bǔ)償電壓，調(diào)整電流感測(cè)比較器的閾值電壓在Lcomp=Ldrain+Lsource(易于確保能夠極佳地再現(xiàn))的情況下，SR MOSFET封裝的寄生電感得到完全補(bǔ)償，系統(tǒng)能夠僅根據(jù)SR MOSFET導(dǎo)通阻抗，精確地檢測(cè)次級(jí)電流此ZCD系統(tǒng)不會(huì)隨著di(t)/dt變化而變化如果忽略Lcomp，此ZC

18、D系統(tǒng)完全兼容于當(dāng)今的ZCD系統(tǒng)。COMP和GND引腳需要短路，且IC的GND引腳必須直接連接至SR MOSFET源極NCP4303寄生電感補(bǔ)償能在電路板上或使用線搭接(wire strap)提供補(bǔ)償電感SR MOSFET門(mén)電壓次級(jí)電流由于采用了專(zhuān)利的NCP4303寄生電感補(bǔ)償技術(shù)，導(dǎo)電周期延至最長(zhǎng)NCP4303寄生電感補(bǔ)償采用寄生電感補(bǔ)償時(shí)能效提高已補(bǔ)償 = 使用了寄生電感補(bǔ)償；未補(bǔ)償 = 未使用寄生電感補(bǔ)償12 V / 20 A LLC應(yīng)用MOSFET器件B在滿(mǎn)載VDCin=350 V、未使用補(bǔ)償時(shí)的波形Ch1- Gate Q6 (DRV IC2)Ch2- Gate Q1 (DRV IC1

19、)Ch3- Current in Drain Q6Ch4- Current in Drain Q1由于未補(bǔ)償TO220封裝寄生電感，驅(qū)動(dòng)器在初期關(guān)閉。FET B由于導(dǎo)通阻抗更低、寄生電感有更大影響，情況更糟糕。Ch1- Gate Q6 (DRV IC2)Ch2- Gate Q1 (DRV IC1)Ch3- Current in Drain Q6Ch4- Current in Drain Q1驅(qū)動(dòng)器差不多在零電流時(shí)關(guān)閉 = 能效提升至最高。MOSFET器件B在滿(mǎn)載VDCin=350 V、使用了補(bǔ)償時(shí)的波形NCP4303觸發(fā)器輸入兩種潛在應(yīng)用：在輕載期間，同步整流的能效可能比傳統(tǒng)整流方法低，因?yàn)镸

20、OSFET壓降減小提供的導(dǎo)電損耗優(yōu)勢(shì)被開(kāi)關(guān)損耗所抵消，開(kāi)關(guān)頻率在輕載時(shí)增加的HB LLC拓?fù)浣Y(jié)構(gòu)猶為如此。2) 輕載條件下關(guān)閉1) CCM應(yīng)用中的初級(jí)端關(guān)閉控制NCP4303在CCM應(yīng)用中觸發(fā)觸發(fā)器在從最小關(guān)閉時(shí)間的末期到最小導(dǎo)通時(shí)間的末期之間消隱，目的有兩個(gè)：抑制輸入噪聲，避免開(kāi)關(guān)電源布線中的寄生振鈴半橋(HB)和HB LLC應(yīng)用中，在同步脈沖太寬、每個(gè)開(kāi)關(guān)周期出現(xiàn)兩次時(shí)，避免門(mén)驅(qū)動(dòng)器錯(cuò)誤關(guān)閉 TRIG信號(hào)的上升沿觸發(fā)驅(qū)動(dòng)關(guān)閉 從觸發(fā)器到驅(qū)動(dòng)輸出的傳播延遲為12 ns (典型值)NCP4303休眠模式 當(dāng)Trig/Disable拉至高于1.5 V電平時(shí),驅(qū)動(dòng)器關(guān)閉 如果TRIA維持高電平的時(shí)

21、間超過(guò)100 s，NCP4303進(jìn)入休眠模式- 電流消耗降低至390 A TRIG信號(hào)釋放時(shí)，NCP4303在500 ns內(nèi)恢復(fù)工作NCP4303休眠模式Trig/disable輸入的工作波形 器件休眠模式過(guò)渡Trig/disable輸入的工作波形 器件喚醒過(guò)渡簡(jiǎn)單及無(wú)噪聲的導(dǎo)通/關(guān)閉控制驅(qū)動(dòng)器鉗位選擇某些SR MOSFET提供低通道阻抗以降低門(mén)電壓，從而提供較低門(mén)電壓鉗位的優(yōu)勢(shì)其它SR MOSFET要求較高的門(mén)電壓NCP4303提供兩種門(mén)鉗位電壓：6 V (B版本)和12 V (版本)某SR MOSFET的理論損耗為輸出電流的函數(shù)評(píng)估板 240 W - 12 V, 20 A 雙電感加單電容(LLC)拓?fù)浣Y(jié)構(gòu) 旨在用于ATX電源或一體機(jī)應(yīng)